FE analysis of the sensitivity of friction calibration curves to dimensional changes in a ring compression test

Abstract

This paper is concerned with an analysis of the sensitivity of friction calibration curves to the frictional shear factor in a ring compression test. The main objective of this study is to examine the sensitivity of the FEA calibration curves of a ring compression test to the frictional shear factor. Different calibration curves were investigated by measuring dimensional changes at different positions of a ring specimen, including changes in the internal diameter at the middle and top section of the specimen, the outer diameter at the middle and top section, and the degree of surface expansion at the top surface. The initial ring geometries employed in the analysis maintain a fixed ratio of 6:3:2, i.e., the outer diameter : inner diameter : thickness ratio of the ring specimen, which is generally known as a 'standard' specimen, in order only to determine the sensitivity of the calibration curves for the measurement of dimensional changes at different positions to the frictional shear factor. A perfectly plastic material was modeled for the simulations using rigid-plastic finite element code. Analyses were performed within a definite range of friction as well as over the entire range of friction to uncover the different sensitivities of calibration curves to interfacial friction given different ranges of friction. The results of this investigation are summarized in terms of a dimensionless gradient. It was determined from the results that the friction calibration curves according to measurements of the dimensional changes at different positions of a ring specimen show different degrees of linearity and sensitivity to the frictional condition on the contact surface. Among these differences, the friction calibration curve upon changes in the degree of surface expansion at the contact boundary was found to be relatively linear and sensitive to the frictional condition over the entire range of friction.