Three-dimensional Finite Element Analyses of pre-cracked small punch test (p-SPT) specimens are performed to evaluate plastic constraint factor (m). The m factor is useful to correlate the J-integral with the crack tip opening displacement (CTOD). The through-thickness square pre-cracked specimen is analyzed for this purpose. Parametric studies are carried out by varying the crack length, the material yield strength and the strain hardening coefficients. Based on the computed results, two new J-CTOD correlations are proposed. These are (a) a correlation as a function of the crack length (a/W) and the yield to tensile strength ratio (σ_YS/σ_UTS) and (b) another correlation as a function of the crack length (a/W), the yield to tensile strength ratio (σ_YS/σ_UTS) and the current applied loading expressed in terms of load-line-displacement/crack length (LLD/a). The second correlation is more versatile. However, it is applicable only for the present geometry. The predicting capabilities of the correlations are checked by comparing the calculated values with the computed results.

对预开裂小冲孔试验 (p-SPT) 试样进行三维有限元分析，以评估塑性约束因子 ( m )。所述米因子是将关联有用Ĵ -积分与裂纹尖端开口位移（CTOD）。为此目的分析全厚度方形预开裂试样。通过改变裂纹长度、材料屈服强度和应变硬化系数来进行参数研究。基于计算结果，提出了两个新的J-CTOD相关性。它们是 (a) 作为裂纹长度 ( a/W ) 和屈服抗拉强度比 ( σ _YS /σ )的函数的相关性_UTS ) 和 (b) 作为裂纹长度 ( a/W )、屈服抗拉强度比 ( σ _YS /σ _UTS ) 和以载荷线位移/裂纹表示的当前施加载荷的另一个相关性长度（ LLD/a）。第二个相关性更通用。但是，它仅适用于当前几何形状。通过将计算值与计算结果进行比较来检查相关性的预测能力。