Analysis of deformation behavior of bolted joint during fastening process

Abstract

This study aims definition of complex phenomena arising under screw thread fastening process and deep understanding of past relevant knowledge. So far, authors have been studied on screw fastening mechanism of a clamped body with M10 bolt-nut by using 3D elastoplastic FE analysis. In this paper, more precise analytical model is developed and the bolt-nut fastening process is calculated. Consequently, following matters were revealed, (a) Greatly complicated deformation of bolt-nut joined threads area under contacting was clarified qualitatively. Supporting contribution percentages of each thread to axial load was calculated; especially the first thread of joining screw thread supported about 31% of axial force, (b) Spring constant of bolt-nut or clamped part calculated by the present FEM was well accorded with some theoretical equations within 7% error. Contribution of elongation of each region with the bolt also agreed with these equations. Most of all, the validity of Sawa-Maruyama's equation was showed, (c) During fastening process, development of stress or strain at the bolted joint was visualized compatibly alongside of past knowledge and information. © 2012 The Japan Society of Mechanical Engineers.