Shock Absorber Modeling and Experimental Testing

Simulation is becoming the fundamental tool to design the main components of a vehicle. The paper describes the shock absorber model which was implemented by the Vehicle Dynamics Research Team of Politecnico di Torino. It is a modular model which can be adopted both for mono-tube and twin-tube shock absorbers. It can be used at different levels of approximation, as a function of the kind of user and his/her targets. The main data which have to be inserted in the model are fluid properties, the basic dimensions of the component and the characteristics of the orifices of the shock absorber. An experimental test bench was conceived to obtain the diagrams plotting flow rate through an orifice of a shock absorber versus the pressure drop between input and output ports. The test rig and the procedure to perform the experimental tests and insert the results in the shock absorber model are described in detail. The conceived model was experimentally validated through the comparison between the simulation results and the experimental results obtained by testing the whole shock absorber on a second test bench. A sensitivity analysis to evaluate the influence of each design parameter (for example, gas pre-charge, fluid Bulk modulus, friction between piston and the tube, etc…) was performed and the main results are commented. The presented shock absorber model can be inserted in a vehicle model to study the influence exerted by the damper on comfort and handling.