Finite element simulation of the effect of loading rate on the stress-strain behaviour of Albany sand

Abstract

Listen

Translate article

In this research, the effect of strain rate on Albany sand has been studied by elastic visco-plastic constitutive model within the framework of three component model. Strain rate effect can be modelled by using any one of the (i) Isotach, (ii) TESRA (temporary effects of strain rate and acceleration) or Viscous Evanescent and (iii) P&N (positive and negative viscosity) models of the three component framework. Usually ‘Isotach’ is appropriate for clay and soft rock, ‘TESRA’ for sand and ‘P&N’ is appropriate for sand with less angularity like Albany sand. In this research triaxial compression (TC) test results of Albany sand at different strain rates have been modelled successfully into a commercially available package called ‘ABAQUS’. The P&N model was implemented into a generalised elasto-plastic isotropic strain-hardening non-linear model in C++. The model was then embedded in the finite element computer programme ABAQUS, which was used for the actual analysis. In order to define the P&N model user subroutine of ABAQUS ‘UMAT’ was written in C++ and used hereafter. ABAQUS is a robust FEM software that allows writing subroutines for describing different material behaviour. Generally UMAT is written in FORTRAN but in this study the main model is written in C++ and then it is called by FORTRAN with appropriate change in ABAQUS environment file. The effect of strain rate on the stress-strain behaviour of Albany sand has been modelled by using the TESRA model with the help of user subroutine UMAT of commercially available FEM software ABAQUS.