Nonlinear three-dimensional anisotropic material model for failure analysis of timber

Abstract

In this paper, a constitutive material model is proposed to model the nonlinear mechanical response of timber, as elastoplastic orthotropic material under three-dimensional (3D) stress state. An associated flow rule model based on Hoffmann yield criterion and plastic potential is adopted for describing the plasticity of timber under compression. Isotropic strain hardening during plastic deformation is incorporated into Hoffman yield criterion by assuming that equivalent yield stress is a function of the equivalent plastic strain. A stress-based continuum damage formulation with four independent failure criteria in tension and compression is used. The proposed model is implemented as a user material subroutine UMAT in ABAQUS. The results obtained in numerical simulations are evaluated and compared with experimental results. A good agreement has been found between numerical simulations and the experimental results. Therefore, the proposed constitutive model can be used further in numerical simulations of the anisotropic behavior of timber.