Hybrid Finite Element Analysis (Hybrid FEA)

In vehicle applications sources of structure-borne noise (i.e. electric motor, engine, gearbox, suspension, etc.) create excitation up to frequencies of several hundred or thousand Hz.

In such situations, the difficulty in using conventional FEA originates from requiring a very large number of elements in order to capture the flexible wavelength of the flexible panels which are present.

In order to address this difficulty the Hybrid FEA combines FEA and EFEA solvers.

The conventional FEA model is modified by de-activating the bending behavior of the flexible panels in the FEA computations and introducing instead a large number of dynamic impedance elements for representing the omitted bending behavior of the panels.

The excitation is applied on the conventional FEA model and the vibration analysis is conducted using the FEA. The power flow through the dynamic impedance elements is computed, and applied as excitation to an EFEA model of the flexible panels, the acoustic treatment, and the acoustic cavities. The vibration at all structural components and the interior noise are computed.

Hybrid FEA results have been compared successfully with test data for many automotive and rotorcraft vehicles.

As sources of excitation (i.e. electric motors, engine, suspension, etc.) in automotive vehicles are encountered in ranges above 200Hz the need for extending the finite element methods for noise and vibration analysis to higher frequencies becomes important. The Hybrid FEA provides this capability.

In rotorcraft applications the gearbox provides excitation up to several KHz. The Hybrid FEA can compute the input power, the vibration of the rotorcraft structure, and the interior noise levels.

The Hybrid FEA computes the transfer functions between the different excitation locations and the interior noise levels. This information is used for determining the optimal placement and selection of acoustic treatment. The simulations allow to balance the reduction in the interior noise level against the increase in the weight by strategically placing the treatment material on the vehicle body.

MES is proud to be a member of the Altair Partner Alliance (APA). EFEA and Hybrid FEA are available through the APA. To learn more, visit https://www.altair.com/efea/.

Altair is a global technology company providing software and cloud solutions in the areas of simulation, high-performance computing (HPC), and artificial intelligence (AI). Altair enables organizations across broad industry segments to compete more effectively in a connected world while creating a more sustainable future.