Frequency domain analysis and design of nonlinear vehicle suspension systems

Abstract

In the analysis and design of vehicle suspension systems, springs and dampers, which are usually inherently nonlinear, are the most crucial elements to improve the ride comfort, assure the stability, and increase the longevity of suspension systems to a large extent. Therefore, it is of great significance to determine a proper stiffness and damping characteristics to meet various requirements in practice. In this study, a nonlinear frequency domain analysis method is introduced for nonlinear analysis and design of vehicle suspension systems. The explicit relationship between system output spectrum and model parameters is derived by using the nonlinear frequency domain analysis method, and the characteristic parameters of interest can therefore be analyzed directly. The optimal nonlinear stiffness and damping characteristics of vehicle suspension systems can then be achieved. Comparative studies indicate that the optimal nonlinear damping characteristics demonstrate better dynamic performance than the corresponding linear counterparts and several existing nonlinear optimal damping characteristics obtained by simulations. Simulation studies based on the full vehicle dynamic model verify the nonlinear advantages in terms of three different vehicle evaluation standards. The study shows that the nonlinear optimal damping characteristic obtained by using the nonlinear frequency domain analysis method is very helpful in improvement of vehicle vibration performance and decrease of suspension stroke. Meanwhile, the optimized nonlinear damper will not cause any negative effect on the handling capability.