Experimental and Numerical Investigations of a Split-Ring Test for Springback

This paper presents an in-depth experimental and numerical investigation of a split-ring test, which provides a simple yet effective benchmark for correlating forming and springback predictive capabilities with experimental measurements. The experimental procedure consists of deep drawing a circular 6111-T4 aluminum alloy into a cylindrical cup of $55mm$ depth, crosscutting nine rings each of $5mm$ wide from the cup, splitting the rings, and measuring their opening displacement, i.e., the springback amount. Experimental data obtained included punch force trajectories, drawn cup profile, thickness distribution after forming, and the ring openings after splitting. A numerical model is built to analyze the process, and both transversely isotropic and fully orthotropic yield criteria are investigated. Simulation results are validated against experimental data. A detailed numerical analysis is also conducted for stress distributions in each ring after each step and their relationship to the total springback amount. Stress and strain signatures suggested that the test is well suited for validating material models, such as anisotropic yield surface models and hardening models.