NVH optimization methodologies based on bead modification analysis in vehicle body design

Nowadays, in automotive industry the vehicle design cycle is mainly ruled by the highly competitive nature of the market and the ever increasing customer demands and expectations. This challenges automotive manufacturers to achieve higher-quality products in ever shorter time frames, while at the same time, reduce the design costs. This can only be achieved when the design cycle takes place largely on the basis of virtual modeling and simulation such that the traditional test phase, which relies on expensive and time-consuming physical prototypes, can be drastically shortened. As a result, nowadays, each stage of the design cycle is supported by CAE (Computer Aided Engineering) methodologies which allow to predict various functional performance attributes, such as NVH (Noise, Vibration & Harshness), crashworthiness, etc. Moreover, researchers have developed many techniques to speed up the calculations, enabling efficient modification approaches and optimizations. This paper focuses on the vehicle interior NVH performance. For a vehicle body Finite Element (FE) model, a reduced formulation has been achieved by using the WBS (Wave-Based Substructuring) technique. More specifically, a modification approach has been applied that is based on the generation of bead patterns on a subcomponent that has been identified as critical for the NVH behavior. By combining the reduced structural model with an efficient ATV (Acoustical Transfer Vector) approach to predict the interior acoustics performance, one can efficiently evaluate the effect of structural modifications on the interior NVH levels, such that the global NVH behavior can be optimized. The main innovation introduced in this paper comprises the optimization of vehicle vibro-acoustics by making use of a structural optimization software in combination with an acoustic target function. Two different methodologies have been worked out, based on two strategies for bead pattern optimization. Finally, the optimized component has been evaluated in terms of radiated Sound Pressure Level (SPL) and manufacturability.