Full surface strain measurement using shearography
Full surface strain measurement using shearography
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DOI：
10.1117/12.449371
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发表时间：
2001-11
期刊：
影响因子：
--
通讯作者：
R. Groves;S. James;R. Tatam
中科院分区：
文献类型：
--
作者：
R. Groves;S. James;R. Tatam
剪切成像是一种全场光学技术，通常用于确定表面应变。对物体变形前后记录的干涉散斑图样进行相关，得到对位移梯度敏感的条纹，由此可以计算表面应变。对表面应变的全面分析需要测量六个位移梯度分量，使用三个照明方向和两个外加剪切方向。此外，剪切成像可用于通过相关震源位移之前和之后获得的干涉图来测量表面斜率，以产生对表面斜率敏感的条纹。坡度的积分产生了对象形状。本文利用剪切术测量了燃气干管在压力作用下的位移梯度的六个分量、管道的表面斜率和管道的形状。对象斜率和形状被用来校正位移梯度测量，以校正跨越对象表面的灵敏度向量的变化，以及由于施加的剪切对对象表面的局部斜率的依赖而引起的灵敏度变化。结合物体形状信息的坐标变换被用来获得相对于表面局部轮廓的面内和面外位移梯度。
Shearography is a full-field optical technique usually used for the determination of surface strain. Correlation of interferometric speckle patterns recorded before and after the object deformation yields fringes sensitive to displacement gradient, from which the surface strain can be calculated. A full analysis of the surface strain requires the measurement of six displacement gradient components, using three illumination directions and two directions of applied shear. Additionally shearography may be used to measure surface slope by correlation of interferograms obtained before and after a source displacement to yield fringes sensitive to surface slope. Integration of the slope yields the object shape. In this paper shearography is used to measure the six components of displacement gradient of a gas main pipe under pressure, the surface slope of the pipe and the shape of the pipe. The object slope and shape are used to correct the displacement gradient measurements for variation in sensitivity vector across the object surface and for sensitivity variations due to the dependence of the applied shear upon the local slope of the object surface. A coordinate transformation, incorporating the object shape information, is used to obtain the in-plane and out-of-plane displacement gradients relative to the local profile of the surface.