Micromechanical analysis of FRP hybrid composite lamina for in-plane transverse loading

In this paper, the micromechanical behaviour of the square unit cell of a hybrid fiber reinforced composite lamina consisting of graphite and boron fibers embedded in epoxy matrix, has been studied. A three-dimensional finite element model with governing boundary conditions has been developed from the unit cells of square pattern of the composite to predict the Young's modulus (E 2 ) and Poisson's ratios (v 21 and v 23 ) of graphite-boron hybrid fiber reinforced lamina for various volume fractions. The stresses at the fiber-matrix interfaces induced due to the in-plane transverse loading, that is applied to predict the in-plane transverse Young's modulus (E 2 ) and the associated Poisson's ratios, are also determined from these models. The finite element software ANSYS has been successfully executed to evaluate the properties and stresses. The variation of the stresses at the fiber-matrix interface with respect to the angular location is discussed. The Young's modulus is found to be increasing with V f indicating that the stiffness of the composite increases with V f , The magnitude of the normal stresses at the fiber matrix interface are maximum at 0 = 0° as the direction of the load is normal to the surface at this location. This may result in the separation of fiber and matrix leading to debonding. This analysis is useful to realize the advantages of hybrid fiber-reinforced composites in structural applications, and to identify the locations with reasons where the stresses are critical to damage the interface.