Modelling the viscoelastic stress relaxation of glass fibre reinforcements under constant compaction strain during composites manufacturing

Somashekar, Arcot; Bickerton, Simon; Bhattacharyya, Debes

doi:10.1016/j.compositesa.2012.02.004

Cited by 47 publications

(37 citation statements)

References 12 publications

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“…Of course, the accuracy of modeling based on infinitesimal sections is limited, because of the fact that the structure is built of single textile plies. Also it is known, that textiles show a complex visco‐plastic compaction behavior which strongly differs in wet and dry state and may require more complex modeling. Nevertheless, the model leads to an important result: During transverse impregnation an inhomogeneous V F – distribution will occur.…”

Section: Transverse Impregnation Modelingmentioning

confidence: 99%

An experimental study of the influence of process parameters on the textile reaction to transverse impregnation

2015

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When applying a transverse impregnation within a liquid composite molding process, the main goal is to decrease impregnation time by reducing flow path lengths within the textile. However, the pressure drops emerging during impregnation cause hydrodynamic compaction of the textile as well as a heterogenization of the fiber volume content distribution. Within this study a new approach for the description of such transverse impregnation behavior is presented and exemplarily shown for a woven and a noncrimp fabric. The starting point is a novel measurement system allowing an on‐line monitoring of flow‐induced compaction during permeability measurement. Using the system, the reaction of both textiles to various flow conditions in terms of pressure drop and flow rate was measured and expressed by a set of functions. These allow continuous interpolation and can be used e.g. as direct input for simulations or to validate existing models. For both textiles a severe reduction of the permeability with increasing pressure drop respectively flow rate was measured. Accordingly, it was found that with increasing injection pressure the flow rate can stagnate or even decrease. Knowledge about such behavior is required for process and tooling optimization concerning cycle‐time and cost‐efficiency. POLYM. COMPOS., 37:2820–2831, 2016. © 2015 Society of Plastics Engineers

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Section: Transverse Impregnation Modelingmentioning

confidence: 99%

An experimental study of the influence of process parameters on the textile reaction to transverse impregnation

2015

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“…Although a number of qualitative explanations for the observed phenomenon have been proposed, as discussed previously, there have been relatively few attempts to derive a predictive model. Somashekar et al and Safraoui et al used conventional spring/dashpot models to characterize viscoelasticity, but although these phenomenological models can be used to characterize the behaviour of particular composites, they do not provide any guidance for optimizing material structure [ 18 , 19 ]. Drozdov et al approached the viscoelasticity of composites by using an energy balance approach [ 20 ].…”

Section: Introductionmentioning

confidence: 99%

Understanding the Stress Relaxation Behavior of Polymers Reinforced with Short Elastic Fibers

2017

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Although it has been experimentally shown that the addition of short-fibers slows the stress relaxation process in composites, the underlying phenomenon is complex and not well understood. Previous studies have proposed that fibers slow the relaxation process by either hindering the movement of nearby polymeric chains or by creating additional covalent bonds at the fiber-matrix interface that must be broken before bulk relaxation can occur. In this study, we propose a simplified analytical model that explicitly accounts for the influence of polymer viscoelasticity on shear stress transfer to the fibers. This model adequately explains the effect of fiber addition on the relaxation behavior without the need to postulate structural changes at the fiber-matrix interface. The model predictions were compared to those from Monte Carlo finite-element simulations, and good agreement between the two was observed.

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“…CSM contains of short fibres (centimetre long) that are oriented arbitrarily. The mechanical properties of CSM polymer composites have been studied by several authors, with focus ranging from measuring the elastic behaviour, the strength properties, fracture properties and viscoelastic behaviour [1][2][3][4][5]. A modelling approach to predict the Young's modulus of a CSM composite has been presented by Christensen et al [6] and Sk et al [7].…”

Section: Introductionmentioning

confidence: 99%

Thermo-mechanical characterisation of in-plane properties for CSM E-glass epoxy polymer composite materials – Part 2: Young's modulus

2013

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Modelling the viscoelastic stress relaxation of glass fibre reinforcements under constant compaction strain during composites manufacturing

Cited by 47 publications

References 12 publications

An experimental study of the influence of process parameters on the textile reaction to transverse impregnation

An experimental study of the influence of process parameters on the textile reaction to transverse impregnation

Understanding the Stress Relaxation Behavior of Polymers Reinforced with Short Elastic Fibers

Thermo-mechanical characterisation of in-plane properties for CSM E-glass epoxy polymer composite materials – Part 2: Young's modulus

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