光弹性法等倾角和等差线相位图的计算机仿真

Computer simulation of isoclinic and isochromatic phasemaps in photoelasticity

确定等倾角和等差线级数是光弹性法的关键。使用六步相移法可以同时确定全场等倾线和等差线参数,通常表示为等倾角和等差线相位图,但求得的等倾角耦合了第一和第二主应力方向角,即得到等倾角相位图存在"不一致"区域。等倾角的不一致会影响到等差线级数的计算,导致等差线相位图出现"失真"区域。针对这个问题,提出一种基于有限元分析结果的等倾角和等差线相位图计算机仿真方法,该方法可以作为光弹实验的辅助,识别出实验等倾角相位图中的"不一致"区域。通过径向受压圆盘实验验证了该方法的可行性,对光弹实验的等倾角和等差线相位图有良好的仿真效果。

Determining the isoclinic angle and the isochromatic fringe order is the key of the photoelasticity. One can obtain the isoclinics and isochromatics in the form of phasemaps by using 6-step phase shifting algorithm. But the isoclinic values obtained do not uniformly represent the direction of one of the principal stresses. The zones where the phasemap refers to another principal stress direction are labelled as inconsistent zones. These will lead to ambiguous zones in the isoclinic phasemap. A methodology is developed to simulation the isoclinic and isochromatic phasemaps from finite element results. The methodology is validated by using the problem of circular disc under diametral compression.The isoclinic data and the isochromatic date obtained by the computer simulation well agree with those by the optical experiment of photoelasticity.