Road Vehicle Robust Design: Chassis and Suspension Tolerances Impact on the Handling and Stability Behaviour

This paper introduces a technique to analyze the influence of the chassis and suspension manufacturing tolerances on the road vehicles handling.

A study on the components tolerances and bushing stiffness has been conducted to evaluate the vehicle handling and stability indexes variations (understeer and sideslip gradient, gains and phases in frequency domain, etc.).

The procedure starts with the 3D model creation, in a CAD environment, of all the components which establish a vehicle suspension assembly. Then, a Computer Aided Tolerance (CAT) software allows to calculate the suspension system tolerance chain in order to identify the equivalent tolerance of the main suspension kinematic points. Furthermore, a multibody full vehicle model has been developed to run a wide set of simulations of quasi-static and transient manoeuvres used to define response diagrams tolerance. A Monte Carlo Design of Experiment is applied to perform all the simulations, to reproduce all the possible kinematic points location and all the possible bushing stiffness (both according to their manufacturing variation). After the investigation, the statistical correlation between chassis and suspension components tolerance and full vehicle handling and stability behaviour is identified.