基于数字图像相关技术的金属冲裁过程材料变形分析

Analysis on material deformation in metal blanking process based on digital image correlation technique

为准确分析金属板料冲裁过程中材料变形及断裂行为,构建了一个基于二维数字图像相关方法的原位应变测量系统。对Cu Sn0.15铜合金板材开展系列冲裁实验,通过该原位应变测量系统有效地跟踪记录了冲裁过程的局部大变形,获取了冲裁过程的各应变分量的应变场分布,在此基础上分析了应变演变规律和不同冲裁间隙的应变场差异。结果表明,剪切应变在冲裁过程前期起主导作用,而拉伸应变的急剧增大是在冲裁过程后期材料内部出现微裂纹的主要原因。不同冲裁间隙的应变场差异主要体现在拉伸应变的分化上,拉伸应变的差异是影响光亮带占比的主要因素。研究结果不仅为冲裁工艺的制定提供基础数据,还可为评定数值模型的有效性提供依据。

In order to investigate the material deformation and fracture behavior in the metal sheet blanking process,an in-situ strain measurement system was established by 2D digital image correlation technique. Then,a series of blanking experiments were carried out on copper alloy sheet CuSn0. 15,and the strain distributions of the strain components in the blanking process were obtained by in-situ strain measurement system recording the localized large-deformation. Furthermore,the regulation of strain and the difference of strain field with different clearances were analyzed further. The results indicate that the shear strain is predominant at the early stage of the blanking process,while a rapid increase of tensile strain at the later stage leads to the micro cracks inside the material. Thus,the difference of strain field with different clearances is mainly shown on the distinction of tensile strain,and the difference of tensile strain is a main factor influencing the proportion of bright region in the thickness direction of sheet metal. The experiment results provide basic data not only for blanking technology,but also for verifying the effectiveness of the numerical model.