Adiabatic heating under various loading situations and strain rates for advanced high-strength steels

Adiabatic softening has an important impact on material behavior under dynamic loading. Temperature rise depends on the amount of plastic work converted into heat, as well as on the quantity of heat dissipation influenced by several parameters. In order to avoid complex thermomechanical coupling in simulation, a pseudo thermomechanical model based on an analytical approach of Dixon and Parry [1] was applied in in the past [2, 3, 4, 5] considering the influence of strain rate on temperature rise. In this work the additional influence of the stress state and the size of the localized zone on temperature rise is investigated for advanced high-strength steels (AHSS). Therefore high speed tests were performed for different multiaxial stress states at loading rates ranging from isothermal to adiabatic conditions. Local strain fields were measured by high-speed video recording, and evaluated by digital image correlation (DIC), and temperature fields were recorded by high-speed infrared (IR) measurement. For shear loading, the results show a significantly larger amount of local plastic work dissipated by heat transfer until failure emergence compared to tensile loading at comparable strain rates. Hence, an extended model "adiabatic tension-shear model (ATS)" is proposed considering adiabatic softening under shear-dominated loading conditions in simulations. (paper)