Role of Washers in Controlling Loosening of Full Threaded Bolted Joints

Abstract Bolted joints are used for fastening components together in the industry, aeronautics and in railways. These joints may get loose with time and if not attended timely may result in catastrophic failure also. The purpose of this study was to examine the effect of tightening torque on loosening. For this purpose tests were conducted using three different tightening torque values, in the vicinity of rated torque. Washers of different types are used in bolted joint, with an understanding that they prevent or retard loosening. This study also attempts to examine the role of two types of most commonly used washers: the plain washer and the spring washer. Trials were also performed on joint without any washer, for the sake of comparison of loosening performance of the joint. The results of this experimental study are shown in terms of starting point of loosening of joint and rate of loosening of the joint. Various combinations of washers for three values of tightening torque are considered in the experimental study. The results are useful in understanding the role of type of washer in prevention of loosening of the bolted joint.