2 - Thermoelastic behavior of laminated composites

Summary

Introduction

Laminated composites are made by bonding unidirectional laminae together in predetermined orientations. The basis for analysis of thin laminated composites is the classical plate theory. When the thickness direction properties significantly contribute to the response of the laminate to an externally applied elastic field, the classical plate theory breaks down.

Fundamental to the treatment of thin laminates is the knowledge of the thermoelastic properties of a unidirectional lamina. These properties are predictable from the corresponding properties of constituent fiber and matrix materials as well as the fiber volume fraction. Having established the elastic response of a unidirectional lamina, the behavior of laminated composites is then analyzed from the strain and curvature of the mid-plane of the laminate as well as the force and moment resultants acting on its boundary edges. Because of the complexity of the constitutive equations for a general anisotropic laminated plate, simplifications of the stress–strain relations are accomplished through the manipulation of the geometric arrangement of the laminae. The lamination theory is a relatively mature subject; its treatment can be found in text books of, for instance, Ashton, Halpin and Petit (1969), Jones (1975), Vinson and Chou (1975), Christensen (1979), Tsai and Hahn (1980), Carlsson and Pipes (1987), and Chawla (1987), and in the review articles of Chou (1989a and b). A modification of the classical plate theory is in the inclusion of higher order terms in the displacement field expansion to account for the transverse shear deformation. An outline of such modifications adopted by various researchers is presented.