A direct micromechanics method for analysis of failure initiation of plain weave textile composites

A micromechanical analysis of the representative volume element (RVE) of a plain weave textile composite has been performed using the finite element method. Stress gradient effects are investigated, and it is assumed that the stress state is not uniform across the RVE. This is unlike most stiffness and strength models, which start with the premise that an RVE is subjected to a uniform stress or strain. For textile geometries, non-uniform stress considerations are important, as the size of a textile RVE will typically be several orders of magnitude larger than that of a unidirectional RVE, for which many analysis techniques are developed. The stress state is defined in terms of the well-known laminate theory force and moment resultants [N] and [M]. Structural stiffness coefficients analogous to the [A], [B], [D] matrices are defined, and these are computed directly using the direct micromechanics method (DMM), rather than making estimations based upon homogenized properties. Failure envelopes for a plain-weave textile composite have been constructed. Transverse failure of the fiber tow was the dominant mode of initial failure. The DMM failure envelope compared closely to the Tsai-Wu failure theory, but was more conservative in some areas.