FEM/BEM Vibroacoustic Simulation in the Automotive Field: High Performance Computation Codes Benchmarking

The relevance of simulation methods for the assessment and the analysis of exterior noise in the automotive and truck industry is likely to increase in the fore coming years. That is due to the announced revision of the ISO 362 regulations as well as to the strong increase in the variety of options for what concerns the definition of the sound package in the engine bay offered to automotive and truck OEMs. As a consequence the manufacturers are forced to look with interest at methodologies that allow making "big" decisions (e.g. which concept to use for an absorber or where to put the shields under a truck's cabin) already in the design phase. Available deterministic simulation methodologies have been tested by the authors during these last years in relation to the above-mentioned problem. The object of the simulations consists in evaluating the exterior Acoustic Transfer Functions (ATFs) of a simplified (but not trivial) vehicle engine bay mockup in the analysis frequency range up to 3.5 kHz. The focus was concentrated on both traditional and more innovative deterministic analysis methods. BEM and FEM acoustic technologies, and their implementations in Siemens Virtual.Lab code as FM BEM and FEM AML, have been mainly tested in this benchmarking activity. The computation performance of the very last approach FEM AO has also been evaluated. A comparison with experimental test results is always taken into account as a reference in order to judge on the methods models accuracy. The capabilities of these methods to well represent both acoustic trim parts effect and apertures positioning around the engine bay was assessed and their computational performance compared.