光弹性五参数法确定Ⅰ-Ⅱ混合型裂纹应力强度因子

Mixed Mode Stress Intensity Factors From Photoelastic Five-parameter Method

在考虑远场非奇异应力σox、σoy、τ0 影响的基础上 ,建立了 - 混合型裂纹应力强度因子与等差线条纹上点的极坐标间的非线性方程 ,为通过该方程确定应力强度因子 ,将θ=0及θ=π/2两极轴与三等差线条纹交点的坐标先后代入方程 ,并利用差分法得到了一种光弹性法确定 - 混合型裂纹应力强度因子的五参数法。作为实例 ,本文测定了环氧树脂及聚碳酸脂在不同载荷、不同裂纹条件下的应力强度因子 ,并将所得结果与相应的理论计算值及三参数法的结果进行了比较 ,发现本文提出的五参数法确定 - 混合型裂纹应力强度因子的方法 ,充分反映了远场非奇异应力的影响 。

The non linear relationship between mixed mode stress intensity factors (SIF S) and the polar coordinates of the point of isochromatic fringes is founded by considering the effects of far field non singular stresses. In order to determine SIF S by the relation, the polar coordinates of the points that two polar axes, θ =0 and θ =π/2, intersect with three different isochromatic fringes are taken into the relation, besides, the differencing technique is used. Thus, a photoelastic five parameter method for determing SIF S is obtained. As examples, SIF S of epoxy and polycarbonate under the condition of different loading and different carcks are determined by the method. The results are compared not only with the theoretic ones but also with that of the three parameter method. It is found that the effects of far field non singular stresses are fully reflected by the present method. So the precision of SIF S from it is higher.