V形切口尖端裂纹起裂方向的主应力判别准则及其验证

围绕V形切口尖端裂纹起裂方向，分析了V形切口尖端裂纹应力场、位移场、应力强度因子,提出了裂纹起裂方向的主应力判别准则。首先，详细给出了V形切口尖端应力应变场的求解方法，通过裂纹尖端场本征值的三次线性拟合及误差分析，确定了V形切口尖端裂纹位移场;然后，建立了V形切口尖端的数值分析模型，运用数值计算方法确定了应力强度因子和切口强度因子，提出了V形切口尖端裂纹起裂方向的主应力判断准则，给出了外推法求解分析过程;最后，以LY8为试验材料，在张角2β＝60°的V形切口情况下，对提出的V形切口尖端裂纹起裂方向计算方法与判别准则进行了试验验证。

Principle Stress Rule for Crack Propagation Direction of V Notch Crack Tip and Its Application

Around the crack propagation direction at the tip of V notch, this paper described the stress field and strain field of crack tip, as well as the stress strength factor. The principle stress rule for cracked direction was discussed in detailed. Firstly, a numerical calculation method was applied to solve the stress and strain field at the tip of V notch. Through the third order fitting of characteristic parameters of crack tip, the calculation errors were analyzed and the displacement field at the tip of notch can be obtained further. Then, a numerical model of crack tip was constructed and the finite element analysis method was adopted to calculate the stress strength factor and notch strength factor. Based on above calculation results, the principle stress rule is proposed to calculate the crack propagation direction at the tip of V notch. Finally, an experiment on LY8 was conducted to validate above calculation method and rule.