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1
Sun, Xiudong. "Analysis of vacuum-assisted resin transfer molding /." The Ohio State University, 1998. http://rave.ohiolink.edu/etdc/view?acc_num=osu1487950658548618.
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2
Al, Omari Ali. "Effect of vacuum level on the vacuum-assisted resin transfer molding process." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1999. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape8/PQDD_0002/MQ43656.pdf.
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3
Song, Xiaolan. "Vacuum Assisted Resin Transfer Molding (VARTM): Model Development and Verification." Diss., Virginia Tech, 2003. http://hdl.handle.net/10919/27168.
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In this investigation, a comprehensive Vacuum Assisted Resin Transfer Molding (VARTM) process simulation model was developed and verified. The model incorporates resin flow through the preform, compaction and relaxation of the preform, and viscosity and cure kinetics of the resin. The computer model can be used to analyze the resin flow details, track the thickness change of the preform, predict the total infiltration time and final fiber volume fraction of the parts, and determine whether the resin could completely infiltrate and uniformly wet out the preform.
Flow of resin through the preform is modeled as flow through porous media. Darcy's law combined with the continuity equation for an incompressible Newtonian fluid forms the basis of the flow model. During the infiltration process, it is well accepted that the total pressure is shared by the resin pressure and the pressure supported by the fiber network. With the progression of the resin, the net pressure applied to the preform decreases as a result of increasing local resin pressure. This leads to the springback of the preform, and is called the springback mechanism. On the other side, the lubrication effect of the resin causes the rearrangement of the fiber network and an increase in the preform compaction. This is called the wetting compaction mechanism. The thickness change of the preform is determined by the relative magnitude of the springback and wetting deformation mechanisms. In the compaction model, the transverse equilibrium equation is used to calculate the net compaction pressure applied to the preform, and the compaction test results are fitted to give the compressive constitutive law of the preform. The Finite Element/Control Volume (FE/CV) method is adopted to find the flow front location and the fluid pressure. The code features the ability of simultaneous integration of 1-D, 2-D and 3-D element types in a single simulation, and thus enables efficient modeling of the flow in complex mold geometries.
VARTM of two flat composite panels was conducted to verify the simulation model. The composite panels were fabricated using the SAERTEX multi-axial warp knit carbon fiber fabric and SI-ZG-5A epoxy resin. Panel 1 contained one stack of the carbon fabric, and Panel 2 contained four stacks of the fabric. The parameters verified included the flow front location and preform thickness change. For Panel 1, the flow front locations were accurately predicted while the predicted resin infiltration was much slower than measured for Panel 2. The disagreement is attributed to the permeability model used in the simulation, which failed to consider the interface flow in the unstitched preform containing more than one stack of the fabric under very low compaction force. The predicted transverse displacements agree well with the experimental measurement qualitatively, but not quantitatively. The reasons for the differences were discussed, and further investigations are recommended to develop a more accurate compaction model. The simulation code was also used to investigate the VARTM of a new form of sandwich structure with through-the-thickness reinforcements, which is being considered for use in primary aircraft structure. The infiltration of three foam core sandwich preforms with different stitch densities was studied. The objective of the study was to determine whether the preforms could be completely infiltrated and how the stitch density affects the infiltration process. The visualization experiments were conducted to verify the simulation. The model accurately predicted the resin infiltration patterns. The calculated filling times underpredicted experimental times by 4 to 14%. The model revealed the resin flow details and found that increasing the stitch spacing shortens the total filling time, but increases the nonuniformity of the flow front shape. Extreme nonuniformity of the flow front shape could result in the formation of the voids.Ph. D.
4
Sayre, Jay Randall. "Vacuum-Assisted Resin Transfer Molding (VARTM) Model Development, Verification, and Process Analysis." Diss., Virginia Tech, 2000. http://hdl.handle.net/10919/27034.
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Vacuum-Assisted Resin Transfer Molding (VARTM) processes are becoming promising technologies in the manufacturing of primary composite structures in the aircraft industry as well as infrastructure. A great deal of work still needs to be done on efforts to reduce the costly trial-and-error methods of VARTM processing that are currently in practice today. A computer simulation model of the VARTM process would provide a cost-effective tool in the manufacturing of composites utilizing this technique. Therefore, the objective of this research was to modify an existing three-dimensional, Resin Film Infusion (RFI)/Resin Transfer Molding (RTM) model to include VARTM simulation capabilities and to verify this model with the fabrication of aircraft structural composites. An additional objective was to use the VARTM model as a process analysis tool, where this tool would enable the user to configure the best process for manufacturing quality composites.
Experimental verification of the model was performed by processing several flat composite panels. The parameters verified included flow front patterns and infiltration times. The flow front patterns were determined to be qualitatively accurate, while the simulated infiltration times over predicted experimental times by 8 to 10%. Capillary and gravitational forces were incorporated into the existing RFI/RTM model in order to simulate VARTM processing physics more accurately. The theoretical capillary pressure showed the capability to reduce the simulated infiltration times by as great as 6%. The gravity, on the other hand, was found to be negligible for all cases.
Finally, the VARTM model was used as a process analysis tool. This enabled the user to determine such important process constraints as the location and type of injection ports and the permeability and location of the high-permeable media. A process for a three-stiffener composite panel was proposed. This configuration evolved from the variation of the process constraints in the modeling of several different composite panels. The configuration was proposed by considering such factors as: infiltration time, the number of vacuum ports, and possible areas of void entrapment.Ph. D.
5
Yang, Huan. "Integrated analysis of unsaturated polyester and Vinylester Resins in vacuum-assisted resin transfer molding (SCRIMP) /." The Ohio State University, 2001. http://rave.ohiolink.edu/etdc/view?acc_num=osu1488205318511314.
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6
Cauthen, Stephen Michael. "Vacuum assisted resin transfer molding in the repair of reinforced concrete bridge structures." Birmingham, Ala. : University of Alabama at Birmingham, 2008. https://www.mhsl.uab.edu/dt/2008m/cauthen.pdf.
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7
Grimsley, Brian William. "Characterization of the Vacuum Assisted Resin Transfer Molding Process for Fabrication of Aerospace Composites." Thesis, Virginia Tech, 2005. http://hdl.handle.net/10919/36062.
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This work was performed under a cooporative research effort sponsored by the National Aeronautics and Space Administration (NASA) in conjunction with the aerospace industry and acedemia. One of the primary goals of NASA is to improve the safety and affordability of commercial air flight. Part of this goal includes research to reduce fuel consumption by developing lightweight carbon fiber, polymer matrix composites to replace existing metallic airframe structure. In the Twenty-first Aircraft Technology Program (TCAT) efforts were focused on developing novel processing methods to fabricate tailored composite airframe structure. The Vacuum Assisted Resin Transfer Molding (VARTM) processing technique offers a safer, more affordable alternative to manufacture large scale composite fuselages and wing structures. Vacuum assisted resin transfer molding is an infusion process originally developed for manufacturing of composites in the marine industry. The process is a variation of Resin Transfer Molding (RTM), where the rigid matched metal tooling is replaced on one side with a flexible vacuum bag. The entire process, including infusion and consolidation of the part, occurs at atmospheric pressure (101.5 kPa). High-performance composites with fiber volumes in the range of 45% to 50% can be achieved without the use of an autoclave. The main focus of the VARTM process development effort was to determine the feasibility of manufacturing aerospace quality composites with fiber volume fractions approaching 60%.
A science-based approach was taken, utilizing finite element process models to characterize and develop a full understanding of the VARTM infusion process as well as the interaction of the constituent materials. Achieving aerospace quality composites requires further development not only of the VARTM process, but also of the matrix resins and fiber preforms. The present work includes an investigation of recently developed epoxy matrix resins, including the characterization of the resin cure kinetics and flow behaviors. Two different fiber preform architectures were characterized to determine the response to compaction under VARTM conditions including a study to determine the effect of thickness on maximum achievable fiber volume fraction. Experiments were also conducted to determine the permeabilities of these preforms under VARTM flow conditions. Both the compaction response and the permeabilities of the preforms were fit to empirical models which can be used as input for future work to simulate VARTM infusion using process models.
Actual infusion experiments of these two types preforms were conducted using instrumented tools to determine the pressures and displacements that occur during VARTM infiltration. Flow experiments on glass tooling determined the fill-times and flow front evolution of preform specimens of various thicknesses. The results of these experiments can be used as validation of process model infusion simulations and to verify the compaction and permeability empirical models. Panels were infused with newly developed epoxy resins, cured and sectioned to determine final fiber volume fractions and part quality in an effort to verify both the infusion and compaction experimental data.
The preforms characterized were found to have both elastic and inelastic compression response. The maximum fiber volume fraction of the knitted fabrics was dependent on the amount of stacks in the preform specimen. This relationship was found in the determination of the Darcy permeabilities of the preforms. The results of the characterization of the two epoxy resin systems the show that the two resins have similar minimum viscosities but significantly different curing behaviors. Characterization of the VARTM process resulted in different infusion responses in the two preform specimens investigated. The response of the saturated preform to a recompaction after infusion indicated that a significant portion of the fiber volume lost during infusion could be recovered. Fiber volume and void-content analysis of flat composite panels fabricated in VARTM using the characterized resins and preforms resulted in void-free parts with fiber volumes over 58%. Results in the idealized compaction tests indicated fiber volumes as high as 60% were achievable with the knitted fabric. The work over the presented here has led to a more complete understanding of the VARTM process but also led to more questions concerning its feasibility as an aerospace composite manufacturing technique.Master of Science
8
McGrane, Rebecca Ann. "Vacuum Assisted Resin Transfer Molding of Foam Sandwich Composite Materials: Process Development and Model Verification." Thesis, Virginia Tech, 2001. http://hdl.handle.net/10919/42108.
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Vacuum assisted resin transfer molding (VARTM) is a low cost resin infusion process being developed for the manufacture of composite structures. VARTM is being evaluated for the manufacture of primary aircraft structures, including foam sandwich composite materials. One of the benefits of VARTM is the ability to resin infiltrate large or complex shaped components. However, trial and error process development of these types of composite structures can prove costly and ineffective. Therefore, process modeling of the associated flow details and infiltration times can aide in manufacturing design and optimization.
The purpose of this research was to develop a process using VARTM to resin infiltrate stitched and unstitched dry carbon fiber preforms with polymethacrylimide foam cores to produce composite sandwich structures. The infiltration process was then used to experimentally verify a three-dimensional finite element model for VARTM injection of stitched sandwich structures.
Using the processes developed for the resin infiltration of stitched foam core preforms, visualization experiments were performed to verify the finite element model. The flow front progression as a function of time and the total infiltration time were recorded and compared with model predictions. Four preform configurations were examined in which foam thickness and stitch row spacing were varied. For the preform with 12.7 mm thick foam core and 12.7 mm stitch row spacing, model prediction and experimental data agreed within 5%. The 12.7 mm thick foam core preform with 6.35 mm row spacing
experimental and model predicted data agreed within 8%. However, for the 12.7 mm thick foam core preform with 25.4 mm row spacing, the model overpredicted infiltration times by more 20%. The final case was the 25.4 mm thick foam core preform with 12.7 mm row spacing. In this case, the model overpredicted infiltration times by more than 50%. This indicates that the model did not accurately describe flow through the needle perforations in the foam core and could be addressed by changing the mesh elements connecting the two face sheets.Master of Science
9
Saw, Kee Hong. "Simulation on filling pattern of vacuum assisted resin transfer molding (VARTM) for sectional wind blade shells." Thesis, Wichita State University, 2012. http://hdl.handle.net/10057/5610.
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The Vacuum Assisted Resin Transfer Molding (VARTM) process is one of the most common and economical processes which has been adapted by many wind blade manufacturers. The significant advantages for this process primarily owed to its simplicity as well as its lower cost of operation. Nevertheless, there are several potential drawbacks from this process such as the delamination and the dryspot issues. The dryspot issue will be the main focus in this thesis.
In this thesis, the methodology includes 3-D solid modeling, finite element modeling and injection simulations. Throughout the framework of this thesis, 3-D non-isothermal conditions would be implemented and double core framework will be incorporated within the sectional blade shells. The standard design of the blade is directly adapted from the Wind PACT Blade Designs. [1]
The modeling work involves the use of CATIA V5 CAD modeling software to create a single full half wind blade shell which later sectioned to two sections. The sectional wind blade shells were equally divided right at the mid-span of the full blade namely, the root section and the tip section of the wind blade shells. Finite element modeling was also incorporated through the use of PATRAN 2008 r2 while the injection simulation is directly simulated through ESI Group of PAM RTM software.
The results from the simulation were discussed and analyzed. Post analysis involves recommended solutions toward the issues found throughout the manufacturing process. Future works were also discussed in the final conclusions to provide potential future development study in the VARTM process.Thesis (M.S.)--Wichita State University, College of Engineering, Dept. of Mechanical Engineering
10
Robinson, Marc J. "Simulation of the vacuum assisted resin transfer molding (VARTM) process and the development of light-weight composite bridging." Diss., Connect to a 24 p. preview or request complete full text in PDF format. Access restricted to UC campuses, 2008. http://wwwlib.umi.com/cr/ucsd/fullcit?p3336692.
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Thesis (Ph. D.)--University of California, San Diego, 2008.Title from first page of PDF file (viewed January 9, 2009). Available via ProQuest Digital Dissertations. Vita. Includes bibliographical references (p. 482-492).
11
Xu, Liqun. "Integrated analysis of liquid composite molding (LCM) processes." Connect to this title online, 2004. http://rave.ohiolink.edu/etdc/view?acc%5Fnum=osu1095688597.
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Thesis (Ph. D.)--Ohio State University, 2004.Title from first page of PDF file. Document formatted into pages; contains xix, 245 p.; also includes graphics. Includes bibliographical references (p. 233-245).
12
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.
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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.
13
Larsson, Turtola Simon, and Adam Rönnbäck. "Utredning av tillverkningsinducerade avvikelser i fiberförstärkt komposit genom blandningsexperiment : En fallstudie enligt DMAIC vid ABB Composites." Thesis, Luleå tekniska universitet, Institutionen för ekonomi, teknik och samhälle, 2020. http://urn.kb.se/resolve?urn=urn:nbn:se:ltu:diva-80031.
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Tillämpningen av fiberförstärkt polymerkomposit har senaste decenniet ökat kraftigt inom flertalet högteknologiska branscher. Trots framgången är förekomsten av tillverkningsinducerade avvikelser fortfarande en utmaning. Avvikelserna försämrar materialets mekaniska egenskaper och förkortar dess livslängd, vilket orsakar kassationer, miljöbelastningar och försvårad produktetablering för industriaktörer. ABB Composites i Piteå står inför en liknande situation. Företaget producerar cylindriska isolatorer i fiberförstärkt komposit till högspänningsindustrin, och behöver utreda förekomsten av en specifik avvikelse, som under senaste tre åren medfört omfattande kvalitetsbristkostnader. Produkten tillverkas genom vakuuminjicering där en hartsblandning impregnerar en glasfiberform, för att sedan övergå från flytande till fast form genom en exoterm reaktion. Hartsblandningens reaktionsförlopp har länge misstänkts påverka avvikelsernas förekomst, men har inte bekräftats, på grund av flera svårkontrollerade egenskaper. Examensarbetets syfte har därför varit att utreda om hartsblandningens egenskaper påverkar förekomsten av tillverkningsinducerade avvikelser vid tillverkning av cylindriska isolatorer. Arbetet har bedrivits som ett Sex Sigma-projekt enligt problemlösningsmetodiken DMAIC. Ett blandningsexperiment med sex komponenter genomfördes i laborationsmiljö där en datagenererad design med 36 delförsök tillämpades, varav sex stycken egenskaper hos hartsblandningen undersöktes. Experimentet påvisade att samtliga egenskaper var möjliga att styra genom att förändra proportionerna av ingredienserna. Däremot visade sig flera av egenskaperna vara korrelerade och kan därav inte justeras oberoende av varandra. Kunskapen användes till att utveckla och testa två nya varianter av hartsblandningen vid tillverkning av cylindriska isolatorer. Resultatet bekräftade att hartsblandningens egenskaper signifikant påverkar förekomsten av tillverkningsinducerade avvikelser. En viss kombination av egenskaperna som kännetecknade ett långsamt reaktionsförlopp minskade förekomsten av avvikelser på isolatorerna med 99.3 procent i jämförelse med den ordinarie hartsblandningen. Förbättringen förväntas medföra betydelsefulla besparingar, ökad konkurrenskraft och förhöjd kvalitetsmedvetenhet för ABB Composites. Examensarbetets kunskapsbidrag anses också betydelsefullt för kompositindustrin i strävan mot fortsatt reducering av tillverkningsinducerade avvikelser.The application of fibre-reinforced polymer composites (FRPC) have during the last decades increased in many high-tech industries. Despite the success, the existence of manufacturing-induced deviations has been a long-standing challenge. These deviations affect the lifetime and the mechanical properties of the composite, which in turn lead to scrap of products and environmental impact, obstructing market exploitation for industry stakeholders. ABB Composites in Piteå is facing a similar scenario. The company produces cylindrical insulators in fibre-reinforced composite for the high-voltage industry and need to investigate a specific deviation, which has caused extensive costs during the last three years. The product is manufactured through vacuum assisted resin transfer molding (VARTM), where a resin blend impregnates a fibreglass preform, as the resin cures and transforms from liquid to solid form through an exothermic reaction. One suspected cause for the deviation has been the curing process of the resin. However, it is dependent on several difficult-to-control characteristics and is yet to be confirmed. The purpose of this thesis has therefore been to investigate whether the characteristics of the resin blend affects the occurrence of manufacturing-induced deviations while producing cylindrical insulators. The work has been conducted as an internal Six Sigma-project following the DMAIC improvement cycle. A mixture experiment with six components was performed, using a computer-generated design with 36 runs, in which six characteristics of the resin blend were examined. The experiment proved that all characteristics could be controlled by changing the proportions of the design factors. However, many of the characteristics were correlated, implying that the characteristics cannot be independently controlled. The knowledge from the experiment were used to develop two new resin blends, which were infused to cylindrical insulators in regular production environment. The result confirmed that the characteristics of the resin blend significantly affects the quality of the insulator. One of the blends, which represented a slower curing process, reduced the deviations by 99.3 percent in relation to the original blend. The improvement is expected to generate substantial savings, increased competitiveness and enhanced quality awareness for ABB Composites. Possible contributions to the industry are related to the development of a method to experimentally investigate the resin blend with the objective of reducing manufacturing-induced deviations.
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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.
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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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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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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.
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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.
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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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Brandley, Mark Wesley. "Void Modeling in Resin Infusion." BYU ScholarsArchive, 2015. https://scholarsarchive.byu.edu/etd/5460.
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Resin infusion of composite parts has continually been reaching to achieve laminate quality equal to, or exceeding, the quality produced with prepreg in an autoclave. In order for this to occur, developers must understand the key process variables that go in to producing a laminate with minimal void content. The purpose of this research is to continue efforts in understanding 1) the effect of process conditions on the resultant void content, with a focus on resin infusion flow rate, 2) applying statistical metrics to the formation, location and size of voids formed, and 3) correlate these metrics with the local mechanical properties of the composite laminate. The variation in dispersion and formation of micro-voids and macro-voids varied greatly between the rates of flow the infusion occurred, especially in the non-crimp carbon fiber samples. Higher flow rates led to lower volumes of micro-voids in the beginning section of the carbon fiber laminates with macro-voids being introduced approximately half-way through infusion. This was determined to have occurred decreasing pressure gradient as the flow front moved away from the inlet. This variation in void content per location on the laminate was more evident in the carbon fiber samples than the fiberglass samples. Micro-voids follow void formation modeling especially when coupled with a pressure threshold model. Macro-void formation was also demonstrated to correlate strongly to void formation models when united with void mobility theories and pressure thresholds. There is a quick decrease in mechanical properties after the first 1-2% of voids signaling strength is mostly sensitive to the first 0-2% void content. A slight decrease in SBS was noticed in fiberglass laminates, A-F as v0 increased but not as drastically as represented in the NCF laminates, G and H. The lower clarity in the exponential trend could be due to the lack of samples with v0 greater than 0% but less than 1%. Strength is not well correlated to void content above 2% and could possibly be related to void morphololgy.
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WANG, PO-TANG, and 王柏棠. "Application of Computational Simulation on Vacuum Assisted Resin Transfer Molding Technologies." Thesis, 2017. http://ndltd.ncl.edu.tw/handle/zcuy6t.
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碩士大葉大學
工業工程與管理學系
106
This study uses computer aided engineering to implement vacuum assisted resin transfer molding technology, and through analysis to find the optimum process parameters. At present, this process is prone to short shot, entrapped air, and incomplete design of gate. At the beginning of the study, Moldex3D software was used to simulate the phenomenon of pressure gradient and surface velocity caused by the difference of permeability when the resin flows through the fiber cloth under constant flow rate filling and grasp the trend of resin flow wave, conversion rate and wave envelope position. In the experimental part, the upper and lower mold and double mold cavity are poured into the flat plate, and observe the situation in wave front of resin flow, impregnation and encapsulation phenomenon. With the computer aided engineering of simulated resin flow in the mold cavity, the use of the relevant parameters for the development of bicycle cranks mold, understand the relationship between different temperatures and resin viscosity, and by the development of the dual-hole molds to produce flat plate test pieces for hardness measurement. The results of the above experiment as a basis for making the processing parameters. Using the computer aided engineering compared with the traditional trial and error method can save cost and time consumed in the process, and by analyzing the results to improve the conditions of perfusion process, effectively improve the process and product competitiveness.
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SANDOYASALAZAR, MOISES BOLIVAR, and 孫摩西. "The Fabrication of a Wind Turbine Blade with Vacuum Assisted Resin Transfer Molding." Thesis, 2012. http://ndltd.ncl.edu.tw/handle/86578210356297081386.
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碩士國立成功大學
航空太空工程學系碩博士班
100
Composite materials are composed by two or more materials. It has multiple advantages of light weight and high strength and is highly popular in the aerospace and automobile industry. VARTM is used to fabricate parts with a combination of epoxy resin and woven glass fiber. The purpose of this research is to identify different ways to fabricate polymer composite parts with VARTM and afterwards choosing the one with the best outcome and fabricate a wind turbine blade. There are three different ways used to build parts using VARTM. After concluding that the process with double vacuum bags yielded best molding results and was used to build the wind turbine blade. A small wind turbine blade was made with the best procedure of VARTM found among the three. The most important parameters to control the process and avoid voids in the final part are the pressure and flow velocity.
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Jhih-Yu-Yang and 楊智宇. "Study on the processability of vacuum assisted resin transfer molding for fiber reinforced polyurethane." Thesis, 2015. http://ndltd.ncl.edu.tw/handle/86780194093883763449.
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碩士國立勤益科技大學
化工與材料工程系
103
In this study, we had investigated the reactivity, rheological and processing parameter of several polyurethane(UM、UB、UH) and an epoxy(EP) resin first. From the results of analysis, we had chosen the formula which can use in vacuum assisted resin transfer molding (VARTM) process suitably, as well as evaluated the effect of vacuum pressure (50.5 kPa、76 kPa、101.3 kPa) on the performance. Then prepared the PU composites with different fiber (CF、GF) by VARTM process to analyze the effect of mechanical properties and thermal properties, and finally observed the fracture mode by scanning electron microscope (SEM). Because of PU had low viscosity, good mobility and high reactivity, so that the fiber can impregnate completely before the initial reaction, and had enough time to operate in VARTM process. Due to PU has long molecular chain, as well as soft segment and hard segment had obvious of microphase separation, thus PU had been endowed the characteristic of the elastomer. Therefore, the impact test shows the impact resisting strength and toughness of PU composites were better than EP composites. From the observation of the failure mode, we knew the PU had good combination for impregnating the fiber even better than EP's. In addition, mixed the epoxy with the diisocyanate to make the epoxy PU Hybrid(UB) can improve the thermal properties and stiffness by formation of the pentacyclic structure such as oxazolidinone.
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Li, Jing Zhang Chuck Wang Ben. "Modeling, design and control of vacuum assisted resin transfer molding (VARTM) for thickness variation reduction." 2006. http://etd.lib.fsu.edu/theses/available/07012006-135801.
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Thesis (Ph. D.)--Florida State University, 2006.Advisors: Chuck Zhang, Ben Wang, Florida State University, College of Engineering, Dept. of Industrial and Manufacturing Engineering. Title and description from dissertation home page (viewed Sept. 18, 2006). Document formatted into pages; contains xiii, 168 pages. Includes bibliographical references.
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Liu, Kuan-Chih, and 劉冠志. "The Application of Fiber Optic Sensors for Monitoring Resin Flow Frout in Vacuum Assisted Resin Transfer Molding (VARTM) Process." Thesis, 2010. http://ndltd.ncl.edu.tw/handle/99502062622467237128.
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碩士臺灣大學
工程科學及海洋工程學研究所
98
The optic fiber is the commonly used in communication, after special processing it can be made a sensing part. At present, fiber optic sensors are applied generally in civil engineering and aeronautics, astronautics engineering for monitoring. The fiber grating sensor unified many merits, for example, the volume is small, the diameter thin and mass is light, not electromagnetic wave disturbance, High transmission, Anti-corrosive, thermostable, easy to embedded in the structure and establish quasi-distributional multiplex monitor network, It’s suitable in the structure strain and the temperature monitoring. Nowadays, composite FRP usually has used to the yacht, aerospace vehicle, windmill rotor structures etc., but tendency of along with the structure of large scale, regarding structure security and quality request, Therefore forewarn monitor of regarding the structure and diagnoses the technology to be important day after day, Because the fiber optical sensor has easy to embedded in structure. So it’s can embed fiber optic sensor in composite structure manufacture in the structure, After the structure formation , advantageously monitor the structure interior condition. This research mainly lies is used fiber grating sensor that applied to Vacuum Assisted Resin Transfer Molding (VARTM) process, fiber grating sensor was embedded between the fabric layers to monitoring the resin flow in composite process, and discusses relations of the fiber grating wavelength change and the resin flow. Practical application resin flow of experiment in thick laminate. Monitoring internal resin flow front in thick laminate. Discussion on experiment result and simulation software analysis result. Serviceability of the confirmation fiber grating sensor monitor resin flow front.
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Li, Shu-Yu, and 李書宇. "Study on the Surface Properties of Composites Made by Air Cushion Method of Vacuum Assisted Resin Transfer Molding." Thesis, 2014. http://ndltd.ncl.edu.tw/handle/13085530989168673758.
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碩士高苑科技大學
機械與自動化工程研究所
102
A new technique, called air cushion method (ACM), is developed to reduce the resin infusion time in vacuum assisted resin transfer molding ( VARTM ) by improving the bag structure. In ACM, a novel vacuum bag consisting of a film and several air cushions replaces single bag utilized in traditional VARTM. During filling, the novel vacuum bag is placed over the perform and seals against the mold to create an airtight cavity. As vacuum is drawn in the cavity, the ambient pressure is applied on the bag that compacts the perform. The isolated air cushions can form the supports and consequently the portion of the bag between air cushions is away the perform. This creates the distribution channels for increasing the resin flow during infiltration. Once enough volume of resin is infused, the air cushions are pierced and then the resin distribution channels disappear. The objective of this research is to investigate the effects of process variables, including air cushion number, air cushion thickness, vacuum pressure and film material, on the surface quality of ACM products. The design of experiment selects two levels for all factors. Through the analysis, the influence of the factor can be understood and then the optimal conditions can be obtained to improve the quality of the finished product
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Chen, Chun-Hao, and 陳俊豪. "Process development and experimental validation of composites carbon fiber reinforced plastics(CFRP) vacuum assisted resin transfer molding (VARTM) technique ---1/5 scale down automobile bonnet model as an example." Thesis, 2016. http://ndltd.ncl.edu.tw/handle/y3xnx5.
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碩士國立中央大學
機械工程學系在職專班
104
ABSTRACT Low-cost non-autoclave, lightweight carbon fiber reinforced resin matrix composites (CFRP) components are widely used in automobile industry. This thesis is used a smaller-scale model (1:5) of automotive bonnet as an example, to systematically investigate the key issues in the development and implementation of assisted resin transfer molding process (VARTM) technology. Key issues such as development conversion design, simulation process parameters of VARTM and prototyping flexibility. In conclusion, this thesis successfully implements the developed process to fabricate low cost efficient CFRP composite bonnets using the VARTM process. It is believed that future successful implementation and conversion of existing car components via the process flow of this thesis can be of great commercial value and very promising in the lightweight construction of various industries. Key words : Carbon Fiber、 Resin Matrix Composites 、Vacuum Assisted Resin Transfer Molding( VARTM)