A study of the suspension system for the diagnosis of dynamic characteristics

Some of the common faults associated with suspension components are damaged or leaking shock absorbers, spring weakness, wearing down of the pivot and bushing and damage to the main support member assembly. To investigate these problems, a seven degree-of-freedom (7-DOF) model has been developed, for a full vehicle, using MATLAB. In the simulation, the suspension faults have been considered via the damage caused to the shock absorbers (dampers) and the faults were seeded by reducing the damper coefficient by 25%, 50% and 80%. This has formed the basis for the characterisation of the ride comfort, road handling and stability of the car. The parameters able to offer a comfortable ride for the passengers were found to be in conflict with the parameters ensuring the stability of the vehicle and the corresponding wheel travel. For a high level of ride comfort, the suspension requires a shock absorber with a low damping coefficient. However, for optimum stability and a minimum level of wheel motion, the suspension requires a shock absorber with a high damping coefficient.