Deformation and failure of bulk metallic glasses under different initial temperatures

J.C Li,X.W Chen,F.L Huang

doi:10.1051/epjconf/20159404017

J.C Li, X.W Chen + Show 1 more

Open Access

https://doi.org/10.1051/epjconf/20159404017

Copy DOI

Abstract

Based on the coupled thermo-mechanical model, a constitutive model for bulk metallic glasses (BMGs), which is generalized to the multi-axial stress state and considers the effects of free volume, heat and hydrostatic stress, has been modified in the present paper. Besides, a failure criterion of critical free volume concentration is introduced based on the coalescence mechanism of free volume. The constitutive model as well as the failure criterion is implemented into the LS-DYNA commercial software by user material subroutine (UMAT). Then FEM simulations for different initial material temperatures are conducted and the evolutions of material parameter as well as corresponding macroscopic mechanical behaviour of material are analyzed. Relative analysis shows that the initial material temperature significantly affects the deformation and failure of material.

Highlights

Bulk metallic glasses (BMGs) have many excellent mechanical and physical performances
The material usually shows an asymmetry between tension and compression [4, 5]. All these particular properties promote that BMGs may have many engineering applications, e.g., the good plasticity is beneficial for the precise microforming process [6], and the localized shear bands may be employed in the material optimization of kinetic energy penetrator (KEP) [7, 8]
Through the user material subroutine (UMAT) subroutine, the above constitutive model and the failure criterion are implemented into the LS-DYNA commercial software

Summary

Introduction

Bulk metallic glasses (BMGs) have many excellent mechanical and physical performances It usually show good plasticity even superplasticity while under the condition of high temperature (within the supercooled liquid region) and low strain rate [1,2,3]. Related analyses show that the initial temperature has a significant effect on the deformation and failure of BMGs. Especially, the microstructure as well as corresponding mechanical behavior of material is extremely different while the initial temperature is below or within the supercooled liquid region. The microstructure as well as corresponding mechanical behavior of material is extremely different while the initial temperature is below or within the supercooled liquid region

Constitutive equations and failure criterion

Finite element implementation of constitutive model

Estimation of material parameters

Deformation and failure of BMGs under different initial temperatures

Conclusions