Investigation of shock-driven dry friction between stainless steel and aluminum alloy

Abstract

Previous researchers studied dynamic friction by using an impacting copper plate to drive a tapered aluminum alloy 5083-H111 cone into a matching recess in a stainless steel outer retainer. The velocity of the rear surface of the cone was measured using velocity interferometry. We have performed experiments on a version of this configuration that has been enlarged so that the sliding surfaces remain in contact for a longer time than with the original configuration. As in the earlier work, the velocity on the axis of the rear surface of the inner cone was measured. In addition, the inner aluminum cones were recovered after the experiment and sectioned and etched. This provided an additional diagnostic for comparison with simulation. Simulations were run using a Lagrangian code with three alternative interface treatments: free sliding, rigidly locked (bonded), and a physics-based friction (PBF) model, details of which are presented. The work clearly indicated that the frictional forces could not be modelled by a freely sliding interface. The best match to the experiments was obtained by modelling the interface using the PBF model in conjunction with an initial gap of a few microns between the cone and outer retainer interface. This treatment reproduced the measured grain structures in the recovered experimental components and also captured many of the features of the observed velocity profiles.