双轴应力状态下正交异性动态光弹性应力-光性定律研究

Studies on Dynamic Stress optic Law for Orthotropic Birefringent Composites in Biaxial stress Fields

基于静态下Ｈｙｅｒ和Ｌｉｕ表述的正交异性应力－光性定律，在前文中，提出了正交异性光弹性复合材料的动态应力－光性定律并证明了其在单轴应力状态下的正确性。本文旨在进一步考察在双轴应力状态下正交异性动态应力－光性定律的适用性，采用的方法是对纤维增强光弹性复合材料制作的平板模型施加冲击荷载，加载方向与材料纤维方向分别成０°、９０°及４５°角，同时进行正交异性动态光弹性实验和动态应变测量，另外，对该模型进行相应的各向异性介质时域边界元计算。把动态应变测量推算出的应力分量以及时域边界元计算出的应力分量分别代入正交异性动态应力－光性定律，得到随时间变化的双折射条纹级数历程，将其与正交异性动态光弹性实验的结果进行比较。实验及计算结果表明，在三个加载方向下，由这三种方法得到的双折射条纹级数历程均吻合良好，从而证明了前文提出的正交异性动态应力－光性定律在双轴应力状态下的正确性。

Stresses in rectangulars of unidirectional fiber reinforced photoelastic composite under impact loading, with the loading direction parallel, perpendicular and at a 45° angle to the fiber direction, are analyzed by dynamic orthotropic photoelasticity, dynamic strain measurement and time domain BEM for anisotropic media respectively. Based on the dynamic stress optic law and by making use of the stress values from strain measurements and BEM calculation, the history of birefringent fringe orders are calculated, and compared with the result of dynamic orthotropic photoelasticity. The good agreement among the three kinds of result proves that the dynamic stress optic law proposed for orthotropic birefringent composites is valid in biaxial stress fields.