Evaluation of transverse mechanical properties of unidirectional composites by using finite element micromechanical analysis

For the analysis of composite structures a variety of mechanical properties are required. These properties can be obtained experimentally by subjecting laminate to axial, shear and transverse loading. Although it is possible to determine the properties of the laminate in axial direction, it is extremely difficult to perform the experimental analysis in transverse direction, as laminate is usually very thin in the transverse direction. An alternate approach is to use the analytical methods which use individual properties of constituent materials to predict the transverse properties of the composite materials. One of these methods is the finite element method. The finite element approach can be effectively used to predict the transverse mechanical properties of the composites because the geometry, the arrangement of the fibers in matrix, and individual material properties of the fiber and matrix can be conveniently described. In this paper a two-dimensional single fiber and multiple fibers finite element models are presented to predict the transverse mechanical properties of unidirectional composite materials. For both, the single fiber and multiple fibers models, the repeating units were identified. The external surfaces of these repeating units were subjected to uniform displacements. A simple technique based on the superposition principle was developed to simulate multi point constrain boundary conditions. The results obtained by using the present single and multiple fibers finite element models are compared with the results from the classical solutions and other finite element models.