An Influence of Thread Torque during Tightening Process on Transverse Fatigue Strength for Non-ferrous Bolt

Abstract

Recently, accidents of mechanical structure which is caused by fatigue of bolted joints frequently occur. Therefore, researches have been required to improve a reliability of bolted joints. Clamping force and thread torque apply on bolts during the tightening process. Influences of the clamping force on fatigue characteristics for bolted joints has been sufficiently investigated. The influence of the thread torque on fatigue characteristics has not been sufficiently investigated yet. In this study, transverse fatigue tests for aluminum alloy A5056 bolts were conducted to investigate the influence of the thread torque on transverse fatigue strength. The result shows that transverse fatigue strengths increased releasing the thread torque during the process.