Reduction of input power to the structure by the configuration of supporting rigid link mechanics

Abstract

Suspension of a vehicle plays an important role on the vibration insulation mechanism for reducing the structure born road noise. Using a low stiffness suspension bush is one of the typical countermeasure for the vibration insulation, but such a countermeasure makes the driving stability and the handling comfort worse. The suspension design which achieves the both performance at high level is required in the automotive industry these day. As one of the possible way to achieve the requirement, the road noise reduction by the suspension geometry which has not been investigated so far is presented in this paper. For simplicity, the two dimensional simple model considering a multi-link suspension which consists of the rigid links as suspension and the simply supported elastic beam as body is used. The motion of the suspension forms the energy flow from the road surface to the vehicle body to which the suspension is connected at multiple points. The energy flow which doesn't supply power to the vehicle body is found by the shape optimization based on the sensitivity analysis with respect to the suspension geometry. The shape optimization result shows maximized negative input power contribution at frequencies of interest. And the energy flow change is done by making the particular mode hardly resonant by having node of its mode shape at the excitation point. Moreover, the effect of the mode shape change appears as input power reduction at other frequency range. These effects are analysed by input power modal expansion.