高应力条纹下光弹实验光源分析

Light Source Analysis for Photoelastic Experiment in High Stress Fringe

摘要: 本文对白炽灯、荧光灯、LED白光灯三种光源在高应力梯度试样条纹的表征能力进行了分析对比。聚碳酸酯制成的试样放置在圆偏振光暗场中，受纯弯曲应力使试样中部上下边缘的条纹级数达到24条。用三种光源分别照射光弹试样，以获取彩色的数字光弹图片。通过MATLAB软件选取图片中试样受压区中间部位垂直中性轴的一条线，将该线的红光、绿光及蓝光分量的强度值随着像素及条纹级数的变化绘制出来，以对比三种光源在试样高条纹级数下的分辨能力。分析结果显示荧光灯照射下人工可识别的条纹级数高达24级，能提供比白炽灯和LED白光灯更高的条纹分辨能力。分析结果有助于正确选择光源开展高应力梯度光弹试验。

Abstract: In this study, we investigated the high stress fringe characterization ability of filament lamp, LED bulb and fluorescent lamp as light source in photoelasticity experiment. Photoelasticity sample that was made of polycarbonate was put in circle polariscope and experienced pure bending to achieve 24 fringes order in the up and down edges. The polariscope was illuminated by filament lamp, LED bulb and fluorescent lamp separately to produce color digital experiment images. In each experiment picture, one line perpendicular to bending neutral axis in middle of compressed zone was extracted by MATLAB software. Then the red, green and blue spectrums of this line were plot versus picture pixel and fringe order to compare the high stress fringe characterization ability. The analysis result shows that among three light sources, fluorescent lamp provides better fringe characterization ability up to 24 fringes. The result helps to select light source for high fringe order photoelasticity experiment properly.