Vibration analysis of built-up thin plate structures like car bodies using a finite element model which accommodates only the dominant in-plane motion

摘要

A car body is built up from numerous inter-connected thin plates. These thin plates can only support the weight of the vehicle and the engine using their large in-plane stiffness. During operation of the vehicle, the powers injected into and transmitted around the structure are controlled by long wavelength in-plane waves. Consequently, a good estimate of the structural response can be obtained using a finite element model constructed from membrane elements which model only the dominant in-plane motion. This model has relatively few degrees of freedom because the long in-plane waves require only a few large elements, making it computationally cost-effective. To test the argument, a 6-sided thin plate perspex box excited at a stiff edge is considered. Predictions of the input and transfer frequency response functions compare favourably with laboratory measurements. The method may be applicable to thin-plate car bodies where it could be useful during preliminary design.