Based on the refined results of the relationship between crack opening displacement (COD) along load line and crack mouth opening displacement (CMOD) obtained from finite element analysis(FEA), the effects of material properties and plastic deformation on the crack tip for front-force compact tension specimen (FFCT) and single-edged bending specimen (SEB) have been analyzed. The results show the influences are existing but ignorable. A more simplified and accurate transform formula used for plastic work calculation in J integral for FFCT specimen was proposed by means of the deformation geometric relationship. The relationship of COD and CMOD of SEB specimen is fitted via the results of FEA. Finally, the relative error analysis was conducted.%根据有限元精细网格计算结果,分析材料硬化及裂尖塑性变形对直通型CT试样(front force compact tension,FFCT)及三点弯曲试样(single edged notched bending,SEB)COD转换的影响.结果表明,材料硬化及裂尖塑性变形对上述两种试样的COD转换均存在影响,但影响较小,均可忽略.通过其试样变形几何关系,提出用于FFCT试样断裂韧性测试中计算J积分塑性功的裂纹嘴张开位移与加载线张开位移的弹塑性转换公式;对于SEB试样,通过对不同本构参数有限元精细网格计算结果进行耦合的方法获得COD转换公式.该文公式形式均较为简单,且与有限元结果相对误差较小,具有较高的置信度.
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