Robust Design Of An Automotive Suspension: A Study On The Reduction Of Tolerances

A new method to optimize manufacturing tolerances of the suspension of road vehicles is presented.

In order to respect the designer requirements on the suspension parameters (static toe, static camber, static caster, bumpsteer 50 mm and more), a study on the control of components significant tolerances and bushing stiffness has been conducted. First, a CAD software is applied to develop a 3D model of a vehicle suspension. Second, by using a Computer Aided Tolerance (CAT) software, the tolerance chain of the suspension system has been computed to define the equivalent tolerance of the main kinematics points of the suspension. Third, the model of the suspension system has been developed in a multibody software. By defining a Monte Carlo DoE and a response surface of the suspension parameters, a wide set of simulations of the kinematic and compliance has been used to define the tolerance of the suspension characteristics, by varying the location of the kinematic points according to their standard deviation, and by varying the bushings' stiffness according to their manufacturing variation. After a sensitivity analysis, the tolerances of some components of the suspension system have been reduced or loosed to avoid settings after the assembly on the vehicle and respect the suspension designer requirements.