Large deformation analysis of trusses considering ductile damage, mixed hardening, strain-rate dependence and thermal effects

Abstract

A new finite element model for the analysis of truss structures is developed accounting for large deformation, ductile damage, mixed hardening, dynamics and thermoviscoplasticity. To this end, a thermodynamically consistent uniaxial model is proposed, including a finite-strain plasticity formulation coupled with damage, thermal effects and strain-rate dependence. The novel character of the constitutive model is the consideration of all those features together. The transient problems are solved numerically using a 3D truss element together with the Newmark and backward-Euler time-integration schemes. A numerical technique of embedding the effects of the evolution of internal variables into the material stiffness is originally developed. The key numerical feature is that the proposed algorithm avoids staggered schemes and a large unsymmetric global system including all the variables to be determined. Three examples involving truss structures are simulated to assess the performance of the proposed model. The influence of the material parameters and time increment on the local and global behaviors are investigated in detail, including monotonic and cyclic loading conditions. Results highlight the importance of using the full model (with all the material features) to accurately predict the mechanical behavior, as well as the effect of the failure of individual members on the global response and the capability of analyzing 3D examples.