Automotive concept modelling: Optimization of the vehicle NVH performance

The NVH optimization of the BIW and seat structure in the advanced phase of the design demands too much time and cost. On the other hand, developing a reliable NVH concept model in the earliest stage of the design to improve dynamic behaviour of the structure and avoid conflicting designs might be an effective approach. To this end, a practical method for CAE-NVH concept modelling is developed. The developed model utilizes beam elements with standard and arbitrary cross sections for the main load carrying components (namely beam-like structures) of the BIW and seat structure. Also, major joints are approximated from the detailed CAE model by taking static model reduction method into account. Due to the indisputable effects of some panels (e.g., roof) on the BIW structural dynamics characteristics, shell element with rough meshing are exploited to model these components. The developed concept models are verified by comparing their resonant frequencies and mode shapes with counterpart advanced CAE models in low frequency range. Having been validated by dynamic domain indicators, the developed concept model is used to improve the NVH performance of the automotive. In one case, modes interaction between BIW and seat structure is characterized. Then, by examining the influence of the beams properties (both BIW and seat) in conflicting modes, the problem is managed. Having been separated the identified interacting modes, the amplitude of the vibration on the seat-back is suppressed about 10 db around corresponding frequency. As a result, by taking advantages of the proposed method in similar cases, the CAE-NVH concept model can be successfully used to lead the right first time design.