Simulation of compression resin transfer molding to manufacture thin composite shells

Pham, Xuan-Tan; Trochu, F.

doi:10.1002/pc.10369

Cited by 48 publications

(25 citation statements)

References 14 publications

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“…For thin preforms (i.e., where the in‐plane dimensions are orders of magnitude greater than the thickness), through‐thickness fluid‐flow is generally neglected. A “thickness‐averaged” mass continuity equation can then be used to relate the mass flow of fluid out of a unit volume to the local laminate thickness ( h ) and the rate of change of thickness (

\overset{h}{true}

) ;

\nabla \cdot (h v) = - \dot{h} .

Equation can be combined with Darcy's law, to give the governing equation for fluid pressure within a laminate :

\nabla \cdot (\frac{h}{μ} k \cdot \nabla P) = - \dot{h} .

Equation governs fluid pressure during compression‐driven flow phases, such as the secondary compression phase of CRTM. Fluid injection phases at constant cavity thickness can be taken as a special case of Eq .…”

Section: Numericalmentioning

confidence: 99%

Simulation and experimental validation of mould tooling forces in RTM and CRTM for nonplanar components

2014

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To date, simulation of the forces exerted on mould tools during RTM and Compression RTM (CRTM) has focused on planar cases. While a flat plate case has some limited validity in practical applications, the majority of applications are for nonplanar geometry components. Such components present a more challenging case to simulate, as the nonplanar geometry introduces an additional out‐of‐plane shear component to the local tooling stresses as well as effects due to the geometry itself (such as race‐tracking in corners). This article presents the first thorough study of mould tooling forces for a nonplanar geometry. A number of RTM and CRTM experiments were undertaken using a truncated‐pyramid mould with an acrylic top platen to allow flow front visualization to be undertaken. Repeatability studies showed variations in fill time and peak tooling forces observed during RTM and CRTM cases which could not be accounted for by variation in the sample mass or fluid viscosity alone. This demonstrated that the processes were influenced by the spatial variability in the areal mass of the preforms. The experimental results were also compared to numerical simulations of the processes. Good agreement between experiment and simulation was observed for both RTM and CRTM cases in terms of flow front evolution. Peak forces were also well predicted, within the variability observed in the experimental results; this was partly due to the out‐of‐plane shear component of the tooling force being well predicted, in combination with the normal component. In addition to the velocity‐controlled mould closure cases, force‐controlled mould closure was also investigated for CRTM. Good agreement with simulation was also achieved for this complex situation. The range of processes and conditions investigated here show that the simulation package is providing good agreement to experiment for both flow evolution and tooling forces and stresses. POLYM. COMPOS., 36:591–603, 2015. © 2014 Society of Plastics Engineers

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\overset{h}{true}

) ;

\nabla \cdot (h v) = - \dot{h} .

Equation can be combined with Darcy's law, to give the governing equation for fluid pressure within a laminate :

\nabla \cdot (\frac{h}{μ} k \cdot \nabla P) = - \dot{h} .

Section: Numericalmentioning

confidence: 99%

Simulation and experimental validation of mould tooling forces in RTM and CRTM for nonplanar components

2014

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“…By rewriting equation (3) in polar coordinates, the pressure gradient in the flow region can be deduced as follows [8]:…”

Section: Constant Volumetric Flow Ratementioning

confidence: 99%

“…The compression speed remains the same. During the radial flow period the pressure gradient in polar coordinates can be deduced as follows [8]:…”

Section: Constant Injection Pressurementioning

confidence: 99%

“…Three typical examples were used to cover the case of induced or forced deformations by using an open-source code, LIMS (Liquid Injection Molding Simulation). Pham et al [8,9] developed a CRTM filling algorithm based on resin conservation on a deformable grid to predict the flow front at each time step. The model allowed study of the effect of compression on the filling of a composite part for different compression speeds and injection pressures.…”

Section: Introductionmentioning

confidence: 99%

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Simulation of Compression Effect on Filling Process in Compression Resin Transfer Molding

Chang

2011

Advanced Composite Materials

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The compression resin transfer molding (CRTM) filling process involves two stages: the injection phase and the compression phase. Two injection modes are considered -constant volumetric flow rate and constant pressure -while the constant compression velocity is utilized in this study. Three typical cases are used to investigate the compression initiation effects on the filling process. When the inlet condition is a constant flow rate, the numerical results show that the compression has both increase and decrease effects on the inlet pressure. Thus, a discontinuity in the inlet pressure is present at the onset or the end of compression. Among three CRTM cases, the process with a simultaneous injection and compression end maximally reduces the inlet pressure by 80% but increases the mold filling time by 65% compared with the resin transfer molding (RTM). For the inlet condition being a constant pressure, the resin may flow out of the mold cavity through the inlet when an excessively low injection pressure and high compression speed are applied concurrently. Compared with RTM, the CRTM processes reduce the mold filling time by 68-76% but cannot ensure a reduction in inlet pressure.

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“…However, modeling of this process is more complex as for the traditional RTM process, because it includes more process parameters and especially a changing cavity geometry during the process. First simulations of CRTM were conducted by Pham [11,12] modeling one-dimensional and two-dimensional resin flow in the cavity based on Darcy's law and using a finite-element method. Shojaei [13] developed a three-dimensional finite-element/control volume method to simulate the resin flow of a CRTM process in thick components, where a through-thickness impregnation can not be neglected.…”

Section: Introductionmentioning

confidence: 99%

Simulating Mold Filling in Compression Resin Transfer Molding (CRTM) Using a Three-Dimensional Finite-Volume Formulation

2018

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Light-weight structural components are increasingly made of continuous fiber reinforced plastics (CoFRP), but their mass production is still very expensive. Because of its high automation potential, especially the Compression Resin Transfer Molding (CRTM) process gains more and more attention. Numerical mold filling simulations help to optimize this process and can avoid expensive experimental studies. Here, we present a new method to simulate mold filling in CRTM using a full three-dimensional finite-volume (FV) method. In comparison to known finite-element (FE) methods, it contains a compressible two-phase/Volume-of-Fluid description of the air-and resin-phase. This approach is combined with a moving mesh to account for the change of cavity height during the process, which results in a change of fiber volume fractions and thus permeabilities. We verify the method by comparison to analytic solutions of the Darcy equation and to solutions of state-of-the-art mold filling simulation software. The presented method enables CRTM mold filling simulation of complex parts, which is shown in two application examples. Furthermore, this shows the potential of using FV-based tools to simulate mold filling in RTM process variants containing non-constant cavity geometries.

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Simulation of compression resin transfer molding to manufacture thin composite shells

Cited by 48 publications

References 14 publications

Simulation and experimental validation of mould tooling forces in RTM and CRTM for nonplanar components

Simulation and experimental validation of mould tooling forces in RTM and CRTM for nonplanar components

Simulation of Compression Effect on Filling Process in Compression Resin Transfer Molding

Simulating Mold Filling in Compression Resin Transfer Molding (CRTM) Using a Three-Dimensional Finite-Volume Formulation

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