The role of fibers on the tensile stress strain response and the fracture toughness of cement based composites are studied by means of a cohesive crack approach. A model is proposed to include the interfacial debonding and pullout of fibers…
The role of fibers on the tensile stress strain response and the fracture toughness of cement based composites are studied by means of a cohesive crack approach. A model is proposed to include the interfacial debonding and pullout of fibers as closing pressure distribution which is expressed as tensile stress crack-width response. R-Curves are then used to account for increased energy dissipation and simulate the crack growth in the matrix response subjected to the closing pressure. The closing pressure, characterized as an exponentially decaying stress crack-width relationship, is integrated to compute the amount of toughening at incremental crack growth lengths. The strain energy release rate of a three point bending specimen interface are equated to the R-Curve, and solved for the critical crack extension. The R- curves are further used to compute the compliance and the load deformation response. The toughening component is due to the closing pressure of fibers which depends on the matrix crack opening. A parametric study of the effects of model parameters on the crack growth is conducted. The present model is also compared with experimental data on glass fiber composites.