改进的数字全息光弹方法-理论研究

RESEARCH ON THE IMPROVEMENT OF DIGITAL HOLOGRAPHIC PHOTO-ELASTIC METHOD

该文通过改变参考光偏振方向,对数字全息光弹法进行改进,从而可以高效、高精度的检测二维应力场。从理论上导出了该方法的实验原理:加载前后在对应的4个不同参考光偏振位置拍摄数字全息图,对这4对数字全息图进行傅里叶变换、滤波及反变换,可以获得4个光强方程,数值求解这4个光强方程,再结合应力-光学定律就可以精确获得二维应力场的2个主应力值和主应力方向。与传统的数字全息光弹法相比,新方法具有以下优点:不需要分离等差线与等倾线条纹;不需要确定条纹级数;方法简单,不需要已有技术以外的实验装置或实验模型。

Through changing the polarization direction of reference light, the digital holographic photo-elastic method has been improved, which can measure two-dimensional stress field with high efficiency and accuracy. The principle of this method is introduced. Before and after loading, four couples of digital holographic images are obtained according to four polarization directions of reference light. With Fourier transform, filtering and inverse Fourier transform on the four couples of digital holographic images, four equations of light intensity can be obtained. By combining the stress-optics law, the value and directions of two principal stresses can be derived by solving the four equations. Compared with the traditional digital holographic photo-elastic method, the new method has the following advantages： no need to separate isochromatic and isoclinic curve; no need to determine the order of the fringes; no requirement for additional experimental devices or samples.