Fiber-reinforced brittle material fracture models capable of capturing a complete set of failure modes including fiber pull-out

Abstract

In this work we propose a model that can take into account all the different failure mechanisms occurring in heterogeneous brittle composite materials such as fiber-reinforced concrete (FRC). The model kinematics is based on a judicious combination of the embedded-discontinuity finite element method (ED-FEM) and the extended finite element method (X-FEM) that can represent inelastic deformation and failure modes of three model constituents: concrete, short fibers, and the bond–slip between fiber and concrete. The general framework combining continuum damage and ED-FEM discrete approximation is used for modeling micro-cracks and macro-cracks in concrete. Fibers are taken to be linear elastic, and bond–slip is inelastic, computed along the fiber until complete pull-out, which is described by X-FEM discrete representation. The computations are performed with an incremental-iterative solution procedure and operator-split scheme that can control the fiber slip in each increment and thus easily handle softening response in fiber pull-out. The proposed model performance is illustrated through several numerical simulations. We include among them the simulation of three-point bending tests on notched specimens with fibers crossing the notch, which provide the validation of the proposed model against the experimental results.