Final Report Summary - HIRF SE (HIRF Synthetic Environment)
Executive Summary:
Before air vehicles (aircrafts and rotorcrafts) can fly, International Certification Authorities (FAA for United States and EASA for Europe are the most influential worldwide) must be assured that:
- Equipment and subsystems are not affected by mutual electromagnetic interactions
- Subsystems/systems can correctly operate when subjected to external electromagnetic disturbances.
It is common practice to demonstrate by testing air vehicle robustness against catastrophic effects induced by electromagnetic disturbances.
The current air vehicle lifecycle foresees the experimental verification at the end of the development phase when the air vehicles are already built and just before their release to the market: this means that it is possible to detect susceptibilities that correspond to weakness in the electromagnetic design only during the certification phases. Rework costs are very high and even the time to market increases considerably once design needs to be reviewed.
In the new and future generations of air vehicles (fly by wire and even fly by wireless) the increasing number of functions with catastrophic effect makes the time required for testing grow exponentially and in the meanwhile high speed electronic equipments poses serious problems to air vehicle safety verification due to EM hazard.
Moreover the electromagnetic environment is characterized by a proliferation of emitters that will bring to higher costs for instrumentation to carry out testing to comply with Certification Regulation demand.
In this scenario the HIRF SE framework has reached an adequate level of maturity to cope with the needs of air vehicle development from design to certification phases and in particular it can be applied to:
- Optimize the global design of air vehicles minimizing the rework activities
- Maintain the duration of certification testing within a reasonable timeframe
- Maintain the costs associated to testing “under control”
- Take into account the in flight conditions that are not possible to be represented during ground testing.
- Maintain or improve the current safety level of air vehicles
Project Context and Objectives:
The HIRF SE framework is an electromagnetic analysis tool operating in the HIRF radio frequency range 10 kHz – 40 GHz. The framework has the capabilities to simulate the air vehicle interaction with both far-field and near-field sources having any polarization and position in the presence or not of the ground. Also HIRF SE is able to predict both the EM field distribution inside the airframe and the induced voltages and currents in the wiring system. The broadband EM perturbations can be simulated according to the following classification:
- External environment (i.e. radars, radio and television broadcast emitters).
- Internal environment (i.e. EM constraints in terms of EM fields and current on cables that air vehicle electronic installation will encounter due to external EM fields or internal emitter devices such as PEDs or WPEDs).
Three different EM sources can be distinguished and these are identified as threats:
- External EM threat (generated, for instance, by airport and radio-television emitters);
- Surface EM threat (generated by on-board emitters);
- Internal EM threat (generated by PED or WPED).
The aforementioned threats are the input of the transfer functions that HIRF SE can compute in the 10 kHz-40 GHz frequency range.
During the project different simulation approaches have been classified and analyzed with respect to a Low Frequency Band (LFB) scenario and a High Frequency Band (HFB) scenario.
- The LFB scenario extends from 10 kHz to 3 GHz. It relies on the use of 3D full wave solvers for calculating both external and internal environments of air vehicles and the use of Multiconductor Transmission Line models for the calculating the response of cable bundles under tests up to 400 MHz. The process for linking the two types of data is based on the field-to-transmission line approach but this process still requires extensive thin wire modeling in the 3D model in order to describe correctly the inner field environment.
- The HFB scenario extends from 3GHz to 40 GHz. It relies on asymptotic 3D solvers for calculating external fields at the level of points of entry of energy inside the air vehicle. The internal response is calculated with so called Power Balance tools making the assumption that the internal field environment can be considered as random.
In addition to those main computer modules, specific sub-modules have been developed in order to bring the EM physics required by HIRF modeling. Among them, material models have been extensively studied in order to be introduced as macro models in 3D computer solvers.
The HIRF SE framework uses the AMELET format in order to standardize the flux of data of the various computer models involved in the LFB and HFB scenarios.
Potential susceptibilities (or the identification of frequency ranges without susceptibilities) can be identified using the HIRF SE framework:
1. Define the environmental level using HIRF SE to compute the EM environment caused by an external or on-board source and surrounding the equipment; The electromagnetic field around equipment is computed in the frequency range 100MHz-40GHz and the coupled currents flowing into equipment connectors are computed in the frequency range 10KHz-400MHz
2. Define the susceptibility margin comparing the computed environmental level with the equipment qualification level (100MHz-18GHz/40GHz) or system test level (10KHz-400MHz)
3. Assessment of Potential Susceptibility:
- For all the frequencies in which the Susceptibility Margin is lower or equal to zero there is a potential susceptibility that need to be investigate by testing;
- For all the frequencies in which the Susceptibility Margin is higher than zero it has been computed a minimum level (in terms of current or EM field) of no susceptibility.
The correct operation of the framework has been verified and validated by comparison with data from real testing on small and medium air vehicles and pre-existing data for large air vehicles.
All the tools that have been integrated inside the HIRF SE framework have been assessed through comparisons with measurement results.
Validation processes followed a gradual approach in term of complexity in order to insure to have the control of the geometrical configuration while carrying out the validation of the tools that have been plugged inside the framework. In particular two main levels of validations have been established
1. On “Simple” and geometrical controlled test cases:
- The goal is to verify that the numerical models correctly compute Maxwell’s Equations
- Tools that passed this level are assessed for air vehicle design applications and can be proposed to the second level of assessment
2. On Air vehicles
- The goal is to verify that the air vehicles are correctly represented by their “electromagnetic synthetic model”, to give guidelines for the modelling and to start to build a database for Coupling Cross Section, point of absorption, point of entrance and point of bonding
- Tools that passed this level can be proposed for air vehicle simulation for certification purposes
In the first level of validation, the test cases are classified in three different categories, corresponding to increasing complexity of the test object and each test case correspond to a HW test case that is used for generating experimental data to be compared with the results of the numerical simulation for assessment and validation of the relevant models, sub-modules and modules.
For the validation process at air vehicle level, the reference data for the comparison were the results of dedicated measurement campaign on small and medium air vehicles and in particular:
- Medium air vehicles: Dassault F7X, EADS-CASA C-295;
- Small air vehicles: Piaggio P180 (Fig.6) PZL M28, Evektor EV55 and Cobra 100, Inta Siva;
- Rotorcraft: Agusta AW139, Eurocopter EC135, EC145.
For the large air vehicles measurement campaign carried out before the starting of the project on BAE System Nimrod MRA4 was used as references.
The common practice, as indicated by Advisory Circular AC-20158 and applicable standard ED107/A-July 2010, for certification of air vehicles can be summarized in three steps:
- Step 1: the air vehicle is exposed to an external Low Level HIRF environment.
- Step 2: evaluation of the internal environment around the equipment in terms of interface currents and in terms of electric field.
- Step 3: the internal environment values are compared with the equipment qualification/system integration results in order to verify compliance with HIRF certification requirements.
It is important to point out that:
1. The second step is normally achieved by means of measurements.
2. The requirement for the air vehicles testing is for free field illumination (as close as possible).
3. The test set-up may influence the illumination:
- The plane-wave is a theoretical concept which does not exist in laboratory,
- A ground plane is always in some vicinity of the air vehicle under test,
- Laboratory illumination is not representative of the operative conditions.
4.The amount of measurements typically achievable ranges between 100 and 1000. These figures might seem small in comparison of the actual complexity of critical systems.
The use of the HIRF SE framework for design and certification purposes and the advantages have been presented and discussed, along the project, with the European certification body EASA. In particular the following points were defined as crucial for future certification roadmaps that will adopt numerical approaches:
- The electromagnetic models of air vehicles are fundamental for the reliability of results
- The electromagnetic models need to be validated against measurement
- An amount of testing will be defined and carried out to validate and calibrate the A/V electromagnetic models
- Once the A/V models will have been validated the rest of the certification campaign can be completed by simulation
With the development of HW architecture and of more efficient codes and algorithms, analysis and simulation are now affordable solutions for solving EMC problems in aeronautic and numerical modelling technique represent the most cost effectiveness approach for HIRF /EMC issues.
The aid of modelling and simulation will reduce the delivery timescales of future air vehicle and systems and simulation can embrace more complex situations than measurement raising to a higher level air vehicle safety.
In this context the HIRF SE Framework is an innovative, collaborative and integrated methodology that allows solving EMC problem from CAD to analysis results in the frequency range from 10 kHz up to 40 GHz and can be applied during early design and certification phases of air vehicle lifecycle.
Project Results:
Before the HIRF SE project took place different software and methodologies for simulation approaches were available but they were not able to deal with the level of complexity required to cope with HIRF/EMC problems of interest for the Aeronautic Industries. All these computational tools were sparse and there were not any integrated solution to face in a whole the wide frequency band of interest (10 KHz – 40 GHz) and to compute the different kinds of required observables (internal environment in term of electromagnetic field and in term of coupled currents).
Moreover general guidelines for the electromagnetic modelling of complex and new generation air vehicles were not established in a standardized way and were not always supported by a rigorous scientific approach.
HIRF SE is a numerical platform for virtual HIRF assessment on air vehicles, in the frequency range 10 KHz-40 GHz capable to deal with:
- The increased use of composite materials and structures
- The complete external and internal electromagnetic environment of an air vehicle
- The complexity of the on-board wiring system
- The uncertainties in the real installation configuration
The computational tools constituting HIRF SE have been assessed, along with the project, applying validation methodologies based on massive analysis of the comparison between measured and simulated data. For this reason a validation methodology (based on different levels of assessment) has been established and a database of benchmark test cases have been put available for the EM community for future development and validation of numerical codes.
The wide amount of data available, both from simulation and measurement, made possible to provide general guidelines for electromagnetic modelling of real scale complex and new generation aircraft and rotorcraft. In particular the following aspects were taken into account:
- Selection of the proper modelling tool to be applied in a specific configuration taking into consideration frequency range, air vehicle size and characteristics, observables, available computational resources
- Selection of the proper type of model to be used for wire modelling
- Selection of the proper type of model to be applied for a specific air vehicle configuration in term of material
- Sensitivity analysis setting the values of parameters that simulate bonding and loads
- Sensitivity analysis of the geometrical configuration defining the level of details that need to be simulated
Aeronautic industry has now available the proper mean to cope with real air vehicle complexity in terms of structures (both material and geometrical configuration) and wiring system (taking into account equipment loads, scattering effect and connectors) in the wide frequency band required by design and certification phases.
In this chapter, a detailed description of the main scientific achievements reached by the project is given. The scientific achievements are grouped and identified as follows:
- The framework: an integrated and modular solution for solving electromagnetic problems on complex test objects
- Complexity of air vehicles in terms of real installation configuration and material used by the modern aeronautic industry
- Simulation of EM coupling on on-board systems applying HIRF SE scenarios
- Module validation processes based on the comparison between measurement and simulation campaigns
1.3.1 The Framework: an integrated and modular solution for solving electromagnetic problems on complex test object
1.3.1.1 Aims of HIRF-SE framework
From a software point of view, the HIRF-SE project aims at implementing the two certification scenarios. These scenarios are represented on the two sketches below:
Low frequency Band scenario High frequency Band scenario
The LFB and HFB scenario have to be implemented inside a unified framework (HIRF-SE Framework)
• Allowing to use all simulation modules provided by consortium members
• Bringing some specific capabilities required by certification issues (information traceability, …)
1.3.1.2 HIRF-SE project – Software main outcomes
1.3.1.2.1 AMELET-HDF Format
HIRF-SE project allows the definition of a format to describe an electromagnetic simulation bringing the capability to exchange full simulation composed of geometric models, EM models, Output requests... AMELET-HDF format is:
• Open and fully specified format. A forum for AMELET-HDF Evolution management is available at http://code.google.com/p/amelet-hdf/downloads/list;
• Suited to manage highly volumetric simulation. It is built on top of HDF5 technology, and has been designed to be compact;
• Available documentation and code snippets. A set of tutorials and implementation of samples of code for AMELET-HDF are available at http://code.google.com/p/amelet-hdf.
1.3.1.2.2 HIRF-SE FrameWork
1.3.1.2.2.1 CuToo platform
The CuToo platform is the tools integration layers of the HIRF-SE framework. It offers the following capabilities:
- Collaboration: Multi users, user groups, Messaging, IM, Rights, Workflow
- Project Management: dedicated Workspaces, data validation
- Object Management (Business Entities):
- History: Ability to have the list of all actions (creation, copy, modifications, …) made by users on each object
- Versioning: Process of assigning either unique version names or unique version numbers to unique states of an object (model, …) or a set of objects (simulation, project, …) and Revision control allows keeping track of different incremented versions
- Traceability: Ability to have a full traceability of the creation process of an object, check the consistency of all these objects (Warning if an object involved in the process has been modified) and capability to Lock all objects and simulations involved in the process of production of a validated result
- Modules Management:
- Capabitility to manage at the same time several versions of a module in the platform with identification of each version of the module and its related integration software components and several implementation of the same module for different OS
- Identification of the version of the module used for a simulation
- Capability to run again all simulations in the same conditions
- Simulation Management:
- Several simulation processes: Queue management of simulations, Load balancing between several hardware resources and Parametric studies:
- Generic Capability that can be used for all modules and all parameters of objects as inputs of Simulations.
- Takes in charge parametric variation of parameters of simulations, Attributes of objects used in a simulation (conductivity of materials, …)
- Objects in the simulation
- Several graphics or computing resources: Local or remote resources, Native management of optimized 2D/3D remote display of interactive module, submission of jobs on supercomputers (schedulers interface)
1.3.1.2.2.2 SDK and Procedure of module integration
- Integration process of modules inside the framework
• Test driven Process
o inspired by the test driven development methodology (TDD)
o Formalized by a set of Integration Test Case (ITC)
• Does not require any modification in the module (Non intrusive)
• Requires implementation of 2 software components in a dedicated Software Development Kit (SDK)
o A wrapper to adapt native input and output of the module the AMELET-HDF format
o A File dedicated to specify the behaviour of the framework’s GUI regarding the integrated module
- More than 50 modules have been plugged inside the platform:
• Interactive modules (2D and 3D) for pre and post processing
• Batch sequential and massively parallel modules
1.3.1.2.3 A set modules allowing to implement LFB and HFB scenarios
The Tools and Softwares components involved in simulation at aircraft level are listed hereafter. Patners that provide these tools are integrated between brackets.
- The platform: CuToo (AXS)
- 3D Preprocessing: General: GiD (CIMNE); FDTD: NASH (AXS) MoM: AEMMesher (IDS-IT), PRE-CONCEPT (TUHH)
- Wiring Preprocessing: CableSim (AXS) ; CRIPTE Edit (ONERA)
- Postprocessing: Post 2D/batch UPC-POST (UPC); 1D, 2D; 3D data viewers: GiD (CIMNE), Paraview (Open)
- Material solvers: MMT (URM), EI (POLITO) - Vector fitting
- 3D FW solvers: UGR-FDTD (UGR), IDSMMMP (IDS-IT), CONCEPT-II (TUHH), MWS (CST), HY3D (BAES)
- MTLN solver: CRIPTE (ONERA)
- 3D Asymptotic solver: SE-RAY (OKTAL-SE)
- Power Balance tools: PWB (ONERA), IDS-OCT (IDS-IT)
1.3.1.2.4 Documentation
The HIRF-SE Framework is fully documented and it is composed of The following documents:
A set of tutorials to give cross-Modules support for LFB and HFB scenarios for LFB scenario (FWTD, FWFD, MTLN) and HFB scenario (Rays, PWB).
1.3.1.2.5 HW infrastructure / Cloud computing
- Very high flexibility for the deployment on HW infrastructure and Operating systems
- From All in one HW architecture …
• Platform and modules installed on the same computer
- … To Cloud Computing capabitilies
• All graphics and computing resources can be remote
• No HW requirement on the user's computer
1.3.2 Complexity of air vehicles in terms of real installation configuration and material used by the modern aeronautic industry
HIRF SE has the main scope of providing a complex electromagnetic computational framework aimed at the modelling of complex air vehicles (AV) as well as next generations of full composite aircraft and rotorcraft. HIRF SE framework includes different computation tools enabling the simulation of the complex 3D external geometry of the AV, the internal configuration including equipment, apertures, seams and slot, furniture and equipment, wiring system, bonding and grounding, considering incident EM field having any polarization and incidence in the frequency range from 10 kHz up to 40 GHz. Observables are the internal and external EM environment, the induced currents on the cable system, AV transfer function. All different types of composite or advanced materials on the AV are modelled by means of effective material approaches. This represents a real innovation since it enables the application of HIRF SE to any modern or next AV generation. Figure 1.3.2.1 shows an overview of the HIRF SE Framework, which is based on a fully parallel architecture, and contains computational modules for pre-processing and meshing of AV, EM field calculation of internal and external environment, cable network modelling and induced effects calculation, post-processing.
In the following the main scientific and technical innovation brought by HIRF SE are summarized.
Material Modelling Tool (MMT-URM)
MMT-URM is a computation tool aimed at the modelling of all different types of materials on an AV by means of effective electrical parameters. Figure 1.3.2.2 shows an overview of all types of different materials simulated by MMT.
Figure 1.3.2.1: Overview of the HIRF SE Framework fully parallel architecture and computational modules
Figure 1.3.2.2: Overview of all types of different materials simulated by MMT
Laminated panels of carbon fiber composites, with or without protective mesh, are modeled by means of effective single-layer panels and simulated in full wave numerical calculation tools by means of effective impedance boundary conditions. All models have been validated through an extensive validation campaign. As an example, Figure 1.3.2.3 demonstrates that the new model of a woven carbon fiber composite allows accurate prediction of the experimentally measured shielding effectiveness in a wide frequency range, whereas previous models available in the literature are limited to 1 GHz.
Figure 1.3.2.3: Progress made in HIRF-SE compared to state of the art (woven carbon fiber composite)
3D calculation: Full Wave Time-domain tools
Different time-domain tools have been implemented and validated in HIRF SE, based on different meshing scheme and resolution algorithms. Two different groups of time-domain tools have been developed:
o Applied/Validated at A/V level: UGRFDTD (UGR), MWS-TD (CST), HY3D (BAES)
o Validated at sub-system level: Quick Wave (QWED), TDFE(BUT), IFS (UoN)
The main features included in these tools are:
- Material models provided by Material Modelling Tool (MMT-URM)
- Sub-cell model for EM field penetration through laminated composites, sandwich panels, etc.
- Slot / aperture models
- Thin wire models
- E fields on central paths to feed Transmission Line models for network analysis
- Parallelization
Table 1.3.2.1 provides an overview of the tool capabilities as integrated in HIRF SE.
Table 1.3.2.2: 3D FWFD capabilities as integrated in HIRF SE
3D calculation: Full Wave Frequency-domain tools
Four frequency-domain tools have been implemented and validated in HIRF SE, based on different meshing schemes and resolution algorithms. Two different groups of frequency-domain tools have been developed:
o Applied/Validated at A/V level: IDSMMMP (IDS), CONCEPTII (TUHH)
o Validated at sub-system level: MDD (Polito), AD (TAS)
The main features included in these tools are:
- Material models provided by Material Modelling Tool (MMT-URM)
- Sub-cell model for EM field penetration through laminated composites, sandwich panels, etc.
- Slot/aperture/seams models
- Thin wire models
- Fast Multipole Method and Multilevel methods
- E fields on central paths to feed Transmission Line models for network analysis
- Low frequency stability
- Parallelization
Table 1.3.2.2 provides an overview of the 3D tool capabilities as integrated in HIRF SE.
Table 1.3.2.2: 3D FWFD capabilities as integrated in HIRF SE
3D calculation: High-frequency tools – External EM environment
Asymptotic solvers have been developed for the 3D calculation of the external EM environment in the GHz frequency-range. Two different tools have been developed:
o Applied/Validated at A/V level: SE-RAY-EM (OKTAL-SE)
o Validated at generic object level: RayTracing (UoM)
The main features are:
o Computation of EM fields on external POEs on A/V
o Materials
o Link with power-balance tools for the prediction of the internal EM environment.
Power balance tools – External EM environment
Power balance solvers have been developed for the calculation of the internal EM environment in the GHz frequency-range. Two different tools have been developed, both validated at AV level: IDS-OCT (IDS), PWB (ONERA).
The main features are:
o Large A/C
o Materials, dissipative mechanisms
o Apertures, slots
o Statistical model of EM environment even applicable in non-fully reverberating environment
o Data-base with elementary models
Cable network tools
This group of tools enables the full simulation of the complex wiring system aboard an AV, including the prediction of the induced currents at the cable ends. The main features implemented are:
o Cable and cable bundle p.u.l. parameters (ALEACAB-ONERA, CANCAN-PRZ, CABLESIM)
o Cable shield transfer impedance (BEATRICS-NLR, ERMES-CIMNE): both numerical and analytical models are implemented
o EM field coupling by Agrawal model and network analysis (CRIPTE-ONERA). The preprocessing and topological model of the complex network is performed on the basis of the AV mesh model using the module CABLESIM (AXESIM)
o Equipment modeling by Thevenin/Norton circuits and connectors (IMEA-THC, EI-Polito).
All tools and computational modules have been validated by comparison with experimental test results, considering test cases of increasing complexity at laboratory level and finally at AV level.
In conclusion, general guidelines have been provided for the use of the different tools of HIRF SE framework in different frequency ranges and with respect to the different HIRF testing configurations, as sketched in Figure 1.3.2.4.
Figure 1.3.2.4: HIRF-SE tool classification with respect to HIRF frequency randge
1.3.3 Simulation of EM coupling on on-board systems applying HIRF SE scenarios
Scenario descriptions:
Figure 1 and Figure 2 represent both LFB and HFB scenarios, identifying the modules/submodules with their outputs, - the links existing between the modules, the output data available as HIRF observables.
Both scenarios are based on a topological decomposition of the problems in which specific volumes are identified. In particular, the external skin of the object under test separates two domains:
- The external domain: this domain contains the whole geometry outside the object, that is to say also the whole external environment and includes in particular the radiating source antenna, the ground plane for test configurations
- The internal domain: this domain contains the whole geometry inside the object. It includes inner volumes (also called elementary volumes) and all the features that are relevant for the internal coupling.
Figure 1 and Figure 2 indicate the typology of models related to penetration points in the topological analysis as identified in WP1: POEs (Points Of Entry) for apertures on the outside surface), POIs (Points Of Interaction) for internal apertures, POCs (Points Of Couplings) for cables, POAs (Points Of Absorption) for lossy volumes and surfaces. Let us make precise that pre and post processing for each of the modules and submodules are common steps for both LFB and HFB scenarios and are not represented in Figure 1 and Figure 2.
Both calculation scenarios are based on a similar scenario in which 3D solvers (Full Wave or Asymptotic) provide source input data for a network model; Multiconductor Transmission Line Network ( (MTLN) or Power Balance models. The network analysis is particularly well suited for parameter analysis and allows qualifying separately each network constituent analytically or numerically (with data files). In both cases, the network design is prescriber for the definition of the output requests required in the 3D codes for the calculation of their source terms.
The LFB scenario relies on the use of 3D solver modules for calculating EM fields in 3D environment up to 3GHz. The model of on which the 3D calculation is made includes both the external and the internal domains. In particular, no distinction is made on inner elementary volumes.
The calculation of the wiring response up to 400 MHz involves either thin wire models meshed within the 3D model or MTLN models for wiring response at pin level. For MTLN, the model of network is completed by the model of equipment which provides the end loads at pin level applying generalized Thevenin description of multiport systems. The Field to Transmission Line (FFTL) process insures the connection between the 3D solver and the MTLN solver. It works in the following way:
- The 3D solver provides the incident fields along the central path of the wiring. In particular, the central path corresponds to the path of a wiring on which incident fields can be calculated. The central path is not part of the meshed 3D model; it is a fictitious route inside the 3D model on which the framework will declare output requests. This central path is split in groups in direct correspondence with the tubes of the network. Along the groups the incident fields are calculated and stored.
- The incident electric fields stored in groups are projected along the central path and therefore provide the distributed voltage sources (Agrawal’s formalism) for each tube of the network.
At the end the MTLN solver makes the final network calculation of total common mode currents (Icm) and currents and voltages at pin level (I and V).
In terms of calculation performance:
- The Full wave calculation on both the external and internal domains is long and may take several hours depending on the size of the 3D model (number of cells of the 3D mesh)
- The MTLN calculation is much shorter; it is typically made in tens of minutes allowing therefore parameter analysis on the same central path (nature of cables, cable bundle internal organization, end connections, cable -shield connections…)
Figure 1: The HIRF SE LFB scenario
The HFB scenario relies on two types of modules:
- An asymptotic solver for the calculation of the input fields at the POEs.
- A Power Balance solver that uses the incident fields at POEs in order to calculate the total power which is injected inside the inner volume. All the penetration points identified in the topological analysis are associated to coupling so-called cross-sections that can be calculated analytically or specified in data files.
In terms of calculation performance:
- The interest of the asymptotic solver is to make possible the calculation on the whole surface of the object at high frequency, which is not possible with currently available Full Wave solvers. The calculation time is about some hours.
- The Power Balance method only calculates in a few tens of seconds and also offers parameter analysis on the various coupling cross-sections.
Figure 2: The HIRF SE HFB scenario
Finally note also that a third scenario derived from LFB and HFB scenarios, called Medium Frequency band (MFB) scenario, was also implemented in HIRF SE to cover the modelling need on the overlapping frequency band between 400 MHz and 3 GHz. This scenario combines the use of a Power Balance tool for the field environment, from which a plane-wave spectrum decomposition is obtained in each zone of the object, and a MTLN tool for the application of Field-to-Transmission line using the plane wave spectrum as incident fields. The FFTL process is optimized with a reciprocity formulation.
Example of application of the LFB scenario:
Figure 3 shows an application of the LFB scenario on the Piaggio P180 nosecone. The object was tested on Alenia-Aermacchi’s open test site in Caselle, Italy, where it was illuminated by various types of antennas in a frequency range up to 400 MHz. For this specific application an instrumented equipment (IE) prototype developed by Selex has been installed inside the bay and allowed measurement of signals at pin levels. It was connected to a remote box with a cable-bundle. The implementation of the LFB scenario on this test-case was made in the following steps and with the following modules:
- Pre-processing: the AEMMESHER tool developed by IDS was used to manage the CAD model and to generate a triangular mesh. The edition of the cable-bundle network model was made with ONERA’s CRIPTE editor module. The model of the equipment common mode input impedance came from the IMEA tool developed by Thales Communication Systems and was completed by CRIPTE-editor in order to introduce differential loads in the impedance model.
- Field calculations were made with IDS’s IDSMMMP Method of Moment tool, both for the calculation of EM fields at local test-points and along the central path of the wiring under test.
- The MTLN calculation was made by the CRIPTE-calculation module from ONERA and provided total common mode current on the bundle and currents at pin level of the IE.
Figure 3: Application of the LFB scenario on the Piaggio 180 nosecone
Example of application of the HFB scenario:
Figure 4 illustrates the implementation of the HFB scenario on Evektor’s VUT100 aircraft. It involved the following steps and the following tools:
- Pre-processing: CIMNE’s GID tool was used to manage the CAD model and generated the triangular mesh. The Power Balance model of the interior domain was obtained with ONERA’s PWB-editor tool.
- Field calculations for the external problem were made on the canopy of the aircraft (considered as the main POE in the aircraft) with OKTAL-SE’s SE-RAY-EM asymptotic tool.
- The Power Balance calculation was made by the PWB-calculation module from ONERA and provided field observables inside two main compartments in the aircraft (cockpit and avionic bay zones).
Figure 4: Application of the HFB scenario on Evektor’s VUT100 aircraft
Modelling status at the end of HIRF SE:
At the end of HIRF SE we can state that all the tools already existing before the project have been improved in parallel to the development of new tools in order to access the level of complexity required for AC/RC modelling. Most of the tools are ready to use and compatible with the AMELET format. Others are still waiting for future implementation. Nevertheless, we can say that the scope of the tools and proposed scenarios widely overcomes the strict scope of the HIRF issue; indeed one can logically think to apply them to indirect lightning and EMC types of problems.
1.3.4 Module validation processes based on the comparison between measurement and simulation campaigns
All the tools, modules and submodules constituting HIRF SE have been object of different validation process in order to assess the computational results. The validation processes are based on the comparison between simulation and measurement results and for this reason, massive campaigns of measurement, simulation and analysis of results have been carried out during the last three years of the project.
The convergence between measurement and simulation results happens only if the three following condition are verified:
- The electromagnetic phenomena are correctly represented by the implemented computational algorithms
- The test set up is well known and correctly modelled
- The numerical model of the object under test is enough representative of the HW ones
Two main levels of validation process have been developed and applied for tool assessment:
- On “simple”/geometrical controlled test cases: the goal is to verify that the numerical models correctly compute Maxwell’s Equations. Tools that passed this level are assessed for air vehicle design applications and can be proposed to the second level of assessment
- On air vehicles: the goal is to verify that the air vehicles are correctly represented by their “electromagnetic synthetic model”, to give guidelines for the modelling and to start to build a database for Coupling Cross Section, POA, POE, POB. Tools that passed this level can be proposed for air vehicle simulation for certification purposes.
1.3.4.1 Validation process on geometrical controlled test cases
The first level of validation was based on about 70 hardware test cases that has been modeled and simulated and was based on the principle of the increasing complexity. The test cases have been divided in three main groups:
- The test cases of group 6.1 are finalized to the validation of models developed in WP3 as standing alone codes, not already integrated in HIRF SE framework, and are used for an early validation of the models before integration. Therefore this type of TCs is characterized by very simple configurations that do not require the combined use of different models.
The group 6.1 of test cases is organized in three different typologies of TCs:
- Materials;
- Cables;
- Equipment.
- The test cases of group 6.2 are finalized to validation of modules as standing alone codes or possibly integrated in HIRF SE framework, applied on simpler test configuration in which all details can be constructed and controlled completely. Therefore this type of TCs is characterized by simple configurations which can be modeled using a combination of two or a few different models. The group 6.2 of test cases is organized in different typologies of TCs:
- Materials
- Material configuration
- Cable bundles and loads
- Material configuration and bundles
- The HW test cases of group 6.3 are finalized to the validation of sub-modules and modules integrated in HIRF SE framework applied on complex test objects representing parts of aircrafts or rotorcrafts.
EMC/HIRF standard, such ED 107, have been taken as reference to carry out the measurement but the most important aspects that ruled the process was the capability to correctly model the test object and test set up: it is more important to know the exact position of the probe or the characteristic of the radiating antenna than to be in far field condition. Moreover measurement are not the soul of the truth and the influence of the test set up and environment need to be evaluated and correctly interpreted to carry out a reliable comparison with simulation results.
Three comparison methods was used for the tool assessment:
- Direct comparison superimposing measured and simulated data on the same graphics.
- Application of IELF methodology.
- Application of IEEE Std1597.1 – 2008 FSV-VSR methodology.
A relevant point in the judgment process is the evaluation of the consistency between the numerical model of the test object, the measurement set up and the real test object and the real set up. For these reason the use of FSV and IELF codes can help in the evaluation process but they can in any case substitute the expert judgments that are mandatory for the assessment.
1.3.4.2 Validation process at air vehicle level
The validation process has demonstrated on several real aircraft that the Framework is able to predict electromagnetic response of complex test objects in various test configurations such as LLDD, LLSC and LLSF. The following platforms have been used:
PIAGGIO P180:
AUGUSTA AW 139
EUROCOPTER EC 135
BAE NIMROD
DASSAULT 7X
EADS CASA C295
EVEKTOR VUT100 EV55
INTA SIVA
The validation process is designed towards specific objectives that the framework has to provide during the development phase and during the certification phase. During the development phase the validation process should answer the following question:
Is the HIRF SE numerical approach valid to allow design decisions?
Although during the Aircraft Type certification phase or Supplemental Type Certification phase the question to be answered is:
Is the HIRF SE numerical approach valid to determine the Electromagnetic environment of Aircraft equipment and system in view of equipment specification?
For these two objectives a validation indicator has to be defined. This validation indicator is called the “pass/fail criteria”
For development phase just looking whether measurements and simulations show the same trend of variation against an installation parameter such as a cable route or a cable shield is sufficient to validate the use of numerical simulation in the development phase.
For certification phase the numerical approach will be considered validated if Equipment and system specifications derived from measurements and specifications derived from computation are less than 6dB apart, In order to verify this pass fail criteria measurement data and simulation data have to be processed in the same manner. The data processing which has been selected is derived from ED 107A/ARP5583A and consists in averaging the responses using the 5% band width filter, followed by a peak spreading over an octave envelope, eventually followed by a general envelope of several data of the same type.
Two aspects of validations have been used in the project one dedicated to the framework validation itself the other dedicated to the validation of the numerical approach. The first one consists in the comparisons of results between different numerical approaches; the second consists in the comparison between measurements and simulations. The conclusions on the final validation are based upon the second aspect only. This second aspect involves two main items. The framework itself upon which the validation is focused on: How well are equations solved, how well is EM coupling represented (bundle complexity, apertures, slots, materials). The second aspect is related to the Aircraft model for which the validation is focused on how well is the aircraft meshed? How well specific EM features are present? Unfortunately the final results aggregate both items.
The conclusion of the validation process can be summarized as follows:
- For LLDD Test configurations the code appears to be validated up to 30MHz frequency above which aperture models, lossy materials models, various skin effects which presumably have an influence on the results are not currently implemented and validated inside the framework.
- For LLSC test configurations it appears that the user’s effort should be concentrated on the validity of the model
- For LLSF test configurations:
• In the region 1-3GHz the 3D approach is validated
• At lower frequencies the validation is jeopardized by the difficulty of the description of the test setup.
• At higher frequencies the statistical approach (PWB methods) will be fully validated once a validated extensive database of Coupling Cross-Sections (CCS) for POEs, POA and POC will be available.
From the above statements the final validation process leads to the following conclusion:
o For development purpose:
The parametric studies have shown that the trends are well represented and therefore that the P/F criteria for development phase is reached by the numerical approach
o For certification purpose:
- For conduction environment:
Since the HIRF SE framework is validated all the effort should be focused on the validation of the A/V-R/C models
The A/V-R/C models should be placed in a normative test setup to be validated, the setup numerical representation should be validated through measurements of surface currents on a sufficient number of locations
The specifications which can be derived from numerical approach are equivalent to the specification which can be derived from measurements
- For radiated environment:
For the external environment of the A/C test setup SC test cases in LLDD have shown that the numerical approach gave after some light tuning fully identical results from measurements and from computation.
For internal environment up to 3GHz, the 3D approach gives results that can be used for certification purpose since due to the lack of slots models and to the under-implementation of lossy materials the computed fields are generally higher than those measured.
For higher frequency the statistical method and PWB method are promising but require the completion of a CCS database for POE, POC, POAs.
Potential Impact:
1.4.1 Potential Impact
The use of HIRF SE framework by aeronautic industry will directly benefit the design and certification phases of air vehicle production.
Application of HIRF SE from the very early stages of the design will bring to a reduction of the serious problems of safety that EM hazard poses by the increased use of high speed electronic equipments in small, medium and large aircraft. The possibility to anticipate and predict the electromagnetic performances of a new aircraft or rotorcraft will bring to a more accurate and tailored design of the electromagnetic protections in particular and air vehicle design in general (e.g. air vehicle wiring routing, equipment installation and placement, material selection).
Application of HIRF SE during the certification phases will allow the aeronautic industries to carry out an intensive testing in a simulated flight condition taking into consideration the ground effect, the proximity of the electromagnetic sources and the under sampling limitation of testing raising to a higher level the safety of air vehicles. Moreover, once the air vehicle models will have been consolidated and validated, it will be possible to reduce the testing time for certification.
The societal beneficial effect is mainly in the increase of safety for the customers and a possible decreasing of cost due to a more efficient design process. In fact the customer safety can be ensured due to the fact that HIRF SE application in the design will aid the implementation of new media and communications systems (e.g. wireless internet connections, mobile phone connections, etc) as well as the integration of new on board maintenance systems and general broadband connection by on ground and satellite links.
According to the framework electromagnetic specification, HIRF SE may be applied, with the same benefits, also to various other ‘scientific’ fields beyond that of aeronautics.
Essentially, since the framework would be able to model the EMC/HIRF aspects of air vehicles, the same principles and, hence, software could also be applied for simulations in the automotive, naval, defence, etc fields.
Examples of potential areas for HIRF SE applications are indicated below:
- Aerospace
- Automotive
- Rail industry
- Naval
- Defence
- Material manufacturers (due to the capability of the tool to deal with materials’ properties from an electromagnetic point of view).
The capability of HIRF SE to simulate the environmental electromagnetic conditions can be exploited even for safety evaluation both for civil air vehicle passengers and inhabitants of urban areas. As a matter of fact, the increasing use of on board wireless systems and transmitting equipment poses the needs to verify which is, under a safety point of view, the electromagnetic environment inside the fuselage and in this sense HIRF SE can be applied for preventing possible sources of hazard for passengers’ health. As well HIRF SE can be applied to evaluate how installations of new or existing antennas modify the urban electromagnetic environment: the level of perturbation can be compared with the existing civil regulation electromagnetic level in order to prevent possible hazard for inhabitants.
1.4.2 Main Dissemination Activities and Exploitation of Results
This section describes the main dissemination activities under the headings used in the DoW.
• Scientific Publications: Research active partners in the programme have been encouraged to publish their results in a range of peer-reviewed venues. The venues are principally peer-reviewed journals and peer-reviewed conferences.
Principal European conferences specifically targeted were EMC Europe (2009 to 2013) ICEAA 2011 and EuroEM 2012. Specific HIRF-SE Workshops or conference sessions were promoted at all these.
The partners were responsible for originating the publications and liaising with other partners in order to produce joint publications. A document entitled “Instructions for the Publication of Scientific Papers arising from HIRF-SE” was issued to all partners detailing the steps to be taken in the production of a scientific paper. These include verifiable permissions for the use of partners’ IP for both publication and presentation. All HIRF-SE papers submitted for publication by partners were subject to Steering Committee review through their presence on a dedicated section of the private web pages. Steering Committee members were notified when a paper was submitted for review and then had thirty days to respond. No response was deemed to be acquiescence. The purpose of the review was to check for IP issues rather than a technical review. Papers were then subject to peer-review as usual and published papers were uploaded onto the private area of the website available to the Steering Committee, the Advisory Board and the EC Review Panel.
A list of all publications appears at the end of this report.
• YSP (Young Scientists’ Programme): the Young Scientists' Programme (YSP) on EMC in Aerospace Systems was offered by the HIRF SE consortium on an annual basis, linked to the annual EMC Europe conference. The YSP was intended for the benefit of young practitioners, Graduate Students and Senior Undergraduate Students. Lectures were presented by experienced industrialists and academics working on the HIRF SE field from within the consortium and the Advisory Board. The programme addressed the shortage of younger practitioners on Aerospace related electromagnetics.
Presentations covered a wide variety of topics in Aerospace EMC and were aimed at encouraging young scientists and engineers to consider making a career in the field. Each YSP comprised around six or eight lectures each of ninety minutes delivered over two days at the start of the conference. Typically audiences of twenty to fifty people attended. The lectures were open to all conference attendees and were attended by a wide range of people.
The powerpoint presentations of all YSP events are available from the Knowledge section of the EMC Portal on the public project website.
The quality of the lectures was monitored by asking the registered attendees to complete an evaluation form. The returns were analysed to facilitate improvements for subsequent years and to ensure that a proper level of presentation was made. Analysis of the returns showed a discernible improvement year-on-year. Return analyses were presented in the annual deliverables D10, D21, D33 and D39 (CPD Courses, Scientific Papers, YSP and Observatory of EMC issues).
The YSP events were held as follows:
o The 1st Course of the YSP was held on the side of the EMC Workshop 2009 conference in Athens, Greece (10-11/6/2009).
o The 2nd Course of the YSP was held on the side of the EMC Europe 2010 conference in Wroclaw, Poland (13-14/9/2010).
o The 3rd Course of the YSP was held on the side of the EMC Europe 2011 conference in York, UK (26-30/9/2011).
o The 4th and final Course of the YSP was held on the side of the EMC Europe 2012 conference in Rome, Italy (17-18/9/2012).
• Internal CPD (Continuous Professional Development): A programme as complex as HIRF-SE requires considerable internal communication between the partners. This was facilitated in part by the development of CPD courses for internal use within the consortium. These courses covered a variety of topics where a particular partner had produced foreground that required structured dissemination to selected partners. CPD courses typically lasted between one day and one week and allowed partners to collect information at an appropriate point in the programme. CPD courses typically comprised lectures or hands-on demonstration sessions. In some cases the material was delivered as a series of online tutorials with the participants working from their own place of work and in communication with the presenters through audio conferencing with online presentation of materials. A similar presentation quality monitoring system to that used for the YSP was implemented for all CPD courses. The outcomes of this process were reported in annual deliverables D10, D21, D33 and D39 (CPD Courses, Scientific Papers, YSP and Observatory of EMC issues). Material presented by Dassault on the technical aspects of WP7 is used as the basis for the course material in D46 (Technical User Guide and Course Delivery).
• External CPD: A number of CPD resources will be available after the end of the project. These are encompassed in D46.
o Technical User Guide; This is an introduction to the Framework, a brief description of each module and directions to more detailed documentation.
o Teaching Materials (TCM1); This is based on the Dassault internal CPD module. It gives technical guidance on the different modelling techniques and tutorials on how to use them.
o Teaching Materials (TCM2); This material based on previous presentations to EASA detailing the certification aspects associated with the Framework.
• Dedicated HIRF SE Workshops: These were typically held at major European events of the EMC field:
o EMC Europe 2009, 2010, & 2011
Workshops held at conferences differ from regular conference sessions in as much as conference papers are peer-reviewed by the conference review panel whereas Workshop contributions are only reviewed by the Workshop convenor. Workshops were the principal visibility of the HIRF-SE programme for the first three years. After this time it was decided that the project was at a sufficient state of maturity that it was able to promote regular conference sessions in which HIRF-SE partners presented peer-reviewed papers alongside other authors. With the exception of one event detailed below all presentations at conferences after EMC Europe 2011 were peer-reviewed regular papers.
In March 2013 project partner UGR organised a Workshop CEMEMC 2013 to highlight the Numerical Test Cases used in the HIRF-SE project. This Workshop was organised around the HIRF-SE project and six papers were presented by members of the HIRF-SE consortium along with papers from co-workers in other projects. The theme of the Workshop was built around the Numerical Test Cases used in the HIRF-SE project. In all, twelve papers were presented at the event.
• Final Dissemination Event: The HIRF SE Project held its Final Dissemination/Stakeholder Event on the 29th of May 2013.
The event was run over a whole day hosted by the co-ordinator ALA in Torino. During the event, the final outcomes/results of the project were disseminated to a targeted audience consisting of related industry stakeholders. In order to facilitate wide dissemination of the work beyond the aeronautic field the EC recommendations concerning invitations to a wide range of stakeholders suggested by project partners have been followed. All partners were asked to provide a list of names of relevant people to invite. This list included people from industry and academia and known workers on other cognate projects in the Built Environment, Road transport and Rail transport. The consolidated list was used by the Dissemination Manager and logistical information for participants was placed on the project public website.
The aim of the event was to publicise the outcome of the project and to act as a portal for interested parties to start their exploitation of the HIRF-SE framework. The main scientific results of the project were described to those attending along with a description of the Framework. The Framework was demonstrated to the attendees. In addition each partner was invited to present a poster detailing their research contribution to the HIRF-SE project. Attendees were provided with copies of the posters on a USB key drive.
• Dedicated Presentations at major industry events: The project objectives, scope and results were promoted through dedicated presentations at major events of the industry, such as:
o Aerodays 2011 (http://www.hirf-se.eu/hirf/themes/garland_HIRF/files/3D3-Aerodays-Presentation-Bozzetti.pdf).
o AES (Advanced Electromagnetics Symposium) 2012 (http://www.hirf-se.eu/hirf/?q=node/117).
The online dissemination ‘means’ used by the project so as to promote its objectives, activities and results are discussed in the following section (“Address of the Project Public Website”).
An important aspect of the project was the HIRF SE application inside certification phases of air vehicles. For this reason EASA has been involved as advisory board members. Several contacts have been established along with the project in order to disseminate project results within authorities or bodies that have influences in regulation or standard for air vehicle certification. Besides EASA, EUROCAE and FAA were contacted and informed about HIRF Se possible application and results.
The roadmap indicated in figure 5 for air vehicle certification based on a numerical approach (always supported by measurement), was worked out with EASA. This roadmap could be used as reference for future upgrade of ED 107.
Figure 5 Certification roadmap and use of numerical approaches
The Project Public Website. The HIRF SE project website promotes the project objectives, results and news via the following address: http://www.hirf-se.eu The project website has both public and private sections.
In the private section all the documentation associated with the project is accessible to the project partners. This includes consortium meetings as well as scientific data and scientific papers under review.
The public section of the website contains general information about the project and the following specific sections.
The complementary ‘Observatory on EMC Issues’ (knowledge) Portal, established as a dedicated action of the project (WT8.4) disseminates project related materials and scientific knowledge through the following address: http://www.hirf-se.eu/portal The portal has a wide range of material including basic science descriptions of HIRF-SE related electromagnetics suitable for university level teaching and all the YSP presentations.
The HIRF SE Public Database (http://public.hirf-se.eu) a database of models, geometries and other files shared by the HIRF SE Consortium and its comprising members with the aim to disseminate the HIRF SE project results to the wider scientific community and to elevate the knowledge 'capital' in the associated scientific area, continues to be available for interested parties to register.
List of Websites:
The HIRF SE website will be kept active even after the end of the project for commercial reasons. The address of the website will be the same as the public ones that was used for HIRF SE dissemination http://www.hirf-se.eu In the following paragraph there is the list of the main point of contact for each partner working of HIRF SE project
Before air vehicles (aircrafts and rotorcrafts) can fly, International Certification Authorities (FAA for United States and EASA for Europe are the most influential worldwide) must be assured that:
- Equipment and subsystems are not affected by mutual electromagnetic interactions
- Subsystems/systems can correctly operate when subjected to external electromagnetic disturbances.
It is common practice to demonstrate by testing air vehicle robustness against catastrophic effects induced by electromagnetic disturbances.
The current air vehicle lifecycle foresees the experimental verification at the end of the development phase when the air vehicles are already built and just before their release to the market: this means that it is possible to detect susceptibilities that correspond to weakness in the electromagnetic design only during the certification phases. Rework costs are very high and even the time to market increases considerably once design needs to be reviewed.
In the new and future generations of air vehicles (fly by wire and even fly by wireless) the increasing number of functions with catastrophic effect makes the time required for testing grow exponentially and in the meanwhile high speed electronic equipments poses serious problems to air vehicle safety verification due to EM hazard.
Moreover the electromagnetic environment is characterized by a proliferation of emitters that will bring to higher costs for instrumentation to carry out testing to comply with Certification Regulation demand.
In this scenario the HIRF SE framework has reached an adequate level of maturity to cope with the needs of air vehicle development from design to certification phases and in particular it can be applied to:
- Optimize the global design of air vehicles minimizing the rework activities
- Maintain the duration of certification testing within a reasonable timeframe
- Maintain the costs associated to testing “under control”
- Take into account the in flight conditions that are not possible to be represented during ground testing.
- Maintain or improve the current safety level of air vehicles
Project Context and Objectives:
The HIRF SE framework is an electromagnetic analysis tool operating in the HIRF radio frequency range 10 kHz – 40 GHz. The framework has the capabilities to simulate the air vehicle interaction with both far-field and near-field sources having any polarization and position in the presence or not of the ground. Also HIRF SE is able to predict both the EM field distribution inside the airframe and the induced voltages and currents in the wiring system. The broadband EM perturbations can be simulated according to the following classification:
- External environment (i.e. radars, radio and television broadcast emitters).
- Internal environment (i.e. EM constraints in terms of EM fields and current on cables that air vehicle electronic installation will encounter due to external EM fields or internal emitter devices such as PEDs or WPEDs).
Three different EM sources can be distinguished and these are identified as threats:
- External EM threat (generated, for instance, by airport and radio-television emitters);
- Surface EM threat (generated by on-board emitters);
- Internal EM threat (generated by PED or WPED).
The aforementioned threats are the input of the transfer functions that HIRF SE can compute in the 10 kHz-40 GHz frequency range.
During the project different simulation approaches have been classified and analyzed with respect to a Low Frequency Band (LFB) scenario and a High Frequency Band (HFB) scenario.
- The LFB scenario extends from 10 kHz to 3 GHz. It relies on the use of 3D full wave solvers for calculating both external and internal environments of air vehicles and the use of Multiconductor Transmission Line models for the calculating the response of cable bundles under tests up to 400 MHz. The process for linking the two types of data is based on the field-to-transmission line approach but this process still requires extensive thin wire modeling in the 3D model in order to describe correctly the inner field environment.
- The HFB scenario extends from 3GHz to 40 GHz. It relies on asymptotic 3D solvers for calculating external fields at the level of points of entry of energy inside the air vehicle. The internal response is calculated with so called Power Balance tools making the assumption that the internal field environment can be considered as random.
In addition to those main computer modules, specific sub-modules have been developed in order to bring the EM physics required by HIRF modeling. Among them, material models have been extensively studied in order to be introduced as macro models in 3D computer solvers.
The HIRF SE framework uses the AMELET format in order to standardize the flux of data of the various computer models involved in the LFB and HFB scenarios.
Potential susceptibilities (or the identification of frequency ranges without susceptibilities) can be identified using the HIRF SE framework:
1. Define the environmental level using HIRF SE to compute the EM environment caused by an external or on-board source and surrounding the equipment; The electromagnetic field around equipment is computed in the frequency range 100MHz-40GHz and the coupled currents flowing into equipment connectors are computed in the frequency range 10KHz-400MHz
2. Define the susceptibility margin comparing the computed environmental level with the equipment qualification level (100MHz-18GHz/40GHz) or system test level (10KHz-400MHz)
3. Assessment of Potential Susceptibility:
- For all the frequencies in which the Susceptibility Margin is lower or equal to zero there is a potential susceptibility that need to be investigate by testing;
- For all the frequencies in which the Susceptibility Margin is higher than zero it has been computed a minimum level (in terms of current or EM field) of no susceptibility.
The correct operation of the framework has been verified and validated by comparison with data from real testing on small and medium air vehicles and pre-existing data for large air vehicles.
All the tools that have been integrated inside the HIRF SE framework have been assessed through comparisons with measurement results.
Validation processes followed a gradual approach in term of complexity in order to insure to have the control of the geometrical configuration while carrying out the validation of the tools that have been plugged inside the framework. In particular two main levels of validations have been established
1. On “Simple” and geometrical controlled test cases:
- The goal is to verify that the numerical models correctly compute Maxwell’s Equations
- Tools that passed this level are assessed for air vehicle design applications and can be proposed to the second level of assessment
2. On Air vehicles
- The goal is to verify that the air vehicles are correctly represented by their “electromagnetic synthetic model”, to give guidelines for the modelling and to start to build a database for Coupling Cross Section, point of absorption, point of entrance and point of bonding
- Tools that passed this level can be proposed for air vehicle simulation for certification purposes
In the first level of validation, the test cases are classified in three different categories, corresponding to increasing complexity of the test object and each test case correspond to a HW test case that is used for generating experimental data to be compared with the results of the numerical simulation for assessment and validation of the relevant models, sub-modules and modules.
For the validation process at air vehicle level, the reference data for the comparison were the results of dedicated measurement campaign on small and medium air vehicles and in particular:
- Medium air vehicles: Dassault F7X, EADS-CASA C-295;
- Small air vehicles: Piaggio P180 (Fig.6) PZL M28, Evektor EV55 and Cobra 100, Inta Siva;
- Rotorcraft: Agusta AW139, Eurocopter EC135, EC145.
For the large air vehicles measurement campaign carried out before the starting of the project on BAE System Nimrod MRA4 was used as references.
The common practice, as indicated by Advisory Circular AC-20158 and applicable standard ED107/A-July 2010, for certification of air vehicles can be summarized in three steps:
- Step 1: the air vehicle is exposed to an external Low Level HIRF environment.
- Step 2: evaluation of the internal environment around the equipment in terms of interface currents and in terms of electric field.
- Step 3: the internal environment values are compared with the equipment qualification/system integration results in order to verify compliance with HIRF certification requirements.
It is important to point out that:
1. The second step is normally achieved by means of measurements.
2. The requirement for the air vehicles testing is for free field illumination (as close as possible).
3. The test set-up may influence the illumination:
- The plane-wave is a theoretical concept which does not exist in laboratory,
- A ground plane is always in some vicinity of the air vehicle under test,
- Laboratory illumination is not representative of the operative conditions.
4.The amount of measurements typically achievable ranges between 100 and 1000. These figures might seem small in comparison of the actual complexity of critical systems.
The use of the HIRF SE framework for design and certification purposes and the advantages have been presented and discussed, along the project, with the European certification body EASA. In particular the following points were defined as crucial for future certification roadmaps that will adopt numerical approaches:
- The electromagnetic models of air vehicles are fundamental for the reliability of results
- The electromagnetic models need to be validated against measurement
- An amount of testing will be defined and carried out to validate and calibrate the A/V electromagnetic models
- Once the A/V models will have been validated the rest of the certification campaign can be completed by simulation
With the development of HW architecture and of more efficient codes and algorithms, analysis and simulation are now affordable solutions for solving EMC problems in aeronautic and numerical modelling technique represent the most cost effectiveness approach for HIRF /EMC issues.
The aid of modelling and simulation will reduce the delivery timescales of future air vehicle and systems and simulation can embrace more complex situations than measurement raising to a higher level air vehicle safety.
In this context the HIRF SE Framework is an innovative, collaborative and integrated methodology that allows solving EMC problem from CAD to analysis results in the frequency range from 10 kHz up to 40 GHz and can be applied during early design and certification phases of air vehicle lifecycle.
Project Results:
Before the HIRF SE project took place different software and methodologies for simulation approaches were available but they were not able to deal with the level of complexity required to cope with HIRF/EMC problems of interest for the Aeronautic Industries. All these computational tools were sparse and there were not any integrated solution to face in a whole the wide frequency band of interest (10 KHz – 40 GHz) and to compute the different kinds of required observables (internal environment in term of electromagnetic field and in term of coupled currents).
Moreover general guidelines for the electromagnetic modelling of complex and new generation air vehicles were not established in a standardized way and were not always supported by a rigorous scientific approach.
HIRF SE is a numerical platform for virtual HIRF assessment on air vehicles, in the frequency range 10 KHz-40 GHz capable to deal with:
- The increased use of composite materials and structures
- The complete external and internal electromagnetic environment of an air vehicle
- The complexity of the on-board wiring system
- The uncertainties in the real installation configuration
The computational tools constituting HIRF SE have been assessed, along with the project, applying validation methodologies based on massive analysis of the comparison between measured and simulated data. For this reason a validation methodology (based on different levels of assessment) has been established and a database of benchmark test cases have been put available for the EM community for future development and validation of numerical codes.
The wide amount of data available, both from simulation and measurement, made possible to provide general guidelines for electromagnetic modelling of real scale complex and new generation aircraft and rotorcraft. In particular the following aspects were taken into account:
- Selection of the proper modelling tool to be applied in a specific configuration taking into consideration frequency range, air vehicle size and characteristics, observables, available computational resources
- Selection of the proper type of model to be used for wire modelling
- Selection of the proper type of model to be applied for a specific air vehicle configuration in term of material
- Sensitivity analysis setting the values of parameters that simulate bonding and loads
- Sensitivity analysis of the geometrical configuration defining the level of details that need to be simulated
Aeronautic industry has now available the proper mean to cope with real air vehicle complexity in terms of structures (both material and geometrical configuration) and wiring system (taking into account equipment loads, scattering effect and connectors) in the wide frequency band required by design and certification phases.
In this chapter, a detailed description of the main scientific achievements reached by the project is given. The scientific achievements are grouped and identified as follows:
- The framework: an integrated and modular solution for solving electromagnetic problems on complex test objects
- Complexity of air vehicles in terms of real installation configuration and material used by the modern aeronautic industry
- Simulation of EM coupling on on-board systems applying HIRF SE scenarios
- Module validation processes based on the comparison between measurement and simulation campaigns
1.3.1 The Framework: an integrated and modular solution for solving electromagnetic problems on complex test object
1.3.1.1 Aims of HIRF-SE framework
From a software point of view, the HIRF-SE project aims at implementing the two certification scenarios. These scenarios are represented on the two sketches below:
Low frequency Band scenario High frequency Band scenario
The LFB and HFB scenario have to be implemented inside a unified framework (HIRF-SE Framework)
• Allowing to use all simulation modules provided by consortium members
• Bringing some specific capabilities required by certification issues (information traceability, …)
1.3.1.2 HIRF-SE project – Software main outcomes
1.3.1.2.1 AMELET-HDF Format
HIRF-SE project allows the definition of a format to describe an electromagnetic simulation bringing the capability to exchange full simulation composed of geometric models, EM models, Output requests... AMELET-HDF format is:
• Open and fully specified format. A forum for AMELET-HDF Evolution management is available at http://code.google.com/p/amelet-hdf/downloads/list;
• Suited to manage highly volumetric simulation. It is built on top of HDF5 technology, and has been designed to be compact;
• Available documentation and code snippets. A set of tutorials and implementation of samples of code for AMELET-HDF are available at http://code.google.com/p/amelet-hdf.
1.3.1.2.2 HIRF-SE FrameWork
1.3.1.2.2.1 CuToo platform
The CuToo platform is the tools integration layers of the HIRF-SE framework. It offers the following capabilities:
- Collaboration: Multi users, user groups, Messaging, IM, Rights, Workflow
- Project Management: dedicated Workspaces, data validation
- Object Management (Business Entities):
- History: Ability to have the list of all actions (creation, copy, modifications, …) made by users on each object
- Versioning: Process of assigning either unique version names or unique version numbers to unique states of an object (model, …) or a set of objects (simulation, project, …) and Revision control allows keeping track of different incremented versions
- Traceability: Ability to have a full traceability of the creation process of an object, check the consistency of all these objects (Warning if an object involved in the process has been modified) and capability to Lock all objects and simulations involved in the process of production of a validated result
- Modules Management:
- Capabitility to manage at the same time several versions of a module in the platform with identification of each version of the module and its related integration software components and several implementation of the same module for different OS
- Identification of the version of the module used for a simulation
- Capability to run again all simulations in the same conditions
- Simulation Management:
- Several simulation processes: Queue management of simulations, Load balancing between several hardware resources and Parametric studies:
- Generic Capability that can be used for all modules and all parameters of objects as inputs of Simulations.
- Takes in charge parametric variation of parameters of simulations, Attributes of objects used in a simulation (conductivity of materials, …)
- Objects in the simulation
- Several graphics or computing resources: Local or remote resources, Native management of optimized 2D/3D remote display of interactive module, submission of jobs on supercomputers (schedulers interface)
1.3.1.2.2.2 SDK and Procedure of module integration
- Integration process of modules inside the framework
• Test driven Process
o inspired by the test driven development methodology (TDD)
o Formalized by a set of Integration Test Case (ITC)
• Does not require any modification in the module (Non intrusive)
• Requires implementation of 2 software components in a dedicated Software Development Kit (SDK)
o A wrapper to adapt native input and output of the module the AMELET-HDF format
o A File dedicated to specify the behaviour of the framework’s GUI regarding the integrated module
- More than 50 modules have been plugged inside the platform:
• Interactive modules (2D and 3D) for pre and post processing
• Batch sequential and massively parallel modules
1.3.1.2.3 A set modules allowing to implement LFB and HFB scenarios
The Tools and Softwares components involved in simulation at aircraft level are listed hereafter. Patners that provide these tools are integrated between brackets.
- The platform: CuToo (AXS)
- 3D Preprocessing: General: GiD (CIMNE); FDTD: NASH (AXS) MoM: AEMMesher (IDS-IT), PRE-CONCEPT (TUHH)
- Wiring Preprocessing: CableSim (AXS) ; CRIPTE Edit (ONERA)
- Postprocessing: Post 2D/batch UPC-POST (UPC); 1D, 2D; 3D data viewers: GiD (CIMNE), Paraview (Open)
- Material solvers: MMT (URM), EI (POLITO) - Vector fitting
- 3D FW solvers: UGR-FDTD (UGR), IDSMMMP (IDS-IT), CONCEPT-II (TUHH), MWS (CST), HY3D (BAES)
- MTLN solver: CRIPTE (ONERA)
- 3D Asymptotic solver: SE-RAY (OKTAL-SE)
- Power Balance tools: PWB (ONERA), IDS-OCT (IDS-IT)
1.3.1.2.4 Documentation
The HIRF-SE Framework is fully documented and it is composed of The following documents:
A set of tutorials to give cross-Modules support for LFB and HFB scenarios for LFB scenario (FWTD, FWFD, MTLN) and HFB scenario (Rays, PWB).
1.3.1.2.5 HW infrastructure / Cloud computing
- Very high flexibility for the deployment on HW infrastructure and Operating systems
- From All in one HW architecture …
• Platform and modules installed on the same computer
- … To Cloud Computing capabitilies
• All graphics and computing resources can be remote
• No HW requirement on the user's computer
1.3.2 Complexity of air vehicles in terms of real installation configuration and material used by the modern aeronautic industry
HIRF SE has the main scope of providing a complex electromagnetic computational framework aimed at the modelling of complex air vehicles (AV) as well as next generations of full composite aircraft and rotorcraft. HIRF SE framework includes different computation tools enabling the simulation of the complex 3D external geometry of the AV, the internal configuration including equipment, apertures, seams and slot, furniture and equipment, wiring system, bonding and grounding, considering incident EM field having any polarization and incidence in the frequency range from 10 kHz up to 40 GHz. Observables are the internal and external EM environment, the induced currents on the cable system, AV transfer function. All different types of composite or advanced materials on the AV are modelled by means of effective material approaches. This represents a real innovation since it enables the application of HIRF SE to any modern or next AV generation. Figure 1.3.2.1 shows an overview of the HIRF SE Framework, which is based on a fully parallel architecture, and contains computational modules for pre-processing and meshing of AV, EM field calculation of internal and external environment, cable network modelling and induced effects calculation, post-processing.
In the following the main scientific and technical innovation brought by HIRF SE are summarized.
Material Modelling Tool (MMT-URM)
MMT-URM is a computation tool aimed at the modelling of all different types of materials on an AV by means of effective electrical parameters. Figure 1.3.2.2 shows an overview of all types of different materials simulated by MMT.
Figure 1.3.2.1: Overview of the HIRF SE Framework fully parallel architecture and computational modules
Figure 1.3.2.2: Overview of all types of different materials simulated by MMT
Laminated panels of carbon fiber composites, with or without protective mesh, are modeled by means of effective single-layer panels and simulated in full wave numerical calculation tools by means of effective impedance boundary conditions. All models have been validated through an extensive validation campaign. As an example, Figure 1.3.2.3 demonstrates that the new model of a woven carbon fiber composite allows accurate prediction of the experimentally measured shielding effectiveness in a wide frequency range, whereas previous models available in the literature are limited to 1 GHz.
Figure 1.3.2.3: Progress made in HIRF-SE compared to state of the art (woven carbon fiber composite)
3D calculation: Full Wave Time-domain tools
Different time-domain tools have been implemented and validated in HIRF SE, based on different meshing scheme and resolution algorithms. Two different groups of time-domain tools have been developed:
o Applied/Validated at A/V level: UGRFDTD (UGR), MWS-TD (CST), HY3D (BAES)
o Validated at sub-system level: Quick Wave (QWED), TDFE(BUT), IFS (UoN)
The main features included in these tools are:
- Material models provided by Material Modelling Tool (MMT-URM)
- Sub-cell model for EM field penetration through laminated composites, sandwich panels, etc.
- Slot / aperture models
- Thin wire models
- E fields on central paths to feed Transmission Line models for network analysis
- Parallelization
Table 1.3.2.1 provides an overview of the tool capabilities as integrated in HIRF SE.
Table 1.3.2.2: 3D FWFD capabilities as integrated in HIRF SE
3D calculation: Full Wave Frequency-domain tools
Four frequency-domain tools have been implemented and validated in HIRF SE, based on different meshing schemes and resolution algorithms. Two different groups of frequency-domain tools have been developed:
o Applied/Validated at A/V level: IDSMMMP (IDS), CONCEPTII (TUHH)
o Validated at sub-system level: MDD (Polito), AD (TAS)
The main features included in these tools are:
- Material models provided by Material Modelling Tool (MMT-URM)
- Sub-cell model for EM field penetration through laminated composites, sandwich panels, etc.
- Slot/aperture/seams models
- Thin wire models
- Fast Multipole Method and Multilevel methods
- E fields on central paths to feed Transmission Line models for network analysis
- Low frequency stability
- Parallelization
Table 1.3.2.2 provides an overview of the 3D tool capabilities as integrated in HIRF SE.
Table 1.3.2.2: 3D FWFD capabilities as integrated in HIRF SE
3D calculation: High-frequency tools – External EM environment
Asymptotic solvers have been developed for the 3D calculation of the external EM environment in the GHz frequency-range. Two different tools have been developed:
o Applied/Validated at A/V level: SE-RAY-EM (OKTAL-SE)
o Validated at generic object level: RayTracing (UoM)
The main features are:
o Computation of EM fields on external POEs on A/V
o Materials
o Link with power-balance tools for the prediction of the internal EM environment.
Power balance tools – External EM environment
Power balance solvers have been developed for the calculation of the internal EM environment in the GHz frequency-range. Two different tools have been developed, both validated at AV level: IDS-OCT (IDS), PWB (ONERA).
The main features are:
o Large A/C
o Materials, dissipative mechanisms
o Apertures, slots
o Statistical model of EM environment even applicable in non-fully reverberating environment
o Data-base with elementary models
Cable network tools
This group of tools enables the full simulation of the complex wiring system aboard an AV, including the prediction of the induced currents at the cable ends. The main features implemented are:
o Cable and cable bundle p.u.l. parameters (ALEACAB-ONERA, CANCAN-PRZ, CABLESIM)
o Cable shield transfer impedance (BEATRICS-NLR, ERMES-CIMNE): both numerical and analytical models are implemented
o EM field coupling by Agrawal model and network analysis (CRIPTE-ONERA). The preprocessing and topological model of the complex network is performed on the basis of the AV mesh model using the module CABLESIM (AXESIM)
o Equipment modeling by Thevenin/Norton circuits and connectors (IMEA-THC, EI-Polito).
All tools and computational modules have been validated by comparison with experimental test results, considering test cases of increasing complexity at laboratory level and finally at AV level.
In conclusion, general guidelines have been provided for the use of the different tools of HIRF SE framework in different frequency ranges and with respect to the different HIRF testing configurations, as sketched in Figure 1.3.2.4.
Figure 1.3.2.4: HIRF-SE tool classification with respect to HIRF frequency randge
1.3.3 Simulation of EM coupling on on-board systems applying HIRF SE scenarios
Scenario descriptions:
Figure 1 and Figure 2 represent both LFB and HFB scenarios, identifying the modules/submodules with their outputs, - the links existing between the modules, the output data available as HIRF observables.
Both scenarios are based on a topological decomposition of the problems in which specific volumes are identified. In particular, the external skin of the object under test separates two domains:
- The external domain: this domain contains the whole geometry outside the object, that is to say also the whole external environment and includes in particular the radiating source antenna, the ground plane for test configurations
- The internal domain: this domain contains the whole geometry inside the object. It includes inner volumes (also called elementary volumes) and all the features that are relevant for the internal coupling.
Figure 1 and Figure 2 indicate the typology of models related to penetration points in the topological analysis as identified in WP1: POEs (Points Of Entry) for apertures on the outside surface), POIs (Points Of Interaction) for internal apertures, POCs (Points Of Couplings) for cables, POAs (Points Of Absorption) for lossy volumes and surfaces. Let us make precise that pre and post processing for each of the modules and submodules are common steps for both LFB and HFB scenarios and are not represented in Figure 1 and Figure 2.
Both calculation scenarios are based on a similar scenario in which 3D solvers (Full Wave or Asymptotic) provide source input data for a network model; Multiconductor Transmission Line Network ( (MTLN) or Power Balance models. The network analysis is particularly well suited for parameter analysis and allows qualifying separately each network constituent analytically or numerically (with data files). In both cases, the network design is prescriber for the definition of the output requests required in the 3D codes for the calculation of their source terms.
The LFB scenario relies on the use of 3D solver modules for calculating EM fields in 3D environment up to 3GHz. The model of on which the 3D calculation is made includes both the external and the internal domains. In particular, no distinction is made on inner elementary volumes.
The calculation of the wiring response up to 400 MHz involves either thin wire models meshed within the 3D model or MTLN models for wiring response at pin level. For MTLN, the model of network is completed by the model of equipment which provides the end loads at pin level applying generalized Thevenin description of multiport systems. The Field to Transmission Line (FFTL) process insures the connection between the 3D solver and the MTLN solver. It works in the following way:
- The 3D solver provides the incident fields along the central path of the wiring. In particular, the central path corresponds to the path of a wiring on which incident fields can be calculated. The central path is not part of the meshed 3D model; it is a fictitious route inside the 3D model on which the framework will declare output requests. This central path is split in groups in direct correspondence with the tubes of the network. Along the groups the incident fields are calculated and stored.
- The incident electric fields stored in groups are projected along the central path and therefore provide the distributed voltage sources (Agrawal’s formalism) for each tube of the network.
At the end the MTLN solver makes the final network calculation of total common mode currents (Icm) and currents and voltages at pin level (I and V).
In terms of calculation performance:
- The Full wave calculation on both the external and internal domains is long and may take several hours depending on the size of the 3D model (number of cells of the 3D mesh)
- The MTLN calculation is much shorter; it is typically made in tens of minutes allowing therefore parameter analysis on the same central path (nature of cables, cable bundle internal organization, end connections, cable -shield connections…)
Figure 1: The HIRF SE LFB scenario
The HFB scenario relies on two types of modules:
- An asymptotic solver for the calculation of the input fields at the POEs.
- A Power Balance solver that uses the incident fields at POEs in order to calculate the total power which is injected inside the inner volume. All the penetration points identified in the topological analysis are associated to coupling so-called cross-sections that can be calculated analytically or specified in data files.
In terms of calculation performance:
- The interest of the asymptotic solver is to make possible the calculation on the whole surface of the object at high frequency, which is not possible with currently available Full Wave solvers. The calculation time is about some hours.
- The Power Balance method only calculates in a few tens of seconds and also offers parameter analysis on the various coupling cross-sections.
Figure 2: The HIRF SE HFB scenario
Finally note also that a third scenario derived from LFB and HFB scenarios, called Medium Frequency band (MFB) scenario, was also implemented in HIRF SE to cover the modelling need on the overlapping frequency band between 400 MHz and 3 GHz. This scenario combines the use of a Power Balance tool for the field environment, from which a plane-wave spectrum decomposition is obtained in each zone of the object, and a MTLN tool for the application of Field-to-Transmission line using the plane wave spectrum as incident fields. The FFTL process is optimized with a reciprocity formulation.
Example of application of the LFB scenario:
Figure 3 shows an application of the LFB scenario on the Piaggio P180 nosecone. The object was tested on Alenia-Aermacchi’s open test site in Caselle, Italy, where it was illuminated by various types of antennas in a frequency range up to 400 MHz. For this specific application an instrumented equipment (IE) prototype developed by Selex has been installed inside the bay and allowed measurement of signals at pin levels. It was connected to a remote box with a cable-bundle. The implementation of the LFB scenario on this test-case was made in the following steps and with the following modules:
- Pre-processing: the AEMMESHER tool developed by IDS was used to manage the CAD model and to generate a triangular mesh. The edition of the cable-bundle network model was made with ONERA’s CRIPTE editor module. The model of the equipment common mode input impedance came from the IMEA tool developed by Thales Communication Systems and was completed by CRIPTE-editor in order to introduce differential loads in the impedance model.
- Field calculations were made with IDS’s IDSMMMP Method of Moment tool, both for the calculation of EM fields at local test-points and along the central path of the wiring under test.
- The MTLN calculation was made by the CRIPTE-calculation module from ONERA and provided total common mode current on the bundle and currents at pin level of the IE.
Figure 3: Application of the LFB scenario on the Piaggio 180 nosecone
Example of application of the HFB scenario:
Figure 4 illustrates the implementation of the HFB scenario on Evektor’s VUT100 aircraft. It involved the following steps and the following tools:
- Pre-processing: CIMNE’s GID tool was used to manage the CAD model and generated the triangular mesh. The Power Balance model of the interior domain was obtained with ONERA’s PWB-editor tool.
- Field calculations for the external problem were made on the canopy of the aircraft (considered as the main POE in the aircraft) with OKTAL-SE’s SE-RAY-EM asymptotic tool.
- The Power Balance calculation was made by the PWB-calculation module from ONERA and provided field observables inside two main compartments in the aircraft (cockpit and avionic bay zones).
Figure 4: Application of the HFB scenario on Evektor’s VUT100 aircraft
Modelling status at the end of HIRF SE:
At the end of HIRF SE we can state that all the tools already existing before the project have been improved in parallel to the development of new tools in order to access the level of complexity required for AC/RC modelling. Most of the tools are ready to use and compatible with the AMELET format. Others are still waiting for future implementation. Nevertheless, we can say that the scope of the tools and proposed scenarios widely overcomes the strict scope of the HIRF issue; indeed one can logically think to apply them to indirect lightning and EMC types of problems.
1.3.4 Module validation processes based on the comparison between measurement and simulation campaigns
All the tools, modules and submodules constituting HIRF SE have been object of different validation process in order to assess the computational results. The validation processes are based on the comparison between simulation and measurement results and for this reason, massive campaigns of measurement, simulation and analysis of results have been carried out during the last three years of the project.
The convergence between measurement and simulation results happens only if the three following condition are verified:
- The electromagnetic phenomena are correctly represented by the implemented computational algorithms
- The test set up is well known and correctly modelled
- The numerical model of the object under test is enough representative of the HW ones
Two main levels of validation process have been developed and applied for tool assessment:
- On “simple”/geometrical controlled test cases: the goal is to verify that the numerical models correctly compute Maxwell’s Equations. Tools that passed this level are assessed for air vehicle design applications and can be proposed to the second level of assessment
- On air vehicles: the goal is to verify that the air vehicles are correctly represented by their “electromagnetic synthetic model”, to give guidelines for the modelling and to start to build a database for Coupling Cross Section, POA, POE, POB. Tools that passed this level can be proposed for air vehicle simulation for certification purposes.
1.3.4.1 Validation process on geometrical controlled test cases
The first level of validation was based on about 70 hardware test cases that has been modeled and simulated and was based on the principle of the increasing complexity. The test cases have been divided in three main groups:
- The test cases of group 6.1 are finalized to the validation of models developed in WP3 as standing alone codes, not already integrated in HIRF SE framework, and are used for an early validation of the models before integration. Therefore this type of TCs is characterized by very simple configurations that do not require the combined use of different models.
The group 6.1 of test cases is organized in three different typologies of TCs:
- Materials;
- Cables;
- Equipment.
- The test cases of group 6.2 are finalized to validation of modules as standing alone codes or possibly integrated in HIRF SE framework, applied on simpler test configuration in which all details can be constructed and controlled completely. Therefore this type of TCs is characterized by simple configurations which can be modeled using a combination of two or a few different models. The group 6.2 of test cases is organized in different typologies of TCs:
- Materials
- Material configuration
- Cable bundles and loads
- Material configuration and bundles
- The HW test cases of group 6.3 are finalized to the validation of sub-modules and modules integrated in HIRF SE framework applied on complex test objects representing parts of aircrafts or rotorcrafts.
EMC/HIRF standard, such ED 107, have been taken as reference to carry out the measurement but the most important aspects that ruled the process was the capability to correctly model the test object and test set up: it is more important to know the exact position of the probe or the characteristic of the radiating antenna than to be in far field condition. Moreover measurement are not the soul of the truth and the influence of the test set up and environment need to be evaluated and correctly interpreted to carry out a reliable comparison with simulation results.
Three comparison methods was used for the tool assessment:
- Direct comparison superimposing measured and simulated data on the same graphics.
- Application of IELF methodology.
- Application of IEEE Std1597.1 – 2008 FSV-VSR methodology.
A relevant point in the judgment process is the evaluation of the consistency between the numerical model of the test object, the measurement set up and the real test object and the real set up. For these reason the use of FSV and IELF codes can help in the evaluation process but they can in any case substitute the expert judgments that are mandatory for the assessment.
1.3.4.2 Validation process at air vehicle level
The validation process has demonstrated on several real aircraft that the Framework is able to predict electromagnetic response of complex test objects in various test configurations such as LLDD, LLSC and LLSF. The following platforms have been used:
PIAGGIO P180:
AUGUSTA AW 139
EUROCOPTER EC 135
BAE NIMROD
DASSAULT 7X
EADS CASA C295
EVEKTOR VUT100 EV55
INTA SIVA
The validation process is designed towards specific objectives that the framework has to provide during the development phase and during the certification phase. During the development phase the validation process should answer the following question:
Is the HIRF SE numerical approach valid to allow design decisions?
Although during the Aircraft Type certification phase or Supplemental Type Certification phase the question to be answered is:
Is the HIRF SE numerical approach valid to determine the Electromagnetic environment of Aircraft equipment and system in view of equipment specification?
For these two objectives a validation indicator has to be defined. This validation indicator is called the “pass/fail criteria”
For development phase just looking whether measurements and simulations show the same trend of variation against an installation parameter such as a cable route or a cable shield is sufficient to validate the use of numerical simulation in the development phase.
For certification phase the numerical approach will be considered validated if Equipment and system specifications derived from measurements and specifications derived from computation are less than 6dB apart, In order to verify this pass fail criteria measurement data and simulation data have to be processed in the same manner. The data processing which has been selected is derived from ED 107A/ARP5583A and consists in averaging the responses using the 5% band width filter, followed by a peak spreading over an octave envelope, eventually followed by a general envelope of several data of the same type.
Two aspects of validations have been used in the project one dedicated to the framework validation itself the other dedicated to the validation of the numerical approach. The first one consists in the comparisons of results between different numerical approaches; the second consists in the comparison between measurements and simulations. The conclusions on the final validation are based upon the second aspect only. This second aspect involves two main items. The framework itself upon which the validation is focused on: How well are equations solved, how well is EM coupling represented (bundle complexity, apertures, slots, materials). The second aspect is related to the Aircraft model for which the validation is focused on how well is the aircraft meshed? How well specific EM features are present? Unfortunately the final results aggregate both items.
The conclusion of the validation process can be summarized as follows:
- For LLDD Test configurations the code appears to be validated up to 30MHz frequency above which aperture models, lossy materials models, various skin effects which presumably have an influence on the results are not currently implemented and validated inside the framework.
- For LLSC test configurations it appears that the user’s effort should be concentrated on the validity of the model
- For LLSF test configurations:
• In the region 1-3GHz the 3D approach is validated
• At lower frequencies the validation is jeopardized by the difficulty of the description of the test setup.
• At higher frequencies the statistical approach (PWB methods) will be fully validated once a validated extensive database of Coupling Cross-Sections (CCS) for POEs, POA and POC will be available.
From the above statements the final validation process leads to the following conclusion:
o For development purpose:
The parametric studies have shown that the trends are well represented and therefore that the P/F criteria for development phase is reached by the numerical approach
o For certification purpose:
- For conduction environment:
Since the HIRF SE framework is validated all the effort should be focused on the validation of the A/V-R/C models
The A/V-R/C models should be placed in a normative test setup to be validated, the setup numerical representation should be validated through measurements of surface currents on a sufficient number of locations
The specifications which can be derived from numerical approach are equivalent to the specification which can be derived from measurements
- For radiated environment:
For the external environment of the A/C test setup SC test cases in LLDD have shown that the numerical approach gave after some light tuning fully identical results from measurements and from computation.
For internal environment up to 3GHz, the 3D approach gives results that can be used for certification purpose since due to the lack of slots models and to the under-implementation of lossy materials the computed fields are generally higher than those measured.
For higher frequency the statistical method and PWB method are promising but require the completion of a CCS database for POE, POC, POAs.
Potential Impact:
1.4.1 Potential Impact
The use of HIRF SE framework by aeronautic industry will directly benefit the design and certification phases of air vehicle production.
Application of HIRF SE from the very early stages of the design will bring to a reduction of the serious problems of safety that EM hazard poses by the increased use of high speed electronic equipments in small, medium and large aircraft. The possibility to anticipate and predict the electromagnetic performances of a new aircraft or rotorcraft will bring to a more accurate and tailored design of the electromagnetic protections in particular and air vehicle design in general (e.g. air vehicle wiring routing, equipment installation and placement, material selection).
Application of HIRF SE during the certification phases will allow the aeronautic industries to carry out an intensive testing in a simulated flight condition taking into consideration the ground effect, the proximity of the electromagnetic sources and the under sampling limitation of testing raising to a higher level the safety of air vehicles. Moreover, once the air vehicle models will have been consolidated and validated, it will be possible to reduce the testing time for certification.
The societal beneficial effect is mainly in the increase of safety for the customers and a possible decreasing of cost due to a more efficient design process. In fact the customer safety can be ensured due to the fact that HIRF SE application in the design will aid the implementation of new media and communications systems (e.g. wireless internet connections, mobile phone connections, etc) as well as the integration of new on board maintenance systems and general broadband connection by on ground and satellite links.
According to the framework electromagnetic specification, HIRF SE may be applied, with the same benefits, also to various other ‘scientific’ fields beyond that of aeronautics.
Essentially, since the framework would be able to model the EMC/HIRF aspects of air vehicles, the same principles and, hence, software could also be applied for simulations in the automotive, naval, defence, etc fields.
Examples of potential areas for HIRF SE applications are indicated below:
- Aerospace
- Automotive
- Rail industry
- Naval
- Defence
- Material manufacturers (due to the capability of the tool to deal with materials’ properties from an electromagnetic point of view).
The capability of HIRF SE to simulate the environmental electromagnetic conditions can be exploited even for safety evaluation both for civil air vehicle passengers and inhabitants of urban areas. As a matter of fact, the increasing use of on board wireless systems and transmitting equipment poses the needs to verify which is, under a safety point of view, the electromagnetic environment inside the fuselage and in this sense HIRF SE can be applied for preventing possible sources of hazard for passengers’ health. As well HIRF SE can be applied to evaluate how installations of new or existing antennas modify the urban electromagnetic environment: the level of perturbation can be compared with the existing civil regulation electromagnetic level in order to prevent possible hazard for inhabitants.
1.4.2 Main Dissemination Activities and Exploitation of Results
This section describes the main dissemination activities under the headings used in the DoW.
• Scientific Publications: Research active partners in the programme have been encouraged to publish their results in a range of peer-reviewed venues. The venues are principally peer-reviewed journals and peer-reviewed conferences.
Principal European conferences specifically targeted were EMC Europe (2009 to 2013) ICEAA 2011 and EuroEM 2012. Specific HIRF-SE Workshops or conference sessions were promoted at all these.
The partners were responsible for originating the publications and liaising with other partners in order to produce joint publications. A document entitled “Instructions for the Publication of Scientific Papers arising from HIRF-SE” was issued to all partners detailing the steps to be taken in the production of a scientific paper. These include verifiable permissions for the use of partners’ IP for both publication and presentation. All HIRF-SE papers submitted for publication by partners were subject to Steering Committee review through their presence on a dedicated section of the private web pages. Steering Committee members were notified when a paper was submitted for review and then had thirty days to respond. No response was deemed to be acquiescence. The purpose of the review was to check for IP issues rather than a technical review. Papers were then subject to peer-review as usual and published papers were uploaded onto the private area of the website available to the Steering Committee, the Advisory Board and the EC Review Panel.
A list of all publications appears at the end of this report.
• YSP (Young Scientists’ Programme): the Young Scientists' Programme (YSP) on EMC in Aerospace Systems was offered by the HIRF SE consortium on an annual basis, linked to the annual EMC Europe conference. The YSP was intended for the benefit of young practitioners, Graduate Students and Senior Undergraduate Students. Lectures were presented by experienced industrialists and academics working on the HIRF SE field from within the consortium and the Advisory Board. The programme addressed the shortage of younger practitioners on Aerospace related electromagnetics.
Presentations covered a wide variety of topics in Aerospace EMC and were aimed at encouraging young scientists and engineers to consider making a career in the field. Each YSP comprised around six or eight lectures each of ninety minutes delivered over two days at the start of the conference. Typically audiences of twenty to fifty people attended. The lectures were open to all conference attendees and were attended by a wide range of people.
The powerpoint presentations of all YSP events are available from the Knowledge section of the EMC Portal on the public project website.
The quality of the lectures was monitored by asking the registered attendees to complete an evaluation form. The returns were analysed to facilitate improvements for subsequent years and to ensure that a proper level of presentation was made. Analysis of the returns showed a discernible improvement year-on-year. Return analyses were presented in the annual deliverables D10, D21, D33 and D39 (CPD Courses, Scientific Papers, YSP and Observatory of EMC issues).
The YSP events were held as follows:
o The 1st Course of the YSP was held on the side of the EMC Workshop 2009 conference in Athens, Greece (10-11/6/2009).
o The 2nd Course of the YSP was held on the side of the EMC Europe 2010 conference in Wroclaw, Poland (13-14/9/2010).
o The 3rd Course of the YSP was held on the side of the EMC Europe 2011 conference in York, UK (26-30/9/2011).
o The 4th and final Course of the YSP was held on the side of the EMC Europe 2012 conference in Rome, Italy (17-18/9/2012).
• Internal CPD (Continuous Professional Development): A programme as complex as HIRF-SE requires considerable internal communication between the partners. This was facilitated in part by the development of CPD courses for internal use within the consortium. These courses covered a variety of topics where a particular partner had produced foreground that required structured dissemination to selected partners. CPD courses typically lasted between one day and one week and allowed partners to collect information at an appropriate point in the programme. CPD courses typically comprised lectures or hands-on demonstration sessions. In some cases the material was delivered as a series of online tutorials with the participants working from their own place of work and in communication with the presenters through audio conferencing with online presentation of materials. A similar presentation quality monitoring system to that used for the YSP was implemented for all CPD courses. The outcomes of this process were reported in annual deliverables D10, D21, D33 and D39 (CPD Courses, Scientific Papers, YSP and Observatory of EMC issues). Material presented by Dassault on the technical aspects of WP7 is used as the basis for the course material in D46 (Technical User Guide and Course Delivery).
• External CPD: A number of CPD resources will be available after the end of the project. These are encompassed in D46.
o Technical User Guide; This is an introduction to the Framework, a brief description of each module and directions to more detailed documentation.
o Teaching Materials (TCM1); This is based on the Dassault internal CPD module. It gives technical guidance on the different modelling techniques and tutorials on how to use them.
o Teaching Materials (TCM2); This material based on previous presentations to EASA detailing the certification aspects associated with the Framework.
• Dedicated HIRF SE Workshops: These were typically held at major European events of the EMC field:
o EMC Europe 2009, 2010, & 2011
Workshops held at conferences differ from regular conference sessions in as much as conference papers are peer-reviewed by the conference review panel whereas Workshop contributions are only reviewed by the Workshop convenor. Workshops were the principal visibility of the HIRF-SE programme for the first three years. After this time it was decided that the project was at a sufficient state of maturity that it was able to promote regular conference sessions in which HIRF-SE partners presented peer-reviewed papers alongside other authors. With the exception of one event detailed below all presentations at conferences after EMC Europe 2011 were peer-reviewed regular papers.
In March 2013 project partner UGR organised a Workshop CEMEMC 2013 to highlight the Numerical Test Cases used in the HIRF-SE project. This Workshop was organised around the HIRF-SE project and six papers were presented by members of the HIRF-SE consortium along with papers from co-workers in other projects. The theme of the Workshop was built around the Numerical Test Cases used in the HIRF-SE project. In all, twelve papers were presented at the event.
• Final Dissemination Event: The HIRF SE Project held its Final Dissemination/Stakeholder Event on the 29th of May 2013.
The event was run over a whole day hosted by the co-ordinator ALA in Torino. During the event, the final outcomes/results of the project were disseminated to a targeted audience consisting of related industry stakeholders. In order to facilitate wide dissemination of the work beyond the aeronautic field the EC recommendations concerning invitations to a wide range of stakeholders suggested by project partners have been followed. All partners were asked to provide a list of names of relevant people to invite. This list included people from industry and academia and known workers on other cognate projects in the Built Environment, Road transport and Rail transport. The consolidated list was used by the Dissemination Manager and logistical information for participants was placed on the project public website.
The aim of the event was to publicise the outcome of the project and to act as a portal for interested parties to start their exploitation of the HIRF-SE framework. The main scientific results of the project were described to those attending along with a description of the Framework. The Framework was demonstrated to the attendees. In addition each partner was invited to present a poster detailing their research contribution to the HIRF-SE project. Attendees were provided with copies of the posters on a USB key drive.
• Dedicated Presentations at major industry events: The project objectives, scope and results were promoted through dedicated presentations at major events of the industry, such as:
o Aerodays 2011 (http://www.hirf-se.eu/hirf/themes/garland_HIRF/files/3D3-Aerodays-Presentation-Bozzetti.pdf).
o AES (Advanced Electromagnetics Symposium) 2012 (http://www.hirf-se.eu/hirf/?q=node/117).
The online dissemination ‘means’ used by the project so as to promote its objectives, activities and results are discussed in the following section (“Address of the Project Public Website”).
An important aspect of the project was the HIRF SE application inside certification phases of air vehicles. For this reason EASA has been involved as advisory board members. Several contacts have been established along with the project in order to disseminate project results within authorities or bodies that have influences in regulation or standard for air vehicle certification. Besides EASA, EUROCAE and FAA were contacted and informed about HIRF Se possible application and results.
The roadmap indicated in figure 5 for air vehicle certification based on a numerical approach (always supported by measurement), was worked out with EASA. This roadmap could be used as reference for future upgrade of ED 107.
Figure 5 Certification roadmap and use of numerical approaches
The Project Public Website. The HIRF SE project website promotes the project objectives, results and news via the following address: http://www.hirf-se.eu The project website has both public and private sections.
In the private section all the documentation associated with the project is accessible to the project partners. This includes consortium meetings as well as scientific data and scientific papers under review.
The public section of the website contains general information about the project and the following specific sections.
The complementary ‘Observatory on EMC Issues’ (knowledge) Portal, established as a dedicated action of the project (WT8.4) disseminates project related materials and scientific knowledge through the following address: http://www.hirf-se.eu/portal The portal has a wide range of material including basic science descriptions of HIRF-SE related electromagnetics suitable for university level teaching and all the YSP presentations.
The HIRF SE Public Database (http://public.hirf-se.eu) a database of models, geometries and other files shared by the HIRF SE Consortium and its comprising members with the aim to disseminate the HIRF SE project results to the wider scientific community and to elevate the knowledge 'capital' in the associated scientific area, continues to be available for interested parties to register.
List of Websites:
The HIRF SE website will be kept active even after the end of the project for commercial reasons. The address of the website will be the same as the public ones that was used for HIRF SE dissemination http://www.hirf-se.eu In the following paragraph there is the list of the main point of contact for each partner working of HIRF SE project