基于三维有限元解的紧凑拉伸试样应力强度因子计算公式

摘要

对标准紧凑拉伸(CT)试样的二维和三维应力强度因子有限元解进行了对比分析,基于三维有限元虚拟裂纹闭合法拟合了一种新的标准 CT 试样的应力强度因子计算公式,并采用 AN-SYS 软件内嵌位移外推法进行了验证.结果表明：基于二维分析所得的应力强度因子计算公式计算结果与实际三维 CT 试样的具有较大的差异；在加载孔等效分布力一定的条件下,CT 试样裂纹前沿大部分区域的应力强度因子与中心点的相近,且与厚度无关；拟合得到的三维 CT 试样裂纹前沿中心点的应力强度因子计算公式具有很高的精度,其计算结果与 ANSYS 软件内嵌位移外推法的相对误差在0．5％以内.%Two-dimensional and three-dimensional finite element calculations of stress intensity factors for standard compact tension(CT)specimens were compared and analyzed.And a new calculation formula of stress intensity factors for standard CT specimens was established based on the three-dimensional finite element virtual crack closure method and verified using displacement extrapolation method of ANSYS.The results show that great differences existed between the stress intensity factors from calculation formula based on the two-dimensional analysis and those of actual three-dimensional CT specimens.Under the certain equivalent distributed force on the load-hole,the stress intensity factors at the most crack front regions were similar to those at the center of the CT specimen and were independent of the thickness.The fitting calculation formula of stress intensity factors at the crack front center of three-dimensional CT specimens was of high precision.And the relative errors between the fitting calculation values and the results of the displacement extrapolation method of ANSYS were less than 0.5%.