Dynamic tensile behavior and constitutive modeling of magnesium based hybrid nanocomposites at elevated temperatures

摘要

The dynamic response and constitutive behavior of magnesium (Mg) based nanocomposites have not been sufficiently investigated. Thus, dynamic tensile stress-strain characteristics of 1.0 mass% hybrid carbon nanotubes (CNTs) and silicon carbide (SiC) nanoparticles reinforced AZ91D matrix composites were studied at high strain rates and elevated temperatures by experiments and simulations in the present work. The dynamic tensile stress-strain curves of the AZ91D matrix nanocomposites at different strain rates and elevated temperatures were experimentally obtained. The experimental results show that the dynamic stress-strain relationship of the AZ91D nanocomposites is strain rate and temperature dependent. By considering the strain rate hardening and the coupled effects of strain rate and temperature, a modified Johnson-Cook (J-C) constitutive model was proposed to predict the dynamic mechanical behavior of the composites at high temperatures and high strain rates. In addition, the modified J-C model is implemented in ABAQUS / Explicit by using the user material subroutine VUMAT. The simulation results using the modified model show a good agreement with the experimental data, proving its capabilty for predicting the dynamic tensile response of the AZ91D nanocomposites well at elevated temperatures.