Mechanical Behaviors of Bolted Joint in Various Clamping Configurations.

Abstract

In a bolted joint, failures usually initiate at the first root of the bolt thread. However, rupture around the bolt head is sometimes reported for a tap bolt because of high stresses produced by tightening torque applied to the bolt head. It is also well known that manufacturing errors of internal threads in a tapped hole are generally much larger than those of external threads. In this paper, mechanical behaviors of bolted joints in various clamping configurations are analyzed using FEM as an axisymmetric elastic contact problem, and the effects of nominal diameter, friction and pitch error upon stress concentrations are evaluated for through bolts, studs and tap bolts. In addition, the tightening process and strength of bottoming studs, which have seldom been studied despite of its good performance in preventing stress concentration at the runout of threads, are also investigated.