Finite element analysis of rig used for fretting experiments

Abstract

Fretting is a damage mechanism which occurs between two tightly clamped components when these two components are subjected to very small amplitude of relative motion. Design and fabrication of fretting rig is essential to conduct fretting tests. The fretting rig has been used to clamp the pads onto the specimen. While conducting the fretting experiments, the normal load was applied through the pads and frictional force was generated at the contact interface between the pad and the specimen. Fretting experiments were conducted with a cyclic load which involves a stress ratio ('R' ratio). To decide 'R' ratio, we need to understand the load transfer ratio (LTR). LTR is the ratio between the load transferred to the top of the specimen and the load applied to the bottom of the specimen. LTR value should be optimum to conduct fretting experiments. So, the fretting rig which produces least LTR value (close to 50%) can be used as rig in fretting experiments. To ensure this condition, initially eleven cases of simple one-dimensional (1-D) fretting rig models have been designed and Finite Element (FE) analysis of these models was carried out. Afterwards four more different fretting rig models have been designed and analyzed with the inclusion of machine constraints and its results are also presented here. Among these models, the finite element model with optimum LTR was selected to conduct fretting experiments and the detailed three-dimensional (3-D) finite element study of the selected model has been performed and its results were validated with one-dimensional finite element analysis results. © 2019 Elsevier Ltd. All rights reserved.