CAE-Based Driving Comfort Optimization of Passenger Cars

One of the key challenges in developing a vehicle for excellent vehicle dynamics is being able to achieve a high level of driving comfort without degrading the steering and handling performance.

The part of driving comfort discussed in this paper are tactile vibrations up to f = 100 Hz. This paper describes how Multi-Body Dynamics (MBD) Computer Aided Engineering (CAE) tools are applied to optimize such vibrations in the early phase of the development process. The approach hereby presented combines system level testing with MBD for the study of ride comfort, similar to the way that system level kinematics and compliance testing is combined with MBD to support steering and handling investigations. Laboratory investigations have been executed to fully characterize a reference suspension with respect to frequency and amplitude behavior. The respective MBD models have been subsequently refined and validated versus physical laboratory measurements. Several examples for a front wheel drive passenger car will be given, which show how these models can be used to effectively support chassis development in early design phases. The first example demonstrates the effect of subframe isolation on ride comfort via analyses of the forces transmitted to the vehicle body. The second example demonstrates the sensitivity of bushing stiffness to impact harshness using a full vehicle model. The final example demonstrates how impact harshness can be optimized using different levels of compliance split between the subframe and suspension bushings.