Methods for measuring material parameters of hardened steel core for failure models

The complex material behavior of hardened steel projectile cores in impact scenarios places high demands on constitutive modeling. To measure material parameters for failure models, miniaturized round tensile, flat tensile, compression and compression-torsion specimens were produced and quasi-static characterization tests were carried out on a material testing system machine. The specimens were made directly from the projectile cores of 14.5 mm caliber AP ammunition, which severely limited the maximum feasible specimen sizes. By using specimens with different geometries and notch radii, failure of the specimens was initiated at different multiaxial stress states. The compression-torsion specimen was used to generate different combinations of stress triaxialities and Lode angles at failure by setting different ratios of torsional to compressive loads. The specific stress states were determined by accompanying numerical simulations. It was exemplarily demonstrated that the measurement results can be used to improve the simulated fragmentation of a B-32 projectile core in a ballistic scenario.