INPLANE RESPONSE OF LAMINATES WITH SPATIALLY VARYING FIBER ORIENTATIONS - VARIABLE STIFFNESS CONCEPT

A solution to the plane elasticity problem for a symmetrically laminat ed composite panel with spatially varying fiber orientations has been obtained. The fiber angles vary along the length of the composite lami nate, resulting in stiffness properties that change as a function of l ocation. This work presents an analysis of the stiffness variation and its effects on the elastic response of the panel. The in-plane respon se of a variable stiffness panel is governed by a system of coupled el liptic partial differential equations. Solving these equations yields the displacement fields, from which the strains, stresses, and stress resultants can be subsequently calculated. A numerical solution has be en obtained using an iterative collocation technique. Corresponding cl osed-form solutions are presented for three sets of boundary condition s, two of which have exact solutions, and therefore serve to validate the numerical model. The effects of the variable fiber orientation on the displacement fields, stress resultants, and global stiffness are a nalyzed.