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Abstract
Bolted joints are everywhere used over the world wide in every sections of engineering applications such as civil engineering bridges and structures, machines and machines structures, transport, railways, shipping and aerospace applications. It is a well proven fact based concept that these joints get loosened when subjected to loadings. The objective of this research study is to develop an experimental set up to investigate loosening of bolted joints and its analytical analysis. In this research study, experiments were carried out over bolted joint subjected to shear loading with various test variables including pretension/ torque values ranging from 20, 22.5 and 25 N-m, number of load cycles ranging from 30000 to 300000 cycles. A series of the tests for different design of experiments with different parameters were fulfilled. These experiments were targeted for three washer conditions which are NW- No Washer, PW- Plain Washer and SW-Spring Washer. The results of the above study were represented in terms of slackening angle with respect to number of load cycles and pretension. A mathematical model was developed between angle of loosening, load cycle and pretension. Analytical analysis of these experiments was carried out; surface plots and contour plots were plotted for the results obtained during the experimental research. A novel mathematical equation was proposed and validated based on the test results. The results obtained will be very useful in controlling loosening of bolted joints. In conclusion, the effect of the role of washers on bolted joint loosening was evaluated.