Modeling inelastic and strength properties of textile laminates: a unified approach

A unified approach based on bridging micromechanics model to the simulation of inelastic and strength properties of textile (woven, braided, and knitted) fabric reinforced composite laminates is reviewed and summarized in this paper. The approach is performed ply by ply. While classical lamination theory is employed to determine the load shared by a lamina ply, the individual ply analysis essentially consists of three steps. In the first step, a representative volume element (RVE) of the lamina is isolated and the geometry of the textile preform in the RVE is identified. According to this geometrical description, the RVE is divided into a series of unidirectional (UD) composites whose orientations have all been known. Thus, the second step is concerned with the analysis of all the UD composites, which is accomplished by using the bridging model. The three fundamental quantities, i.e. the stress increments in the fiber, the stress increments in the matrix, and the overall compliance matrix of the composite, are explicitly obtained at each load level. The last step deals with an assemblage of all the UD composites to obtain the mechanical response characteristics of the considered ply. The ply failure is assumed if the internal stress state in any constituent attains its ultimate value, and a progressive failure process of the laminate results. Otherwise, the ply instantaneous compliance matrix is adapted to define the overall instantaneous stiffness matrix of the laminate for additional analysis. Ultimate failure strengths of different textile composite laminates subjected to in-plane, fatigue, as well as out-of plane bending loads have been obtained, which compare favorably with our experimental data.