用三种钢材研究了不同a/W值对COD和J积分值的影响。实验结果表明:浅裂纹的J_i及δ_1值远大于深裂纹值。用滑移线场理论及双参数断裂理论分析了塑性约束对断裂韧度的影响,并指出其在工程实际上的应用价值。 The effects of different a / W values ​​on the integral values ​​of COD and J were studied using three types of steel. The experimental results show that the J_i and δ_1 values ​​of shallow cracks are much larger than those of deep cracks. The influence of plastic restraint on fracture toughness was analyzed by using slip-line theory and two-parameter fracture theory, and its practical application value was pointed out.