Ändra sökning
Avgränsa sökresultatet
1 - 20 av 20
RefereraExporteraLänk till träfflistan
Permanent länk
Referera
Referensformat
  • apa
  • harvard1
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Annat format
Fler format
Språk
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Annat språk
Fler språk
Utmatningsformat
  • html
  • text
  • asciidoc
  • rtf
Träffar per sida
  • 5
  • 10
  • 20
  • 50
  • 100
  • 250
Sortering
  • Standard (Relevans)
  • Författare A-Ö
  • Författare Ö-A
  • Titel A-Ö
  • Titel Ö-A
  • Publikationstyp A-Ö
  • Publikationstyp Ö-A
  • Äldst först
  • Nyast först
  • Skapad (Äldst först)
  • Skapad (Nyast först)
  • Senast uppdaterad (Äldst först)
  • Senast uppdaterad (Nyast först)
  • Disputationsdatum (tidigaste först)
  • Disputationsdatum (senaste först)
  • Standard (Relevans)
  • Författare A-Ö
  • Författare Ö-A
  • Titel A-Ö
  • Titel Ö-A
  • Publikationstyp A-Ö
  • Publikationstyp Ö-A
  • Äldst först
  • Nyast först
  • Skapad (Äldst först)
  • Skapad (Nyast först)
  • Senast uppdaterad (Äldst först)
  • Senast uppdaterad (Nyast först)
  • Disputationsdatum (tidigaste först)
  • Disputationsdatum (senaste först)
Markera
Maxantalet träffar du kan exportera från sökgränssnittet är 250. Vid större uttag använd dig av utsökningar.
  • 1.
    Larsson, R.
    et al.
    Chalmers University of Technology.
    Rouhi, Mohammad
    Chalmers University of Technology.
    Wysocki, Maciej
    RISE - Research Institutes of Sweden, Material och produktion, SICOMP.
    Free surface flow and preform deformation in composites manufacturing based on porous media theory2012Ingår i: European journal of mechanics. A, Solids, ISSN 0997-7538, E-ISSN 1873-7285, Vol. 31, nr 1, s. 12-janArtikel i tidskrift (Refereegranskat)
    Abstract [en]

    In the present contribution an infusion simulation tool is developed, applicable to a quite wide range of composites manufacturing technologies. The paper focusses on isothermal, infusion like manufacturing processes involving highly deformable preforms and a free surface resin flow. There are two major issues addressed at the modelling of the infusion processes: The first one is the highly deformable preform and its shape due to the interaction between external pressure loading and the intrinsic fluid pressure. The second issue concerns the migrating free surface due to resin infiltration into the fibrous preform. To resolve these both issues simultaneously, a compressible two-phase porous media formulation is put forward involving an additional liquid mass balance relationship as compared to the standard compressible porous media formulation. As a result a governing equation for saturation degree evolution is established, which is used to monitor the free surface problem directly in terms of the compressible continuum formulation traversing into incompressibility with increasing partial saturation degree. A staggered finite element based solution procedure is advocated for the total solution advancement, involving, on the one hand, the saturation dependent porous media formulation, and, on the other hand, the computation of the saturation degree. The proposed formulation has been implemented and numerical results are provided, showing the convergence of the staggered approach, and the assessment of the proposed approach against a 1D analytical model. In addition, the infusion of a "hat" beam is considered. © 2011 Elsevier Masson SAS. All rights reserved.

  • 2.
    Larsson, Ragnar
    et al.
    Chalmers University of Technology, Sweden.
    Gutkin, Renaud
    Volvo Car Corporation, Sweden.
    Rouhi, Mohammad
    RISE - Research Institutes of Sweden, Material och produktion, SICOMP.
    Damage growth and strain localization in compressive loaded fiber reinforced composites2018Ingår i: Mechanics of materials (Print), ISSN 0167-6636, E-ISSN 1872-7743, Vol. 127, s. 77-90Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    To increase the use of polymeric structural composites, a major issue is to properly account for intra-laminar failure mechanisms, such as fiber kinking which is typically induced in compression. We propose a new set of continuum damage models that are able to predict fiber kinking response under compression. A structure tensor based formulation is established at the unidirectional ply level, where the elastic material response is governed by transverse isotropy. To consider geometrical effects in conjunction with fiber kinking instability, a continuum damage formulation at finite strain is developed. The fracture area progression includes a convective and a local damage production involving a finite progression speed. In this framework, two damage evolution models are considered; one non–local model including the gradient damage effect and a local one, without the gradient enhancement. The models are implemented in a FE–code and validated for a compression loaded specimen. The models are computationally robust and can predict the localized nature of fiber kinking. A thorough sensitivity study is presented to show how the different formulations influence the predicted responses.

  • 3.
    Larsson, Ragnar
    et al.
    Chalmers University of Technology, Sweden.
    Rouhi, Mohammad
    Chalmers University of Technology, Sweden.
    Gutkin, Renaud
    RISE - Research Institutes of Sweden, Material och produktion, SICOMP.
    Modelling of kink-band growth based on the geometrically non-linear theory2016Ingår i: ECCM 2016 - Proceeding of the 17th European Conference on Composite Materials, 2016Konferensbidrag (Övrigt vetenskapligt)
    Abstract [en]

    We propose a new and computationally ecient continuum damage based model, able to predict fibre /matrix shear failure under longitudinal compression for a UD ply. A structure tensor based continuum damage formulation is placed in context with the UD ply, where the elastic material response is governed by transverse isotropy. To represent the proper energy dissipation, an elastic damage model is formulated in the invariants of fibre/matrix shear and fibre compression, including failure initiation and progressive damage modeling. We are guided by the anisotropic elastic model to define four strain invariants, representing key features of the UD-ply microstructure. The damage model is applied to a Non-Crimp Fabric (NCF) composite and compared to a state of the art model based on kinking theory [6]. Instead of invoking the geometric instability into the material model, a key feature is to consider the geometrical fibre kinking instability on the macro-level based on a finite strain formulation

  • 4. Larsson, Ragnar
    et al.
    Rouhi, Mohammad
    RISE - Research Institutes of Sweden, Material och produktion, SICOMP.
    Wysocki, Maciej
    RISE - Research Institutes of Sweden, Material och produktion, SICOMP.
    Infusion modelling using two-phase porous media theory2010Konferensbidrag (Övrigt vetenskapligt)
  • 5. Larsson, Ragnar
    et al.
    Rouhi, Mohammad
    RISE - Research Institutes of Sweden, Material och produktion, SICOMP.
    Wysocki, Maciej
    RISE - Research Institutes of Sweden, Material och produktion, SICOMP.
    Modeling resin flow and preform deformation in composite manufacturing based on partially saturated porous media theory2010Konferensbidrag (Övrigt vetenskapligt)
  • 6. Larsson, Ragnar
    et al.
    Rouhi, Mohammad
    RISE - Research Institutes of Sweden, Material och produktion, SICOMP.
    Wysocki, Maciej
    RISE - Research Institutes of Sweden, Material och produktion, SICOMP.
    Resin Flow and Preform Deformation in Composites Manufacturing Based on a Partially Saturated Porous Medium2011Konferensbidrag (Övrigt vetenskapligt)
  • 7.
    Rouhi, Mohammad
    et al.
    RISE - Research Institutes of Sweden, Material och produktion, SICOMP.
    Costa, Sergio
    RISE., Swerea.
    Wysocki, Maciej
    RISE - Research Institutes of Sweden, Material och produktion, SICOMP.
    Gutkin, Renaud
    Chalmers University of Technology, Sweden.
    Coupling process and structural simulations in crash application2016Ingår i: 31st ASC Technical Conference and ASTM D30 Meeting, 2016Konferensbidrag (Övrigt vetenskapligt)
    Abstract [en]

    The energy absorbed during crushing of composite structures is strongly dependent on the layup, fiber architecture and type of resin used. Modeling of the crash behavior of composites is therefore highly influenced by the composite material system chosen, and current constitutive models must be improved to include/account for the inherent properties from the manufacturing step. The ultimate goal of this contribution is to optimize the material system and manufacturing method for the required crushing performance in terms of energy absorption and cost. A first outcome of the study will be to provide information regarding the properties of the final manufactured composite material such as residual stresses and effects of defects. These properties are then used in the development of crash models. A robust link between manufacturing, experiments and crushing simulations is vital where there should be a generic routine towards the data transfer and constitutive models. The study of effects of defects will affect the input data into the material and constitutive models in form of change in strength and stiffness properties of the material. In this contribution, an experimental study on the material response under quasistatic crushing is performed where the manufacturing effects on the material properties are considered based on estimated data provided from vacuum infusion simulation. The crushing simulations are performed with ABAQUS where the material model developed in-house, which is a physically based damage model based on the LaRC05 failure criterion and progressive damage, is chosen to model the constitutive behavior. The parameters that are transferred to the system from manufacturing simulation are fiber content and voids. Consideration of these parameters into the constitutive behavior of the structure will directly influence the structural response. A parametric study is completed and results are discussed.

  • 8.
    Rouhi, Mohammad
    et al.
    RISE - Research Institutes of Sweden, Material och produktion, SICOMP.
    Juntikka, Magdalena
    RISE - Research Institutes of Sweden, Material och produktion, SICOMP.
    Landberg, Johan
    RISE - Research Institutes of Sweden, Material och produktion, IVF.
    Wysocki, Maciej
    RISE - Research Institutes of Sweden, Biovetenskap och material, Kemi och material.
    Assessing models for the prediction of mechanical properties for the recycled short fibre composites2019Ingår i: Journal of reinforced plastics and composites (Print), ISSN 0731-6844, E-ISSN 1530-7964, Vol. 38, nr 10, s. 454-466Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Processing of polymer fibre composites has a remarkable influence on their mechanical performance. These mechanical properties are even more influenced when using recycled reinforcement. Therefore, we place particular attention on the evaluation of micromechanical models to estimate the mechanical properties and compare them against the experimental results of the manufactured composites from recycled carbon fibre material. For the manufacturing process, an epoxy matrix and carbon fibre production cut-offs as reinforcing material are incorporated using a vacuum infusion process. In addition, continuous textile reinforcement in combination with the epoxy matrix is used as reference material to evaluate the degradation of mechanical performance of the recycled composite. The experimental results show higher degradation of the composite strength compared to the stiffness properties. Observations from the modelling also show the same trend as the deviation between the theoretical and experimental results is lower for stiffness comparisons than the strength calculations. Yet still, good mechanical performance for specific applications can be expected from these materials.

  • 9.
    Rouhi, Mohammad S.
    et al.
    RISE - Research Institutes of Sweden, Material och produktion, SICOMP. Chalmers University of Technology, Sweden.
    Wysocki, Maciej
    RISE - Research Institutes of Sweden, Material och produktion, SICOMP. Chalmers University of Technology, Sweden.
    Larsson, Ragnar
    Chalmers University of Technology, Sweden.
    Experimental assessment of dual-scale resin flow-deformation in composites processing2015Ingår i: Composites. Part A, Applied science and manufacturing, ISSN 1359-835X, E-ISSN 1878-5840, Vol. 76, s. 215-223Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    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.

  • 10.
    Rouhi, Mohammad S.
    et al.
    RISE - Research Institutes of Sweden, Material och produktion, SICOMP. Chalmers University of Technology, Sweden.
    Wysocki, Maciej
    RISE - Research Institutes of Sweden, Material och produktion, SICOMP. Chalmers University of Technology, Sweden.
    Larsson, Ragnar
    Chalmers University of Technology, Sweden.
    Holistic modeling of composites manufacturing using poromechanics2016Ingår i: Advanced Manufacturing: Polymer & Composites Science, ISSN 2055-0340, Vol. 2, nr 1, s. 14-26Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    AbstractIn the present paper, we present a novel finite-element method capable of handling most of the physics arising in the resin wet-out step for any composite system and processing case. The method is based on a compressible two-phase continuum formulation where a key feature is to model the involved physics via innovative use of the compressibility of the phases. On the one hand, the fluid-phase compressibility is used to capture the physics of the advancing resin front as well as the physics behind the flow front. On the other hand, solid-phase compressibility is used to model micro-infiltration of the resin and the corresponding preform compaction, essentially considered as a fluid sink problem. Finally, the generic porous media model is formulated in the finite strain regime. The model is implemented and demonstrated for different manufacturing methods and the results with respect to each example are presented. The degree of saturation, pressure distribution, preform deformation, and reaction forces are some of the post-processed results for different manufacturing methods. The ultimate goal of this contribution is to establish a unified generic and general simulation tool for structural (long fiber) composite processing where, to this date, there is no single FE-based tool available commercially for this purpose.

  • 11.
    Rouhi, Mohammad S.
    et al.
    RISE - Research Institutes of Sweden, Material och produktion, SICOMP.
    Wysocki, Maciej
    RISE - Research Institutes of Sweden, Material och produktion, SICOMP.
    Larsson, Ragnar
    Modeling of coupled dual-scale flow–deformation processes in composites manufacturing2013Ingår i: Composites. Part A, Applied science and manufacturing, ISSN 1359-835X, E-ISSN 1878-5840, Vol. 46, s. 108-116Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The present contribution is a part of the work towards a framework for holistic modeling of composites manufacturing. 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 Vacuum Bag Only (VBO) prepregs. The formulation considers coupling effects between macro-scale preform processes and meso-scale ply processes as well as coupling effects between the solid and fluid phases. The framework comprises a nonlinear compressible fiber network saturated with incompressible fluid phase. Internal variables are introduced in terms of solid compressibility to describe the irreversible mesoscopic infiltration and reversible preform compaction processes. As a main result a coupled displacement–pressure, geometrically nonlinear, finite element simulation tool is developed. The paper is concluded with a numerical example, where a relaxation–compression test of a planar fluid filled VBO preform at globally un-drained and partly drained conditions is considered.

  • 12.
    Rouhi, Mohammad
    et al.
    RISE - Research Institutes of Sweden, Material och produktion, SICOMP.
    Wysocki, M.
    RISE - Research Institutes of Sweden, Material och produktion, SICOMP.
    Larsson, R.
    Chalmers University of Technology.
    Constitutive modelling of anisotropic two-scale flow2012Konferensbidrag (Refereegranskat)
    Abstract [en]

    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.

  • 13.
    Rouhi, Mohammad
    et al.
    RISE - Research Institutes of Sweden, Material och produktion, SICOMP.
    Wysocki, Maciej
    RISE - Research Institutes of Sweden, Biovetenskap och material, Kemi och material.
    SIMULATION OF 3D PREPREG CONSOLIDATIONPROCESS USING SOLID SHELL ELEMENTS2018Konferensbidrag (Övrigt vetenskapligt)
    Abstract [en]

    In process simulation of composite materials, 3D simulation of manufacturing processes is desirableconsidering the manufacturing trend where parts became more complex leading to complex3D stress-strain states. Moreover, coupling of sub-processes that are happening simultaneouslysuch as macro-scale preform processes, micro-infiltration and solid and fluid interactionrequires full 3D description of the problem.The development is exemplified considering compression moulding process of prepregs wherethe main focus of the modeling will be on the compression and compaction of directionalprepreg laminate and flow consolidation. To this end, the theory of two phase porous mediais used along with assuming hyper-elastic material response for the laminate to formulatethe problem. A finite element formulation and implementation of the two-phase problem is developedfor incompressible constituents and is implemented in a user defined element (UEL)to be used with Abaqus.

  • 14.
    Rouhi, Mohammad
    et al.
    RISE - Research Institutes of Sweden, Material och produktion, SICOMP.
    Wysocki, Maciej
    RISE - Research Institutes of Sweden, Material och produktion, SICOMP.
    Larsson, R.
    Chalmers University of Technology.
    Modeling of coupled dual-scale flow-deformation processes in composites manufacturing2013Ingår i: Composites. Part A, Applied science and manufacturing, ISSN 1359-835X, E-ISSN 1878-5840, Vol. 46, nr 1, s. 108-116Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The present contribution is a part of the work towards a framework for holistic modeling of composites manufacturing. 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 Vacuum Bag Only (VBO) prepregs. The formulation considers coupling effects between macro-scale preform processes and meso-scale ply processes as well as coupling effects between the solid and fluid phases. The framework comprises a nonlinear compressible fiber network saturated with incompressible fluid phase. Internal variables are introduced in terms of solid compressibility to describe the irreversible mesoscopic infiltration and reversible preform compaction processes. As a main result a coupled displacement-pressure, geometrically nonlinear, finite element simulation tool is developed. The paper is concluded with a numerical example, where a relaxation-compression test of a planar fluid filled VBO preform at globally un-drained and partly drained conditions is considered. © 2012 Elsevier B.V. All rights reserved.

  • 15.
    Rouhi, Mohammad
    et al.
    RISE - Research Institutes of Sweden, Material och produktion, SICOMP.
    Wysocki, Maciej
    RISE - Research Institutes of Sweden, Material och produktion, SICOMP.
    larsson, Ragnar
    Composite manufacturing modeling using porousmedia theory2012Konferensbidrag (Övrigt vetenskapligt)
    Abstract [en]

    We recently developed a simulation tool to simulate a quite wide class ofcomposites manufacturing processes based on a compressible porous media theory formulationinvolving three constituents, solid, fluid and pore gas embedded in the voids. The aim of thistool is: firstly to model the highly deformable preform and its interaction with external loadingand the intrinsic fluid pressure as well as the resulting changes in permeability, compaction andlevel of saturation. Secondly, the aim is to track the resin flow front during the infusion processusing the continuum formulation itself, thereby avoiding methods like level set

  • 16.
    Rouhi, Mohammad
    et al.
    RISE - Research Institutes of Sweden, Material och produktion, SICOMP.
    Wysocki, Maciej
    RISE - Research Institutes of Sweden, Material och produktion, SICOMP.
    Larsson, Ragnar
    Modeling resin flow, preform deformations and residual stresses in RTM manufacturing2011Konferensbidrag (Övrigt vetenskapligt)
  • 17.
    Rouhi, Mohammad
    et al.
    RISE - Research Institutes of Sweden, Material och produktion, SICOMP.
    Wysocki, Maciej
    RISE - Research Institutes of Sweden, Material och produktion, SICOMP.
    Larsson, Ragnar
    MODELING THE CONSTITUTITVE REPONSE OFAN ANISOTROPIC DUAL-SCALE FLOW2012Konferensbidrag (Övrigt vetenskapligt)
  • 18.
    Rouhi, Mohammad
    et al.
    RISE - Research Institutes of Sweden, Material och produktion, SICOMP.
    Wysocki, Maciej
    RISE - Research Institutes of Sweden, Material och produktion, SICOMP.
    Larsson, Ragnar
    PROCESS MODELING OF COMPOSITEMATERIALS - A HOLISTIC AND GENERICSIMULATION TOOL USING POROMECHANICS2014Konferensbidrag (Övrigt vetenskapligt)
  • 19.
    Rouhi, Mohammad
    et al.
    RISE - Research Institutes of Sweden, Material och produktion, SICOMP.
    Wysocki, Maciej
    RISE - Research Institutes of Sweden, Material och produktion, SICOMP.
    Larsson, Ragnar
    Chalmers University of Technology, Sweden.
    SIMULATION OF 3D RTM PROCESS USING SOLID SHELL ELEMENT2016Ingår i: 13th International Conference on Flow Processes in Composite Materials (FPCM 13), 2016Konferensbidrag (Övrigt vetenskapligt)
    Abstract [en]

    In the era of process modeling of composite materials, 3D simulation of manufacturing processesis desirable considering the manufacturing trend where parts became more complexleading to complex 3D stress-strain states. Moreover, coupling of sub-processes that are happeningsimultaneously such as macro-scale preform processes, flow advancement and solidand fluid interaction requires full 3D description of the problem.The development is exemplified considering RTM process where the main focus of the modelingwill be on the flow advancement into fiber preform and flow front capturing. To thisend, the theory of two phase porous media is used along with assuming hyper-elastic materialresponse for the fiber bed to formulate the problem. A finite element formulation and implementationof the two-phase problem is developed for incompressible constituents

  • 20.
    Wysocki, Maciej
    et al.
    RISE - Research Institutes of Sweden, Material och produktion, SICOMP.
    Rouhi, Mohammad
    RISE - Research Institutes of Sweden, Material och produktion, SICOMP.
    Vyas, Gaurav
    RISE - Research Institutes of Sweden, Material och produktion, SICOMP.
    Toll, Staffan
    KTH Royal Institute of Technology, Sweden.
    Constitutive models for transversely isotropic fibreprefrom in composite manufacturing2016Ingår i: 13th International Conference on Flow Processes in Composite Materials (FPCM 13), 2016, artikel-id 20Konferensbidrag (Övrigt vetenskapligt)
    Abstract [en]

    The present contribution is an attempt to model a prepreg that is assumed to have approximatelystraight and parallel fibers which in an unloaded state has a transversely isotropicsymmetry about the fiber axis n. It is further assumed that the prepreg behaves elastic undera purely volumetric deformation, as well as under axial stretching in the fiber direction.A two-scale flow highly coupled to the fiber bed deformation is also being modelled usingporomechanics. The framework comprises a nonlinear compressible fiber network saturatedwith incompressible fluid phase.

1 - 20 av 20
RefereraExporteraLänk till träfflistan
Permanent länk
Referera
Referensformat
  • apa
  • harvard1
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Annat format
Fler format
Språk
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Annat språk
Fler språk
Utmatningsformat
  • html
  • text
  • asciidoc
  • rtf
v. 2.35.7