Stress redistribution around fiber breaks in unidirectional steel fiber composites under longitudinal tensile loading

Mutlu, Çağlar
Due to their significant advantages, such as high strength-to-weight, stiffness-to-weight ratio, flexibility in design and excellent fatigue resistance, use of fiber-reinforced composite materials has increased remarkably. Because of their widespread use, a comprehensive understanding of failure of composite materials is an important issue. Recently, steel fibers are increasingly seen as reinforcement material in composites thanks to their advantages like ductility, high stiffness and wide range of production diameters. Strength and failure strain of composites are calculated by strength models. Stress concentration factor and ineffective length are two important input parameters for these strength models. Some parameters that arise from the properties of steel fibers may affect the mechanical behavior of steel fiber composites under loading. In this study, effects of these parameters on stress concentrations and ineffective length in unidirectional steel fiber composites under longitudinal tensile loading are investigated. A parametric study is performed by using 3D finite element models with random fiber packings. Non-circular cross-sections of steel fibers are shown to have a negligible effect on the results. Also, it is found that mechanical properties of constituent materials and applied strains cause differences in the results. Loading and reloading processes are found to have similar results for same applied strains. Reloading to a lower loading levels than the one in loading resulted in different results.