Determination of contact pressure at pneumatic seal/rod interface from radial force measurement

Abstract

This work relates to the experimental evaluation of contact pressure at the interface between an elastomeric rod seal for pneumatic cylinders and its metallic counterpart, without interposing any intrusive measuring device. Results were obtained using a suitable test bench able to detect the radial force exerted by the rod seal, displaced at constant velocity on a sensorized portion of a cylinder rod over time. Pressure load was applied on the seal to reproduce actual working conditions. A data postprocessing methodology was developed for an indirect evaluation of contact pressure, starting from the experimental data set of the radial force exerted by the seal on the rod. At first, the measured radial force signal was filtered and properly fitted, obtaining a differentiable function; then, contact pressure distribution was computed as a function of the radial force time derivative, seal velocity and rod diameter. The experimental test bench and the computational methodology described can be applied to pneumatic rod seals with geometries and materials other than that described in this study.