【摘要】 焊缝焊趾处往往存在很高的非线性分布应力,非线性分布应力的存在改变了焊趾周围应力场的分布,因此也必然影响焊趾处疲劳裂纹的扩展行为。文章采用有限元法分析了表面裂纹应力强度因子的非线性分布应力修正系数,并拟合了修正系数的计算式;基于Newman-Raju的半椭圆表面裂纹扩展假设考虑了非线性分布应力对裂纹扩展形状的影响;同时,从对裂纹尖端的应力场和裂纹扩展形状两个方面的影响研究了非线性分布应力对裂纹扩展寿命的影响。计算结果表明非线性分布应力的存在将改变表面裂纹扩展形状并将大幅降低裂纹扩展寿命。更多还原

【Abstract】 The high nonlinear distribution stress across the plate thickness caused by weld toe affects surface crack growth in the vicinity. In this paper, the magnification factors of the stress intensity factors caused by the nonlinear distribution stress are evaluated by using the finite element method, and the fitting equations of the magnification factors are also proposed. The effect of the nonlinear distribution stress on the surface crack shape is discussed based on the assumption of semi-ellipse proposed by Newman and Raju. Meanwhile, the effect of the nonlinear distribution stress on the crack propagation life is analyzed by considering the effects of the crack-tip stress and the crack shape. The numerical results show that the nonlinear distribution stress influences the crack shape change and reduces the crack propagation life significantly.更多还原