Monitoring the age of vehicle shock absorbers

Abstract

Shock absorber performance is critical to the operation of military vehicles. The Australian Army is interested in implementing health and usage monitoring systems for improved maintenance and fleet management. Shock absorbers typically break down by the failure of the seal where the rod shaft enters the main body, or the seal at the end of the piston within the body. There are few practical options for monitoring the condition of shock absorbers due to harsh operating environments (temperature, dirt, shock loading and continual vibration). Instead of monitoring the change in dynamic performance of a suspension system, it is proposed that the age of a shock absorber can be estimated by measuring the cumulative work done using a calorimetry method involving temperature sensors. This paper describes a simplified thermo-mechanical model that can be used to estimate the cumulative work done by a shock absorber, which is indicative of its age.