本文在文献的基础上,对韧性材料紧凑拉伸试样提出了一个无量纲参数 S(?)(塑性系数)。通过对紧凑拉伸试样进行分析,得到了相应的塑性系数、裂纹扩展力和相对裂纹深度的关系曲线,并讨论了 J 积分的有效范围。分析表明,用塑性系数确定 J 积分的有效性、进行 J 积分的试验设计和绘制 J 阻力曲线是合适的。 Based on the literature, a dimensionless parameter S (?) (Plasticity coefficient) is proposed for compact tensile specimens of ductile materials. Through the analysis of the compact tensile specimen, the corresponding plasticity coefficient, crack propagation force and relative crack depth are obtained, and the effective range of J integral is discussed. The analysis shows that it is suitable to determine the validity of J integral by plastic coefficient, to design J integral test and to plot J resistance curve.