立体视觉和坐标网格法测量应力应变曲线的技术研究

Study on Stress-strain Curve Measurement via Stereo Vision and Coordinate Grid Method

材料应力应变的同步采集和应变快速准确获取是测量材料应力应变曲线测量的关键。为此设计了载荷获取和图像拍摄的同步采集硬件装置和控制方法,有效保证了应力与应变在时序上的精确同步。针对试件表面标识的坐标网格,提出一种基于网格传播的网格图像处理技术实现了网格节点拓扑关系建立和节点坐标的精确定位。再利用双目立体视觉技术对网格三维变形进行跟踪,根据有限应变理论实现应变测量。现场实验结果显示本文的方法与传统方法相比在精度和适应性上具有综合优势。

The synchronous data capturing of stress and strain, and the fast accurate acquision of strain are the key steps for measuring stress-strain curve. Firstly, a hardware circuit is designed for the synchronous acquisition of loading force and images, which can guarantee the accurate synchronization of the stress and strain in timing sequence. Subsequently, a grid-propagting method to realize topology build-up and precise coordinate extraction of grid nodes is proposed. After that, a binocular stereo vision technology is thus leveraged to track 3D deformation of the grids and to measure strain combining with the finite strain theory. The experimental results demonstrate the present method has the integrated advantage on the accuracy and efficiency comparing with the traditional method.