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| 5. |
- 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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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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| 11. |
- 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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| 12. |
- 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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| 13. |
- 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. |
- Saseendran, Sasha, et al.
(författare)
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Characterisation of viscoelastic material properties during curing processes
- 2015
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Ingår i: ICCM International Conferences on Composite Materials. - : International Committee on Composite Materials. ; 2015-July
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Konferensbidrag (refereegranskat)abstract
- The present contribution is toward systematic characterisation of the thermo-viscoelastic properties of a curing epoxy resin system, here we use Huntsman LY5052/HY5052 as model material. The main focus is to verify the existence of equivalence relation (linearity) between time, temperature and degree (time) of cure. As a starting point, the cure kinetics behaviour of the model material has been characterised using DSC equipment and the results have been used to identify parameters in a generic Kamal cure kinetics model. In the subsequent work the DSC data and Kamal model was used to carefully monitor the degree of cure in the resin in all the subsequent experiments. The thermo-viscoelastic response of the curing epoxy was characterised using a dynamic mechanical thermal analyser (DMTA). All the DMTA experiments were focused on rubbery and glassy states only, were the material was subject to tests at various isothermal and non-isothermal loading conditions. The results were used to investigate the linearity between the three factors above (time, temperature and curing time). To summarize, the results indicate that these three parameters indeed obey a linear relationship in the linear viscoelastic regime.
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| 17. |
- Toll, Staffan, 1964, et al.
(författare)
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Process rheology of fibre composites
- 2005
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Ingår i: Proc. Nordiska Polymerdagarna, August 17-19, Gothenburg, Sweden.
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)
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| 18. |
- Wysocki, Maciej, 1969, et al.
(författare)
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Anisotropic and tension-compression asymmetric model for composites consolidation
- 2010
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Ingår i: Composites. Part A, Applied science and manufacturing. - : Elsevier BV. - 1359-835X .- 1878-5840. ; 41:2, s. 284-294
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Tidskriftsartikel (refereegranskat)abstract
- A constitutive model for anisotropic and tension-compression asymmetric response of a fibrous preform is developed and solved using a FE software. Applicability of the method to complex geometries is demonstrated by analysis the consolidation of an axisymmetric filament wound pressure vessel made from commingled yarns. Three different winding patterns are considered. In conclusions, the consolidation of the whole vessel, except at the opening, is prevented by the loading mode, where the pressure is applied on the interior. To succeed in manufacturing of this type of pressure vessel, use of an oversized preform that allows extension in the fibre direction is suggested.
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| 20. |
- Wysocki, Maciej, 1969
(författare)
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Continuum modelling of composites consolidation
- 2006
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- This work describes the consolidation of commingled yarn-based thermoplastic composites. The consolidation operation involves deformation of the preform, wetting and compaction of fibre bundles, and resin flow through the preform. The model framework comprises a continuum formulation of a non-linear compressible porous solid saturated with an incompressible fluid. In this model, the solid phase represents the fibres plus any uninfiltrated void space within the fibre bundles, and the fluid phase represents the resin. Constitutive equations governing the forming process are developed. These are the effective stress response of the preform, compaction of the solid phase, and Darcian interaction between the phases. Particular attention is paid to the compaction of the solid phase (consisting of a fibre packing mechanism and a viscous wetting process), the volumetric response of the preform and the tension-compression asymmetric response of the fibres. The fibre packing is described by a hyperelastic packing model, and the wetting of bundles by microscopic Darcy flow is described as a viscous compaction of the solid phase. An experimental method for the measurement of the volumetric response of the preform in separation from other processes is introduced. A phenomenological constitutive model for tension-compression asymmetric of a fibre is proposed. The constitutive equations for solid and preform compaction are assessed against experimental data, while the tensioncompression asymmetric model is fitted to a simple tension-compression experiment. Finally, the work is concluded by a numerical example that demonstrates the versatility of the approach, where the material science is combined with two-phase continuum mechanics.
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| 23. |
- Wysocki, Maciej, 1969, et al.
(författare)
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Modelling multiple scales in composites manufacturing
- 2010
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Ingår i: Proceedings of The 10th International Conference on Flow Processes in Composite Materials (FPCM10), Monte Verità, Ascona, CH – July 11-15, 2010.
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Konferensbidrag (refereegranskat)abstract
- In this contribution, we develop a generic two-phase porous media continuum and the associated FE implementation aimed for modelling simultaneous sub-processes accruing at different spatial and temporal scales. The development is based on our previous work [1], where focus has been on coupling the preform deformation on different scales to the process of micro infiltration. In this work, we extend the previous developments with respect to the Darcian interaction on the macro scale. The background idea is to identify a set of relevant phases, i.e. solid and fluid, and assign a separate continuous medium to each phase. 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 allow for phase compressibility and introduce internal variables to describe irreversible micro-processes in the system, such as microscopic infiltration. A coupled displacement-pressure, fully non-linear, finite element model is presented. The approach is applied to a representative numerical example, displaying the relevance of the involved sub-processes.
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| 26. |
- Wysocki, Maciej, 1969, et al.
(författare)
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Wysocki, Maciej
- 2002
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Ingår i: 9th Int. Conf. on Fibre Reinforced Composites, FRC 2002..
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Konferensbidrag (refereegranskat)
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