ON THE RESEARCH OF TAYLOR IMPACT TECHNIQUE UNDER ELEVATED TEMPERATURE AND ITS APPLICATION IN THE VALIDATION OF CONSTITUTIVE PARAMETERS OF METAL

The Taylor impact experiment under elevated temperature offers a novel approach to the validation of strain rate and temperature-dependent material constitutive model. Based on the air-gun equipment, the technique of Taylor impact under elevated temperature was established. Three critical techniques, which contain realization and controlling of specimen velocity, realization of elevated-temperature of specimens and designing the equipment, measuring the dynamic response parameters of elevated-temperature specimens, were successfully addressed. The validation and optimization of the constitutive parameters of 05Cr17Ni4Cu4Nb were carried out by using the Taylor impact technique under elevated temperature. Firstly, Tensile tests were conducted on 05Cr17Ni4Cu4Nb steel under the temperatures ranging from room temperature to 900 °C and strain rates ranging from 1.0 × 10⁻³ to 1.0 × 10³ s⁻¹. The stress-strain curves under different temperatures and strain rates were obtained. Based on the variation of flow stress with plastic strain under the referenced strain rate, the variation of yield strength with strain rate and the variation of yield strength with temperature, the strain rate and temperature-dependent Johnson-Cook constitutive model parameters were acquired. Secondly, using the Taylor impact technique under elevated temperature, Taylor impact tests were conducted on 05Cr17Ni4Cu4Nb steel under room temperature, 300, 500, 570 and 710 °C. The specimen sizes after impact were measured. Finite element numerical simulation analysis of Taylor impact under room temperature and high-temperature was carried out. Optimization process and algorithm for the constitutive model were established. The optimization of constitutive model parameter of 05Cr17Ni4Cu4Nb steel was carried out by choosing the average size deviation of specimens as the optimization objective function. The Johnson-Cook constitutive model parameters of 05Cr17Ni4Cu4Nb steel after optimization were obtained. It was found that the constitutive model parameters obtained from uniaxial stress state over estimate the strain hardening, strain rate hardening and temperature softening behaviors of 05Cr17Ni4Cu4Nb steel under complex stress states.