Internal geometry variability of two woven composites and related variability of the stiffness

Abstract

In this work, the internal geometry measurements of two woven composites are analyzed: cross section of the yarns, fiber volume fraction, crimp, misalignment of the samples, thickness of the plates, nesting value, and so forth. The chosen textile composites are produced using the same resin reinforcement and same architecture, but have different yarn size (3K and 12K). The dispersion of measured geometrical parameters is introduced in a numerical multiscale modeling approach to evaluate the macroscopic stiffness values. A sensitivity analysis is performed for each geometrical parameter and laminate stiffnesses are derived. These are linked to the experimentally obtained elastic properties by tensile tests. Finally, the unit cell size scale effect for measured geometry variability and experimentally obtained elastic properties are evaluated. POLYM. COMPOS., 2012. © 2012 Society of Plastics Engineers

Multiscale modeling of combined deterministic and stochastic fabric non-uniformity for realistic resin injection simulation

“…Comparing equation (18) with Darcy's law, which (for the 1D case) can be expressed as v~K Dp gL (20) implies that…”

“…Local random variations in yarn crosssectional shapes in real fabrics were studied by Olave et al 20 While irregular non-symmetrical shapes can currently not be handled and are not considered here, variations in simplified yarn cross-sections due to local lateral compression are approximated. Estimation of yarn cross-sections, which typically show characteristics of elliptical, lenticular and rectangular shapes, and numerical calculation of the equivalent permeability of interyarn gaps as demonstrated by Nordlund and Lundströ m 21 is too complex and timeconsuming to be employed for each finite element individually.…”

“…A mesh sensitivity study indicated that the solution converged if the average edge length of finite elements in the CFD simulations was 0.01 mm or less. The average flow velocity obtained from the simulations allowed the equivalent axial channel permeability to be determined according to equation (20). Then, c was calculated according to equation (21).…”

Identification of Uncertainty and Quantification of Variability in Woven Composite Materials Based on Carbon Fibre Weaves

“…Colours indicate the tows which are intersected. Olave et al [23] discuss the details of this measurement campaign.…”

Effects of layer shift and yarn path variability on mechanical properties of a twill weave composite

“…Examples of such modelling include but not limited to modelling of laminated woven composites under quasi-static tension 2,3 and high strain rate compaction, 4 composites with braided reinforcement 5 and 3D composites. 6 However, the conventional unit cell approach cannot predict variability of the mechanical properties from sample to sample which is usually associated with variability in the intrinsic properties of constituents 7,8 and the geometry of reinforcements such as yarn and layer misalignments 9 arising from textile and composite manufacturing. This study focuses only on the effects of variability of textile reinforcement geometry, namely yarn paths and layer shift variability.…”