Development of a Computer-Based Measurement Methodology For Determination of General Parameters in Mechanics

在过去的一个世纪里，测量三维物体在任意载荷或边界位移作用下的法向位移一直是实验者面临的一个主要问题。复杂的光学方法，包括全息术和散斑干涉法，只适用于样品表面为平面的二维问题。最近，摄像机和计算机(存储容量)的改进导致了可以有效地用于记录位移的图像分析的显著进步。该方法是以像素形式记录和存储处于变形和未变形状态的样品的表面特征。然后使用强度内插方法来识别样本上的小子集，并确定这些子集的位移。该方法适用于平面变形的二维体。拟议的计划将利用两个摄像机和立体成像程序将这些方法扩展到三维样品，以获得确定位移所需的图像。在位移测量中，将采用先进的图像相关方法来实现亚像素精度。

Measurement of the normal displacement of a three-dimensional body subjected to arbitrary loading or boundary displacements has been a major problem for experimentalists for the past century. Elaborate optical methods including holography and speckle interferometry are only applicable to the two dimensional problem where the specimen surface is plane. Recently, improvements in video cameras and computers (storage capacity) have led to significant advances in image analysis which can be effectively employed to record displacements. The approach is to record and store in pixel form the surface features of the specimen in its deformed and undeformed state. Intensity interpolation methods are then employed to identify small subsets on the specimen and to determine the displacement of these subsets. The method has been established for two-dimensional bodies undergoing plane deformation. The proposed program will extend these methods to three- dimensional specimens by utilizing two video cameras and stereo imaging procedures to obtain the images required for displacement determinations. Advanced methods of image correlation methods will be employed to achieve sub-pixel accuracy in the displacement measurements.