Mechanical Behaviors of Bolted Joint during Tightening Using Torque Control

Abstract

In the tightening process of a bolted joint using torque control, the effects of friction on axial tension of bolt and torque is an issue of great interest. In this study, the mechanical behaviors of a bolted joint during tightening, such as variations of axial tension and torque, are investigated both experimentally and numerically. Hence, friction coefficients on pressure flank of screw thread and the nut loaded surface are estimated by measuring the total torque applied to nut, axial tension and thread friction torque, and compared with variations of axial tension and torque. The validity of the finite element approach proposed here for evaluating changes in torque and axial tension is ascertained by comparing the numerical results to the experimental ones. It is also shown that the size of grip length influences, to some extent, the reduction rates of torque and axial tension.