Calibration of triaxiality and Lode angle parameter-dependent failure models for high- and ultra-high-hardness steel based on experimental material characterization tests

• Experimental characterization of high-hardness and ultra-high-hardness steel. • Calibration of four triaxiality and Lode angle parameter-dependent failure models. • Comparison of model calibration for proportional and non-proportional loading. Discussion of suitability of the four failure models for description of the test data. We explore the failure characteristics of high-hardness armor (HHA) and ultra-high-hardness (UHA) armor steel. We provide experimental data on the plasticity and ductility of two representative materials. A calibrated Johnson-Cook model effectively describes plasticity across multiple types of experiments. Based on this, we calibrate four different failure models, including triaxiality and Lode angle parameter-dependent variants. Among the failure models evaluated, the Chocron-Erice-Anderson model demonstrates the best performance, followed by Xue-Wierzbicki, Hosford-Coulomb, and Johnson-Cook. In comparing two parameter identification methods, we find that the combined experimental–numerical method that accounts for varying triaxiality and Lode angle parameter produces the most accurate models of material ductility.