双材料界面端应力奇异性的数字光弹性分析

DIGITAL PHOTOELASTICITY ANALYSIS OF STRESS SINGULARITY OF BIMATERIAL JOINTS

在双材料界面端奇异性应力场方程的基础上,采用数字相移光弹性方法分析了具有实数应力奇异性的界面端应力强度因子。实验选择铝合金/环氧树脂双材料形成135°和90°界面端切口进行四点弯曲测试,利用数字相移光弹性法得到界面端全场等色线级数作为原始数据。将应力光学定律和界面端奇异性应力场方程相结合,分别得到条纹级数距离界面端成线性对数分布规律和条纹级数平方距离界面端成幂函数多项式分布形式,界面端的应力强度因子随载荷逐渐递增,实验结果与数值计算趋势一致。

Based on singularity stress field equations of bimaterial joint at the interface corner,a phase-shifting digital photoelasticity method is applied to calculate stress intensity factors at the interface corner for the case with a unique positive stress singularity order.Aluminum alloy/ epoxy bimaterial joints having notch angle 90o and 135o have been respectively selected to perform four-point bending tests.The full-field isochromatic fringe orders near the joints obtained by the digital phase-shifting photoelasticity are regarded as raw data.Expressing the two principal stresses in terms of the equations of singularity stress field and substituting them into the stress-optics law,a linear logarithm relationship for 135o interfacial joint and a power function relationship for 90o interfacial joint are respectively deduced and are further fitted to the experimental data of fringe orders vs.distance to the joints.The experimental results reveal that the stress intensity factors increase gradually with the applied loads and have similar trend with the numerical calculation.