Taguchi Method (DOE) Based Performance Optimization of a Three Link Rigid Axle Passenger Car Suspension Using MBD Simulations 2011-01-0734

This paper describes dimensional synthesis, analysis and performance optimization of a three-link rigid-axle suspension system. This suspension architecture has two longitudinal links and panhard rod as a transverse link. In case of rigid axle with three links, roll stiffness is primarily governed by springs, anti-roll bar, suspension link dimensions and its orientations. Because of suspension architecture, the bushings connecting the longitudinal link to axle will also contribute to the suspension roll stiffness. Typically, this contribution is comparable to the contribution due to the suspension springs. Hence, this paper explores the process of reducing roll stiffness of three-link rigid-axle suspension by identifying and changing high impact parameters. In the multi-step process, the first step is to evaluate the kinematics and compliance performance. This analysis is performed using "ADAMS®" - the multibody dynamics analysis software. Out of all kinematics performance parameters, roll stiffness is one of the major parameters which has significant effect on ride and handling characteristics of vehicle. Handling performance of a vehicle is a critical performance attribute defining and differentiating a vehicle from its competitors.

Typically, with such suspension architecture, problem of excess rear roll stiffness is common. Reduction in spring stiffness is not an option as its specification is governed by other vehicle performance viz. ride comfort, load capacity, etc. Hence, a detailed study has been performed to understand the governing design variables and its sensitivity to the performance metrics (in the present case, the roll stiffness). The prominent design variables that have been studied are Side view axle bush separation, Side view longitudinal link inclination, and Top view axle side bush separation (between LH and RH). With these design variables DOE is performed using Taguchi Method of orthogonal array. The results of this study have been presented to aid intuitive inferences. The key benefit of this study is with minimum number of experiments understanding sensitivity of the governing design variables and therefore a definite dimensional synthesis procedure to design a required suspension performance.