Failure Testing Under In-Plane Biaxial Tension and Out-of-Plane Compression

The deformation and failure behavior of 2024 aluminum was investigated under combined in-plane equi-biaxial tension and out-of-plane compression. This loading configuration yields stress states of Lode parameter = -1 and triaxialities ranging from -0.67 to 0.17. Testing was performed using a variation of the standard ASTM quasi-static hemispherical punch test, with a reduced punch diameter and the addition of an annealed copper backing plate behind the specimen. The reported stress states at the failure point were then determined numerically using LS-DYNA.