title: On a general constitutive description for the inelastic and failure behavior of fibrous laminates. I. Lamina theory
abstract: It is well known that a structural design with isotropic materials can only be accomplished based on a stress failure criterion. This is, however, generally not true with laminated composites. Only when the laminate is subjected to an in-plane load, can the ultimate failure of the laminate correspond to its last-ply failure, and hence a stress failure criterion may be sufficient to detect the maximum load that can be sustained by the laminate. Even in such a case, the load shared by each lamina in the laminate cannot be correctly determined if the lamina instantaneous stiffness matrix is inaccurately provided, since the lamina is always statically indeterminate in the laminate. If, however, the laminate is subjected to a lateral load, its ultimate failure occurs before last-ply failure and use of the stress failure criterion is no longer sufficient; an additional critical deflection or curvature condition must also be employed. This necessitates development of an efficient constitutive relationship for laminated composites in order that the laminate strains/deflections up to ultimate failure can be accurately calculated. A general constitutive description for the thermomechanical response of a fibrous laminate up to ultimate failure with applications to various fibrous laminates is presented in the two papers. The constitutive relationship is obtained by combining classical lamination theory with a recently developed bridging micromechanics model, through a layer-by-layer analysis. This paper focuses on lamina analysis
keyphrases: general constitutive description failure behavior fibrous laminates lamina theory structural design isotropic materials stress failure criterion composites in-plane load last-ply failure instantaneous stiffness matrix lateral load laminate strains thermomechanical response micromechanics model layer-by-layer analysis inelastic behavior critical deflection condition critical curvature condition laminate deflections multidirectional tape laminae woven fabric composites braided fabric composites knitted fabric reinforced composites elastoplasticity elastic-viscoplasticity