Preforming simulation of the reinforcements of woven composites: Continuous approach within a commercial code (original) (raw)
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Shear deformation analysis for woven fabrics
Composite Structures, 2005
A new mechanical model is proposed in this paper to evaluate the shearing properties for woven fabrics during the initial slip region. Compared to the existing mechanical model for fabric shear, this model involves not only bending but also torsion of curved yarns. This model has the advantage of taking into consideration the yarn undulation in fabrics while keeping mathematical rigor. Moreover, an erroneous formula in the previous research work from a referenced paper is modified. Analytical results show that this model provides better agreement with the experiments for both the initial shear modulus and slipping angle than the existing model. The approach for this model can be extended to predict other mechanical properties of fabrics in order to obtain more precise results.
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.
paper deals with some practical aspects of the analysis of fabric (tension) structures. It is limited in scope to problems of small strain with large rotation for linear isotropic fabrics. It is Newtonian in approach and begins with a discussion of the effect of prestress upon the analysis required; the geometric stiffness matrix is then discussed and it is shown how this matrix can be developed using only equilibrium equations; finally, computer programs for the analysis of fabric structures are discussed. The highly nonlinear constitutive equations of some common fabrics will be considered in a later effort.
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.
Modelling the Shear-Tension Coupling of Woven Engineering Fabrics
Advances in Materials Science and Engineering, 2013
An approach to incorporate the coupling between the shear compliance and in-plane tension of woven engineering fabrics, in finite-element-based numerical simulations, is described. The method involves the use of multiple input curves that are selectively fed into a hypoelastic constitutive model that has been developed previously for engineering fabrics. The selection process is controlled by the current value of the in-plane strain along the two fibre directions using a simple algorithm. Model parameters are determined from actual experimental data, measured using the Biaxial Bias Extension test. An iterative process involving finite element simulations of the experimental test is used to normalise the test data for use in the code. Finally, the effectiveness of the method is evaluated and shown to provide qualitatively good predictions.
Modelling and Analysing the Tensile and Shearing Behaviour of Fabric Samples
2014
Textiles and woven fabrics have widely been used in different constructions such as covering sheets or fibre reinforced polymer composites. The poster is about a fibre-bundle-cells based structural-mechanical model for describing the tensileand shearing behaviour of woven fabrics. The modelling method is based on some idealized statistical fibre-bundle-cells as model elements, developed earlier, and the parallel and serial connections of them. For phenomenological applications modelling software FibreSpace has been used. The simplified FBC model of the fabric samples made it possible to study and analyse the effects of the cutting angle and the place of the critical cross section. In the case of instantaneous failure mode the simplified FBC model without any structural correction strongly underrated the mean breaking force for the cutting angles between 15 and 75 while this model with correcting the yarn orientation and the shearing effects related adhesion provided good fitting bet...