中文摘要：

针对板料成形极限试验中传统应变测量方法的不足,提出并实现一种基于数字图像相关法的板料成形极限应变测量方法。对其中涉及的关键技术进行深入研究。针对板料成形中大变形测量的难题,根据系列变形图像相邻状态变形的连续性,提出一种大变形分步匹配算法,并介绍三维坐标重建和三维应变求解的方法。根据测得的试件表面应变分布,提出一种通过构建应变场截面线来拟合成形极限曲线的方法。基于Visual Studio 2010开发环境,开发用于板料成形极限应变测量的计算软件。为了验证方法的可行性,结合自研的图像采集装置和改进的板料成形试验机搭建成形极限测量试验平台。对SPCC钢板试件的测量结果显示所提出的方法能够快速、有效、直观地测量试件在整个成形过程中的表面应变分布,为建立成形极限图提供一种有效手段,且与传统的坐标网格等方法相比优势明显。

英文摘要：

To achieve limit strains measurement of metal sheet forming, a dynamic deformation measurement method is proposed and implemented based on digital image correlation. The applied key technologies are investigated. To solve the problem of large deformation and strain measurement in metal sheet forming, a fractionized matching algorithm based on deformation continuity of adjacent image sequences is proposed, a successful image matching results even in large deformation situation is provided. The algorithms for three-dimensional coordinates reconstruction and strain calculation are discussed separately. Based on section line of the measured strain field, a fitting algorithm for forming limit curve is proposed. Based on these algorithms and the Visual Studio 2010 platform, a forming limit strains measurement system is developed. With our self-developed image acquisition setup and a sheet metal forming machine, a steel cupping test is conducted to validate the performance of our method. Experimental results demonstrate that the proposed method is applicable to the measurement of 3D deformation and limit strain of the sheet metal forming. Compared with the traditional measurement methods, the method can be more comprehensive and more intuitive to achieve the strain measurements during the whole forming processes. It provides a good solution for forming limit prediction.