The Effects of Fluid and Mechanical Compliance on the Performance of Hydraulic Shock Absorbers

Dimensionless differential equations are developed which model a hydraulic shock absorber. These equations are solved numerically to determine quantitatively the effects of fluid compressibility and series and parallel springs on the shock absorber operation. Both variable and constant orifice area are considered for a system protecting a mass during impact against a rigid wall. The results show that a finely tuned variable area shock absorber is degraded by the considered forms of compliance. Performance of the constant area shock absorber can be improved by including compliance and, with an appropriate parallel spring, the ideal flat deceleration profile can be obtained without variable orifice area.