E3 Support for Optimized Aerospace Designs
Ensuring the safety, efficiency, and reliability of aircraft starts by focusing on electromagnetic environmental effects (E3).
“Lighting, HIRF, and RF interference require you to understand the structure, understand how the cables are laid out, understand where things are, and the external environment and that’s really difficult,” EMA Principal Scientist II Justin McKennon says. “It’s going to be different on just about every platform.”
EMA consulting and simulation allows manufacturers to avoid unnecessary testing and analysis.
“Ultimately, your requirement is not to pass MIL-STD 461 or DO-160 tests, it’s to expose your equipment to the onboard electromagnetic environment and prove that catastrophic failures don’t occur,” McKennon says. “I can run a simulation far faster and far cheaper than it costs to put this test together.”
E3 Challenges
E3 analysis becomes a major challenge when not handled correctly. McKennon advises evaluating lightning and high-intensity radiation fields (HIRF) at the platform level. He emphasizes that a design decision may be compatible with one system of the aircraft but not with another. For instance, engineers may discover that they cannot use a fastener type after building a prototype.
“If you wait until you are doing complicated testing, you’re going to miss a lot of root causes,” McKennon says. “If you find that you’re getting high cable bundle transient levels during your lightning testing or during your HIRF testing, you’re getting your swept current too high, how do you fix that? Well, everything’s integrated at that point, and you change one thing, you’re probably changing something else, and that’s really where you can lose it.”
Fig. 1. Physical airplane testing. Courtesy of Embraer.
E3 Analysis
Get to the root cause of problems with E3 support from EMA.
A significant advantage of working with EMA is Ansys EMC Plus simulation. This modeling provides opportunities to assess and improve the aircraft design for E3 while significantly reducing programmatic risk and schedule.
“For simulation, all you need is CAD,” McKennon says. “This lets us peel back the onion and start to interrogate measurements that we can’t make until far later in the program.”
Fig. 2. Example of airplane simulation in Ansys EMC Plus.
Simulation plays a key role in E3 analysis because it can:
· Accurately predict the internal environment with relatively few details
· Easily evaluate changes to the aircraft or wire routing
· Perform lightning zoning
· Calculate valuable information that cannot be measured
Deliverables
EMA provides comprehensive E3 support and simulation activities. All analysis will be the worst case of FAA and EASA requirements. If necessary, EMA can look at more severe requirements.
Lightning Zoning
As a part of any lighting certification program, lightning zoning is required to understand where the initial attachment and hand-on locations will occur. Once the initial attachment is determined, the environments of ARP5412 can be appropriately applied for verification and certification.
There are three accepted methods for lightning zoning initial attachment determination:
· Scale Model Testing: A small model version is tested in a high voltage lab. The model is adjusted to see where lightning arcs are likely to attach.
· Rolling Sphere Analysis: A sphere whose radius is related to the possible peak lightning current is rolled over the aircraft outer mold line (OML) to see where an attachment is likely to occur.
· Electric Field Modeling: Using EMC Plus simulation, a leader is brought near an aircraft model to see where the E-field is most likely to attach.
Fig. 3. Example of lightning strike zone details for swept wing business jet.
EMA will decide the best method for each program.
Manufacturers will need to provide OML CAD data for the aircraft and general material properties for all extremities.
EMA will generate a zoning report with OML images that identify lightning zone locations similar to what ARP5414 identifies.
IEL Simulation for TCLs
EMA will update the OML model for indirect effects lightning (IEL) simulation to include a basic metallic interior and representative harnesses on vehicle extremities. Details of simulations include:
· 3 attach/ detach configurations
· Bundle current for all harnesses
· Voc and Isc for 10 pins
To complete initial IEL simulations, EMA will work with the manufacturer on basic representative harness routing. The manufacturer will also need to provide material properties for exterior and internal structures. Composite and engineered coated fabrics (ECF) resistive properties may not be known at this time and EMA will suggest engineering approximation for electromagnetic parameters.
EMA will generate a report identifying transient control levels (TCL) similar to what is identified in ARP5414 and used for standardized DO-160 Section 22 testing.
HIRF Simulation for LLSC and LLSF
EMA will use the same model developed for IEL for HIRF simulation but with additional field probes added in the cockpit and avionics regions for low-level swept field (LLSF) evaluation. This simulation technique provides field data up to ~1GHz. This works for low-level swept current (LLSC) coupling up to 400 MHz. EMA has simulation techniques to go to higher frequencies but would be outside the scope of initial analysis.
Details of simulations include:
· 6 configurations: 3 incidence angles x 2 polarizations for each incidence like those shown in Figure 4.
· Bundle current for all harnesses (LLSC)
· 3 Electric Field regions (LLSF)
Fig. 4. Sample illustration orientations for HIRF assessment of aircraft.
No additional information is needed for this HIRF simulation; however, EMA will confirm field probe locations with the manufacturer.
EMA will generate a report identifying LLSC and LLSF enveloped category data in report similar to what ARP5583 identifies and what is used for standardized DO-160 Section 20 testing.
Test Services
Once simulation is complete, EMA can also handle HIRF and lightning testing. Tests can be used to verify estimated test and design levels (ETDL) and actual transient levels (ATL) with an acceptable margin for Level A systems, characterize current distributions on wiring and structural components, and validate simulations.
Fig. 5. EMA lightning generator.
The lighting transient generator can take voltage, current, or magnetic field measurements in addition to:
· Using Component A generator (up to 3kA) and Component H generator (up to 200A) to take current and voltage measurements on pins, cable bundles, and structural components. This provides the necessary inputs for qualification and certification activities.
· Open circuit voltage and short circuit current measurements for pin test definitions.
· Cable bundle measurements for multiple burst and multiple stroke environments.
· HIRF and TPED testing to quantify the internal electromagnetic environment to establish the certification/qualification levels needed for equipment and systems.
· Laboratory testing for low level arc threshold and qualification campaigns.
EMA will travel to your locations for measurements. The process is different for each project and will depend on the goals of the test or lightning verification program.
Start Now
“Safety is what drives 95% of the work in electromagnetic effects,” McKennon says. “But the downside is that the safer or less risk that you have in your platform, it is almost one-to-one with added costs and reduced performance.”
EMA supported E3 analysis allows for cost efficiency without compromising on performance. EMA has provided E3 simulation, design, and certification support for many prominent aviation and aerospace platforms such as the Bombardier C-Series, Embraer E2 jets, and Lockheed Martin NASA Orion MPCV.
Benefits of partnering with EMA include:
· On-site support around the world in all aspects of electromagnetic effects (EME)
· A full authority lighting FAA Designated Engineering Representative (DER) on staff
To learn more about our aircraft certification simulation program watch the Solving Electromagnetic Challenges webinar “Leveraging Test and Simulation to De-risk Certification” by clicking here.
Ansys is the exclusive seller of Ansys EMC Plus. To learn more about using the software talk to your Ansys representative or click here.
To see how EMA can support all of your E3 projects, reach out to our team here.
