High Complexity Vehicle Models Analysis & Simulation Methods

In view of the foreseen ISO 362 standard update in a more restrictive way, power-train exte-rior noise is likely to become a relevant issue in the automotive industry. This will lead to a strong focus on the design of engine shields and other thermo-acoustic trim parts positioned inside the engine bay. The possibility of designing such parts in an efficient and cost-effective way will call for reliable simulation methods to tackle real industrial cases. These methods cannot be easily taken for granted since, to be useful in the design of engine bay components aimed at exterior noise reduction, they have to satisfy quite challenging require-ments as being able to: 1) take into account large frequency ranges and big model sizes in a reasonable computation time (about 1 day), 2) represent very complex domains and 3) repre-sent design changes affecting sources or acoustic transfer paths. This article intends to docu-ment the progress made in these last years by commercially available deterministic simula-tion methodologies 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 mock-up. The focus was concentrated on both traditional and more innovative deterministic analysis methods: the Boundary Elements (BE) method, Finite Elements (FE) related methods (Infinite Elements, Perfectly Matched Layer (PML) method) and the Patch Transfer Functions (PTF) method, pushing them to cover all the frequency range up to 3.5 kHz. The capabilities of these methods to well represent both acoustic trim parts effect and apertures positioning around the engine bay was assessed and their computa-tional performance compared.