Feasibility Study for Ride Comfort Application by Functional Vehicle Models: New Excitation Method and Model Extension

Ride comfort has become one of the most important vehicle characteristics perceived by the costumer, on the same level of style, infotainment, safety and performance. In the last years, OEMs have been investing more and more time on improving ride comfort characteristics, in order to keep up with the increasing customer expectations. Today’s high level has been achieved combining two branches of vehicle dynamics development: testing and simulation.

The role of vehicle dynamics simulation has been extended massively in the past years, reducing development time and costs for physical prototypes. Multi-body models are commonly used for ride comfort and handling simulation: they ensure good correlation with real measurements at the cost of high computational time and preparation effort. As most multi-body models are computationally not yet capable of real-time execution, functional models with highly reduced degrees of freedom have been developed. This enables OEMs to use virtual prototypes to perform subjective evaluations at early stage (e.g. Driver in the Loop). While handling properties can be represented quite well, limitations are still existing for higher frequency effects happening for example in ride comfort.

The Chassis CAE and Controls team in the HMETC Chassis department has investigated the capabilities of functional models for ride comfort development, focusing on the vertical excitation path (e.g. tire, spring, damper, top mount). The results obtained with the multi-body software (MSC Adams/Car) were compared against those of the functional model (VI-grade VI-CarRealTime) for ride comfort frequency range [0–30] Hz. A simplified excitation methodology consisting of sinusoidal shaped road profiles with different amplitude and frequency has been introduced to evaluate both tools in a controlled environment. The limits of the functional model have been analyzed and shown deficiencies in the frequency range beyond 5 Hz. To improve the functional model in this aspect a model enhancement of the rubber connection between damper and the vehicle’s body has been implemented.