【摘要】 基于J-A2双参数断裂理论,对带半椭圆表面裂纹和单边贯穿裂纹的拉伸试件进行弹塑性断裂分析.计算并比较了X80和X100钢裂纹体在裂纹宽度相同、深度不同时的断裂驱动力J和约束参数A2.根据2种钢的断裂失效曲线,对椭圆裂纹最深点及相应深度的单边裂纹进行断裂分析比较.结果表明:椭圆裂纹深度的改变主要影响J积分值而对约束水平影响不大;裂纹深度及J积分均相同时,椭圆裂纹最深点与单边裂纹拉伸试件裂纹尖端的约束情况有较大差异,裂纹较深时,单边裂纹拉伸试件裂尖的约束水平要高于半椭圆裂纹情形;一般情况下对这2种钢椭圆裂纹体进行失效评估时,利用平面应变模型的计算结果会偏于保守,但对X100钢的浅椭圆裂纹则相反.更多还原

【Abstract】 The elastic-plastic fracture J-A2 method was performed to study the semi-elliptical surface crack and the single edge through thickness crack tension specimens of X80 and X100 steels.By 3D and 2D finite element analysis,the fracture driving forces of J-integral and the constraint parameters,A2 of semi-elliptical surface crack were calculated same length and different depths for X80 and X100.Accor-ding to J-A2 failure curves of the two steels,the fracture analysis and comparison were conducted between the elliptical cracks and the corresponding single edge cracked tension specimens.The results show that the elliptical crack depth mainly affects the J-integral value with slight influence on crack-tip constraint level.The constraint situation of the deepest point of semi-elliptical crack and the crack-tip of the single edge cracked tension specimen is quite different when their crack depth and J-integral are same.Constraint level on the crack-tip of the single edge cracked tensile specimen is higher than that of semi-elliptical crack in middle and large scale yielding.The failure assessment for X80 and X100 pipeline steel with deep semi-elliptical crack by the calculation of plane model is conservative,but the situation is the opposite for X100 steel with shallow crack.更多还原