Mechanism for Reducing Stress Concentrations in Bolt-Nut Connectors

Abstract

As the structural systems become more and more complicated, bolt-nut connectors play an increasingly important role in the safety and reliability of structures. If the strength of bolt-nut connectors is insufficient, fatigue failure can initiate at the point of maximum principal stress. In this study, reduction mechanism of the stress concentration in bolt-nut connectors was investigated by performing shape optimization using finite element method (FEM implementing progressive quadratic response surface modeling (PQRSM and the growth-strain method (GSM. The best reduction mechanism of stress concentration was achieved by stress control of GSM It was also found that stress concentration can significantly be reduced by uniformly distributing stresses over the entire threads as far as possible.