三通内拐角椭圆裂纹应力强度因子分析

Stress Intensity Factors of Elliptical Cracks in Tee Joint Inner Corner

应力强度因子KI是缺陷结构安全评定参数,三通内拐角椭圆裂纹应力强度因子计算十分复杂。用ANSYS软件建立内压载荷下三通内拐角椭圆裂纹有限元模型,计算了不同几何结构参数下裂纹的应力强度因子KI,拟合了裂纹前缘的形状因子F计算公式。结果表明:内压下三通内拐角椭圆裂纹前缘形状因子最大值出现在主管或支管表面位置;三通主管壁厚增加,形状因子F减小;内压下椭圆裂纹有扩展为圆形裂纹的趋势。

Stress intensity factors K1 are necessary parameters in safety evaluation of defected structures. However, the com- prehensive data of the stress intensity factors of the elliptical crack in tee joint corner is still unknown. The finite element model of the elliptical crack in tee joint corner under internal pressure was established by using the finite element software ANSYS. The stress intensity factors of the crack under different geometrical parameters were calculated. Moreover, the calculating equations of the shape factors F of stress intensity factors were fitted. Results show that the shape factor （F） of the elliptical front crack a- chieves at the surface of main or branch tee. The shape factor F decrease with the increase of the thickness of main tee joint. El- liptical crack in tee joint corner under internal pressure tends to be circular crack under internal pressure.