Effective elastic moduli of a plain wave ceramic textile composite with local processing defects in the flexible graphite matrix

Abstract

Effective elastic moduli of a plain woven textile composite with a flexible graphite based matrix (made by rolling of foil layers) and ceramic fibers were predicted. We examined the layer of a textile composite of 2,5D thickness with the reinforcement plain woven fabric formed by ceramic fibers round in their cross-sections with diameter D . The warp and weft cloth fiber curvature was set by the segment of a circle with the central angle α = π/4 and a straight line section. Due to a small amount of strain angles, α were assumed as invariable under layer loading. We investigated the most typical local technological defects, i.e. caverns that are formed as a result of a random warp or weft breakage and occur by the prick stitch of textile layers, but can also be contained in the source textile before the prick. The dimensions of examined defects were commensurable with the characteristic scale of heterogeneity; they did not considerably change integral reinforcement coefficients of the composite or were partly or completely filled by the matrix material. The influence of the length scale and presence of local technological defects on the values of the effective Young moduli and Poisson ration were determined. The obtained results demonstrate that the concentration (i.e. the number of breakages and pinched fibers) of the separate local technological defects located at least at the distance of two or three length scales of meshes (caused by the fiber weaves of a reinforcement plain woven fabric) in a structure element made of a textile composite is not a crucial factor that significantly influences the values of elastic moduli. However the local defect concentration predetermines the scenario of the damage evolution.