Effect of inclination angle on fiber rupture load in fiber reinforced cementitious composites

A model has been formulated for analyzing the influence of fiber inclination angle on its rupture load in fiber reinforced cementitious composite. As a stiff fiber is pulled with an angle to the direction of pulling, the fiber rupture load decreases compared to the case with zero inclination angles. This phenomenon is called fiber apparent strength (defined as rupture load divided by fiber cross-section area) degradation. A parametric study, including the influence of elastic moduli of fiber and matrix, fiber/matrix interfacial bond strength as well as fiber orientation in matrix on the fiber apparent strength is carried out. The model results indicate that with the increase of fiber inclination angle, fiber apparent strength decreases. In addition, fiber apparent strength degradation degree is influenced by the elastic moduli of fiber and matrix and fiber/matrix interfacial bond strength. A fiber rupture test of carbon fiber in cementitious matrix was used for model verification. Model predictions based on independent parametric input compare favorably with experimental measurements of fiber apparent strength.