数字散斑相关方法测量混凝土裂缝尖端演化过程

Measurement of Evolutionary Process of Concrete Crack Tip by DSCM

阐述了数字散斑相关方法的基本原理.采用爬山搜索法进行整像素搜索,基于梯度的搜索算法计算亚像素位移、位移场局部最小二乘拟合计算应变场.测量了混凝土三点弯曲梁裂缝尖端的演化过程,给出了试件加载过程的载荷-位移曲线以及裂缝扩展的过程.由DSCM分析结果,获得了试件在不同载荷下裂缝尖端的位移场与应变场.为深入研究含裂纹体材料和结构的断裂破坏提供了一个有效的实验方法.

The basic principles of DSCM （digital speckle correlation method） were explicated. The integer pixel search was carried out by the mountain-climb searching, and the subpixel displacement was calculated based on the gradient searching algorithm and the strain field on the least-square fitting of local displacement. The authors measured the evolutionary process of crack tip on 3-point bending concrete beam to present the load-displacement curves in specimen loading and the crack expanding process, and obtained from DSCM analytical results the displacement and strain fields of crack tip with the specimen under different loads, which provides an effective experimental method for probing into the fracture and damage of materials and structures with discontinuities.