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在分解Ｊ积分法调制的弹塑性大变形有限元程序计算基础上，用阻力曲线法研究了两种油井钻杆材料不同Ⅰ－Ⅱ复合比下的Ｊ积分阻力特性，结果表明：随Ⅱ型分量增加，以Ｊ积分形式表示的断裂抗力降低，提出了一个适于钻杆钢等中低强度、塑韧性较好的材料的复合型延性断裂准则：Ｊｃ＝ＪⅡｃ—（α—１）ＪⅡ（其中α为一材料常数，但在实验范围内，试样尺寸对α还有一定影响）．并结合复合延性断裂微观过程的观察，对该准则和α值做了解释和讨论。
Based on the finite element program of elastic-plastic deformation with J-integral method, the J-integral resistance characteristics under different Ⅰ-Ⅱ composite ratios of two kinds of oil well drill pipe materials were studied by resistance curve method. The results show that with the type Ⅱ component And the fracture resistance in J integral is reduced. A composite ductile fracture criterion suitable for medium and low strength, ductile and ductile materials such as drill stem steel is proposed: Jc = JⅡc- (α-1) JⅡ α is a material constant, but in the experimental range, the sample size has some influence on α). Combined with the observation of microscopic process of composite ductile fracture, the criterion and α value are explained and discussed.