Numerical Characterization of Mechanical Properties of Fiber Network Materials

The present PhD thesis performs a comprehensive numerical study to explore the mechanical response of materials with a fibrous network microstructure. At first, the tensile response of lattice structure made of linear elastic and elastoplastic struts is studied. Three types of lattices, including diamond, hexagonal, and triangular, are selected. The results indicate that the stiffness and the strength decrease by increasing the percentage of elastoplastic material. Then, the mechanical behavior of lattices composed of bi-modulus elastic material is investigated. It is seen that the overall modulus of bi-modulus lattice decreases as the ratio of compression to tension modulus decreases. Besides, the influence of material nonlinearity of individual fibers is investigated on the shear response of the random fiber network. Three material models are assumed for induvial fiber, from very low to very high. The overall shear modulus of the fibrous network has a dependency on the bending rigidity of fibers and average connectivity. It is found that the fibrous network of nonlinear fibers exhibits a stiffer response than those consist of linear elastic fibers. Furthermore, the significance of uniaxial prestress is explored on the mechanical response of the branched network. Initially, the benched network is generated by diluting regular hexagonal lattices. Then, the effect of irregularity in the network architecture, average network connectivity, the material property of individual fibers, and randomness in the mechanical behavior of fibers are studied. It is seen that tension/compression uniaxial prestress induce stiffening/softening in the shear response of the branched network, respectively.