STRAIN RATE AND STRAIN RATE HISTORY EFFECTS ON THE DYNAMIC BEHAVIOR OF METALLIC MATERIALS

[[abstract]]The constitutive equations for strain hardening (f.c.c. metals and alloys) and strain softening-hardening metallic materials (b.c.c. metals and alloys) have been developed. The development is within the framework of the endochronic theory of viscoplasticity. The intrinsic time is dependent on the plastic strain rate. Sets of constant-strain-rate stress-strain curves have been theoretically obtained for both classes of metallic materials mentioned. The strain rate history effect is studied in terms of low-high and high-low strain rate change test sequences. For a fixed strain rate history in the case of strain hardening materials, a similar pattern of subsequent material behavior is obtained, independent of the strain magnitude at which the strain rate change takes place. However, in the case of strain softening-hardening materials, the strain magnitude at which the strain rate change occurs affects the subsequent material behavior. Theoretical results are compared with experimental data found in the literature[[fileno]]2020226010016[[department]]動機