| Pub. Date | : May, 2021 |
|---|---|
| Product Name | : The IUP Journal of Mechanical Engineering |
| Product Type | : Article |
| Product Code | : IJME10421 |
| Author Name | : Abhay Kakirde and Shriram Dravid |
| Availability | : YES |
| Subject/Domain | : Engineering |
| Download Format | : PDF Format |
| No. of Pages | : 23 |
Bolted connections are used all over the world in almost every engineering application. It is an established fact that these joints get loosened when subjected to dynamic loadings. The objective of this paper is to develop an experimental setup to investigate loosening of bolted joints and its analytical study for establishing the role of the washer subjected to dynamic loading. Experiments were carried out over bolted joint subjected to shear loading with various test variables, including pretension/torque values ranging from 20 N-m, 22.5 N-m and 25 N-m, and number of load cycles ranging from 30,000 to 300,000 cycles. Several tests as per DOE were performed. These tests were carried out following 3 washer conditions: NW-No Washer; PW-Plain Washer; and SW-Spring Washer. The results were represented in terms of slackening/loosening angle with respect to torque/pretension and load cycles. A mathematical model is also developed between angle of loosening, load cycle and pretension. Analysis of this test was performed; contour and surface plots were analyzed. A new mathematical equation was proposed and validated based on the experimental outcomes. The study concludes that washers play a very vital role in preventing loosening failures of bolted joints.
Fasteners are engineering devices which join two or more mechanical components to each other. Normally, it is a general practice to use bolted joint for semipermanent joint between any two parts. Mainly bolted joint assembly contains two main parts: (1) bolt; and (2) nut. The bolted joints are classified into two categories depending upon the direction of the external load acting on a joint. When the forces on the bolted joint are acting parallel to the axis of bolt, the joint is said to be loaded in tensile and is called tensile joint. Tensile joint is mostly used joint in the structures. When the forces on the joint are acting perpendicular to the axis of the bolt, then the joint is called shear joint (Boresi et al., 1993). It is generally believed that vibration causes bolt loosening. By far, the most occurring root cause of loosening is side sliding of the nut or bolt head relative to the fastened joint, resulting in the relative motion occurring within the threads. If this can be prevented, then the bolts will not loosen, even if the joint is subjected to severe vibration.
Bolted connections, Washer, Pretension, Dynamic loading