Anisotropic Effects of Quasi-Isotropic Composites(Ⅰ)──Modelling

Experimental obseryations show that quasi-isotropic materials, such as N-axial fibre-reinforced composites and woven materials, exhibit various degrees of anisotrpy in elasticity and strength, and the anisotropy in strengty is normally stronger than that in elasticity.In view of some available experimental data and based on the general formulation of the constitutive equations and failure criteria of quasi-isotropic materials established by using the theory of repesentations for tensor functions, we postulate several applicable models of the constitutive equations and strength for 3 and 4-axial quasi-isotropic materials to reveal the anisotropic effects In a continued work (Part II) the anisotropic effect in strength of an infintely large plate with a single elliptical hole or crack is studied, and the proposed stiffness and strength modelsare verified in terms of micro-mechanical analyses.