A study on role of washers in bolted joint loosening failures

Abstract

Bolted joints are essential parts in almost all the machines or structure. Performance of these joints depends up on prevention of slackening of bolted joint. newlineResearch has shown that bolted joints have a tendency of self loosening or slackening when subjected to loading. No research on role of washers over loosening or slackening in shear loading and bending load along with, preload values for prevention of loosening or slackening of bolted joints were available; also no significant research was done on different options of washers. newlineThis research aims to overcome this research gap with main objective to study the role of washers on bolted joint loosening failures and how failures can be prevented or minimised. Some more objectives along with it includes; finding out revolutions required for the start of loosening or slackening at various values of pretension and rate of loosening. More importantly to investigate the principal constituent that most effectively prevent loosening failure of bolted joint. newlineThis research study successfully achieved all the objectives stated above under the application of shear and bending load. newlineResults showed that slackening is more and start of slackening is also earlier in case of bolted joint having full threaded bolt than that of, with plain shank bolt when the joint is subjected to shear loading. So, slackening of bolted joint can be controlled with the use of bolt with plain shank in place of full threaded bolt. Similar results have been obtained when the joint is subjected to bending load also. newlineOn the basis of this research study it can be concluded that slackening of the bolted joint could be controlled by using washers as locking device. The plain washer, proved to be the most effective in control of loosening of the bolted joint. Reliability of bolted joints can be increased along with savings in cost of maintenance. newlineKeywords: Bolted joint, Shear loading, Bending load, Pretension, Locking device. newline