A Micromechanics Approach for Fatigue of Unidirectional Fibrous Composites.

The overall mechanical properties of composite materials are dependent on the mechanical response of individual constituents and their interactions while they may be relatively easy to determine. This paper represents a simulation process by which the cyclic stresses and fatigue loadings on its constituents could be predicted for an under fatigue loading lamina. Hence, the unidirectional composites fatigue would be studied through its constituents. The proposed model introduces a new coupled stiffness/strength technique by relating lamina stiffness to the stress field in its constituents. Therefore, the stress field and strength considerations in its constituents could be studied when the lamina stiffness is determined by a non-destructive process. For representing a complete description of the constituents properties and their interactions, the effect of fibre/matrix interface debonding was introduced into the model. A number of experiments are conducted to verify the simulated relations. The comparison of theoretical and experimental predictions shows that the results are satisfactorily in good agreement.