Numerical model of cracking pattern in laminated bamboo specimens under tensile and shear loads

Abstract

This work describes a two-dimensional numerical model that allows detecting the appearance of cracks and calculating their propagation in elements made of laminated bamboo, under tension and shear. This composite material has long parallel strong cellulose fibers embedded in a weak lignin matrix. The mechanical model that represents the failure and fracture process of laminated bamboo is still unknown. This numerical model simulates localized strains, showing the beginning and progression fracture in the material. The model is based on a two-dimensional scheme for plane stresses, using the finite element method. A one-dimensional plasticity constitutive model, based on Weibull probability distribution, is used to describe the mechanical response of the fibers, and a continuum damage constitutive model controls the behavior of the matrix. The homogenization process is done with the rule-of-mixtures, and vanishing fiber diameter simplification. Continuum strong discontinuities approach is taken as a technique to detect a jump in the displacement field, during the fracture process. This numerical model is used to simulate the failure on tensile and shear tests of laminated bamboo Guadua angustifolia, which were then compared to experimental findings. The results show that the numerical model detects the same crack patterns obtained in tests.