A Method for Determination of Constant and Varying Friction Factors During Ring Compression Tests

Abstract

Available mathematical analyses have been applied to develop a reliable method for treating experimental results from ring compression tests with and without bulge formation to obtain quantitative evaluation of constant and varying friction factors, m, and stress-strain curves of the test material. Ring compression tests were made at room temperature on dry and lubricated rings of aluminum, copper, and 1018 steel with 6:3:2 and 6:2:1 (outside diameter:inside diameter:height) nominal dimensions. Neutral radii of the rings at each test height during compression were determined mathematically from measurements of ring dimensions. Substitution of calculated neutral radii and measured ring dimensions into mathematical equations provided quantitative values of the friction factor, m, at each height after compression. Load measurements, made during compression tests, were utilized for verifying the validity of the method.