Many factors influence the fatigue and crack growth behavior of welded joints. Some structures often undergo fairly large static loading before they enter service or variable amplitude cyclic loading when they are in ...Many factors influence the fatigue and crack growth behavior of welded joints. Some structures often undergo fairly large static loading before they enter service or variable amplitude cyclic loading when they are in service. The combined effect of both applied stress and high initial residual stress is expected to cause the residual stresses relaxation. Only a few papers seem to deal with appropriate procedures for fatigue analysis and crack growth by considering the combined effect of variable amplitude cyclic loading with residual stresses relaxation. In this article, some typical welded connections in ship-shaped structures are investigated with 3-D elastic-plastic finite element analysis. The effect of residual stress relaxation, initial residual stress, and the applied load after variable amplitude cyclic loading is revealed, and a formula for predicting the residual stress at hot spot quantitatively is proposed. Based on the formula, an improved fatigue procedure is introduced. Moreover, crack growth of typical weld joints considering residual stresses relaxation is studied.展开更多
Results indicate that under cyclic tension the growth rate of short fatigue crack from notch root will be lowered greatly by tensile pre-loading,but only a little change by compressive pre-loading. The effect of tensi...Results indicate that under cyclic tension the growth rate of short fatigue crack from notch root will be lowered greatly by tensile pre-loading,but only a little change by compressive pre-loading. The effect of tensile pre-loading will decrease with the increase of stress ratio.The variation of short fatigue crack growth rate is related to the residual stress distribution around notch root.展开更多
基金supported by the National Natural Science Foundation of China(No.50609009)Natural Science Foundation of College of Jiangsu Province(No.07KJD580056)
文摘Many factors influence the fatigue and crack growth behavior of welded joints. Some structures often undergo fairly large static loading before they enter service or variable amplitude cyclic loading when they are in service. The combined effect of both applied stress and high initial residual stress is expected to cause the residual stresses relaxation. Only a few papers seem to deal with appropriate procedures for fatigue analysis and crack growth by considering the combined effect of variable amplitude cyclic loading with residual stresses relaxation. In this article, some typical welded connections in ship-shaped structures are investigated with 3-D elastic-plastic finite element analysis. The effect of residual stress relaxation, initial residual stress, and the applied load after variable amplitude cyclic loading is revealed, and a formula for predicting the residual stress at hot spot quantitatively is proposed. Based on the formula, an improved fatigue procedure is introduced. Moreover, crack growth of typical weld joints considering residual stresses relaxation is studied.
文摘Results indicate that under cyclic tension the growth rate of short fatigue crack from notch root will be lowered greatly by tensile pre-loading,but only a little change by compressive pre-loading. The effect of tensile pre-loading will decrease with the increase of stress ratio.The variation of short fatigue crack growth rate is related to the residual stress distribution around notch root.
