Microstress fields and the mechanical properties of disordered fiber composites

Conclusion

The effective elastic moduli and Poisson's ratios and the mean characteristics of the stress fields in the components of unidirectional fiber composites with a stochastic structure are nearly the same as the corresponding values calculated for a regular model of the composite. Relatively small increase (up to 6%) is seen in the transverse shear moduli with the transition from a regular structure to a stochastic structure. In the latter, there is a substantial increase in the stress concentration factor. Here, the difference between the stochastic structure and the regular structure increases with an increase in fiber stiffness and is particularly great (with a difference of two to three orders of magnitude) in the case of shear loading. The probability of the occurrence of microscopic fracture in the binder of the investigated materials is higher in transverse tension, but the difference from the results obtained for the regular models is more significant in the case of shear loading. Microscopic fracture nuclei will be formed in the matrix of the composite with the stochastic structure at considerably lower macroscopic stresses than are required for the regular structure.