Non‐isothermal ‘2‐D flow/3‐D thermal’ developments encompassing process modelling of composites: flow/thermal/cure formulations and validations

Ngo, N. D.; Tamma, Kumar K.

doi:10.1002/nme.85

Cited by 23 publications

(12 citation statements)

References 25 publications

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“…This consists of using a two-dimensional flow ''extruded'' through the thickness to provide a fully three-dimensional solution of the energy equation to predict the temperature. This approach has evolved and improved with time [8][9][10]. However, the resulting numerical scheme is often in a less-than desirable form from computational standpoint.…”

Section: Numerical Simulation Of the Rtm Processmentioning

confidence: 99%

Approximate numerical method for prediction of temperature distribution in flow through narrow gaps containing porous media

Šimáček

Advani

2003

Computational Mechanics

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The paper examines an approximate solution to the problem of temperature distribution in the flow through a narrow gap filled with porous medium. This problem is relevant for composite material manufacturing processes, such as the resin transfer molding and its derivatives. In such processes, cold resin is sometimes injected into a closed heated cavity containing a network of stationary fibers. The cavity can be long and wide, but it is usually only a few millimeters thick. The approximate solution is based on an estimated through-the thickness temperature profile that allows one to reduce the complexity from fully threedimensional to two-dimensional and significantly improve the computational efficiency. The implementation of this solution within an existing simulation code for non-isothermal filling of closed mold is briefly described. Finally, several examples are presented to illustrate the accuracy of the proposed method to predict the midplane temperature of the resin as it impregnates the preform to fill the mold cavity.

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Section: Numerical Simulation Of the Rtm Processmentioning

confidence: 99%

Approximate numerical method for prediction of temperature distribution in flow through narrow gaps containing porous media

Šimáček

Advani

2003

Computational Mechanics

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“…In this section, another resin system (mixed urethane resin) is used to verify the applicability of this optimization method to different types of resins. The viscosity of resin and curing kinetics equation G ( a , T ) can be described as:

u_{resin} = u_{0} \exp ((), \frac{E_{u}}{italicRT}) {(\frac{a_{g}}{a_{g} - a})}^{f ((), a, T)}

f ((), a, T) = - 0.96 + 6.48 ((), a - \frac{2.13 ((), T - T_{ref})}{374.5 + ((), T - T_{ref})}) - 3.2 {(a - \frac{2.13 (T - T_{italicref})}{374.5 + (T - T_{italicref})})}^{2}

G ((), a, T) = A \exp ((), \frac{- E}{italicRT}) {(1 - a)}^{n}

where u 0 is the initial degree of viscosity, E u is the activation energy, R is the gas constant, T is the temperature of resin, a is the degree of cure, and a g is the resin gel point, T ref , A , n are all constants. The properties of resin are shown in Table .…”

Section: Resultsmentioning

confidence: 99%

Optimization method to reduce three‐dimensional thermal gradients in resin transfer molding

Yang

Liu

2020

J of Applied Polymer Sci

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Presently, the mold and resin are heated to promote resin flow and shorten curing period in order to improve manufacturing efficiency of resin transfer molding (RTM). This nonisothermal manufacturing process easily generates three-dimensional thermal gradients in the direction of resin flow and thickness of composite part. However, the existing heating systems only consider the thermal gradients along thickness direction. The thermal gradients in direction of resin flow cannot be reduced which will lead to residual stress even deformation and cracking in composite part. This article aims at reducing the three-dimensional thermal gradients in the direction of resin flow and thickness of composite part. Based on the theory of energy and fluid flow, an optimization method of heating system design by using numerical simulation is proposed. The results show this method reduces the three-dimensional thermal gradients effectively in composite part manufactured by RTM process. This study can provide powerful tools for heating system design to manufacture composites products in polymer industry.

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“…Bogetti and Gillespie 5,6 and Hubert et al 7 ) and RTM (e.g. Bruschke and Advani, 8 Mal et al, 9 Ngo and Tamma, 10 Park et al, 11 Shojaei, 12 Abbassi and Shahnazari, 13 Young, 14 Antonucci et al, 15,16 and Shi F and Dong 17 ). These studies have focused primarily on developing models that capture the effects of local temperature on resin thermochemical and thermomechanical properties, and that predict the impact of spatial variations on large-scale fluid migration within preforms, and the formation of residual stresses.…”

Section: Thermal Gradientsmentioning

confidence: 99%

Effects of thermal gradients on defect formation during the consolidation of partially impregnated prepregs

Centea

Peters

Hendrie

et al. 2017

Journal of Composite Materials

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We describe the effects of thermal gradients on the consolidation of partially impregnated prepregs. Laminates were cured on a heated tool in isothermal and nonisothermal conditions. Key process parameters were varied, including thermal gradient magnitude, air evacuation direction, and vacuum quality. Laminate quality was assessed using microscopy of polished cross-sections and X-ray computed tomography, and interpreted relative to the evolution of resin and prepreg properties during cure. The results show that thermal gradients influenced the rate of impregnation of the prepreg and the rate of gas transport, and affected the amount and distribution of porosity when air was not fully evacuated. Temperature distributions that led to cold regions at the ply boundaries were advantageous, typically exhibiting lower porosity than isothermal baselines. Conversely, gradients resulting in hotter-than-average part perimeters effectively sealed air within the laminate, degrading quality. The results clarify fundamental defect formation mechanisms for partially impregnated prepregs and other processes reliant on air evacuation through an unsaturated preform and provide guidelines for part, tool, and process design.

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Non‐isothermal ‘2‐D flow/3‐D thermal’ developments encompassing process modelling of composites: flow/thermal/cure formulations and validations

Cited by 23 publications

References 25 publications

Approximate numerical method for prediction of temperature distribution in flow through narrow gaps containing porous media

Approximate numerical method for prediction of temperature distribution in flow through narrow gaps containing porous media

Optimization method to reduce three‐dimensional thermal gradients in resin transfer molding

Effects of thermal gradients on defect formation during the consolidation of partially impregnated prepregs

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