Influence of Rear Suspension Local Stiffness on Full Vehicle Ride & Handling Performance

One of the biggest challenges for automotive industry is with respect to material saving and to have control on cost of development and still meeting performance in each aspect. Stringent weight targets help industries to have good margin on component costs. In recent times we have seen vehicle underbody contribution to total vehicle is significant in range of 12% to 18%. Total weight directly impacts the range of electric vehicle which is a key metric for success from real-world usage point of view and customer appeal. Hence control on suspension and frame design for light weighting is prominent trend in industry, this leads to deterioration of suspension compliance as well as vehicle ride and handling performance. Sub-frame and knuckle play crucial role in definition of overall suspension stiffness.

Present Study focusses on electric vehicle rear cradle design for weight saving with minimum reduction of stiffness. Understanding compliance which obtained from frame\cradle in vehicle cannot be negated if not improved in early stage of projects. This study focuses on vehicle’s rear suspension links, knuckle, and cradle performance for enhancing vehicle integrity, this later reflects in improved compliance. Total compliance at subframe level have big impact on full vehicle ride and handling performance. Analysis was performed on MSC ADAMS offline simulation tool for rigid suspension links & flex bodies. Lateral, longitudinal, and aligning torque compliances as well as full vehicle handling tests data was used to formulate compliance contribution matrix and identify areas of improvements. New design solutions were identified to enhance corresponding local stiffness with minimal weight addition. As a result of the study target component stiffnesses were defined for future design requirements.