Deformations in wide, center-notched, thin panels, part I: three-dimensional shape and deformation measurements by computer vision
Deformations in wide, center-notched, thin panels, part I: three-dimensional shape and deformation measurements by computer vision
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DOI：
10.1117/1.1566001
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发表时间：
2003-05-01
影响因子：
1.3
通讯作者：
McNeill, SR
中科院分区：
文献类型：
--
作者：
Helm, JD;Sutton, MA;McNeill, SR
研究了宽、薄、中心切口的2024-T3铝板在远场拉伸载荷作用下的响应。三个面板的缺口长度面板宽度为0.33和宽度为305，610，和1016毫米进行远场拉伸载荷。作为实验计划的一部分，两对摄像机被配置成单独的立体视觉系统，并用于同时捕获板的全局响应和缺口尖端附近的局部响应。全球区域，大小从250 x 250 mm到550 x 550 mm不等。对每个面板进行成像。第二个立体视觉系统记录一个缺口尖端前方10 x 20 mm小区域的图像。使用三维数字图像相关的立体视觉测量数据的后处理从全球和本地系统被用来获得完整的位移场在感兴趣的区域中的每个点。在一般情况下，结果表明，立体视觉和三维数字图像相关的组合是能够准确地测量真实的，三维结构变形的区域经历大的平面外位移和大位移梯度。此外，3-D测量的面板试样附近的抓地力的位置，显示提供一个独立的评估的真实边界条件，与试样滑移清楚地指出，在1016毫米的试样。广泛的缺口宽板实验程序的结果表明：（a）每个板的初始形状偏离平面度达3 mm，最大偏离发生在缺口中心，（B）对于远远超过缺口区域大的面外位移开始的载荷水平，整体载荷-位移响应基本上是线性的，以及（c）增加带切口的薄板试样的尺寸导致明显不同的表面变形和变形形状，在最大板的平面外分量中具有三个独立的最大值/最小值。拉伸开口应变高于2%的区域在孔前方延伸几毫米，而平行于缺口方向的压缩应变包含在孔的几毫米内。面内剪切应变沿沿着圆瓣集中，与水平方向成+/-45 °，这一趋势与平面应力条件基本一致。(C)2003年，由光学仪器工程师学会（Society of Photo-Optical Instrumentation Engineers）主办。
The response of wide, thin, center-notched, 2024-T3 aluminum panels undergoing far-field tensile load is investigated. Three panels with a notch length to panel width of 0.33 and widths of 305, 610, and 1016 mm were subjected to far-field tensile loading. As part of the experimental program, two pairs of cameras were configured into separate stereovision systems and used to simultaneously capture both the global response of the sheet and the local response near a notch tip. Global areas, ranging in size from 250 x 250 mm to 550 x 550 mm,. were imaged for each panel. A second stereovison system recorded images of a small area, 10 x 20 mm, ahead of one notch tip. Postprocessing of the stereovision measurement data from global and local systems using three-dimensional digital image correlation was used to obtain the complete displacement field at each point in the region of interest. In general, results demonstrate that the combination of stereovision and three-dimensional digital image correlation is capable of accurately measuring true, three-dimensional structural deformations in regions undergoing both large out-of-plane displacements and large displacement gradients. Furthermore, 3-D measurements on the panel specimen near the grip location, are shown to provide an independent assessment of the true boundary conditions, with specimen slippage clearly noted in the 1016-mm specimen. Results from the extensive notched, wide panel experimental program demonstrate that (a) each panel has an initial shape that deviates up to 3 mm from planarity, with the greatest deviations occurring at the center of the notch, (b) the global load-displacement response is essentially linear for load levels that are well beyond the onset of large, out-of-plane displacements in the notch region, and (c) increasing the size of the notched, thin panel specimen results in distinctly different surface deformations and deformed shapes, with three separate maxima/minima in the out-of-plane component of the largest panel. The region where tensile opening strains are above 2% extends several millimeters ahead of the hole, while compressive strains parallel to the notch direction are contained within a few millimeters of the hole. The in-plane shear strains are concentrated along circular lobes at +/-, 45 deg from the horizontal direction, a trend which is generally consistent with plane stress conditions. (C) 2003 Society of Photo-Optical Instrumentation Engineers.