斜裂纹对转子扭转剪应力的影响

The Influence of Slant Cracks on Rotor's Torsional Shear Stress

为研究斜裂纹对转子扭转剪应力的影响,分析计算了转子倾角(裂纹面与轴线的夹角)大于60°的斜裂纹在不同裂纹深度比下不同位置的应力强度因子KⅢ。计算结果表明:相同倾角的斜裂纹在同一位置的应力强度因子随着裂纹深度比a/R的增大而增加;在相同深度比和倾角的情况下,应力强度因子KⅢ随着与裂纹中心距离的增大逐渐减小,并且倾角越大在边缘处衰减得越快。拟合了不同裂纹深度比a/R(a/R<0.4)和不同倾角下所对应的应力强度因子曲线,定义了斜裂纹与横向裂纹扭转剪应力的临界相对差值Wcr,确定了在不同工程允许误差所对应的临界倾角cθr。该临界倾角可以在工程应用中用来判断何时可以采用横向裂纹模型代替斜裂纹模型。

In order to study the influence of slant cracks on rotor／＇s torsional shear stress,the mode Ⅲ stress intensity factors（KⅢ）in different positions of slant crack rotor,with dip angles（the angle between crack surface and axial line） greater than 60 degrees and at different depth ratios of shafting,are analyzed and calculated.The results show that the stress intensity factor of the same position and dip angle grows with the increase of depth ratio（a/R）.In the case of the same depth ratio and dip angle,the stress intensity factor decreases with the growth of the distance to the crack center,and the greater the dip angle is,the faster nearby crack edge declines.The corresponding curves of stress intensity factor under different depth ratio a/R（a/R0.4） and dip angle are drawn out,and a critical relative distinction（Wc r）concerning the torsional shear stress between slant cracks and transverse cracks is defined.Furthermore,the critical dip angle（θc r）with regard to different engineering allowable errors is confirmed,which would be used to decide when the transverse crack could be used to substitute the slant crack model in engineering applications.