Computational Electromagnetics

The Advantages of Using Computational Electromagnetics

Computational Electromagnetics (CEM) tools allow for highly complex scenarios (lightning effects, high-intensity radiated fields, cable cross talk, etc.) to be evaluated with a high degree of accuracy. EMA has worked on solving these types of problems for well over 40 years.

Common questions EMA encounters are with regards to the workflow of incorporating and using these simulations effectively. Often, many companies wish to employ simulation and modeling for electromagnetic problems but have misconceptions about when it is best to use them or when the data is accurate enough to use for decisions. Companies often feel as if they have to do extensive testing prior to beginning simulation work.

Figure 1- CAD Rendering of an F-16

EMA is a big supporter of employing simulation and analysis early and often to aid in risk reduction and decision making. The beauty of today’s CEM tools, especially EMA3D, is their compatibility with CAD data. Many companies are under the impression that simulation data is not valid or useful until testing can be performed. Testing, in many cases, is not feasible at the points in a design where simulation would be most valuable. Why build something as expensive as an aircraft if you have risks that would cause expensive re-work?

In EMA’s experience, it’s appropriate to employ simulation and analysis for electromagnetic problems early in the design. Maxwell’s equations, which are the governing mathematical equations used in CEM, rely on two key features to ensure model accuracy given that the mesh, time stepping, and other aspects are appropriate as well. The first feature is the physical geometry. Most designs begin in a CAD-based format, such as CATIA or CREO. EMA3D can directly import these files and use them for simulation. In doing so, the vast majority of coupling and distribution mechanisms can be captured with a high degree of accuracy. The second feature, which is equally as important, is material parameters. Many of these parameters are well understood, but composites and other anisotropic or complex materials should be measured. By using a CAD-based geometry and reasonable material parameters, the accuracy of spatial relationships and the overall fidelity of the model will be quite high.

Figure 2 – Fully Configured F-16

Testing is needed to determine specific material parameters in complex regions like seams and joints. Testing is particularly important for the indirect effects of lightning at the pin level and HIRF transfer functions. Many of these tests can be done at the coupon level to provide the necessary inputs to the simulation. These help “tune” the model to be as accurate as possible. Material properties are simple to change and require little to no geometry changes to incorporate in most cases.

 

Figure 3- Meshed Plane Wave (HIRF) Configuration For a Military Helicopter

Another advantage of CEM is the compatibility between different types of analyses. Running a “lightning” model is commonly done on the same physical model that is used for cable analyses, RF analyses, and more. This means there is no duplication of work to build a separate “model” for other types of analyses! Additionally, many features are not required for different types of analyses. For zoning and initial leader attachment analyses, most cabling, joints, and fasteners are not required.

Figure 4 – Cable Measurements

Even approximate wire locations can provide valuable insights in cases where final routings or specifications are not yet available. Approximate routings or cable packings, with reasonable structural fidelity, can highlight problem areas where efforts can be focused earlier in projects. As designs mature, it simply becomes a case of moving wire paths and packings, which typically does not result in widescale geometry changes. The time it takes to make these updates is not long! Contact us today to learn more about how we can assist you!

Figure 5 – Plane Wave Induced Current Traversal

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