Strain analysis is an essential step in sheet forming applications to understand the deformation behaviour of the material. The strain analysis is conventionally performed by Circle Grid Analysis (CGA). In CGA, a grid of circles with 2 mm–5 mm diameter is printed on a flat sheet and deformed into the required shape. The length of major and minor axes of the deformed ellipses are measured to estimate the strains at different locations of the formed component. The major and minor axes length of the deformed ellipses are measured either by using a manual method or automatic methods. The automated methods are faster and accurate compared to manual methods, but to perform strain measurement using commercially available automatic strain measurement system, is very expensive. Therefore, in this paper, an image processing based software has been developed with user-friendly Graphical User Interface (GUI) for strain measurement and analysis in sheet metal forming operations. The software has been tested on images obtained by printing the ellipses of known dimensions on the flat sheet by laser etching, electrochemical etching and screen printing, which are generally used for printing circular grids on flat sheets for strain analysis in sheet metal forming. It is observed that the edges of the laser engraved ellipse are very slim and easily detected by software compared to other grid printing methods. The developed software can measure the ellipse dimensions with a maximum absolute percentage error of 1.975%. Further, the results of CGA software has been compared with the commercial strain measurement system called Grid Pattern Analyzer (GPA). The mean absolute error in strain measurement using CGA and GPA was found to be 0.0106 and 0.0178, respectively. The statistical test results reveal that there is no evidence to support a claim that there is a difference in mean performance between the two methods.

应变分析是在板材成型应用中了解材料变形行为的必不可少的步骤。应变分析通常通过圆网格分析（CGA）进行。在CGA中，将直径2毫米至5毫米的圆形网格打印在平板上，然后变形为所需的形状。测量变形椭圆的长轴和短轴的长度，以估计成形零件不同位置处的应变。变形椭圆的长轴和短轴长度可以通过手动方法或自动方法进行测量。与手动方法相比，自动方法更快，更准确，但是使用可商购的自动应变测量系统执行应变测量非常昂贵。因此，在本文中，基于图像处理的软件已经开发出来，具有用户友好的图形用户界面（GUI），可用于钣金成形操作中的应变测量和分析。该软件已在通过激光蚀刻，电化学蚀刻和丝网印刷在平板上印刷已知尺寸的椭圆所获得的图像上进行了测试，这些图像通常用于在平板上印刷圆形网格以在钣金成形中进行应变分析。可以看出，与其他网格打印方法相比，激光雕刻椭圆的边缘非常纤细，易于通过软件检测。开发的软件可以测量椭圆尺寸，最大绝对百分比误差为1.975％。此外，CGA软件的​​结果已与称为网格模式分析器（GPA）的商业应变测量系统进行了比较。发现使用CGA和GPA进行应变测量时的平均绝对误差分别为0.0106和0.0178。统计测试结果表明，没有证据支持这两种方法的平均性能存在差异。