Micromechanics-based FEM simulation of fiber-reinforced cementitious composite components

Fiber bridging along cracks is an important mechanism governing the fracture toughness and the pseudo-ductility of fiber-reinforced brittle materials and structures. This paper attempts to predict structural behavior of fiber-reinforced cementitious composite (FRCC) components using the finite-element procedure with micromechanics-based constitutive modeling of the stress-displacement relation along the crack. The tensile stress-displacement relation along a Mode I (opening) crack is established based on fiber pullout curves derived from a micromechanical model. A statistical model is used to account for random fiber distribution. Two-dimensional finite-element simulations of beam behavior are performed with the finite-element package ADINA. Using the discrete crack approach, strain softening truss elements are placed along the crack to simulate the fiber bridging effect. Experiments of beams under four-point bending are performed with specimens containing different fiber volume fractions (up to 1.5%). The numerical results for the load vs deformation behavior of the beams agree well with the experimental results. The FEM procedure for micromechanics-based design and analysis of FRCC components is therefore established. Simulation of component behavior to identify the most cost-effective design can, hence, be carried out.