Optimization methodologies based on structural modification analysis in automotive NVH design

Nowadays, in automotive industry the design cycle of vehicle bodies is predominantly ruled by the highly competitive nature of the market, the ever increasing customer demands and expecta-tions and the strict legislation concerning the environmental impact. Higher-quality products must be achieved in ever shorter time frames, while reducing the design costs. This only occurs when the design cycle takes place mainly on a virtual environment such that the traditional physical prototype phase can be drastically shortened. As a result, each stage of the design cycle is supported by CAE (Computer Aided Engineering) methodologies which allow predicting various functional perform-ance attributes, such as NVH (Noise, Vibration & Harshness), crashworthiness, etc. Moreover, re-searchers have developed many techniques to speed up the calculations, enabling modification ap-proaches in view of design optimization. This paper focuses on the vehicle interior NVH performance in the low frequency range, which is governed by the global modes of the vehicle body and its enclosed cavity. For a vehicle body Finite Element (FE) model, a reduced formulation has been achieved by using the WBS (Wave-Based Substructuring) technique. From the nominal FE model, a panel subcomponent is firstly selected as critical for the global NVH behavior and subsequently selected as target for the bead modification. By combining the WBS-reduced model with an ATV (Acoustical Transfer Vector) approach one can efficiently evaluate the effect of bead modifications on the NVH behavior in an optimization loop. The main innovation introduced in this paper comprises the optimization of vehicle vibro-acoustics with an acoustic target by making use of a structural optimization software running un-coupled structural FE analyses. Several methodologies have been worked out, mainly based on two state-of-the-art optimization strategies for bead pattern generation. Finally, the optimized WBS-model has been evaluated in terms of Sound Pressure Level and manufacturability.status: publishe