Optimization of the fatigue life of threaded connections by the positioning method

Abstract

The presented paper addresses the problem of optimization of the fatigue life of threaded connections by the positioning method. This method presents a technique operating upon the periodic mutual change of nut and stud positions in order to increase the fatigue life. The modelling of the fatigue life of threaded connections using the positioning method is based on concept of damageability curve. A mathematical model is formulated in terms of mathematical programming taking into account technological and operation constraints. The performance and possibilities of the model are demonstrated by numerical experiments. The influence of weighting and constraints on the fatigue life of threaded connection, the influence of the heights of inter-turnings on threaded connection fatigue life and the influence of a number of positioning periods on threaded connection fatigue life when the height of inter-turnings is constant are presented.