A Photoelastic Study of Bolt and Nut Fastenings

Abstract

Abstract Six different nut designs have been investigated by the three-dimensional “stress freezing” photoelastic method, obtaining the maximum stress values at the bottom of the threads for each design. It has been found that by the application of either a tapered-thread nut or a nut with a tapered lip the strength of the fastening can be increased by more than 30 per cent. This improvement in strength can be expected only in cases where the type of loading or conditions of application are conducive to brittle failure, i.e., dynamic loads or static loads at elevated temperatures.