Evaluation of mechanical behavior of trapezoidal threads and square threads by helical thread FEM models

Abstract

Fatigue failures of bolted joints frequently lead to serious accidents of machines and structures. It is well known that fatigue failure is likely to occur around the first bolt thread adjacent to the nut loaded surface and the run-out of bolt thread. However, mechanical behaviors of trapezoidal threads and square threads have scarcely been studied so far.

In this study, stress distributions along thread root in trapezoidal thread and square thread are evaluated by threedimensional finite elemental methods using helical thread models with accurate geometry, the numerical results are compared with those of triangular threads.