DOES THE SHEAR-LAG MODEL APPLY TO RANDOM FIBER NETWORKS

The shear-lag type model due to Cox (Br. J. Appl. Phys. 3, 72 (1952) i s widely used to calculate the deformation properties of fibrous mater ials such as short fiber composites and random fiber networks. We comp are the shear-lag stress transfer mechanism with numerical simulations at small, linearly elastic strains and conclude that the model does n ot apply to random fiber networks. Most of the axial stress is transfe rred directly from fiber to fiber rather than through intermediate she ar-loaded segments as assumed in the Cox model. The implications for t he elastic modulus and strength of random fiber networks are discussed .