Load and stress distribution in screw threads

Abstract

The load distribution and the normalized stress distribution in the threads of an ISO metric nut and bolt were found by frozen-stress photoelastic analysis employing a fringe-multiplying polariscope in conjunction with a recording microdensitometer. Previous investigators assumed that these distributions were identical, whereas the present study shows that this is not the case. It has been further shown that deducing the load distribution from measurements of the nut deformation is unsatisfactory. The results of the reported method correlate closely with Sopwith's theoretical load distribution. Three recent finite-element analyses of nut-bolt systems have been compared indirectly to the experimental load distribution. That of Bretl and Cook was found to give the best comparison.