Implementing Digital Image Correlation for Determining the Tensile Characteristics of Post-Processed Thin Sheet Metal

Acquiring material properties for finite element analysis is a necessity for producing accurate response outputs. In the sheet metal forming industry, there are many challenges in gaining material property definition from post-processed and/or extremely thin sheet metal. The difficulty in obtaining this information is the founding reason for applying digital image correlation in the characterisation process of post-processed beverage cans. These beverage cans have been cupped, drawn, re-drawn, ironed and stoved, so these can be described as “pre-necked” beverage cans. Due to the residual stress/strain worked into the material, it means that the specimens curl, hence, there are difficulties in attaching contact extensometers. This experiment has shown that the preparation and testing of test specimens is critical in obtaining accurate and robust results. The robustness has been fulfilled by ensuring the data matches contact extensometers, and the number of test specimens used is sufficient. This experiment has proven that the application of digital image correlation has produced reliable and useful tensile properties for the finite element model, whilst demonstrating the the thermal effects imposed during the stoving process, which in-turn has raised questions over the impact of thermal effects in the processing of cans.