本文主要论述单试样测J_(Ic)法中确定开裂点的方法,提出从P-Δ记录曲线计算加载过程中裂纹长度增长的解析方法和以测量裂纹顶端张开位移量为基础的方法,井用实例证明两法的有效性。本文还针对J积分与形变功间的关系报道了新近的实验结果,证实了对紧凑拉伸试样的滑移线场的假设和对极限载荷P_L所获得的结果,也证实了我们对紧拉试样所提出的J-U关系。 This paper mainly discusses the method to determine the crack initiation point in a single specimen and proposes an analytical method based on the P-Δ recording curve to calculate the crack growth during loading and the method based on the measurement of the crack opening displacement. Well with examples to prove the validity of the two methods. The paper also reports recent experimental results on the relationship between J-integral and deformation work, confirms the assumptions of the slip-line field for compact tensile specimens and the results obtained for the ultimate load, P_L, The sample proposed by the relationship between JU.