Prediction of fiber-matrix interphase effects on damping of composites using a micromechanical strain energy/finite element approach

Few previous micromechanical models of damping in a unidirectional composite lamina have dealt with the fiber-matrix interphase, and none of these models have considered loading conditions other than the uniaxial longitudinal case. This paper describes the use of a general purpose strain energy/finite element method for micromechanical modeling of both damping and stiffness in composites including the fiber-matrix interphase region. Composite damping and moduli for longitudinal and transverse normal loading and inplane and out-of-plane shear loading are obtained. Particular interest is paid to the effects of the size of the fiber-matrix interphase on composite damping, and to the contribution of the interphase to the total energy dissipation in the composite. The determination of the four inplane loss factors should be of use for macromechanical analysis of damping of laminated composite structures, which requires lamina damping data as input.