The role of fiber volume fraction in tensile strength of fibrous composites Rypl, Rostislav; Vořechovský, Miroslav; Chudoba, Rostislav
It has been proved experimentally that a finer crack pattern in brittle matrix composites with heterogeneous fibrous reinforcement increases the reinforcement efficiency in terms of fiber strength by up to 100 %. In the present paper, we simulate this phenomenon by a semi-analytical model of a composite crack bridge based on probabilistic fiber bundle models. The model is able to quantify the reinforcement efficiency increase with finer crack spacing given the information on the reinforcement heterogeneity. Possible sources of heterogeneity are variabilities in fiber diameter, modulus of elasticity or bond quality. With finer crack spacing, the heterogeneous stress state of the reinforcement is homogenized which leads to a more efficient load bearing behavior. Since the crack spacing is (within the practical range of values) a monotonic function of the fiber volume fraction and fiber diameter, these quantities should be taken into account in structural analysis and design of composites with heterogeneous reinforcement.
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