Research on the equivalent elastic modulus of mechanical joint interface

¹ College of Mechanical Engineering and Applied Electronics Technology, Beijing University of Technology, Beijing, 100124, P.R. China
² Biomechanics and Medical Information Institute, Beijing University of Technology, Beijing 100022, P.R. China

^a Corresponding author: yjzeng@bjut.edu.cn

Received: 20 February 2016
Accepted: 1 September 2016

Abstract

Mechanical joint interfaces widely exist in all kinds of components. Their properties are extremely complex as there are a variety of factors affecting contact characteristics such as material, surface roughness, processing method and heat treatment. This study investigated the static mechanical performances of joint interface under cyclic compression loads. A new joint model was established and described as one continuum with three layers of materials, wherein the joint interface was assumed as a layer of material with thickness h_c. Then the corresponding theoretical expressions of Total Equivalent Elastic Modulus (E_t) and Interface Equivalent Elastic Modulus (E_i) were proposed. A series of cyclic compression experiments were conducted. And the effects of loading stress, number of cycles and surface roughness on E_t and E_i was discussed respectively. Results indicated that E_t increases first and then levels off with the stress increasing. E_t approaches a steady state with the increasing number of cycles. And the modulus decreases with the increase of surface roughness of the joint interface. In addition, E_i is a function of E_t and the thickness of joint interface h_c. The cumulative plastic strain occurs with a repeated loading on the joint interface.