IMAGE-ANALYSIS TO MEASURE STRAIN IN WOOD AND PAPER
IMAGE-ANALYSIS TO MEASURE STRAIN IN WOOD AND PAPER
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DOI：
10.1007/bf00225465
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发表时间：
1991-01-01
影响因子：
3.4
通讯作者：
HANNA, RB
中科院分区：
文献类型：
--
作者：
CHOI, D;THORPE, JL;HANNA, RB
提出了一种快速、准确的应变测量方法，用于利用视频图像量化木材和纸张的微观变形。两个或多个视频图像，其中一个是未变形的，其他的变形，数字化和比较使用的图像相关技术。这种数字计算机模式识别技术允许测量图像中任何点的位移。然后，在这个观测领域的任何两个点之间的应变可以计算，因此，正常，剪切应变和泊松比可以直接测量。独立应变测量表明，使用视频图像的方法提供了准确的应变测量，并可应用于木材和木制品等复杂材料。使用图像分析的应变测量不仅产生正常应变，而且产生正常应变的应变分布。从应变分布图中，可以检测出可能超出弹性范围的应变集中的局部区域。由于它是利用图像相关技术从一组视频图像中测量位移和应变，因此该方法是非接触的，并且可以通过改变光学器件的放大率来容易地调整观察范围。因此，该方法可以应用于木材和木制品的机械测试，从细胞水平到全尺寸木材，并且不再受被测材料的易碎性、行业标准或设备限制的限制。
A fast and accurate strain measurement method was developed to quantify microscopic deformation in wood and paper using video images. Two or more video images, one of which was undeformed and the others of which were deformed, were digitized and compared using the image correlation technique. This digital computer pattern recognition technique permitted the displacement of any point in the image to be measured. Then, strain between any two points in this observation field could be calculated and, hence, normal, shearing strains and Poisson's ratio could be measured directly. Independent strain measurements showed that the method using video images provided accurate strain measurements and could be applied to complex materials like wood and wood products. The strain measurements using the image analysis produced not only normal strains but strain profiles of the normal strains. From the strain profiles, it was possible to detect local areas of strain concentration which might be beyond the elastic range. As it measures displacements and strains from a set of video images using the image correlation technique, the method is non-contact and the observation field can be adjusted easily by changing magnifying power of the optical devices. Thus, the method can be applied to mechanical testing of wood and wood products from the cellular level to full size lumber and will no longer be limited by the fragile nature of the material being tested, industry standards, or equipment restrictions.