Abstract: To obtain straight crack propagation front of the Compact Tension (CT) specimen, the side groove of the CT specimen were parameterized to study the effects of the side groove on the stress intensity factor of the crack tip by finite element method. A side groove shape was obtained in which the variance of stress intensity factor at the crack tip of the CT sample was less than 0.1(MPa·m^1/2)² along the thickness direction. Compared with the standard CT specimen fatigue crack propagation test, the results show that the CT specimen with the optimized side groove is more uniform in crack front along the thickness direction, and the variance is 30% of the standard CT specimen. In order to study the applicability of the empirical formula of the potential drop (PD) method to calculate the crack length of the CT specimen with side groove, a comparative analysis was carried out. The result shows that，for CT specimen with side groove, the error is smaller between the crack length calculated by the nonlinear formula and the test result, not exceeding 0.7%. The crack propagation of the CT sample with the optimized side groove is straighter. The error of the crack length calculated by the nonlinear equation is smaller with the crack length of CT specimen with side groove measured by PD method.

Key words: Compact tension specimen;Side groove;Stress intensity factor;Crack growth;Direct current potential drop method;Ni-base superalloy

摘要： 为了获得平直的紧凑拉伸（Compact Tension，CT）试件裂纹扩展前缘，对带侧槽CT试样的侧槽进行参数化表征，采用有限元方法研究侧槽对裂纹尖端应力强度因子的影响规律，对CT试样的侧槽进行优选。获得了使CT试样裂纹尖端应力强度因子沿厚度方向方差小于0.1(MPa·m^1/2)²的侧槽形状。与标准CT试件裂纹扩展试验对比，结果表明，优选的带侧槽CT试件沿厚度方向裂纹扩展更为均匀，方差为标准CT试件的30%。为了研究电位法经验公式计算带侧槽CT试样裂纹长度的适用性，进行了对比分析。结果表明，对于带侧槽CT试件，利用非线性公式计算的裂纹长度与试验结果误差最小，不超过0.7%。优选侧槽CT试样裂纹扩展更平直；电位法测量带侧槽CT试件裂纹长度，非线性公式计算裂纹长度的误差更小。

关键词: 紧凑拉伸试样;侧槽;应力强度因子;裂纹扩展;直流电位法;镍基高温合金