Prediction of Draping Behaviour of Woven Fabrics over Double-Curvature Moulds using Finite Element Techniques (original) (raw)
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）The fabrication of textile reinforced polymer composites requires the pre-forming of textiles over open, or within closed moulds before the introduction of the resin. This study is therefore concerned with the draping behavior of jute and glass fibres of various areal densities over double curvature moulds. Experimental investigation of the draping behavior was performed over a specially designed mould comprising different geometries of fillets and sharp edges. Simulation of the deformation behavior using PamForm2G application revealed similar results. Large shear deformations are found around large curves and acute angles. The interaction of geometries further forces woven fabrics to undergo severe shear deformations often leading to the creation of wrinkles.
Modelling of fabric draping: Finite elements versus a geometrical method
Thermoplastic composite materials can be processed by Rubber Press Forming at elevated temperatures. Process specific boundary conditions are difficult to incorporate in the classical geometric drape simulation methods. Therefore, a fabric reinforced fluid model was implemented in the Finite Element package DIEKA, which is capable of modelling the boundary conditions as well. The model predictions of both types of simulations are compared for a double dome geometry, having separated contact areas, leading to different results.
Finite element simulation of draping with non-crimp fabrics
: The draping process of non-crimp fabrics (NCF) on a doubly curved mould determines the fibre distribution and hence the processing and performance of the NCF product. A composite Finite Element (FE) model is developed to simulate the draping process of NCFs on arbitrary geometries. Tool-part interaction is taken into account. Problem regions with possible fibre buckling can be indicated and the fibre distribution in the final NCF is predicted. The model contains a novel modelling approach to simulate the slip of the individual fibre layers. Additional layers and degrees of freedom were added to a membrane element to simulate the slipping layers with one element through the thickness. This enables efficient FE simulations of the draping process. Several experiments were performed: measurement of the thickness change during shear deformation, fibre pull-out experiments and a drape experiment. The latter is compared with FE simulations.
In-plane Shear Behaviour of Novel Thick Stitched Textile Reinforcements Part I: Experimental Work
AL-MUKHTAR JOURNAL OF ENGINEERING RESEARCH, 2021
Novel thick, net-shape, drapable, high fibre volume fraction (vf) textile reinforcements used toward manufacturing aerospace polymer matrix composites (PMCs) are being developed at the University of Ottawa. The technology, referred to in this paper as University of Ottawa advanced preforming technology (uO-APT), it enables the manufacturing of flat, drapable multilayered near net-shape preforms. The in-plane shear behaviour of such novel thick reinforcement textiles was investigated to understand and define the behaviour of such thick fabric reinforcements when formed into required shapes. Wrinkling is one of the most common and critical defects that may occur during draping and forming operations performed on textile reinforcements. The behaviour of dry thick fabrics subjected to in-plane shear plays an important role, along with the bending behaviour, in the onset of wrinkles during draping and forming. Wrinkling is especially critical to single layer, thick fabrics such as uO-APT fabrics being investigated in this paper. Since the ability of biaxial stitched non-crimp reinforcement fabrics to conform to a surface featuring double curvatures depends directly on their inplane shear behaviour, that behaviour must be probed and quantified for uO-APT fabrics in order to identify their ability to deform upon draping, which is a required procedure in manufacturing processes for dry preforms used towards the production of composite parts.
Key Engineering Materials, 2019
The wet compression molding (WCM) process enables short cycle times for production of fiber-reinforced plastics due to simultaneous infiltration, viscous draping and consolidation in one process step. This requires a comprehensive knowledge of occurring mutual dependencies in particular for the development of process simulation methods and for process optimization. In this context, it is necessary to develop suitable test benches to enable an evaluation of the outlined viscous draping behavior. In order to evaluate and suitably design the draping process, grippers are mounted on a surrounding frame, which enables targeted restraining of the local material draw-in during forming. In supporting the development of the new test bench, first experimental and simulation results are compared, which thereby enables a first validation of the simulation approaches. Results show a good agreement between experimental and numerical results in terms of shear deformation and final gripper displace...
Single Curvature Bending of Structural Stitched Textile Reinforcements Part I: Experimental Work
IJEIT ON ENGINEERING AND INFORMATION TECHNOLOGY, 2021
Aerospace structural components made from polymer matrix composites (PMCs) offer numerous advantages. Their high stiffness and high strength combined with low densities enable lower fuel consumption coupled with higher payloads. As a result, PMCs provide an important economic advantage over typical metallic airframes. Textile reinforcements for PMCs are made by assembling reinforcement fibres, typically carbon. Then, the textile reinforcements are typically cut into smaller pieces, stacked, draped and assembled into a dry assembly called a preform, the shape of which generally approaches that of the PMC part to be made. This manufacturing process is labour intensive and expensive. Novel thick, net-shape, drapable, high fibre volume fraction (vf) textile reinforcements used toward manufacturing aerospace PMCs are being developed at the University of Ottawa. The technology enables the manufacturing of flat, drapable multilayered near net-shape preforms. The bending and in-plane shear behaviours of such novel thick reinforcement textiles was investigated to understand and define the behaviour of such thick fabric reinforcements when formed into required shapes. A bending apparatus was developed for investigating the bending behaviour of these novel thick reinforcement fabrics.
Geometrical and mechanical draping of composite fabric
Revue européenne des éléments finis, 2005
This paper presents an optimization based method for simulation of forming processes of woven fabric reinforced composites. Two approaches are proposed for the simulation of the forming of woven fabric: geometrical and mechanical. The geometrical approach is based on a fishnet model. It is well adapted to pre-dimensioning fabrics and to give a suitable quantification of the resulting flat patterns. The mechanical approach is based on a mesostructural model. It allows us to take into account the mechanical properties of prepreg fabric and the various dominating mode of deformation of woven fabrics during the forming process. Some numerical simulations of forming process are proposed and compared with the experimental results in order to demonstrate the efficiency of our approaches. RÉSUMÉ. Ce papier traite le problème d'optimisation de la mise en forme des tissus composites pré-imprégnés. Deux approches complémentaires sont proposées pour modéliser le drapage de ces matériaux : une approche géométrique et une approche mécanique. La première est basée sur le modèle du filet et s'inscrit dans une démarche de prédimensionnement, la seconde est basée sur une approche mesostructurale et s'inscrit dans une perspective d'optimisation de la conception et la fabrication de pièces composites.
Composites Part A: Applied Science and Manufacturing, 2019
Wet compression moulding (WCM) provides high-volume production potential for continuous fibre-reinforced composite components via simultaneous draping and infiltration. Experimental and theoretical investigations proved strong mutual dependencies between resin flow and fabric deformation, which are not fully understood yet. This limits development of suitable process simulation methods and applies in particular for the characterisation of infiltrated bending behaviour-essential for an accurate prediction of draping effects. Therefore, a comparative characterisation of the bending behaviour of dry and infiltrated woven fabrics is presented using a modified cantilever and a rheometer bending test. Experimental results reveal both, rate-and viscosity-dependencies. A comparison of the quantitative results exposed an explicable systematic deviation between the two tests, whereas qualitative results are comparable. Finally, Finite Element forming simulations, comprising two bending models corresponding to cantilever and rheometer test are performed to evaluate the experimental findings on component level.
Mathematical Modelling of Internal Geometry and Deformability of Woven Preforms
International Journal of Forming Processes, 2003
The paper presents an approach to model the behaviour of a representative volume element (unit cell) of textile reinforcement in in-plane deformation (bi-axial tension and shear) and in compression. The model is a further development of a virtual textile concept implemented in the WiseTex software, and is based on the concept of hierarchical description of textile properties and systematic application of the principle of minimum energy to calculate the textile geometry in the relaxed and deformed state. With the internal geometry of the unit cell built, the model computes overall parameters of the deformed textile, such as fibre volume fraction, porosity etc. The internal geometry is visualised and such properties as pore structure in typical cross-sections are analysed. The load-deformation curves for compression, tension and shear are computed via the balance between change of the internal energy of the unit cell and mechanical work of the applied loads. The internal geometry description is further fed into flow modelling software, which allows computing local permeability of the deformed reinforcement, and micro-mechanical modelling to calculate homogenised local stiffness of the composite.