The influence of carbon fabric weave on the in-plane shear mechanical performance of epoxy fiber-reinforced laminates

Abstract

Woven fabrics used in composite materials are designed to fulfill specific manufacturing or structural requirements. Knowledge of the influence of the weave structure on the mechanical properties of the composite is essential to properly optimize the design of structural components. The focus of this work is to investigate the influence of the type of weave used for fabric reinforcement in polymers particularly on the in-plane shear mechanical performance. The selected materials are carbon fibers and epoxy resin. The laminates are manufactured by vacuum infusion. Three woven structures are selected for manufacturing the composite laminates: (a) a plain weave with unidirectional orientation in the warp direction, (b) a plain weave with balanced properties in the warp and weft directions and (c) a 2/2 twill weave with balanced properties in the warp and weft directions. The laminates are tested according to the ASTM D 4255 standard by a two-rail shear test under quasi-static monotonic and cyclic loading conditions. The resulting stress–strain curves are used to study the initial in-plane shear modulus and its evolution (which directly correlates with material damage) and the hardening produced by plastic strain. The results show that for vacuum infusion manufacturing, the weave structure has an influence on the resulting fiber and void volume fractions and, consequently, on the mechanical performance. However, for similar fiber volumes, the weave structure is found to have little effect on the experimental results.

Damage characterization of composites to support an orthotropic plasticity material model

“…Medina et al. 20 have experimentally investigated damage evolution during in-plane shear tests as a function of the composite architecture, including unidirectional laminates. The cyclic shear tests showed that the shear modulus reduces as much as 50% as plastic strain increases.…”

Invariant based approaches in the design of composite laminates

“…Firstly, the choice of shear test method has an impact on the results. The Composite Materials Handbook MIL-HDBK-17-1F [23] notes that the V-notched rail shear test (ASTM D7078) is the most accurate for determining shear modulus but acceptable predictions can also be made with the ±45º tensile shear test, used for much of the data in Figure 2 and Figure 3, including all those from NIAR. However, the ±45º tensile shear test does not create a pure stress state.…”

“…However, the ±45º tensile shear test does not create a pure stress state. Therefore the shear modulus extracted from test data is an effective shear modulus rather than an absolute one [23].…”

In-plane shear of nanoprepreg/nanostitched three-dimensional carbon/epoxy multiwalled carbon nanotubes composites

“…28 It was shown that the woven fabric patterns have limited effect on the composite shear performance which was carried out by a two rail shear. 29 The filament interfacial properties were modified by surface treatment and about twofold enhancement on its intra-layer and inter-layer shear strength was obtained. 30 Deng and Ye found that the fiber-matrix adhesion by fiber surface treatment and sizing improved the fracture toughness as well as the inter-layer and the intra-layer shear strength of the graphite/epoxy composites.…”