Theoretical Prediction and Numerical Simulation Investigation of the Thermal Forming Limit of 7075 Aluminum Alloy Based on Continuum Damage Mechanics

doi:10.3901/JME.2020.24.051

Abstract

Abstract: Hot uniaxial tensile tests and forming limit tests of 7075 alloy are conducted. Stress-strain curves and forming limit curves at different temperatures and strain rates are obtained. The results show that reduction of strength and improvement of formability are observed at relatively higher temperatures and strain rates. In order to describe the thermal damage evolution of 7075 alloy, a modified continuum damage model is proposed and incorporated into a set of multi-axial unified visco-plastic constitutive equations. The parameters in equations are calibrated with NSGAII algorithm based on experimental results. The set of calibrated constitutive equations can commendably predict the thermomechanical behavior and forming limit strains of 7075 alloy. Moreover, numerical simulation is carried out in the simulation software Abaqus by implementing the set of constitutive equations via the user material subroutine VUMAT. The results show the forming limit curves and strain field of simulation are in good agreement with experimental and theoretical grades, which proves the established set of mult-axial constitutive equations coupled with damage is valid and appropriate for the numerical simulation of thermal forming limit.

Key words: continuum damage, visco-plastic constitutive model, 7075 alloy, forming limit, numerical simulation

CLC Number:

TG156

RONG Hai, YING Liang, HU Ping, HOU Wenbin. Theoretical Prediction and Numerical Simulation Investigation of the Thermal Forming Limit of 7075 Aluminum Alloy Based on Continuum Damage Mechanics[J]. Journal of Mechanical Engineering, 2020, 56(24): 51-60.

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