Micromechanical study of thermoelastic behavior of composites with periodic fiber waviness

A finite element-based micromechanical modeling for fibrous materials is introduced for investigation of thermoelastic behavior of continuous fiber composites with fiber waviness. A periodic unit cell based on hexagonal fiber packing is assumed as a representative volume element. The orthotropic stiffness and thermal expansion parameters of the wavy fiber material are predicted by volume averaging stresses and strains. The thermal residual stresses generated per unit temperature change are studied in detail by volume averaging over slices (sub-volumes) of the representative volume element along the wavelength of the fiber, and also, within the fiber and the matrix individually. The sub-volume averaging scheme exposes the variation of the internal stresses and strains within the representative volume. It is shown that fiber waviness has a moderate impact on coefficients of thermal expansion, and the associated thermal (internal) stresses are generally little changed from those of a straight fiber material.