Adaption and evaluation of transversal leaf spring suspension design for a lightweight vehicle using Adams/Car

Abstract: This investigation deals with the suspension of a lightweight medium-class vehicle for four passengers with a curb weight of 1000 kg. The suspension layout consists of a transversal leaf spring and is supported by an active air spring which is included in the damper. The lower control arms are replaced by the leaf spring ends. Active ride height control is introduced to compensate for different vehicle load states. Active steering is applied using electric linear actuators with steer-by wire design. Besides intense use of light material the inquiry should investigate whether elimination of suspension parts or a lighter component is concordant with the stability demands of the vehicle. The investigation is based on simulations obtained with MSC Software ADAMS/Car and Matlab. The suspension is modeled in Adams/Car and has to proof it's compliance in normal driving conditions and under extreme forces. Evaluation criteria are suspension kinematics and compliance such as camber, caster and toe change during wheel travel in different load states. Also the leaf spring deflection, anti-dive and anti-squat measures and brake force distribution are investigated. Based on a simplified version of the leaf spring suspension design a full vehicle model is created. The comparison between the suspension models evaluates the same basic suspension parameters to ensure the compliance. Additionally roll rate and understeer gradient are investigated. It can be shown that the vehicle equipped with transversal leaf spring instead of lower control arms fulfils the set kinematics and compliance requirements. Road holding performance is assured for normal driving conditions on public roads.