Large deformation nonlinear response of soft composite structures via laminate analogy

The large deformation behavior of fiber preform and angle ply composites wi th very soft matrix is the subject of this paper. For these materials, larg e strains and therefore significant changes in the fiber orientations occur due to the application of small traction, thus drastically changing their mechanical properties. The present method uses a laminate analogy with very low stiffness matrix t o compute the finite element properties. The assumptions are that fibers do not elongate, the laminate is made of symmetrically woven fibers and that during a finite element step the properties can be considered constant. Bas ed on these assumptions, a simple way to compute the fiber angle changes is proposed. It is noted that a rectangular box on the soft matrix composite with fibers as its diagonal will deform into a box of different aspect rati o. The large displacement approach is valid since the properties depend on the global Poisson's ratio computation that is proven accurate. A traction tes t is simulated to demonstrate the method.