Determination of material constants for high strain rate constitutive model of high entropy alloys

Abstract

The paper deals with constitutive models determination for a group of high entropy materials (coded Bl-x). The procedure includes the following steps: experimental determination of mechanical characteristics for quasi-static domain through compression tests, correction of experimental data of quasi-static tests using numerical simulation, acquisition of experimental data obtained on the Split Hopkinson Pressure Bars and their simulated interpretation. Using the processed data, the constitutive patterns of the materials under investigation are drawn. The experimental data correction for quasi-static tests performed using numerical simulation involves drawing the engineering stress/strain diagram, the transition to the plastic characteristic diagram in the hypothesis of perfectly cylindrical shape of the specimen throughout the test, simulation of the compression deformation process in the presence of friction force on the end specimen surfaces and the correction of the characteristic plastic diagram using the calculated error. Dynamic data obtained on Split Hopkinson Pressure Bar were interpreted using a methodology previously published. Experimental data under real conditions are compared with data obtained by numerical simulation on an elasto-plastic model. The viscous component of the dynamic response is the difference between the real and simulated on the elasto-plastic model responses.