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Rudd, Christopher. "Preform processing for high volume resin transfer moulding (RTM)." Thesis, University of Nottingham, 1989. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.543834.
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Sakka, Aymen. "Investigation of Heat Conduction Through PMC Components Made Using Resin Transfer Moulding." Thèse, Université d'Ottawa / University of Ottawa, 2012. http://hdl.handle.net/10393/23508.
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The increasing demand for polymer matrix composites (PMCs) from the airframe industry raises the issues of productivity, cost and reproducibility of manufactured PMC components. Performance reproducibility is closely related to the manufacturing technique. Resin transfer moulding (RTM) offers the advantage of flexible manufacturing of net-shape PMC components with superior repeatability starting from ready-to-impregnate dry reinforcements. An RTM apparatus was developed for manufacturing PMC plates and demonstrator components representative of actual, PMC components and PMC moulds made and used in the airframe industry. The RTM process developed in this work involved making net-shape dry carbon fibre preforms and impregnating them an epoxy resin, targeting mould applications. Thermal repeatability of different net-shape PMC components manufactured using the RTM apparatus developed in-house was investigated. Effects of bonding an outer copper plate onto the PMC material, targeting mould applications known as integrally heated copper tooling (IHCT), were explored. Heat conduction through the PMC components was studied using simulation models validated by experimental data obtained primarily by thermography. Manufactured PMC components showed good repeatability, particularly in terms of thermal behaviour. The IHCT technique was found to be well suited for mould applications. Expected advantages of thermography were materialised. Finally, the simulation models developed were in good agreement with experimental data.
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Schulte, zur Heide Jan. "Analyse des Harzinjektionsverfahrens für die Verarbeitung flammgeschützer, partikelgefüllter Harzsysteme = Analysis of the resin transfer moulding (RTM) processfor the processing of fire retardant, particle-filled resin systems /." Aachen : Mainz, 2008. http://bvbr.bib-bvb.de:8991/F?func=service&doc_library=BVB01&doc_number=017087647&line_number=0001&func_code=DB_RECORDS&service_type=MEDIA.
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Dippenaar, D. J. "A technical and economical evaluation of RP technology for RTM tooling." Thesis, Stellenbosch : University of Stellenbosch, 2010. http://hdl.handle.net/10019.1/4193.
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Thesis (MScEng (Mechanical and Mechatronic Engineering))--University of Stellenbosch, 2010.ENGLISH ABSTRACT: This project investigates the use of Rapid Prototyping (RP), with specific focus on Three Dimensional Printing (3DP), in the manufacture of complex shaped advanced composite parts, using variants of the Resin Transfer Moulding (RTM) method of composite manufacture. This study developed design guidelines, cost models and a process chain by studying data obtained by making example parts, from literature and consultation with industry. Advanced composite materials offer some of the best low weight and high specific strength properties for the solution of design problems. A major disadvantage of these processes, however, is the low production rates possible and the need of costly moulds. The 3DP technologies combined with the RTM composite process was found to enable a lowering of costs and increase in productivity if smaller batch sizes are considered. The most meaningful area of application for RP techniques seems to be for smaller and more complex components. The geometrical freedom allowed by RP technologies allowed the manufacture of parts which are challenging to manufacture by conventional technology such as CNC machining. Example part case studies were completed for a simple part utilising the one sided mould Resin Infusion RTM variant as well as for a complex part utilising the closed mould Vacuum Assisted Resin Transfer Moulding (VARTM) process variant. During these two case studies it was clear that proper part infusion with resin is critical for the manufacture of good quality composite parts free of voids and dry spots. It is possible to improve the resin infusion by correct placement of resin inlet and outlet ports as well as resin channels incorporated in the mould. Correct placement of these features for the case studies was obtained through simulations done with RTM-Worx software. Results also indicated that another useful application of RP technology to RTM is the manufacture of disposable cores for parts with thick cross sections. Resin channels were included on the surface of these cores to improve the mould filling with resin and consequently part quality. An early cost estimation model, based on the work of Veldsman (1995), was developed for the combined RP and RTM manufacturing process. This model may help designers to eliminate expensive design features and enables a quick cost comparison with competing processes. Drawbacks of applying RP techniques to RTM include the limited lifetime of moulds produced with 3DP and the size and accuracy limitations of the RP t echnology.
AFRIKAANSE OPSOMMING: Hierdie projek handel oor die toepassing van die drie-dimensionele druk metode van Snel-Prototipering (Rapid Prototyping) op die vervaardiging van komplekse gevorderde saamgestelde materiaal komponente met die Hars-Inspuit Giet (Resin Transfer Moulding) metode. Die projek behels die opstel van ontwerpsriglyne, koste-modelle en ’n proses-ketting deur data te bestudeer wat bekom is deur middel van die vervaardiging van eksperimentele parte, literatuurstudie asook raadpleging met individue in die industrie. Gevorderde saamgestelde materiale verskaf van die beste sterk, dog ligte oplossings vir sekere ontwerpsprobleme. ’n Ernstige nadeel van hierdie materiale is egter die stadige produksietempo moontlik en die vereiste van duur gietstukke. Die Snel- Prototipering metodes, gekombineerd met ’n saamgestelde materiaal vervaardigingsproses, maak laer kostes met beter produktiwiteit moontlik indien ontwerpers die part grootte- en akkuraatheidsbeperkings in ag neem. Die mees betekenisvolle area van toepassing blyk kleiner en meer komplekse komponente te wees. Die vryheid in geometrie wat moontlik gemaak word deur die Snel- Prototipering tegnologie laat die vervaardiging toe van parte wat uitdagend is om te vervaardig met konvensionele tegnologie soos CNC masjinering. ’n Gevallestudie is voltooi vir ’n eenvoudige part vervaardig met die enkelkant gietstuk vakuum-infusie weergawe van die Hars-Inspuit Giet metode asook vir ’n komplekse part wat vervaardig is met die geslote gietstuk Vakuum Hars-Inspuit Giet weergawe van die basiese metode. Dit het tydens die twee gevallestudies duidelik geword dat deeglike hars infusie van kritieke belang is vir die vervaardiging van goeie kwaliteit parte sonder enige droë kolle of lugruimtes. Dit is moontlik om die hars infusie te verbeter deur hars inlate en uitlate asook hars kanale in die korrekte posisies te plaas. Die korrekte posisies vir hierdie komponente is verkry deur middel van ’n reeks simulasies met die RTM-Worx sagteware. Resultate dui ook daarop dat Snel-Prototipering tegnologie handig te pas kom by die vervaardiging van verbruikbare kerne vir saamgestelde materiaal parte met groter diktes. Hars kanale kan maklik op die kerne se oppervlak geskep word om die hars verspreiding en gevolglik part kwaliteit te verbeter. ’n Vroeë kostevoorspellings model, gebaseer op werk voltooi deur Veldsman (1995), is saamgestel vir die gekombineerde Snel-Prototipering en Hars-Inspuit Giet proses. Hierdie model kan gebruik word om duur ontwerpsbesonderhede op parte te elimineer en om ’n vinnige koste vergelyking met ander vervaardigingsprosesse te toon. Nadele van die toepassing van Snel-Prototipering tegnieke op Hars-Inspuit Giet sluit die beperkte gietstuk-leeftyd en beperkte akkuraatheid in.
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Dvořák, Vlastimil. "Návrh křidélka z kompozitních materiálů." Master's thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2008. http://www.nusl.cz/ntk/nusl-228273.
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This diploma thesis called „Aileron Design of Composite Materials” deals with the technologies of production used in aricraft industries. It shows appropriate conceptions of composite structures for the airplane aileron of Aero L-159A/B as well as a proposal of an accetable structure for RTM process.
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Rojas, Mariana. "Energy Efficient Composites for Automotive Industry." Thesis, Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, 2021. http://urn.kb.se/resolve?urn=urn:nbn:se:ltu:diva-86091.
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Hybrid composites play a key role in sustainable development. For many years, carbon fibres in an epoxy matrix have been an attractive option for many structural applications because of their higher specific mechanical properties mostly. However, recycling and sustainability are some of the composite shortcomings; and in that context, natural fibres have gained popularity. The present study aimed to design and manufacture short carbon/flax hybrid composites. Two different arrangements were chosen: random and layers configuration. Resin Transfer Moulding (RTM) was used to fabricate these hybrid composites. Mechanical tests and optical microscopy technique were conducted to understand the effect of the interaction of these two different reinforcements. Mechanical tests showed a remarkable difference between the hybrid configurations under flexural loadings. Furthermore, outstanding property values were observed in the hybrid configurations compared to single fibre composites. The resultant materials have seemed an attractive combination of fibres with a remarkable balance between mechanical performance and eco-friendliness.
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Lowe, Julian Robert. "Void formation in resin transfer moulding." Thesis, University of Nottingham, 1993. http://eprints.nottingham.ac.uk/11626/.
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In recent years interest has grown in the use of composite components within the automotive industry. Fibre reinforced plastic (FRP) components are of particular interest to the industry, since lower tooling costs and part consolidation can be utilised, whilst lighter, stiffer components can be produced. Several methods are available to produce FRP components at high volumes, including compression moulding (using dough and sheet moulding compounds), reinforced reaction injection moulding (RRIM) and liquid moulding processes (resin transfer moulding (RTM) and structural reaction injection moulding (SRIM)). RTM is a closed mould process, which is widely used to produce components economically in low volumes using matched moulds to produce two good surfaces. The absence of a high volume manufacturing technology, however, has impeded the acceptance and advance of RTM within the automotive industry. A research programme was established at the University of Nottingham to address the problems associated with the use of RTM for high volume manufacture. This programme has considered the topics of process technology, processing characteristics of polyester resin systems and fibre preforms, fibre wet-out and interfacial bonding, mould design, microwave pre-heating of reactive resin systems and process modelling. This thesis concerns the research which was undertaken to identify the causes of void formation during the impregnation and polymerisation stages of RTM, and methods of reducing the final void content within the component. The impregnation phase of the RTM process was identified as being the stage where the majority of voids were formed. A study of oil impregnation (having a similar viscosity to that of resin) into reinforcement was undertaken to determine the reasons for uneven flow and air entrapment. The dry reinforcements were studied to assess the microstructure of the preforms in order to determine reasons for obstruction of the resin flow. Fabric stitching, thermoplastic binder and size deposits were identified as potential causes of flow impediment. Fibre orientation and preform stacking were also assumed to assist in the development of uneven flow, leading to air entrapment. A major factor determining the formation of microvoids within fibre bundles was identified as the transverse impregnation of resin into high Tex fibre bundles. The major moulding process variables of injection pressure, vent pressure, fibre volume fraction, mould temperature and resin pre-heating have been assessed, to determine their effect on the void content within unidirectional and CFRM reinforced polyester laminates. It was observed that vacuum assistance during impregnation reduced void formation, although higher exotherm pressures and the possibility of monomer boiling arise from its use. A simple impregnation model was developed to assess the microscopic impregnation rates between fibre bundles, in the capillary between fibres and transversely into fibre bundles. The results from this model were compared with actual moulding histories. The findings of the overall work are discussed and suggestions proposed for the reduction of void content in RTM automotive components.
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Al-Hamdan, Ali. "Resin transfer moulding of sandwich structures." Thesis, University of Nottingham, 1997. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.362997.
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Weitzenböck, Jan Rüdiger. "Flow characterization in resin transfer moulding." Thesis, University of Southampton, 1996. https://eprints.soton.ac.uk/403475/.
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Hill, David John. "Microwave preheating of thermosetting resin for resin transfer moulding." Thesis, University of Nottingham, 1993. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.300723.
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Abraham, David. "Resin transfer moulding component design and manufacture." Thesis, University of Ulster, 1997. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.243618.
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Skordos, Alexandros A. "Modelling and monitoring of resin transfer moulding." Thesis, Cranfield University, 2000. http://dspace.lib.cranfield.ac.uk/handle/1826/3861.
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Modelling and monitoring tools appropriate for the resin transfer moulding composites manufacturing route were developed in this study. A simulation of the curing stage of the process based on a finite elements solution of the non-linear heat conduction equation was implemented. The simulation involved appropriate submodels for the incorporation of thermal properties and cure kinetics. A novel non-parametric procedure which utilises interpolation applied directly to experimental Winefics data proved adequate for the simulation of chemical and structural phenomena occurring during the cure. The application of the heat transfer model was successful, the magnitude of thermal gradients was shown*to be significant and the character of degree of cure gradients temporary. An inversion of the heat transfer simulation based on genetic algorithms enabled an optihisation of the cure process parameters to be performed. The heat transfer simulation was combined with thermal monitoring results in order to achieve an extension of the local temperature measurements to the whole component. This combined scheme reproduced successfully the' temperature and degree of cure distributions. The same approach was implemented with similar outcomes using artificial cure monitoring results. Impedance cure monitoring was used in order to follow in real time the reaction progress. An interpretation was found for the manifestation of vitrification in the impedance signals. A new equivalent circuit representing accurately the behaviour of the resin system investigated was developed. A methodology which correlates the progress of cure with the imaginary impedance spectrum evolution was established. Dielectric flow monitoring techniques appropriate for the filling stage of resin transfer moulding were devised. Lineal sensors enabled monitoring of the progress of filling to be made in both conductive and non-conductive reinforcements.
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Blanchard, Patrick James. "High speed resin transfer moulding of composite structures." Thesis, University of Nottingham, 1995. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.325309.
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Semling, M. "Minimisation of filling time in resin transfer moulding." Thesis, University of Warwick, 1999. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.343145.
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Kiuna, Ngugi. "Investigation of flow perameters in resin transfer moulding." Thesis, Imperial College London, 2003. http://hdl.handle.net/10044/1/7298.
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McCallum, Stuart Craig. "Experimental, analytical and computational studies in resin transfer moulding." Thesis, Imperial College London, 2003. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.406353.
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Johnson, Michael S. "The application of microwave preheating in resin transfer moulding." Thesis, University of Nottingham, 1995. http://eprints.nottingham.ac.uk/11752/.
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Fibre reinforced plastics (FRP) are of considerable interest to the automotive industry. Intelligent application of these materials could reduce vehicle weight for higher operating efficiency, at a reduced manufacturing cost. The principal use of FRP in high volume (greater than 100,000 parts per annum) has been restricted to non-structural body panels made from short fibre reinforcement. Long fibre reinforced composites are ideal for load bearing structures resulting from a high specific strength. However, a high volume technique to produce these components at a moderate cost has not been realised. One long fibre reinforcement process with the potential to meet the high volume demands of the automotive industry is resin transfer moulding (RTM). Prolonged cycle times are an obstacle to high volume RTM. Cycle time is dictated by thermal quench near the injection gate from cold resin entering the hot mould. Heat recovery by the mould, and coincident heating of the resin to initiate cure is necessary to complete the cycle. Microwave preheating of the resin before injection reduces thermal quench. Since microwave heating is volumetric, low conductivity resins can be heated uniformly and efficiently. In-line resin preheating has been developed for its compatibility with high volume RTM. The use of an in-line microwave resin preheating system to reduce cycle time was investigated. This system was incorporated into the automatic RTM cycle. The resin temperature could be held constant or profiled during injection using a proportional-integral-derivative (PID) power controller. Both injection techniques reduced cycle time, although temperature profiling enabled coincident resin cure across the mould for a maximum cycle time reduction. Resin preheating had no adverse affects on the RTM process or laminates. This suggested that the microwave resin preheating system could be retrofitted within an existing RTM facility to reduce the component cycle time without damaging the mould or degrading component quality.
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Xing, Jun. "Permeability identification of porous media in resin transfer moulding." Thesis, University of Southampton, 2001. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.390733.
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Duffy, Christopher M. "The application of on line modification of resin kinetics to resin transfer moulding." Thesis, University of Nottingham, 1998. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.263410.
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Octeau, Marc-Andre. "Composite bicycle fork design for vacuum assisted resin transfer moulding." Thesis, McGill University, 2001. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=31065.
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The carbon fork developed for this thesis is a lightweight fork intended for the road racing athletes and amateurs. The work performed for this thesis includes geometrical and structural design of the fork but also concentrates on developing and optimizing a manufacturing process to create a complete solution for composite fabrication using vacuum assisted resin transfer moulding (VARTM). In the past many research projects concentrated on structural design and finite element analysis but failed to show satisfactory practical results due to poor manufacturing method for prototypes. This thesis emphasizes the development of the fabrication process. The stages for this thesis consist of analyzing previous work done on a carbon fibre fork and, from there, creating and developing a new fork whose weight will be reduced and performance increased. Using this new design, a new custom manufacturing process is implemented for VARTM. The final stage consists of producing prototypes and evaluating their performance and resistance under static and fatigue loadings.
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Pomeroy, Ross Alexis Henry. "Permeability characterisation of continuous filament mats for resin transfer moulding." Thesis, University of Plymouth, 2010. http://hdl.handle.net/10026.1/2691.
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This thesis seeks to examine both permeability measurement and material characterisation of Continuous Filament Mat (CFM) glass fibre reinforcements. As an alternative to fabrics, which generally provide higher in-place properties, CFMs are often employed as low cost, 'lofty' (high uncompressed thickness, and therefore good specific flexural stiffness), easy to process reinforcements for Resin Transfer Moulded (RTM) parts. Within this project, investigation of permeability measurement has involved the development of two (radial and linear) liquid flow permeability techniques to provide a reliable and robust data set for a specific CFM (Unifilo U813-300). Then two novel (radial and linear) airflow techniques were developed for the measurement of CFMs, these providing comparative results with the liquid flow measurements. The benefits of airflow versus liquid flow include cleaner, lower pressured flow using a fluid that may be produced by compressor rather than stored, therefore having significant benefits for both laboratory and industrial measurements of permeability. Material characterisation is necessary to analytically investigate reinforcement materials, as permeability has a non-linear relationship with overall porosity. Permeability is therefore considered as a function of pore distribution, which encompasses the two scales of intra and inter fibre-bundle flow. Two areas have been investigated, these involving permeability measurement and microstructure characterisation. Comparative permeability measurements of a second CFM (Unifilo U850-300), consisting of a different arrangement of fibre bundle sizes, were undertaken using the 1D airflow method, and inter-laminar flow was investigated using the radial airflow method. These resulted in a permeability ratio of between 0.54 and 0.64 (U813/U850) across a 0.1 to 0.3 fibre volume fraction range for the two CFMs, and no significant inter-laminar pore space effect. Microstructural characterisation initiated with image analysis of electron micrographs, providing measurement of fibre diameters and intra-bundle porosity. Kozeny-Carman modelling then showed the permeability of intra-bundle areas to be insignificant resulting in a focus on inter-bundle flow. Although limited by assumptions made for various material parameters, semi-empirical models to provide inter-bundle porosity and fibre bundle geometries were developed. Relation with permeability was then achieved through calculating hydraulic radius and mean hydraulic radius and provision of a range of Kozeny constants (0.55 to 6.17) and coefficients to replace the Kozeny constant, which provide upper and lower bounds for the remaining factors of permeability. The overall future industrial benefits for material engineers rely on the addressing of these limitations for quantifying geometries, so as to provide clarity of the relationship between controllable material parameters and permeability. Towards this goal, suggestions of further work here investigate employing micro-CT imaging and the use of 3D modelling that have the
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Gebart, Rikard. "Analysis of heat transfer and fluid flow in the resin transfer moulding process." Doctoral thesis, Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, 1992. http://urn.kb.se/resolve?urn=urn:nbn:se:ltu:diva-26582.
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This thesis contains an analysis of fluid flow and heat transfer problems in the resin transfer moulding (RTM) process for manufacturing of polymer based fibre composites and it consists of five separate papers. The permeability of unidirectional fabrics, that are often used in advanced composites, is considered in Paper A and a theory for the permeability dependence on the micro geometry is developed. The theory is based on lubrication theory for narrow gaps which is motivated by the fact that most of the flow resistance comes from a small region where the fibres are closest to each other. Despite this limitation the results agree excellently with numerical results. 'Me best performance of the theory is expected at high fibre volume fractions (Vf) but the dependence on Vf is surprisingly good even at as low values as 0.3. Although the theory is formulated for an idealised geometry it can be used to predict the variation of the anisotropic permeability tensor with fibre volume fraction in real fabrics after fitting of three model parameters. Paper B is a study of the influence from different process parameters on the void content in the laminate. The void content is shown to be reduced strongly by an applied vacuum during mould filling. The main mechanism for void formation appears to be mechanical entrapment at the flow front. The voids are convected by the flow so that their concentration is highest close to the flow front. Microscopy investigation of the bubbles show that they are of two basic types, large spherical bubbles in the interstices between fibre bundles and smaller cylindrical bubbles inside the fibre bundles. The positive influence of vacuum compared to no vacuum can be explained as a combined effect of an increased mobility due to larger volume changes during mould filling and compression by the increased pressure during cure. In Paper C a comparison is made between the mould filling times for different injection strategies. The possible alternatives for a normal laminate are point injection, edge injection and peripheral injection. Theoretical results are derived that can be used to estimate the mould filling time with the different alternatives. In addition, fundamental theoretical results are derived from the governing equations showing the scaling of the mould filling time with the process parameters. This analysis also shows that the flow front motion during mould filling is only a function of the anisotropy of the reinforcement and the location of the gates. Paper D presents an analysis of the non-uniform flow at the flow front during impregnation of a stack of fabrics consisting of layers with different flow resistance. A detailed derivation of the theory and an analytical solution to the equations are presented in an addendum to Paper D. The theoretical model is compared with experimental results and is found to describe the experiment qualitatively well. The resulting permeability of a stack of different fabrics is derived from the basic equations and is found to be a weighted average of the permeability in the individual layers. This result is compared with experiments with different stacking sequences and it is found that the stacking sequence has no influence on the resulting permeability as expected from the theory. Experimental results in excellent agreement with Darcy's law are also presented for the case with radial flow and with unidirectional flow. Finally, Paper E is a theoretical study of the curing behaviour of thick laminates. A general solution independent of the cure kinetic model is derived. The solution is valid for low exothermal peak temperatures and it is characterised by two dimensionless numbers. The first parameter is the ratio between the time scales for the reaction and for heat conduction, the second parameter is the ratio between the processing temperature and the adiabatic temperature rise. The general solution is specialised to a second order autocatalytic cure model so that the results can be compared to numerical results. The agreement between the numerical and the analytical solution is excellent for small exothermal peak temperatures, as expected. The particular model used also serves as an example of the additional dimensionless parameters that are introduced by a specific kinetic model.Godkänd; 1993; 20070426 (ysko)
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Thériault, France. "Optimized design of a composite helicopter structure by resin transfer moulding." Thesis, McGill University, 2007. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=99795.
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This research project is partnership project involving industrial, university and government collaborators. The overall objective is to develop and enhance tools for use in Resin Transfer Moulding (RTM) design technology in order to re-design existing metallic parts using composite materials.The specific objective of this work is to present preliminary research findings of the development of an optimized design of a leading edge slat (horizontal stabilizer component) from the Bell Model 407 Helicopter. The results presented here focus on the static stress analysis and the structure design aspects. The findings will serve as a basis for future design optimization as well as further developments in the use of RTM technology in re-designing metallic aeronautic components and can be considered to be "semi-optimized".
This research is based on extensive finite element analysis (FEA) of several composite material configurations, with a comparison made with the original metallic design. Different key criteria of the part design such as ply lay-up, bracket geometry, angle and configuration are tested using FEA technology with the objective of selecting the design which is minimizing stress concentrations. The influence of the modification of model-related parameters was also studied.
Preliminary comparative studies show that the slat configuration with half brackets opened towards the inside with an angle of 70 degrees (angle between the top of the airfoil and the side of the bracket) is the best option according to minimum stress concentration and structural flexibility. This choice is confirmed by other factors such as material savings and ease of processing.
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Ghiasi, Mohammad. "Multi-objective optimization of composite structures made by resin transfer moulding." Thesis, McGill University, 2009. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=66909.
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Due to the wide range of variables involved and sophisticate d analysis techniques required, optimum structural design of laminated composite materials is known to be a challenge for designers. The complexity of the design problem is increased when manufacturing issues are also taken into account due to their strong connection with the structural performance. The major challenge involved in the coupled design problem is to handle multiple conflicting objectives. The problem, with its proper consideration through multi–objective optimization, is studied in this research. To solve the related multi–objective optimization problem, which for its intrinsic nature does not have a single solution, three strategies are proposed here. The first strategy requires reduced computational effort, while it yields only one solution. The second strategy requires more computational effort and returns a moderate number of optimum solutions. The third strategy, though involves high computational effort, provides a large number of optimum solutions and a clear image of the trade–off among objectives. For each strategy a hybrid algorithm consisting of a local search, a global search and a multi–objective optimization technique is proposed. The hybrid algorithms are developed particularly to provide a convergence rate higher than the one provided by available GA–based optimization methods. The extent of achieving this goal is evaluated by several test problems. The proposed hybrid algorithms are applied to two practical composite design problems, the results of which confirm the presence of a strong interconnection among structural and manufacturing objectives and demonstrate the effectiveness of the coupled design approach in providing alternative designs. Although dominated by the structural parameters, performance of a composite structure made by resin transfer moulding is shown to be strongly affected by the manuUne méthodologie de conception pour incorporer les paramètres de fabrication dans le processus de conception structurale a été proposée. Son application pour la conception des matériaux composites stratifiés fabriqués par le procédé d'injection sur renfort est démontrée.Le défi principal dans l'optimisation simultanée des paramètres structuraux et de fabrication est le traitement de multiples objectifs contradictoires. Comme le problème d'optimisation à objectifs multiples n'a pas une solution unique, le problème de conception a été traité en utilisant trois stratégies différentes. La première stratégie, exigeant peu d'effort informatique, renvoie seulement une solution en fonction des préférences définies par l'utilisateur pour les objectifs. La deuxième stratégie, requérant un nombre modéré d'évaluations de fonction, fournit un nombre restreint de solutions optimales et présente un compromis approximatif des objectifs. La troisième stratégie fournit un grand nombre de solutions optimales donnant une image précise du compromis entre les objectifs et requiert un grand nombre d'évaluations de fonction.Pour chaque stratégie, un différent algorithme hybride consistant d'une recherche locale, d'une recherche globale, et d'une technique d'optimisation à objectifs multiples est proposé. Les algorithmes hybrides sont élaborés de manière à fournir un taux de convergence plus haut que le taux de convergence obtenu avec des méthodes d'optimisation d'algorithmes génétiques (GA) disponibles. Le degré d'achèvement de cet objectif est testé en utilisant les algorithmes hybrides proposés pour la résolution de plusieurs fonctions mathématiques.Les algorithmes hybrides proposés sont ensuite appliqués à deux problèmes pratiques de conception de matériaux composites. Les résultats confirment une forte interconnexion entre les paramètres structuraux et de fab
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Davallo, Mehran. "Mechanical behaviour of glass-polyester composite formed by resin transfer moulding." Thesis, Manchester Metropolitan University, 2000. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.301045.
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Louisy, Elodie. "Synthèse de composites à matrice polylactide par procédé RTM (Resin Transfer Molding)." Thesis, Lille 1, 2019. http://www.theses.fr/2019LIL1R037/document.
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Cette étude concerne l’élaboration de composites à matrice polylactide par procédé RTM (Resin Transfer Molding). Elle se focalise sur la polymérisation par ouverture de cycle (POC) in situ, du L-lactide, en procédé RTM avec comme objectif d’obtenir en une seule étape de synthèse, un composite présentant une matrice biosourcée, biodégradable et biocompatible, avec une bonne imprégnation des fibres par la matrice pour un taux de renfort élevé. Dans un premier temps, des essais préliminaires de polymérisation en masse (sans solvant) du L-lactide en ballon à l’échelle du gramme et en l’absence de renfort ont été réalisés. Ces expériences ont permis de déterminer les conditions initiales permettant l’obtention de matrices PLLA présentant le moins de L-lactide résiduel possible (conversions supérieures à 90 %) et les masses molaires les plus élevées (Mn = 70 000 - 100 000 g.mol-1). Ces caractéristiques sont en effet primordiales pour avoir des propriétés thermomécaniques optimales de la matrice PLLA et adaptées à des applications composites. Cette étude a été suivie d’essais de polymérisation, toujours à l’échelle du gramme, en présence de fibres de différentes natures afin d’étudier leur influence sur la polymérisation, les fibres présentant le moins d’influence étant les fibres de verre tissées (conversion et masses molaires supérieures à 90 % et 70 000 g.mol-1, respectivement). Les conditions expérimentales déterminées précédemment ont été transposées et ajustées pour l’élaboration, en procédé RTM, de composites polylactide/fibres de verre par polymérisation du L-lactide catalysée par l’octanoate d’étain. L’optimisation du procédé RTM a été réalisé en faisant varier la masse de monomère, la concentration en catalyseur, la quantité de fibres, le mode de chauffe de la cuve, la pression d’injection et la pression et température dans le moule. Les propriétés physico-chimiques et mécaniques de composites obtenus ont été également étudiées. Les composites obtenus présentent des conversions de plus de 95 % et des masses molaires pouvant atteindre 80 000 g.mol-1. Les conditions RTM n’influencent pas les propriétés thermiques (Tg = 50 °C ; Tf = 170 °C) et structurales (cristallisation en phase α) du polylactide matricielle. De plus les résistances à la traction et modules d’Young des composites PLLA/fibres de verre peuvent atteindre les 200 MPa et 6 GPa respectivement. La dernière partie concerne l’élaboration de composites à matrice PLLA par procédé RTM en présence de catalyseurs présentant une plus faible toxicité, afin de remplacer l’octanoate d’étain, catalyseur de référence pour la polymérisation du L-lactide qui présente cependant une certaine toxicité et qui pourrait dans un futur proche être proscrit des procédés industriels. Des catalyseurs à base de titane, zinc, magnésium et calcium ont ainsi été étudiés, mais seul le catalyseur de zinc conduit à un matériau satisfaisant pour une application composite (conversion supérieure à 90 % et Mn supérieure à 30 000 g.mol-1), bien que les propriétés mécaniques résultantes soient inférieures à celles obtenues avec le catalyseur d’étain (σ = 93 MPa et E = 3,3 GPa). Enfin, l’utilisation de fibres recyclées en tant que renfort a également été étudiée. Bien que les hautes conversions (95-98 %) et masses molaires (Mn jusqu’à 60 800 g.mol-1) aient été atteintes, les propriétés mécaniques résultantes sont bien inférieures à celles obtenues en présence de fibres de verre (σ = 65 MPa et E = 2,2 GPa)This study deals with the development of polylactide based composites by RTM (Resin Transfer Molding). It focuses on the in-situ ring opening polymerization (ROP) of L-lactide in the RTM process in order to obtain, in a single step, a composite with a biobased, biodegradable and biocompatible matrix, presenting a good impregnation of the fibers by the matrix for a high reinforcement rate. First, preliminary mass polymerization tests (solvent-free) of L-lactide in flasks at the gram scale and in the absence of reinforcement were carried out. These experiments enable to choose the initial conditions enabling to reach high molecular mass PLLA matrices (Mn = 70 000 - 100 000 g.mol-1) containing the lowest residual L-lactide content (conversions up to 90 %). These characteristics are indeed essential to reach optimal thermomechanical properties of the PLLA matrix, suitable for composite applications. Polymerization tests on a gram scale in the presence of fibers of different kinds have then been carried out in order to evaluate their influence on the polymerization. Woven glass fibers display the least influence (conversion and molecular masses up to 90% and 70 000 g.mol-1, respectively). The experimental conditions determined above have been first transposed and adjusted for the production by RTM of polylactide/glass fiber composites obtained from L-lactide catalyzed by tin octoate. The RTM process was optimized by varying different experimental parameters such as the monomer mass, catalyst concentration, fiber quantity, tank heating, injection pressure and mold pressure and temperature. The physico-chemical and mechanical properties of the composites obtained were also studied. PLLA/glass fiber composites display conversions up to 95% and molar masses of up to 80 000 g.mol-1. The RTM conditions show no influence on the thermal (Tg = 50 °C; Tf = 170 °C) and structural (crystallization in the α phase) properties of the polylactide matrix. In addition, the tensile strength and Young's modulus of those composites can reach 200 MPa and 6 GPa respectively. The last part concerns the production of PLLA matrix composites by RTM process in the presence of catalysts presenting lower toxicity than tin octoate, the catalyst used industrially for the polymerization of L-lactide. Catalysts based on titanium, zinc, magnesium and calcium were consequently studied, but only the zinc catalyst leads to a material suitable for composite application (conversion and Mn up to 90% and 30 000 g.mol-1). Although the resulting mechanical properties are lower than those obtained with the tin catalyst (σ = 93 MPa and E = 3,3 GPa).Finally, the use of recycled fibers as the reinforcement instead of glass fibers was also studied in the presence of tin octoate. Although the high conversions (95-98%) and molar masses (Mn up to 60 800 g.mol-1) have been achieved, the resulting mechanical properties are much lower than those obtained in the presence of glass fibers (σ = 65 MPa and E = 2,2 GPa)
27
Eriksson, Carl-Johan, and Jonas Erlingsson. "FRP i brokonstruktion : -varför används FRP inte i Sverige." Thesis, Högskolan i Halmstad, Akademin för ekonomi, teknik och naturvetenskap, 2015. http://urn.kb.se/resolve?urn=urn:nbn:se:hh:diva-30284.
Full textAbstract:
FRP stands for Fiber Reinforced Polymer. FRP materials have yet to be introduced inbridge construction in Sweden. Composite materials can through combined componentsand manufacturing processes be tailored to fit advanced bridge designs. FRP materials arestrong, durable and of low weight. FRP materials give the superstructure reduced weightand are therefore a suitable alternative for industrial prefabrication. This report shows thatFRP materials are possible to use in bridge construction. With the introduction of a specificEurocode we are confident that FRP materials will become a competitive alternative inbridge construction in Sweden in the future.Broar är förenade med stora kostnader, dels för att bygga och dels för att underhålla ochreparera. FRP står för Fiber Reinforced Polymer är ett erkänt material för många andraanvändningsområden, exempelvis flyg och bilindustri. I Europa finns en mängd FRP-broar,men materialet har ännu inte introducerats i någon bro i Sverige.FRP är ett kompositmaterial som genom olika kombinationer av komponenter ochtillverkningsprocesser kan skräddarsys för den aktuella uppgiften i en konstruktion. FRPmaterialär starka, beständiga och har en låg vikt. Fördelar med FRP inom brokonstruktionär att det ger överbyggnaden en minskad egenvikt och därmed är ett lämpligt alternativ attprefabricera industriellt, då bland annat transport- och lyftbarhet gynnas samt att en högbeständighet ger minskat underhåll.Då ingen litteratur hanterar FRP i Brokonstruktion har de intervjuades åsikter varit mycketviktiga för arbetet. Litteraturstudien har legat till grund för en ökad förståelse för egenskaperutmärkande för olika typer av FRP. Intervjuer har utförts med personer som i dagslägetkommit i kontakt med materialet inom brokonstruktion. Detta har gjorts för att nå ett relevantresultat med möjlighet att kunna identifiera materialets för- respektive nackdelar samtanledningen till det låga användandet i Sverige.Rapporten visar att materialet har positiva egenskaper och är möjligt att använda vidkonstruktion av broar. Det saknas i dagsläget en specifik Eurokod som på ett enhetligt sättredovisar hur materialet ska hanteras. Med införandet av en specifik Eurokod och om en nykompetens arbetas fram inom branschen är vi övertygade om att FRP-material kommer attbli ett konkurrenskraftigt alternativ vid brokonstruktion.
28
Searle, Timothy John. "The manufacture of marine propellers in moulded anisotropic polymer composites." Thesis, University of Plymouth, 1998. http://hdl.handle.net/10026.1/2766.
Full textAbstract:
This thesis examines the feasibility of manufacturing small marine propellers from continuous fibre reinforced polymer composite materials. An appraisal of some current applications of composite materials in the marine industry is given, together with the moves shown towards the use of composites in the area of propeller design. It has been shown that manufacturing propellers in composite materials is theoretically more cost effective than traditional materials. The manufacturing route investigated is Resin Transfer Moulding, where some detailed investigations have highlighted some of the critical processing parameters necessary for successful production of laminates suitable for propellers and other high performance marine structures. A thorough testing programme of 4 novel designs of composite propeller is reported. Trials at sea on university run vessels has enabled many hours use to be logged, which has shown the fitness for purpose of propellers made from glass reinforced, epoxy composite. Experimental tank testing has helped to shape the remainder of the research by identifying the possibility of using hydroelastic tailoring to improve the efficiency of the propeller when a variety of operating conditions are required from the propulsion system. Further experience is required with respect to the the tooling construction and the life assessment of the propeller. To facilitate appropriate modelling of the propeller, spreadsheet based load prediction models have been used. Finite element analysis (FEA) was used to model the elastic characteristics of one particular design of novel composite propeller. This indicated that traditional geometries may be too stiff to allow significant performance advantages from the anisotropy of the material. However the potential does exist for modified propeller geometries made from composite to give some performance benefit. For specific applications, small marine propellers made from continuous glass fibre reinforced epoxy composite are likely to yield cost savings over traditional propeller materials.
29
Sas, Hatice Sinem. "Modeling Of Particle Filled Resin Impregnation In Compression Resin Transfer Molding." Master's thesis, METU, 2010. http://etd.lib.metu.edu.tr/upload/12612158/index.pdf.
Full textAbstract:
Compression Resin Transfer Molding (CRTM) is an advanced liquid molding
process for producing continuous fiber-reinforced composite parts in relatively
large dimensions and with high fiber volume fractions. This thesis investigates
this process for the purpose of producing continuous fiber reinforced composites
with particle fillers. In many composites, fillers are used within the resin for
various reasons such as cost reduction and improvement of properties. However,
the presence of fillers in a process involving resin impregnation through a
fibrous medium can result in a composite with non-homogeneous microstructure
and properties. This work aims to model the resin impregnation and particle
filtration during injection and compression stages of the process. For this
purpose, a previously developed particle filtration model is adapted to CRTM.
An appropriate commercial software tool is used for numerical solution after a
survey of available packages. The process is analyzed based on the developed
model for various process scenarios. The results of this study aim to enhance the
understanding of particle-filled resin impregnation and particle filtration
phenomena in the CRTM process and are likely to be used towards designing
optimum process configurations for a desired outcome in the future.
30
Khoun, Karine. "Process-induced stresses and deformations in woven composites manufactured by Resin Transfer Moulding." Thesis, McGill University, 2009. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=66887.
Full textAbstract:
This work investigated the factors leading to the generation of process-induced stresses and deformations in woven composites manufactured by Resin Transfer Moulding (RTM). Both intrinsic and extrinsic mechanisms were examined. First, a comprehensive methodology was applied to characterize the thermal, chemorheological and thermomechanical properties of the CYCOM 890RTM epoxy resin. The developed models were essential to establish a clear understanding of the resin behaviour during the processing conditions. Then, the thermomechanical properties of 5-Harness satin woven fabrics were investigated using a micromechanical approach. Different fibre volume fractions between 50% and 62%, corresponding to typical volume fractions used in the RTM process, were examined. These thermomechanical properties were compared to the properties of equivalent unidirectional crossply laminates in order to validate the use of crossply configuration to model the behaviour of woven fabric laminate. The developed resin models and the fibre properties were then implemented in a finite element software, ABAQUS/COMPRO in order to predict the evolution of the laminate properties during the RTM process. Fibre Bragg Grating sensors were then used to characterize experimentally the tool-part interaction occurring during the RTM process. The separation of the composite from the mould during the cool down period was measured by the optical sensors. The maximal shear stress allowed by the laminate before the debonding was estimated to be 140 kPa for a steel mould. The observed tool-part interaction was simulated using frictional contact conditions at the composite/mould interface in a finite element analysis. Finally, using the ABAQUS/COMPRO interface, the manufacturing of a composite structure by RTM was modelled, taking into account simultaneously the intrinsic and extrinsic mechanisms examined. This case study demonstrates the capacity of the process modCe travail étudie les facteurs conduisant au développement de contraintes et déformations résiduelles induites par le procédé d'injection sur renforts dans le cas de composites à renforts tissés. Les mécanismes intrinsèques ainsi qu'extrinsèques ont été pris en considération. Tout d'abord, une méthodologie a été utilisée pour caractériser les propriétés thermo-chimiques et thermo-mécaniques de la résine époxy CYCOM 890RTM. Le développement de modèles mathématiques pour décrire les différentes propriétés est une étape essentielle pour comprendre clairement l'évolution du comportement de la résine lors du procédé de fabrication. Ensuite, les propriétés thermo-mécaniques d'un tissu satin de 5 ont été examinées en utilisant une approche de micromécanique sur un motif élémentaire. Différentes fractions volumiques de fibre entre 50% et 62%, correspondant aux fractions volumiques de fibre typiquement utilisées pour le procédé d'injection sur renfort, ont été étudiées. Les propriétés ont été comparées aux propriétés obtenues pour des laminés unidirectionnels croisés équivalents. En général, les propriétés des deux configurations sont comparables. Ceci justifie l'utilisation des propriétés de fibre unidirectionnelle dans une configuration croisée pour simuler le comportement d'un laminé à renfort tissé satin de 5. Les modèles des propriétés de la résine et des fibres ont été ensuite implémentés dans un logiciel d'éléments finis, ABAQUS/COMPRO, afin de prédire l'évolution des propriétés du laminé pendant le procédé d'injection sur renforts. Des fibres optiques à réseaux de Bragg ont été également utilisées pour caractériser expérimentalement les interactions entre le composite et le moule générées pendant le procédé. Les fibres optiques saisirent la séparation entre le composite et le moule pendant le refroidissement. La contrainte
31
O'Flynn, Julian. "Design for manufacturability of a composite helicopter structure made by resin transfer moulding." Thesis, McGill University, 2008. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=21940.
Full textAbstract:
Resin transfer moulding (RTM) is a promising composite manufacturing method capable of producing high quality parts while meeting the rising demand for cost effectiveness. A collaborative research project involving academia, industry, and government in the Montreal area is under way to optimize RTM and help transfer this technology to local industries. As a technology demonstrator, the leading edge slat of the Bell 407 helicopter is being redesigned using composite materials and RTM. This thesis presents the mould design, part design for manufacturability, and actual production of half-length prototype parts. The mould and part designs were carried out concurrently taking into consideration results from stress analysis and flow modelling, as well as manufacturing constraints. A total of eight prototypes were manufactured. During the development of this project, important improvements were made in the way composite parts are manufactured by RTM. The lessons learned from this prototype design and manufacturing work will help to produce the full-size version of the slat as well as other components in the future.Le moulage par injection sur renfort (resin transfer moulding, RTM) est un procédé de fabrication prometteur, produisant des pièces en matériaux composites de haute qualité tout en ayant des coûts de production avantageux. Un projet de recherche incluant des collaborateurs du secteur académique, industriel, et gouvernemental dans la région de Montréal est en cours afin d'optimiser le procédé RTM et de faciliter le transfert de cette technologie aux industriels locaux. Pour démontrer cette technologie, le bec de bord d'attaque de l'hélicoptère Bell 407 est reconçu utilisant des matériaux composites fabriqué avec le procédé RTM. Cette thèse présente la conception du moule et de la pièce en fonction de la facilité de fabrication ainsi que de la production de prototypes demi-longueurs. Le moule et la pièce ont été conçus simultanément considérant les résultats des analyses de contraintes, d'écoulement de résine dans le renfort tout en tenant compte des contraintes pouvant être encourues lors de la fabrication. Huit prototypes demi-longueurs ont été fabriqués. L'expérience acquise lors de la conception et la fabrication du moule ainsi que des prototypes aideront à la production du bec de bord d'attaque pleine longueur en plus d'être utile lors de conceptions futures.
32
Roy, Steven. "Mechanical modeling and testing of a composite helicopter structure made by resin transfer moulding." Thesis, McGill University, 2009. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=40829.
Full textAbstract:
The design and mechanical performance of a helicopter horizontal stabilizer slat made by resin transfer moulding (RTM) can be evaluated with finite element analysis (FEA). To verify the validity of the assumptions used in the modelling of the slat structure, static mechanical tests were performed on prototype slats which were half of the full-size length. The slat complex boundary conditions were simplified to make static mechanical testing possible. Two fixtures were designed and built to introduce simplified loads in specimens with two different bracket configurations: a full and a half bracket. A finite element (FE) model of the specimens was made with shell elements and the finite element solution was compared with the experimental results. In most cases, comparison between the finite element analysis solution and experimental results showed good agreement in terms of structure stiffness, strength, strain and damage location. It is believed that out-of-plane stresses should be considered to improve the finite element solution accuracy.Le design et la performance mécanique d’un bec de bord d’attaque de stabilisateur horizontal d’hélicoptère fabriqué par moulage par injection sur renfort (« resin transfer moulding ») peuvent être évalués par des analyses par éléments finis. Pour vérifier la validité des hypothèses utilisées dans la modélisation du bec de bord d’attaque, des essais mécaniques ont été effectués sur des prototypes demi-longueurs. Les conditions frontières complexes ont été simplifiées pour rendre les essais mécaniques possibles. Deux gabarits ont été conçus et construits pour introduire les chargements simplifiés dans les pièces d’essai possédant deux configurations de support: un support complet et un demi-support. Un modèle par éléments finis des pièces d’essai a été réalisé avec des éléments de type membrane et la solution est comparée avec les résultats expérimentaux. Dans la plupart des cas, la comparaison entre la solution par éléments finis et les résultats expérimentaux coïncide concernant la rigidité de la structure, la résistance, l’allongement et la localisation de l’endommagement. Les contraintes hors du plan devraient être considérées pour améliorer la précision de la solution par éléments finis.
33
Vogt, Christian. "An experimental cost model for composite parts using vacuum assisted resin transfer moulding (VARTM)." Thesis, Stellenbosch : University of Stellenbosch, 2011. http://hdl.handle.net/10019.1/6579.
Full textAbstract:
Thesis (MScEng (Mechanical and Mechatronic Engineering))--University of Stellenbosch, 2011.ENGLISH ABSTRACT: Vacuum assisted resin transfer moulding (VARTM) belongs to the category of resin infusion techniques that use lower than atmospheric pressure to infiltrate a reinforced cavity. This technique has various advantages; however, manufacturing costs can be relatively high due to more difficult shapes fabricated and a lack of knowledge regarding cost driving factors. The objective of this study was to develop a cost model for composite parts. Such a model allows the estimation of manufacturing costs of shapes of different geometries. Therefore, it provides a comparison to alternative manufacturing techniques, such as metal forming or composite spray lay-up and helps to avoid unnecessarily expensive design features. The proposal was made to split complex shaped composite parts into individual basic shapes, which are further investigated here. For the basic shapes, an experimental approach was used where the manufacturing times of each process step are measured and then statistically analysed. Infusion simulation software was used to obtain additional filling times to complete the design of experiments. This method allows the estimation of manufacturing times of composite parts with different geometries. The manufacturing times were validated to that of a complex shaped industrial part, with reasonable results. Finally, a flexible cost model was developed to compare different manufacturing techniques and to estimate the manufacturing costs.
AFRIKAANSE OPSOMMING: Vakuumgesteunde harsinspuitingsgietwerk (VARTM) behoort tot die kategorie harsinspuitingstegnieke wat laer-as-atmosferiese druk gebruik om ʼn versterkte holte binne te dring. Hierdie tegniek hou verskeie voordele in. Tog kan vervaardigingskoste betreklik hoog wees wanneer dit by ingewikkelder vorms en ʼn gebrek aan kennis met betrekking tot kostesnellers kom. Die doelwit van hierdie studie was om ʼn kostemodel vir saamgestelde onderdele te ontwikkel. Die model maak voorsiening vir die raming van die vervaardigingskoste vir verskillende afmetings. Sodoende bied dit ʼn vergelyking met alternatiewe tegnieke, en help voorkom onnodig duur ontwerpkenmerke. Daar is voorgestel dat dele met ingewikkelde vorms in individuele basiese vorms verdeel word, wat dan hier verder ondersoek word. Vir die basiese vorms word ʼn eksperimentele benadering gebruik waar die vervaardigingstye in elke prosesstap gemeet en statisties ontleed word. Voorts word inspuitingsimulasiesagteware gebruik om komplementêre inspuitingstye te bepaal ten einde die eksperimentele ontwerp te voltooi. Hierdie metode maak dit ook moontlik om die vervaardigingstye vir saamgestelde materiaal onderdele van verskillende afmetings te raam. Die vervaardigingstye word dan bevestig aan die hand van dié van ʼn kompleks gevormde industriële onderdeel, met redelike resultate. Uiteindelik word ʼn buigsame kostemodel ontwikkel om verskillende vervaardigingstegnieke te vergelyk en die vervaardigingskoste te raam.
34
Jung, Yeonhee. "An efficient analysis of resin transfer molding process using extended finite element method." Phd thesis, Saint-Etienne, EMSE, 2013. http://tel.archives-ouvertes.fr/tel-00937556.
Full textAbstract:
Numerical simulation for Resin Transfer Molding (RTM) manufacturing process is attempted by using the eXtended Finite Element Method (XFEM) combined with the level set method. XFEM allows to obtaining a good numerical precision of the pressure near the resin flow front, where its gradient is discontinuous. The enriched shape functions of XFEM are derived by using the level set values so as to correctly describe the interpolation with the resin flow front. In addition, the level set method is used to transport the resin flow front at each time step during the mold filling. The level set values are calculated by an implicit characteristic Galerkin FEM. The multi-frontal solver of IPSAP is adopted to solve the system. This work is validated by comparing the obtained results with analytic solutions.Moreover, a localization method of XFEM and level set method is proposed to increase the computing efficiency. The computation domain is reduced to the small region near the resin flow front. Therefore, the total computing time is strongly reduced by it. The efficiency test is made with simple channel or radial flow models. Several application examples are analyzed to demonstrate ability of this method. A wind turbine blade is also treated as industrial application. Finally, a Graphic User Interface (GUI) tool is developed so as to make easy the pre/post-processing of the simulation.
35
Miskbay, Onur Adem. "Process Characterization Of Composite Structures Manufactured Using Resin Impregnation Techniques." Master's thesis, METU, 2009. http://etd.lib.metu.edu.tr/upload/12610351/index.pdf.
Full textAbstract:
The aim of this study is to investigate and compare the properties of two layer carbon epoxy composite plates manufactured using various resin impregnation techniquesResin Transfer Molding (RTM), Light RTM (LRTM), Vacuum Assisted RTM (VARTM) and Vacuum Packaging (VP). Throughout the study a different packaging method was developed and named Modified Vacuum Packaging (BP). The mechanical properties of composite plates manufactured are examined by tensile tests, compressive tests, in-plane shear tests and their thermal properties are examined by Differential Scanning Calorimetry (DSC) and Thermo Gravimetric Analysis (TGA) tests. All tests were performed according to suitable ASTM standards. The performance of specimens from each process was observed to vary according to the investigated property
however the VP process showed the highest performance for most properties. For most of the tests, VARTM, LRTM and RTM methods were following VP process in terms of performance, having close results with each other.
36
Akgul, Eralp. "Effects Of Mold Temperature And Vacuum In Resin Transfer Molding." Master's thesis, METU, 2006. http://etd.lib.metu.edu.tr/upload/2/12607952/index.pdf.
Full textAbstract:
The purpose of this study was to investigate the effects of mold temperature, initial resin temperature, and the vacuum, applied at resin exit ports, on the mechanical properties of epoxy matrix woven glasss fiber reinforced composite specimens produced by Resin Transfer Molding (RTM).
For this purpose, six different mold temperatures (25º, 40º
, 60º
, 80º
, 100º
, and 120º
C), two initial resin temperatures (15º
and 28º
C), and vacuum (0.03 bar) and without vacuum (~1 bar) conditions were used. Specimens were characterized by using ultrasonic (C-Scan) inspection, mechanical tests (Tensile, Flexural, Impact), thermal analyses (Ignition Loss, TGA) and scanning electron microscopy (SEM). It was generally observed that mechanical properties of the specimens produced with a mold temperature of 60º
C were the best (e.g. 16%, 43%, and 26% higher tensile strength, Charpy impact toughness and flexural strength values, respectively). When vacuum was not applied, the percentage of &ldquo
voids&rdquo
increased leading to a decrease in mechanical properties such as 26% in Charpy impact toughness and 5% in tensile and flexural strength. Lower initial resin temperature also decreased mechanical properties (e.g. 14% in tensile strenght and 18% in Charpy impact toughness).
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Amico, Sandro Campos. "Permeability and capillary pressure in the infiltration of fibrous porous media in resin transfer moulding." Thesis, University of Surrey, 2000. http://epubs.surrey.ac.uk/1011/.
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Häffelin, Daniel [Verfasser]. "Verfahren zur Integration von Folien in den RTM-Prozess (resin transfer molding) für endlosfaserverstärkte Schalenteile / Daniel Häffelin." München : Verlag Dr. Hut, 2017. http://d-nb.info/1137023708/34.
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Cioffi, Maria Odila Hilário. "Resina epóxi reforçada com tecido de carbono não dobrável por processo RTM /." Guaratinguetá : [s.n.], 2011. http://hdl.handle.net/11449/106718.
Full textAbstract:
Banca: Herman Jacobus Cornelis VoorwaldBanca: Maysa Furlan
Banca: Sergio Frascino Muller de Almeida
Banca: Durval Rodrigues Junior
Banca: Paulo Roberto Mel
Resumo: Com o objetivo de ganhar competitividade no mercado internacional e contribuir para o desenvolvimento tecnológico no país, o presente trabalho apresenta a técnica de processamento de moldagem por transferência de resina (RTM), utilizada na fabricação de materiais compósitos estruturais e ainda pouco estudada no Brasil. Os compósitos processados por essa técnica apresentam maior fração volumétrica de fibras, melhor acabamento superficial e pouca ou nenhuma necessidade de acabamento do componente produzido. Este trabalho compreende a caracterização de compósitos produzidos com resina epóxi monocomponente RTM6 e o tecido não dobrável de fibra de carbono. Os compósitos produzidos pela Hexcel Composites foram analisados pela técnica de ultrassom C-Scan e os resultados mostraram que os laminados processados estão homogêneos quanto à impregnação. Ensaios mecânicos mostram que os laminados com tecido apresentam características comparáveis à dos compósitos produzidos em autoclave com maiores porcentagens de reforço. Em fadiga, os laminados apresentaram um alto e curto intervalo, com tensões próximas à de tração. Quanto ao comportamento térmico observou-se melhora nas propriedades com a adição do reforço de fibras de carbono, que promoveram o aumento da temperatura de transição vítrea (Tg). Quanto ao comportamento viscoelástico, foi observado a influencia da temperatura e freqüência no material. Considerando as propriedades mecânicas e térmicas, ambos os compósitos foram classificados como adequados à aplicação proposta.
Abstract: Aiming at gaining competitiveness on international market and contribute with technological development in the country, this work presents a processing technique of resin transfer molding (RTM), used to manufacture structural composites that Brazilian researches have yet few background. Composites processed by this method have a higher volume fraction of fibers, better surface finish, and requires little or none surface finish of the final component. This work includes the characterization of composites made with RTM6 monocomponent epoxy resin and carbon non-crimp fabric (NCF). Composites produced by Hexcel Composites were analyzed by C-scan ultrasound technique, which showed a homogeneous impregnation of the processed panels. Mechanical tests showed that RTM composites properties are comparable to those of autoclaving composites with higher fiber volume fraction. In fatigue, composites showed high and short interval, close to ultimate tensile strength (UTS), with an interval between 60-75% of UTS. Regarding the thermal behavior, it was observed an improvement in properties with the addition of carbon fiber reinforcement, which caused an increase in Tg. In regard to the viscoelastic behavior, it was observed the temperature and frequency influence on the material. Considering these mechanical and thermal properties, both composites are considered suitable for the application proposal.
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Petrescue, Laura. "An investigation of defect evolution in foam core sandwich structures produced using vacuum assisted resin transfer moulding." Thesis, University of Ottawa (Canada), 2007. http://hdl.handle.net/10393/27904.
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In this work, a resin infusion process used by Flight Dynamics Corp. was investigated for the fabrication of low-cost composite sandwich structures. Trials were performed to establish a complete set of potential defects that could develop during the manufacture of E-glass epoxy vinyl ester sandwich panels. A series of non-destructive evaluation techniques were examined for their potential to identify two representative defects. It was found that thermography and bondline analysis were effective at detecting defects such as dry spots and incomplete resin infiltration. However, due to technical limitations of these methods visual inspection of high quality digital images proved to be the most accurate method for evaluating the specimens. The effect of these defects was also evaluated through a selection of compression tests. These tests showed that the sensitivity of this test to the presence of defects is low. A parametric study of the infusion process was performed to evaluate the potential of defect evolution under controlled conditions. The evolution of defects was most affected by the vacuum pressure level and the method for distributing resin through the thickness of the sandwich panel. As part of this study, the resin flow front was evaluated to determine the effect on the evolution of defects. A series of defect metrics were developed for a variety of resin distribution methods. In general, it was found that defect evolution due to a single variable was limited and that further evaluation of the interaction of process parameters would be useful to optimize the process.
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Nguyen, Van-Hau. "Characterization and modeling of flax fiber reinforced composites manufacturing by resin transfer molding process." Thesis, Lille 1, 2014. http://www.theses.fr/2014LIL10156.
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Ce travail de thèse présente la caractérisation expérimentale de fibres de lins et une modélisation de l’écoulement de résine lors du procédé de Resin Transfer Molding (RTM) utilisant ces mêmes fibres. La variation du diamètre des filaments de lins immergés dans différents liquides tests est caractérisée par observation au microscope. Le taux et la vitesse d’absorption de liquides tests dans les fibres sont ensuite obtenus par centrifugation. Un nouveau modèle de perméabilité est ainsi développé afin de prendre en compte les effets du gonflement des fibres sur la perméabilité quelque soit le liquide test considéré. Le modèle est validé après comparaison avec les perméabilités expérimentales. Les propriétés de mouillage des fibres de lin en présence de différents liquides tests sont mesurées en utilisant un tube capillaire et une mèche de fibres de lin. Un modèle prenant en compte le gonflement des fibres ainsi que le phénomène d’absorption est proposé pour déterminer la tension de surface et l’angle de contact décrivant la mouillabilité. L’écoulement insaturé dans le tissu de fibres de lin est modélisé en utilisant l’équation de conservation de la masse, la loi de Darcy ainsi que les modèles de gonflement et d’absorption précédemment définis. Le flux massique absorbé dans les fibres et la modification du taux local de fraction volumique sont introduits par l’intermédiaire de termes puits dans l’équation de conservation de la masse. La variation de perméabilité spatiale et temporelle non uniforme peut ainsi être considérée dans le modèle complet proposé. Ce modèle est validé par comparaison avec un suivi expérimental de l’écoulement dans une préforme de fibres de linThis thesis presents an experimental characterization of flax fiber and a modeling of the resin flow during the resin transfer molding process with flax preform. The change of diameter of flax fiber filament immersed in different test liquids was characterized using optical microscope. The sorption rate of the resin mass into the fiber filament immersed in the test liquids was also experimentally characterized using centrifuge test. A new permeability model was proposed to predict the permeability taking into account the fiber swell effect, regardless of test liquid and the model was validated by a comparison with the experimental measurement data. The wetting properties of flax fiber in contact with different test liquids were measured by capillary rise test using flax fiber yarn and a new model was established to obtain surface tension and contact angle by considering the fiber swell effect and the liquid sorption into the fiber filament. The unsaturated resin flow in the flax fiber preform was modeled by modifying the conventional mass conservation equation and Darcy’s law in order to take into account the effects of fiber swell and liquid sorption. The mass rate absorbed into the fiber and the change of fiber volume were considered as sink terms in the mass conservation equation. The permeability change due to the fiber swell was modeled in terms of time of fiber’s immersion in liquid. In particular, the sink term and permeability were considered as spatially and temporally non-uniform in the flow model. The proposed model was validated by a comparison with the experimental measurement of flow advancement in the flax fiber preform
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Lonné, Sébastien. "Modélisation de la propagation ultrasonore dans les matériaux composites obtenus par le procédé de fabrication RTM (resin transfer molding) /." [Gif-sur-Yvette] : [CEA Saclay, Direction des systèmes d'information], 2004. http://catalogue.bnf.fr/ark:/12148/cb39209790v.
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Lonné, Sébastien. "Modélisation de la propagation ultrasonore dans les matériaux composites obtenus par le procédé de fabrication RTM (Resin Transfer Molding)." Bordeaux 1, 2003. http://www.theses.fr/2003BOR12751.
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Le procédé de fabrication des matériaux composites RTM (Resin Transfer Molding) est utilisé pour produire des pièces de géométrie complexe. Lors du contrôle ultrasonore de ces pièces, une mesure d'atténuation est effectuée pour caractériser le taux de porosité éventuel (défaut possible dans ces matériaux). Cependant, une grande variabilité d'atténuation est observée y compris pour des pièces saines de géométrie plane. L'objectif de notre travail est d'expliquer ce fait en développant un modèle de propagation et d'atténuation des ondes ultrasonores dans ces pièces dont la microstructure complexe présente un aspect multi-échelles. Un modèle original a été développé pour prédire l'atténuation à l'échelle élémentaire d'une couche unidirectionnelle de fibres de carbone dans une matrice d'époxy, couplant les phénomènes de diffusion multiple par les fibres et d'absorption par effet viscoélastique. Il a été validé expérimentalement et est applicable à tous les composites fibreux à deux phases, quelle qu'en soit la concentration de fibres. À l'échelle supérieure d'un pli constitué de plusieurs couches élémentaires de différentes orientations, une homogénéisation suffit à prédire le comportement anisotrope des ondes ultrasonores et leur atténuation. Une plaque réelle est constituée d'un ensemble de plis séparés de couches de résines pures, l'épaisseur des différents plis et couches étant fortement variable. Une étude statistique a été menée pour prédire l'influence de ces variations géométriques sur la transmission des ultrasons modélisée suivant un formalisme dérivé de la méthode de Thomson-Haskell. La variabilité d'atténuation ultrasonore observée en pratique est quantitativement reproduite et expliquée par l'irrégularité géométrique de la micro-structureThe Resin Transfer Molding process for manufacturing composite materials is used to produce parts of complex shape. During the ultrasonic examination of such parts, attenuation is measured to characterize possible porosity content (a potential defect in this material). However, strong variation of attenuation is observed including on sound plates. The present study aims at explaining this by developing a model for ultrasonic propagation and attenuation in such parts which complex micro-structure exhibits a multiple-scale aspect. An original model has been developed to predict attenuation at the elementary scale of an unidirectional layer of Carbon fibers in an epoxy matrix. It couples multiple-scattering by fibers and viscoelastic losses phenomena. It has been experimentally validated and applies to arbitrary two-phase fiber reinforced composites whatever the fiber volume fraction. At the upper scale of a ply made of several elementary layers of various orientations, the anisotropic behavior of ultrasonic waves and their attenuation are obtained by a homogenization procedure. An actual plate is made of several plies separated by pure resin layers. Plies and layers thicknesses are highly variable. A statistical study has been conducted to evaluate the influence of these geometrical variations on the ultrasonic transmission predicted by a model derived from Thomson-Haskell formalism. Ultrasonic attenuation variability practically observed is quantitatively reproduced and explained as resulting from the geometrical irregularity of the microstructure
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Mohammed, U. "Experimental studies and mathematical modelling of the draping and shear deformation of woven fabrics in resin transfer moulding." Thesis, University of Surrey, 2000. http://epubs.surrey.ac.uk/604/.
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Aaboud, Bouchra. "Modélisation et simulation de la formation, la compression et le transport des bulles d'air en milieux fibreux à double échelle de pores : application au procédé RTM." Thesis, Le Havre, 2016. http://www.theses.fr/2016LEHA0023/document.
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Ce travail traite la problématique des bulles d’air contenues dans les pièces composites mises en œuvre par le procédé RTM. La modélisation des phénomènes de création, de compression et de transport de ce type de défauts est présentée. Notamment l’adoption d’un nouveau modèle de création des bulles d’air, de transport, et l’estimation des porosités à double échelle de pores ainsi que la saturation finale de la préforme sont donnéesThis work covers the problematic of air bubbles entrapped during manufacturing composite parts via the RTM process. Modeling creation, compression, and transport of this type of defaults is presented here. Likewise, a new approach of air bubble’s creation, transport modeling, simulation of porosities at dual scale of pores, and estimation of the final saturation of the preform are given
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Agogué, Romain. "Analyse expérimentale et numérique de la fabrication de pièces composites par le procédé RTM." Phd thesis, Université d'Orléans, 2011. http://tel.archives-ouvertes.fr/tel-00628046.
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Cette thèse s'intéresse à la fabrication de pièces composites par le procédé Resin Transfert Molding (ou RTM), appliquée à des tubes de protection thermiques. Plus particulièrement, cette thèse vise à démontrer la faisabilité d'utiliser ce procédé pour la fabrication cette pièce complexe. La phase d'imprégnation de préformes sèches est plus particulièrement étudiée. Après mise en oeuvre, cette pièce peut présenter des défauts tels que de la porosité ou des déplacements de plis constituant la préforme. L'objectif de cette thèse est donc de comprendre l'origine de ces défauts et de minimiser voire de d'empêcher leur apparition. Pour cela, une démarche expérimentale a été mise en place. Celle ci comprend la réalisation d'un pilote de laboratoire permettant d'appliquer différentes conditions d'imprégnation aux préformes considérées. La perméabilité des renforts considérés a aussi été évaluée à différentes échelles grâce à l'utilisation de moyen dédiés à l'échelle macroscopique (banc de perméabilité planaire et transverse), et grâce à l'utilisation d'un code de calcul se basant sur des images de tomographie synchrotron à l'échelle microscopique. Enfin, une analyse de la qualité des prototypes réalisés a été menée en suivant des procédures mises en place lors de ce projet et les résultats analysés et mis en relation avec les conditions de mise en oeuvre. Cette approche expérimentale est couplée aux simulations numériques de la phase d'imprégnation que nous avons aussi mise en oeuvre au cours de cette thèse. Par l'utilisation combinée de la simulation numérique et des essais expérimentaux, nous avons défini des critères estimant le risque d'apparition des défauts. Ces critères ont montré leur efficacité sur les solutions innovantes que nous avons proposées puisque répondant aux exigences du cahier des charges industriel.
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Feret, Victor. "Development of a mixed-mode fracture criterion for a five harness satin carbon/epoxy manufactured by resin transfer moulding." Thesis, McGill University, 2009. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=66675.
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This investigation considers the influence of manufacturing on a composite material's resistance to delamination. Mixed-mode toughness data was measured for a five harness satin (5HS) carbon/epoxy manufactured by resin transfer moulding (RTM). The effect of fibre volume fraction on both initiation and propagation fracture toughness was also determined. Fibre volume fractions of 57% and 66% were considered under Mode I (interlaminar tension), Mode II (interlaminar shear) and Mixed-Mode I-II loading of 25%, 50% and 75%. Flat rectangular plates, from which specimens were obtained, were manufactured by RTM. Double cantilever beam (DCB) specimens were used for Mode I and Mixed-Mode I-II, following ASTM standards D5528 and D6671. End-notched flexure (ENF) specimens were used for Mode II. Initiation toughness therefore increased as the contribution of Mode II towards Mixed-Mode I-II delamination growth increased. Important toughening mechanisms were observed in all cases, which resulted in propagation fracture toughness being at least 200% higher than initiation fracture toughness. The dominant mechanism responsible for fracture work was the energy dissipated in creating and translating the crack tip damage zone across a non-planar path. The increase in fibre volume fraction decreased initiation fracture toughness at all mixed-mode ratios, and increased propagation fracture toughness at high Mode I contributions towards Mixed-Mode I-II delamination growth. Increasing the fibre volume fraction had no effect on propagation fracture toughness at a Mixed-Mode ratio of 75%. Additionally, the Virtual Crack Closure Technique (VCCT) implemented in Abaqus® was evaluated as an analysis tool to model the initiation and growth of delaminations in composites. Two finite element models of DCB specimen were built (2D and 3D). The material's delamination behavior was governed by the mixed-mode fracture data measured experimenCe projet visait à étudier l'influence du procédé de fabrication sur la capacité d'un matériau composite à résister au délaminage. Les données en mode mixte ont été mesurées pour un composite avec une résine d'époxy et un tissu de carbone d'armure satin à cinq harnais (5HS carbon/epoxy), fabriqué à l'aide du moulage par transfert de résine (RTM). L'effet du pourcentage volumique de fibre sur la ténacité à la rupture, à l'initiation et à la propagation, a également été déterminé. Des pourcentages volumiques de 57% et 66% ont été considérés en Mode I (tension interlaminaire), en Mode II (cisaillement interlaminaire) et en Mode-mixte I-II à 25%, 50% et 75%. Des plaques rectangulaires ont été fabriquées par RTM, desquelles tous les échantillons ont été découpés. Des échantillons en double poutre encastrée (DCB) ont été utilisés pour les essais en Mode I et en Mode-mixte, selon les standards ASTM D5528 et D6671. Des échantillons de type end-notched flexure (ENF) ont été utilisés pour les essais en Mode II. La ténacité à l'initiation de la rupture a donc augmenté lorsque la contribution du Mode II a été augmentée lors des essais en Mode-mixte. Des mécanismes de renforcement ont été observés dans tous les cas, faisant en sorte que la ténacité à la propagation de la rupture était au moins 200% plus élevée que la ténacité à l'initiation de la rupture. Le principal mécanisme responsable du travail de rupture était la dissipation d'énergie associée à l'avancement de la fissure le long d'un chemin non-planaire. Ceci est caractéristique des composites tissés. L'augmentation du pourcentage volumique de fibre a fait diminuer la ténacité à l'initiation de la rupture dans tout les cas, et a également fait augmenter la ténacité à la propagation de la rupture lorsque la contribution du Mode I en Mode-mixte était élevée. L'augmentation du t
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Mouton, Serge. "Intégration des contraintes d’industrialisation des pièces en matériaux composites pour l’aide à la décision en conception préliminaire appliquée au procédé RTM." Thesis, Bordeaux 1, 2010. http://www.theses.fr/2010BOR14029/document.
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L’intégration des contraintes d’industrialisation, des pièces en matériaux composites, en conception préliminaire, est un enjeu majeur de la compétitivité des entreprises, et s’inscrit dans une démarche de développement durable. Un travail de captation et de mise en forme de la connaissance industrielle a permis de développer une stratégie d’optimisation. Cette stratégie repose sur une approche multi-métiers, elle permet d’estimer la performance technique et économique d’une solution d’industrialisation. L’estimation de la performance est basée sur l’évaluation, pour chaque solution d’industrialisation, du risque de rupture du composant assemblé, du niveau d’intégration fonctionnelle et du coût de fabrication. La définition de la meilleure alternative est obtenue par la comparaison de la performance de solutions et s’appuie sur des méthodes et outils d’aide à la décision. Le risque de rupture est estimé à partir des écarts entre des caractéristiques de la pièce fabriquée par procédé Resin Transfer Molding (RTM) et les caractéristiques nominales. Les caractéristiques de la pièce fabriquée prises en compte sont : - les écarts géométriques, - les écarts de caractéristiques mécaniques. Dans l’industrie aéronautique, certaines pièces de structure en matériaux composites sont réalisées par le procédé RTM. Dans ce type de mise en forme, les caractéristiques mécaniques du composant sont directement liées au niveau d’imprégnation de la préforme. Dans le travail de thèse, les défauts d’imprégnation sont identifiés comme des écarts volumiques d’imprégnation. Ces écarts ont pour conséquence d’altérer les propriétés mécaniques du matériau qui constitue la pièce. L’estimation des écarts volumiques d’imprégnation est obtenue à partir de l’analyse des résultats de la simulation par éléments finis de l’écoulement de résine dans le renfort fibreux (logiciel Pam RTM®). La géométrie de la pièce obtenue par procédé RTM diffère de la géométrie nominale, cet écart est due en partie aux différences entre les caractéristiques physiques des constituants du matériau composite. Les variations géométriques de la pièce fabriquée sont identifiées comme des écarts géométriques de fabrication. Les écarts géométriques sont compensés, lors de la phase d’assemblage, par des déformations garantissant les contacts avec les pièces adjacentes. Ces déformations génèrent un état de contraintes mécaniques au sein de la pièce. La quantification de l’état de contraintes mécaniques est obtenue à partir d’une simulation thermomécanique par éléments finis réalisée par le logiciel Samcef®. L’aide à la décision est basée sur l’étude combinée de l’état de contraintes mécaniques due à la compensation des écarts géométriques et de l’incidence des écarts volumiques d’imprégnation sur les propriétés mécaniques de la pièce. Trois critères permettent d’estimer le risque de rupture du composant assemblé : un critère de rupture des matériaux composites quantifie le risque de rupture, les deux autres critères, prenant en compte les défauts d’imprégnation, majorent le risque de rupture. Afin de faciliter l’interprétation des résultats et la phase de comparaison de solutions, le risque de rupture est présenté sous forme d’une cartographie. En fonction des couplages des valeurs des critères, une optimisation de la conception et/ou de l’industrialisation est proposée. Une évaluation du niveau d’intégration fonctionnelle ainsi que du coût de fabrication complète la démarche d’aide à la décisionIntegrating industrialization constraints of composite materials into preliminary design is a major challenge for companies in terms of competitiveness, and is part of a sustainable development approach. Work on capturing and formatting industry knowledge has helped develop a design optimization strategy. This strategy is based on multidisciplinary rules, and estimates the technical and economic performance of an industrialization solution. This estimate is based on the evaluation of failure risk of component assembly, level of functional integration and manufacturing cost. The definition of the best alternative is obtained by comparing solution performances, relying on decision support methods and tools. The failure risk is estimated from differences between the characteristics of the part manufactured by Resin Transfer Molding Process (RTM) and the nominal part (CAD). The following characteristics of the manufactured part are taken into account: ? - geometric deviations, ? - characteristic mechanical deviations. In the aviation industry, some structural composite parts are manufacture by RTM. In this type of manufacture, the mechanical properties of the component are directly related to the level of preform impregnation. In this thesis, the impregnation defects are identified as volumic impregnation deviations. These deviations have the effect of altering the mechanical properties of material. Estimated volume impregnation deviations are obtained by analysing the results of the finite element simulation of resin flow into the fibrous reinforcement (software Pam RTM ®). The part geometry obtained using the RTM process differs from the nominal geometry, with the deviation due partly to differences between the physical components of the composite material. The geometric variations in the manufactured part are identified as geometric manufacturing deviations. These geometric deviations are offset, in the assembly phase, by deformations due to contact with adjacent parts, which generate a state of mechanical stress within the part. The mechanical stress state is quantified from a finite element thermomechanical simulation carried out using the Samcef ® software. Decision support is based on the combined study of the state of mechanical stress due to the compensation of geometric deviations and the incidence of volume impregnation deviations on the mechanical properties of the part. Three criteria are used to estimate the failure risk of the assembled component: a composite materials failure criterion quantifies failure risk; the other two criteria, taking into account the impregnation defects, increase the failure risk. To facilitate interpretation of results and the solution comparison phase, the failure risk is represented by mapping. Depending on the coupling values of the criteria, optimizing the design and/or industrialization is proposed. An evaluation of the level of functional integration and manufacturing cost complete the decision support process
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Samet, Naïm. "Évaluation ultrasonore des propriétés d'une résine et détection de porosité à l'aide d'un transducteur multiéléments : application aux matériaux composites en cours de fabrication." Le Havre, 2012. https://theses.hal.science/tel-00786143/document.
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Les études expérimentales menées au LOMC sur le procédé de fabrication des matériaux composites RTM (Resin Transfer Moulding), montrent l’apparition de bulles, à différentes échelles, au cours de la diffusion de la résine dans le réseau fibreux. Elles se déplacent pendant le processus, certaines se résorbent, d’autres persistent et diminuent ainsi la qualité globale du produit fini. Le sujet de cette thèse consiste à étudier l’apparition des bulles le long de fibres enfermées dans un canal de production. L’utilisation de mesures ultrasonores permet de suivre le front de liquide lors de son déplacement. Au moyen de ces mesures, l’apparition et l’évolution des bulles sont reliées aux processus qui les génèrent pour tenter de trouver des améliorations à la technique de mise en forme. Par traitement des signaux, des bulles sont détectées et leur évolution est suivie sur le trajet d'écoulement de la résine. Trois parties principales sont abordées au cours de cette thèse. Dans la première partie le comportement des ondes ultrasonores interagissant avec la résine en cours de polymérisation a été étudié. La deuxième partie consiste à étudier les conditions de détections de bulles en utilisant un transducteur multiéléments au sein de la résine. Dans la dernière partie, le suivi d’évolution des bulles dans le matériau composite en cours de fabrication a également été réalisé. Le but est de quantifier les concentrations de bulles relativement au taux de fibres et de résine. En perspective, des techniques d’imagerie ultrasonore utilisant l’effet Doppler ou encore des propriétés de l’acoustique non linéaire pourraient être envisagées. Le développement des techniques de contrôles d’END (Evaluation Non Destructive) lors de la réalisation de matériaux composites vise à permettre une meilleure compréhension des phénomènes et à compléter les bases de données utilisées lors des simulations numériquesThe experimental studies conducted in the LOMC on the manufacturing of composite materials by use of the RTM (Resin Transfer Molding) process, show the appearance of bubbles at different scales, during the diffusion of the resin into the fiber matrix. They move during the process, a few are absorbed; others persist and alter the overall quality of the finished product. The subject of this thesis is to study the appearance of bubbles along fibers enclosed in a production channel. The liquid front is followed as it moves by ultrasound techniques. The appearance and the evolution of the bubbles are related, through these measures, to the processes that generate them in order to try and find improvements to the fabrication techniques. The bubbles are detected by signals processing and their evolution is followed in the flow path of the resin. Three main parts are discussed in this thesis: in the first part the behavior of ultrasonic waves interacting with the resin during polymerization is studied. The conditions for bubbles detection within the resin, by use of a phased array transducer, are discussed in the second part. The last part presents the monitoring of the evolution of the bubbles in the composite material during the manufacturing process was also performed. The aim is to quantify the concentration of bubbles relative to the rate amount of fiber and resin. In perspective, imaging techniques using the Doppler effect or nonlinear ultrasonic properties could be considered. The development of control techniques of NDT (Nondestructive Evaluation) during the production of composite materials is to should lead to a better understanding of the phenomena and to complete the feeding of the databases used in numerical simulations
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Häffelin, Daniel [Verfasser], Klaus [Akademischer Betreuer] [Gutachter] Drechsler, and Volker [Gutachter] Altstädt. "Verfahren zur Integration von Folien in den RTM-Prozess (resin transfer molding) für endlosfaserverstärkte Schalenteile / Daniel Häffelin ; Gutachter: Klaus Drechsler, Volker Altstädt ; Betreuer: Klaus Drechsler." München : Universitätsbibliothek der TU München, 2017. http://d-nb.info/1133261914/34.
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