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| 2. |
- Rouhi, Mohammad Sadegh, 1983, et al.
(författare)
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Experimental assessment of coupled dual-scale flow-deformation processes in composites manufacturing
- 2015
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Ingår i: Composites Part A: Applied Science and Manufacturing. - : Elsevier BV. - 1359-835X. ; 76, s. 215-223
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Tidskriftsartikel (refereegranskat)abstract
- In this paper we are concerned with the assessment of sub-models within a two-phase continuum mechanical FE framework for process modeling of composites manufacturing. In particular, the framework considers the inclusion of two deformation dependent models describing resin flow related to: (1) meso-scale wetting and compaction of individual plies and (2) overall preform deformation and macroscopic Darcian flow. Using micro-mechanical modeling, we model the physics of these sub-processes in relation to the recently developed Out-Of-Autoclave (OOA) prepergs. The models are placed in context with a compression–relaxation experiment, employed to study the preform deformations considered separated from other sub-processes. Finally, calibrations and model validations are carried out against the relaxation experiment to relate the FE framework to the mechanical response of the preform. Therefore, using the above experiment, parameter values out of the literature and those estimated from micrographs gave a fair agreement between the simulation and experiments.
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| 3. |
- Rouhi, Mohammad Sadegh, 1983, et al.
(författare)
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Holistic modeling of composites manufacturing using poromechanics
- 2016
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Ingår i: Advanced Manufacturing: Polymer and Composites Science. - : Informa UK Limited. - 2055-0359 .- 2055-0340. ; 2
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Tidskriftsartikel (refereegranskat)abstract
- In the present paper we present a novel finite element method capable of handling most of thephysics arising in the resin wet-out step for any composite system and processing case. The methodis based on a compressible two-phase continuum formulation where a key feature is to model theinvolved physics via innovative use of the compressibility of the phases. On the one hand, thefluid phase compressibility is used to capture the physics of the advancing resin front as well asthe physics behind the flow front. On the other hand, solid phase compressibility is used to modelmicro infiltration of the resin and the corresponding preform compaction, essentially consideredas a fluid sink problem. Finally, the generic porous media model is formulated in the finite strainregime. The model has been implemented and demonstrated for different manufacturing methodsand the results with respect to each example is presented. The degree of saturation, pressuredistribution, preform deformation and reaction forces are some of the post-processed results fordifferent manufacturing methods. The ultimate goal of this contribution is to establish an unifiedgeneric and general simulation tool for structural (long fiber) composite processing where, to thisdate, there is no single FE based tool available commercially for this purpose.
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| 4. |
- Rouhi, Mohammad Sadegh, 1983
(författare)
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Poromechanical Modeling of Composites Manufacturing
- 2015
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Fibre reinforced composite materials are used extensively in today's industry. On one hand, the low-weight feature of this kind of material gives important advantages such as lower fuel consumption and lower amount of CO2 emissions. On the other hand, corrosion and high temperature resistance has made them suitable for different type of environments. Composite materials are also assumed to grow significantly in automotive industry in near future. In these perspectives, especial attention has risen up towards development of advanced manufacturing technologies where higher production rate, lower cost and lower environmental issues are desired. To achieve this goal, numerical simulations and CAE tools are employed to predict the behavior of manufacturing methods with respect to the process optimization and the product properties.The focus of this research thesis is toward development of a framework for holistic modeling of fiber reinforced composites manufacturing. The manufacturing process can be considered as a fluid filled porous material, which can be described, on macro scale as well as micro scale, by the Theory of Porous Media (TPM). The TPM has been further enhanced by introducing the concept of phase compressibility of the biphasic mixture of solid and fluid, in order to describe the physical sub-processes happening in different scale. The model of the considered problem is then put forward to be solved by Finite Element Method (FEM). In the discretization of the numerical domain a quadratic six-node triangular element is used and a staggered solution procedure is chosen to solve the highly coupled problem in a finite strain regime. The most important challenges, that the numerical solution procedure is able to capture, are(1) modeling the compressible volumetrically-deformable fiber preform and the shape of membrane due to the different considered loading situations (2) the dual scale resin flow motion through the fibrous preform and the compaction of individual plies (3) deformation dependent permeability models (4) the free surface problem when the flow is moving with respect to a flow front velocity into the vacuum zone of the porous material.The framework that is developed here is capable of simulating different manufacturing processes based on the chosen initial conditions, boundary conditions and material parameters. Liquid Composite Molding (LCM), Liquid Resin Infusion (LRI), Resin Transfer Molding (RTM), Out of Autoclave (OoA), press forming prepregs, Engineering Vacuum Channels (EvaC) and similar manufacturing methods are some examples of the processes that have been simulated.
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| 5. |
- Wu, Da, 1985, et al.
(författare)
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Modeling and experimental validation of the vartm process
- 2019
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Ingår i: ICCM International Conferences on Composite Materials. ; 2019-August
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Konferensbidrag (refereegranskat)abstract
- The vacuum assisted resin transfer molding (VARTM) process is broadly used for producing large-scale and thin-walled fiber reinforced polymer composite (FRPC) components. The characteristics of the resin flow and the fibrous preform deformation, e.g., thickness variations, significantly affect the cycle time and quality of final products. To predict and simulate the process in a computationally efficient manner, we treat the 3-D resin flow as in-plane flow; and limit the preform deformation only in the normal of the mold surface. A vacuum infusion experiment is carried out for calibration and validation. The comparison shows a good match between the simulation and the experiment results. The present model efficiently predicts realistic results of the preform thickness variation and the flow front location.
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| 6. |
- Wu, Da, 1985, et al.
(författare)
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Modeling and Experimental Validation of the VARTM Process for Thin-Walled Preforms
- 2019
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Ingår i: Polymers. - : MDPI AG. - 2073-4360. ; 11:12
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Tidskriftsartikel (refereegranskat)abstract
- In this paper, recent shell model is advanced towards the calibration and validation of the Vacuum-assisted Resin Transfer Molding (VARTM) process in a novel way. The model solves the nonlinear and strongly coupled resin flow and preform deformation when the 3-D flow and stress problem is simplified to a corresponding 2-D problem. In this way, the computational efficiency is enhanced dramatically, which allows for simulations of the VARTM process of large scale thin-walled structures. The main novelty is that the assumptions of the neglected through-thickness flow and the restricted preform deformation along the normal of preform surface suffice well for the thin-walled VARTM process. The model shows excellent agreement with the VARTM process experiment. With good accuracy and high computational efficiency, the shell model provides an insight into the simulation-based optimization of the VARTM process. It can be applied to either determine locations of the gate and vents or optimize process parameters to reduce the deformation.
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| 7. |
- Wu, Da, 1985, et al.
(författare)
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Modeling of the vacuum assisted resin transfer molding process
- 2019
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Ingår i: ICCM22 Proceedings.
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Konferensbidrag (refereegranskat)abstract
- The vacuum assisted resin transfer molding (VARTM) process is widely used for producing large-scale and thin-walled fiber reinforced polymer composite materials. The resin flow movement and the fiber preform deformation essentially affect the quality of the final products. To predict and simulate those facts, we treat the resin flow as in-plain flow and allow the preform deform only along the normal direction. So that, instead of using expensive 3-D models, the present 2-D model is developed and can be applied to predict the VARTM process for large-scale and thin-walled composite products.
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