二段多重変動振幅荷重下のスポット溶接継手における疲労限度以下荷重による疲労損傷

抄録

Fatigue damage of spot-welded joints by loading range below the fatigue limit under multi two steps variable amplitude load was evaluated by the degree of influence α, according to the modified minor’s rule. However, the experimental verifying is not sufficient. From the degree of influence α, it is expected that crack propagation will occur due to the load less than the fatigue limit in the two-stage multiple variable amplitude fatigue test, but it is difficult to extract and confirm only this crack growth. The crack propagation length caused by the high load range under variable amplitude is the same as that of the constant amplitude. Therefore, in this paper, fatigue tests were carried out for tensile shear specimens under constant amplitude loading and multi two steps variable amplitude loading, and the length of fatigue crack was measured. From the measurement results of the crack length, it was possible to confirm the effectiveness of the influence 1 - α in the high load region. As a result, the effectiveness of influence degree α was confirmed.