Hardening and fracture behaviors at ultra-high strain rates for metallic materials

Abstract

This dissertation is concerned with the dynamic hardening and fracture behaviors of metallic materials at a wide range of strain rates from $10^{-3}$ /s to $10^6$ /s. The main outcomes of this dissertation are: (i) experiments to obtain hardening behaviors and fracture strains at a wide range of strain rates from $10^{-3}$ /s to $10^3$ /s and temperatures from 25$\circ C$ to 200$\circ C$

(ii) consideration of thermal softening effect at various strain rates due to large plastic deformation

(iii) development of a rate and temperature dependent constitutive model to describe strain rate hardening and thermal softening behaviors

(iv) investigation of a novel systematic procedure to calibrate hardening behaviors at ultra-high strain rates ranging from $10^4$ /s to $10^6$ /s where hardening behaviors are difficult to acquire from conventional experiments

(v) development of a strain rate dependent fracture criterion which can decently estimate experiment results at various strain rates and loading paths

and (vi) prediction of sequential deformed shapes and fractured shapes of projectiles from Taylor impact tests for different metallic materials.