In this paper, the effect of multiaxial non-proportional stress states on the fatigue life of welded joints is investigated. The non-proportional stress states are caused by various phase shifts between the normal and shear stresses. In total 45, welded tube-to-tube specimens are tested under multiaxial proportional and non-proportional loading. The increase in fatigue damage caused by non-proportional stresses, compared to proportional stresses, is quantified by penalty factors. A set of penalty factors are derived from the fatigue experiments for use with the governing multiaxial fatigue criteria by the International Institute of Welding (IIW) and Det Norske Veritas (DNV). The experimental results show that phase shifts decrease the fatigue life. However, this reduction is not to the extend proposed by the governing guidelines. Furthermore, the results indicate that different degrees of phase shift do not induce varying levels of fatigue life degradation.

中文翻译：

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不同相移引起的非比例应力状态对焊接接头疲劳寿命的影响


本文研究了多轴非比例应力状态对焊接接头疲劳寿命的影响。非比例应力状态是由法向应力和剪切应力之间的各种相移引起的。总共 45 个管对管焊接样本在多轴比例和非比例载荷下进行了测试。与比例应力相比，非比例应力引起的疲劳损伤的增加可以通过惩罚因子来量化。一组罚因子是从疲劳实验中得出的，用于国际焊接协会 (IIW) 和挪威船级社 (DNV) 的多轴疲劳控制标准。实验结果表明，相移会降低疲劳寿命。然而，这种减少并未达到管理指南建议的程度。此外，结果表明不同程度的相移不会引起不同程度的疲劳寿命下降。