Novel Approach to Determine Effective Flow Areas at Shock Absorber Restrictions

Modeling of shock absorbers is often used to either study and/or tune its parameters or to calculate the damping force as an input to the vehicle oscillation simulation. Shock absorber damping is accomplished by the oil resistance to flow-through restrictions. Due to their complex design and flow paths, one of the major difficulties is to determine the flow discharge coefficient and actual geometric flow area at these restrictions. This paper proposes an approach where the effective flow area (product of discharge coefficient and geometric flow area) is calculated based on the results of a simple vehicle oscillation test, combined with a shock absorber model. Governing equations are solved numerically resulting in useful dependence of the effective flow area at the absorber restrictions and the pressure differential between the compression and rebound chambers. The Methodology is described in detail. The Proposed Approach is verified by comparing the results of two-dimensional (2D) vehicle oscillation with the experiment.