アルミニウム合金製ボルトの疲労強度と疲労破壊箇所への平均応力の影響

抄録

Accidents due to fatigue of bolted joints frequently occur. In fatigue characteristics of bolts made of high strength steel alloy, it is well-known that the mean stress which is applied on the bolt as clamping force does not have an influence on the fatigue strength. But an influence of the mean stress on fatigue strength for bolt made of non-ferrous materials has not been investigated yet. In this study, fatigue test for a bolted joint made of aluminum alloy A5056 were conducted to investigate the influence of mean stress on fatigue strength. The result showed that fatigue strengths for A5056 bolts decreased with an increase in the mean stress. It is considered as one of the causes that fatigue fracture origins were different in A5056 bolt. And fatigue fracture origins tended to be affected by stress amplitude.