Numerical Simulation of Resin Injection Molding in Molds with Preplaced Fiber Mats

Hourng, Lih‐Wu; Chang, Chich-Yuan

doi:10.1177/073168449301201005

Cited by 13 publications

(3 citation statements)

References 6 publications

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“…This design ensures the air being properly vented out, therefore, it reduces the air entrapment and prevents the dry spot formation. Simulation tools such as direct filling simulations [2][3][4][5][6][7][8][9][10][11] or fast algorithm [12,13] may be used to predict the LPF locations based on the specification of the inlet conditions and the prescribed permeability field. However, those LPF locations may not be in ideal locations from the viewpoint of proper mold design that would require the vents to be in particular locations.…”

Section: Design Case Study Achieve the Predetermined Vent Locationmentioning

confidence: 99%

“…Some of the problems during the filling stage may be alleviated by proper placement of inlet gates and exit vents as well as by adjustment of inlet conditions during filling. Current RTM process design relies on the use of direct filling simulation tools [2][3][4][5][6][7][8][9][10][11] that predict the filling pattern based on the specification of the inlet locations and conditions as well as the prescribed permeability field of the fiber mats. The predicted filling pattern reveals the Last Point to Fill (LPF) and the locations where dry spots form.…”

Section: Introductionmentioning

confidence: 99%

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A Methodology to Obtain a Desired Filling Pattern during Resin Transfer Molding

Minaie

Chen

Mescher

2002

Journal of Composite Materials

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In Resin Transfer Molding (RTM), dry spot formation and air entrapment during the filling stage often lead to defective parts and high scrap rate. These problems are usually caused by improper design of inlet conditions and vent locations that prevent the Last Point to Fill (LPF) location from coinciding with the preset vent location. Use of direct filling simulation as a design tool for the RTM process often involves trial-and-error procedures in order to find the appropriate inlet conditions and locations as well as exit vent locations. This design procedure becomes complex when adesign involving multiple inlet gates is being considered, especially in large parts. There may also be uncertainty as to whether the final design (obtained using trial-and-error simulation procedures) is indeed the optimum design. This paper presents a methodology to design the RTM process with a desired filling pattern free of dry spots and knitlines. Unlike the traditional filling simulation that predicts the filling pattern using prescribed inlet conditions and the specification of the preform permeability field, this methodology calculates the optimum inlet conditions based on the specification of the desired filling pattern and the prescription of preform permeability. The use of this algorithm greatly enhances

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Section: Design Case Study Achieve the Predetermined Vent Locationmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

A Methodology to Obtain a Desired Filling Pattern during Resin Transfer Molding

Minaie

Chen

Mescher

2002

Journal of Composite Materials

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“…As such, the entrapped air cannot be properly vented out. Ideally, using filling simulation [3][4][5][6][7][8][9][10], vent location prediction [11][12][13], or vent location optimization [14], the LPF location may be predicted and appropriate placement of the vent at that location may prevent dry spot formation. In a practical situation, the fiber preform permeability and the temperature-dependent resin viscosity are rarely accurately known and the LPF location cannot be precisely predicted using the aforementioned numerical design tools.…”

Section: Introductionmentioning

confidence: 99%

Adaptive Control of Filling Pattern in Resin Transfer Molding Process

Minaie

Chen

2005

Journal of Composite Materials

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During the Resin Transfer Molding (RTM) process, the filling pattern is strongly affected by race-tracking phenomenon and this usually leads to dry spot formation at the end of the filling stage and results in defective parts. This situation can be alleviated by placing air vents at the locations of the Last Point to Fill (LPF), where dry spots usually form. However, due to the variation of the race-tracking effects, the LPF location does not remain in the same position during RTM batch cycle production. Dry spots can still form and the part is still scraped. In order to ensure that the LPF location always coincides with the predetermined vent during RTM batch cycle production, an adaptive control strategy based on a model reference adaptation system that can regulate the LPF location during the RTM filling stage is proposed, to adjust the inlet pressures on-line. Multiport flow is simplified as many individual one-dimensional ‘spine’ flows and each ‘spine’ extends from the gate to the vent along the short path. The spine flow is controlled independently by adjusting the pressure of the related inlet. The control input is the distance between the inlet and the flow front along the spines, and the reference model of the flow is that the resin is driven by a uniform velocity from the gate to the vent along the spine. The proposed adaptive control has the capability to adapt to high levels of system disturbances. The proposed adaptive control is tested numerically by incorporating the control algorithm into a RTM time-implicit filling simulation. The resulting simulations show that the proposed control strategy can eliminate the dry spot formation under a wide range of situations resulting from the variations in the race-tracking effects.

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Numerical characterization of mold injection in resin transfer molding process

Kuan

El‐Gizawy

2000

Adv. Polym. Technol.

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A control volume technique based on the finite difference method is used to characterize the flow behavior in resin transfer molding (RTM) of composite structures. Resin flow through fiber mats is modeled as a two‐phase flow through porous media. The transient time terms are considered, and the concept of the fraction volume of fluid (VOF) is applied in order to accurately describe the behavior of the free boundary at the interface between the two fluids involved in the process, the resin and the air. Flow experiments in a transparent mold were performed to verify the numerical model. Experimental results on flow behavior of EPON 826 epoxy resin into irregular mold cavity with fiberglass mats agree well with the present numerical simulation. Several parametric studies using the developed model are conducted to investigate the effects of injection pressure and mold design on resin flow pattern, mold filling time, and pressure distribution inside the mold. © 2000 John Wiley & Sons, Inc. Adv Polym Techn 19: 173–179, 2000

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Numerical Simulation of Resin Injection Molding in Molds with Preplaced Fiber Mats

Cited by 13 publications

References 6 publications

A Methodology to Obtain a Desired Filling Pattern during Resin Transfer Molding

A Methodology to Obtain a Desired Filling Pattern during Resin Transfer Molding

Adaptive Control of Filling Pattern in Resin Transfer Molding Process

Numerical characterization of mold injection in resin transfer molding process

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