Full-field strain measurements are applied in studies of textile deformability during composite processing: (1) in testing of shear and tensile deformations of textiles (picture frame, bias and biaxial extension test) as an ''optical extensometer'', allowing accurate assessment of the sample deformation, which may differ significantly from the deformation applied by the testing device; (2) to study mechanisms of the textile deformation on the scale of the textile unit cell and of the individual yarns (meso-and micro-scale full-field strain measurements); (3) to measure the 3D-deformed shape and the distribution of local deformations (e.g., shear angles) of a textile reinforcement after draping, providing input data for the validation of material drape models and for the prediction of the consolidated part performance via structural finite element analysis. This paper discusses these three applications of the full-field strain measurements, providing examples of studies of deformability of woven (glass, glass/PP) and non-crimp (carbon) textile reinforcements. The authors conclude that optical full-field strain techniques are the preferable (sometimes the only) way of assuring correct deformation measurements during tensile or shear tests of textile.

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The contact behaviour during forming of woven reinforced thermoplastic composites determines the quality of the formed product. This paper evaluates different descriptive models for the ply-ply and tool-ply frictional properties of thermoplastic woven composites under process conditions. An alternative descriptive model, based on the experimental observation of the traction behaviour during tool-ply and ply-ply slip is presented. This model is implemented in ABAQUS-explicit and forming simulations are performed. The maximum compressive stress during forming is found to heavily depend on the orientation between adjacent plies.

Thermostamping of woven fabrics shows promise for being a viable means for making high-volume low-cost composites. A number of research teams around the world have been developing finite element methods for simulating this thermostamping process, and in an effort to understand the strengths and limitations of the different simulation methods, an international benchmark survey was conducted for a double-dome geometry. Comparisons were made by observing the resulting draw-in of the fabric and shear angles developed in the fabric after stamping. In this paper, simulations results as submitted by the various research teams are compared. Where possible, the simulation results are compared to experimental data. Forming parameters for a next round of simulations for comparison amongst the participating labs are presented.