Abstract:

The quasi-static and dynamic material properties, including the strength relation and fracture criterion, from room temperature to 250 益are investigated using a universal testing machine, a torsion testing machine, a split Hopkinson tension bar and the Taylor impact test. The Johnson-Cook constitutive relation with a modification on the strain hardening term and the Johnson-Cook fracture model with a mod- ification on the temperature softening item were proposed to fit the test results. The material constants were calibrated by a combination of experimental tests and numerical simulations. It is concluded that the strain strengthening and temperature softening effect is obvious, while the strain rate hardening effect is not significant; the fracture strain increases with temperature and strain rate and decreases with stress tri- axiality.

Key words: solid mechanics, constitutive relation and fracture criterion, 2A12 aluminum alloy, John- son-Cook strength and fracture models