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- Rouhi, Mohammad Sadegh, 1983, et al.
(författare)
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Composite manufacturing modeling using porous media theory
- 2012
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Ingår i: 25th Nordic Seminar on Computational Mechanics (NSCM25), Lund, Swede, 25-26 October 2012. ; , s. 295-298
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Konferensbidrag (refereegranskat)abstract
- We recently developed a simulation tool to simulate a quite wide class of composites manufacturing processes based on a compressible porous media theory formulation involving three constituents, solid, fluid and pore gas embedded in the voids. The aim of this tool is: firstly to model the highly deformable preform and its interaction with external loading and the intrinsic fluid pressure as well as the resulting changes in permeability, compaction and level of saturation. Secondly, the aim is to track the resin flow front during the infusion process using the continuum formulation itself, thereby avoiding methods like level set.
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| 6. |
- Rouhi, Mohammad Sadegh, 1983, et al.
(författare)
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CONSTITUTIVE MODELLING OF ANISOTROPIC TWO-SCALE FLOW
- 2012
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Ingår i: 15th European Conference on Composite Material (ECCM15) - Venice- Italy 2012. - : European Conference on Composite Materials, ECCM.
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Konferensbidrag (refereegranskat)abstract
- We recently developed a simulation tool to simulate a quite wide class of infusion processes based on a compressible porous media theory formulation involving three constituents, solid, fluid and pore gas embedded in the voids. The aim of this tool is: firstly to model the highly deformable preform and its interaction with external loading and the intrinsic fluid pressure as well as the resulting changes in permeability, compaction and level of saturation. Secondly, the aim is to track the resin flow front during the infusion process using the continuum formulation itself, thereby avoiding methods like level set, etc. [1]. In this contribution, we present a permeability model applied within the modeling framework to account for anisotropic flow in the fibre bed. The ultimate goal of the approach is to be able to simulate the infusion of high performance, large scale composite structures, in an optimized and controlled fashion.
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| 7. |
- 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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| 8. |
- Rouhi, Mohammad Sadegh, 1983, et al.
(författare)
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FE modeling and numerical implemtation of flow-deformation processes in composites manufacturing
- 2013
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Ingår i: ICCM International Conferences on Composite Materials. - : International Committee on Composite Materials. ; 2013-July, s. 5292-5299, s. 5292-5299
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Konferensbidrag (refereegranskat)abstract
- In present work, we attempt to unify the modeling of different sub-processes under the umbrella of two-phase porous media theory. Two sub processes are considered: (1) the wetting and compaction of individual plies and (2) the overall preform deformation and macroscopic Darcian flow. The idea is to identify a set of relevant constituents, i.e. particles, voids and liquids, and assign them to pertinent media. The result is a set of overlapping continuous media, each having its own density-, velocity- and stress field on the macroscopic scale. In addition, we introduce internal variables to describe irreversible micro-processes in the system, such as microscopic infiltration and preform deformation. In this work we extend the previous developments, coupling the preform deformation on different scales to the process of micro infiltration, with respect to the modeling of the micro-compaction as well as the Darcian interaction on the macro scale. A coupled displacement-pressure, geometrically non-linear, finite element model is presented. The approach is applied to a representative numerical example where we used parameter values out of the literature and estimates from our own micrographs.
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| 9. |
- 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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| 10. |
- Rouhi, Mohammad Sadegh, 1983, et al.
(författare)
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Large Scale Additive Manufacturing of Recycled Polymer Composites
- 2023
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Ingår i: Proceedings of the American Society for Composites - 38th Technical Conference, ASC 2023. - : DEStech Publications. ; , s. 2405-2411
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Konferensbidrag (refereegranskat)abstract
- The production of large-scale products is currently undergoing a considerable shift in the manufacturing sector in favor of additive manufacturing (AM). Complex structures and elaborate designs that were previously impossible to produce using conventional manufacturing techniques are now possible thanks to the usage of additive printing technology. At the same time, using recycled materials in the production process has also risen to the top of the industry's priority list as a result of a growing focus on sustainability. In this context, the use of recycled polymer composites in large-scale additive manufacturing (LSAM) is beginning to attract attention from both industry and research. Indeed, recycled polymer composites offer several benefits, including not only lower costs but also significantly reduced environmental impact and improved mechanical properties compared to virgin polymer materials. However, several challenges are still associated with using recycled materials in AM, including issues with material properties and compatibility with the AM process. Perhaps the most difficult polymer for AM is nylon where different grades pose different printing properties and challenges, thus printing large-scale objects in recycled nylon is a challenge that few have taken on. One objective of our project is to improve the properties of recycled polymers for LSAM by investigating how different additives, such as mineral wastes and/or recycled short fibers, influence the LSAM process and the properties of the resulting printed object. One way to achieve this objective is by simulating the AM process where we use ABAQUS AM capabilities that enable us to optimize the process and material parameters. Thermal and mechanical analyses using the element activation technique in ABAQUS AM allow us to implement multi-scale multi-physical models for material and process simulation and ensure that the final product meets the desired mechanical and structural properties. To truly reach a circular economy, a systems-level transformation of manufacturing must be achieved [1]. Our vision is to digitally transform manufacturing by turning recycled polymers and other industrial wastes into secondary raw materials and composites for LSAM of final products. However, further research on different industrial use cases and applications is needed to address the remaining challenges associated with this approach and to fully realize its potential in the manufacturing industry.
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| 11. |
- Rouhi, Mohammad Sadegh, 1983, et al.
(författare)
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Modeling of coupled dual-scale flow–deformation processes in composites manufacturing
- 2013
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Ingår i: Composites Part A: Applied Science and Manufacturing. - : Elsevier BV. - 1359-835X .- 1878-5840. ; 46:1, s. 108-116
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Tidskriftsartikel (refereegranskat)abstract
- The present contribution is a part of the work towards a framework for holistic modeling of compositesmanufacturing. Here we focus our attention onto the particular problem of coupled dual-scale deformation–flow process such as the one arising in RTM, Vacuum Assisted Resin Infusion (VARI) and VacuumBag Only (VBO) prepregs. The formulation considers coupling effects between macro-scale preform processesand meso-scale ply processes as well as coupling effects between the solid and fluid phases. Theframework comprises a nonlinear compressible fiber network saturated with incompressible fluid phase.Internal variables are introduced in terms of solid compressibility to describe the irreversible mesoscopicinfiltration and reversible preform compaction processes. As a main result a coupled displacement–pressure, geometrically nonlinear, finite element simulation tool is developed. The paper is concludedwith a numerical example, where a relaxation–compression test of a planar fluid filled VBO preform atglobally un-drained and partly drained conditions is considered.
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| 12. |
- Rouhi, Mohammad Sadegh, 1983, et al.
(författare)
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Modeling resin flow and preform deformation in composite manufacturing based on partially saturated porous media theory
- 2010
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Ingår i: Procedeing of 23rd Nordic Seminar on Computational Mechanics. ; , s. 142-145
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Konferensbidrag (refereegranskat)abstract
- In this contribution a generic algorithm to simulate resin infusion in composites manufacturing technologies such as Liquid Resin Infusion (LRI) and Resin Transfer Molding(RTM) is developed. The most important challenge to be addressed is the migration of free surface due to resin infiltration into the highly deformable fibrous preform. To do so, a compressible two-phase porous media formulation is put forward for the problem formulation and a staggered finite element based solution procedure is advocated for the total solution advancement. The approach automatically monitors the free surface, whereby the monitoring of the resin front migration using e.g. level set or front tracking control is completely avoided. The method is exemplified using a hat stringer geometry considering both manufacturing methods.
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| 13. |
- Rouhi, Mohammad Sadegh, 1983, et al.
(författare)
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Modeling resin flow, preform deformations and residual stresses in RTM manufacturing
- 2011
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Ingår i: Proc. of International Conference on Manufacturing of Advanced Composites, ICMAC 2011, Belfast, Northern Ireland.
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Konferensbidrag (refereegranskat)abstract
- In the present contribution a generic algorithm is developed to simulate resin infusion in a wide range of popular composites manufacturing technologies, such as Liquid Resin Infusion (LRI) and Resin Transfer Molding (RTM). The ultimate goal is to model a complete manufacturing chain, allowing us to predict the final product properties of the composite material. The major challenges to be addressed by in this modelling vary between different processing steps. One of the most important one concerns the migration of the free surface due to resin infiltration into the highly deformable fibrous preform. Considering the LRI process, the modeling challenge is to predict the final shape of a highly deformable preform due to interaction between external loading and the intrinsic fluid pressure. Moreover, in the RTM process the constant compaction load due to rigid top part of the mold needs to be modeled. To resolve both these processes in one single framework, a compressible two-phase porous media formulation is put forward. The developed model involves a fluid compressibility and permeability dependence on the saturation degree. This is to account for the coupled response of partially saturated solid-fluid media, typical for the transition zone at the free surfacebetween full- and non-saturation. The approach automatically monitors the free surface, whereby the monitoring of the resin front migration using e.g. levelset or front tracking control is completely avoided. The proposed formulation of the manufacturing infusion has been implemented and used for both LRI and RTM simulations, and numerical results are provided for a hat stringer problem.To complete the manufacturing process chain, the curing step is considered in the present contribution as a simple thermal shrinkage problem, whereby the fiber content obtained from the LRI or RTM–simulations is used for the evaluation of residual stresses and component distortion.
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| 14. |
- Rouhi, Mohammad Sadegh, 1983, et al.
(författare)
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MODELING THE CONSTITUTIVE RESPONSE OF AN ANISOTROPIC DUAL-SCALE FLOW
- 2012
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Ingår i: 11th International Conference on Flow Processing in Composite Materials (FPCM11) - Auckland - New Zealand 2012.
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Konferensbidrag (refereegranskat)abstract
- Today’s trend in composites manufacturing is to reduce cost by, among other things, cutting down the number of operations required to produce a component. For example all the steps of impregnation the reinforcement, consolidation, forming and finally curing may be, in some cases, combined into a single processing operation. This leads to increasingly complex manufacturing processes with many interacting sub-processes occurring simultaneously on different spatial and temporal scales. In this context we are developing an unified finite-strain continuum framework [1],[2],[3],[4], which we recently adopted towards modeling of dual-scale flows in composite manufacturing [5]. In this context, in the present work we consider the manufacturing of the so called Engineering Vacuum Channel (EVaC) prepreg materials as discussed in e.g. [6]. Even though our numerical framework is capable of modeling all the interacting sub-processes at ones, the constitutive models for these are still rare and have not been generalized in a proper continuum context. In summary, the idea of the present work is to emanate from the existing model for fluid follow in a rectangular channel (the so called Poiseuille flow) and generalize it in the finite-strain continuum context. The major task is then to extend our framework to account for anisotropic Darcian interaction on the macro scale and implement the constitutive model into it, while the minor task is to examine the interaction between preform deformation on different scales and the process of micro infiltration and macro flow. The major task is accomplished by introducing the anisotropic permeability model to our coupled displacement-pressure, non-linear finite element model, while the minor task is approached using a representative numerical example, displaying the relevant interactions between the involved sub-processes. The algorithm is then tested for drained conditions, and results are compared to the one in [5] for isotropic flow.
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| 16. |
- 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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| 17. |
- Rouhi, Mohammad Sadegh, 1983
(författare)
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Process Modeling of Composite Manufacturing
- 2013
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Licentiatavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The focus of this research thesis is toward developing a framework for holistic modeling of composites manufacturing of fiber reinforced structural composites. The processes that have been considered are Liquid Composite Molding (LCM) and Out Of Autoclave (OOA) processes, ranging from Liquid Resin Infusion (LRI) and Resin Transfer Molding (RTM) in LCM processes, to Vacuum Bag Only (VBO) and Evac prepregs in OOA processes. To develop this framework the theory of two phase porous media has been extensively used and developed. A finite element formulation and implementation of the two phase problem has been developed for compressible-incompressible constituents using Taylor-Hood element assuming hyper-elastic material response for the fiber bed. The issues that are considered during the simulations are analysis of process physics such as (1) modeling the highly deformable preform and the shape of the membrane due to the considered loading conditions, (2) the free surface problem when the flow front is moving with respect to a flow front velocity into the vacuum zone of the porous media, (3) the coupling effects between macro-scale preform processes and meso-scale ply processes, (4) development of an anisotropic permeability model, (5) coupling effects between the solid and fluid phases.The proposed formulation has been implemented and numerical results are provided for both cases of LCM and OOA processes. As a main result a coupled displacement-pressure, geometrically non-linear, finite element simulation tool is developed. Numerical examples of an infusion problem of a hat-beam, simulating both RTM and LRI, and also a relaxation-compression test of a planar fluid filled VBO preform, for LCM and OOA processes respectively, are considered.
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| 19. |
- 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.
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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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| 20. |
- 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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| 21. |
- 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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