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

Abstract

ArticleEffects of layer shift and yarn path variability on mechanical properties of a twill weave composite MY Matveev, AC Long, LP Brown and IA Jones Abstract Experimental and numerical analyses of a woven composite were performed in order to assess the effect of yarn path and layer shift variability on properties of the composite. Analysis of the geometry of a 12 K carbon fibre 2 Â 2 twill weave at the meso-and macro-scales showed the prevalence of the yarn path variations at the macro-scale over the meso-scale variations. Numerical analysis of yarn path variability showed that it is responsible for a Young's modulus reduction of 0.5% and CoV of 1% which makes this type of variability in the selected reinforcement almost insignificant for an elastic analysis. Finite element analysis of damage propagation in laminates with layer shift showed good agreement with the experiments. Both numerical analysis and experiments showed that layer shift has a strong effect on the shape of the stress-strain curve. In particular, laminates with no layer shift tend to exhibit a kink in the stress-strain curve which was attributed solely to the layer configuration.

Uncertainty in geometry of fibre preforms manufactured with Automated Dry Fibre Placement and its effects on permeability

“…relative shifts using Fourier correlation of images; 4. Perform edge detection algorithms 11,12 on each image separately to extract tape edges; 5. Combine detected tape edges together using information from Step 3.…”

“…The average autocorrelation function exhibits some oscillations and is negative in some regions. Instead of exponential approximation, as was performed in other studies, 8,9,11,12 the autocorrelation function was analysed using the power spectral density of the detrended series and extracting frequencies corresponding to its peaks. 29 The detrending was required to avoid zero frequency which appears due to either decreasing or increasing trends in the measured gap widths.…”

“…6 While all of these sources of variability remain relevant for composite manufacturing, this article focuses on variability of preform permeability owing to geometrical variability. The variability of geometry of a noncrimp fabric 7 and various woven textiles [8][9][10][11][12][13][14][15] has been studied by means of image analysis. Most of those studies attempted to describe the amplitude and the correlation length of the variability.…”

“…Most of those studies attempted to describe the amplitude and the correlation length of the variability. Experimental data from those studies were used in the models of textile reinforcements with variability in the geometry and used for prediction of probability of draping outcomes, 8 distribution of mechanical properties 12 and permeability. 7,[16][17][18][19][20] In particular, it was demonstrated that the mould fill time can be several times longer than the fill time in the deterministic case.…”

“…The detailed characterisations of textile reinforcements, including correlation lengths, can be found in the literature. [8][9][10][11][12]14 However, no such data are available for ADFP preforms which are inherently different from woven reinforcements.…”