Combined loading micromechanical analysis of a unidirectional composite

A microscopic region of a unidirectional composite is modelled by a finite element micromechanical analysis using a generalized plane strain formulation, but including longitudinal shear loading. The analysis is capable of treating elastic, transversely isotropic fibre materials, as well as isotropic, elastoplastic matrix materials. Matrix material properties are considered to be temperature- and/or moisture-dependent. The longitudinal shear loading capability permits the analysis of the shear response of unidirectional composites in the fibre direction. In conjunction with a laminated plate point stress analysis, the present micromechanical analysis has been used to predict the stress/strain response into the inelastic range of a graphite/epoxy [±45] 4s laminate. Available experimental data for various environmental conditions indicate excellent agreement with the analytical predictions.