基于裂纹尖端张开角准则的多裂纹薄壁结构剩余强度分析

评估由中央裂纹（M(T)）试样获得的裂纹尖端张开角(CTOA)预测多裂纹薄壁结构剩余强度的有效性.利用ABAQUS软件建立含有M(T)试样的二维有限元模型，采用裂纹尖端张开角断裂准则和平面应力模型模拟其裂纹扩展过程.对具有不同初始裂纹长度的M(T)试样，该方法预测的剩余强度和载荷-裂纹扩展增量曲线与试验结果接近，误差小于6%；但对于含有多条裂纹试样的剩余强度预测值偏大，相对误差在20%左右.通过增加对裂纹尖端周围单元约束的改进，采用平面应变核模型可以有效提高剩余强度预测精度；对具有不同多裂纹构型的薄壁结构进行分析，采用恒定裂纹尖端张开角和平面应变核的方法均可以得到与试验相近的结果，剩余强度预测误差基本都在10%以内.

Residual Strength Analysis of Thin-Walled Structures with Multiple Site Damage Based on Crack Tip Opening Angle Method

This paper is to validate the crack tip opening angle (CTOA) obtained from the M(T) specimens to predict the residual strength of the thin walled structures with multiple site damage. Using ABAQUS software to build the 2D M(T) finite element model, the crack growth process was simulated by CTOA fracture criterion with plane stress model. The predicted residual strength and load crack extension curves are close to the experimental results, the relative error is less than 6%. But for the multiple site damage specimens, the relative error is about 20%. Then the constraint around the crack tip is improved by using plane strain core (PSC) model. The constant CTOA and PSC were used to analyze thin walled structures with multiple cracks configuration. The predicted results have good agreement with experiment， the relative error is less than 10%. Thus, the CTOA criterion and the
PSC model are useful and reliable to predict the residual strength for structures with multiple site damage.