Fabrication of high quality composite laminates by pressurized and heated-VARTM

Yalcinkaya, Mehmet; Sozer, Emre; Altan, M. Cengiz

doi:10.1016/j.compositesa.2017.08.017

Cited by 53 publications

(39 citation statements)

References 49 publications

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“…Actively controlling the pressure at the inlet/exit after the complete mold filling has been proposed as a possible method to reduce the thickness variation along the laminates . Various other approaches such as placing a caul plate on the preform or applying a constant external pressure were utilized to reduce the thickness variation . Despite modest improvements in dimensional uniformity, most of these methods did not considerably improve the overall compaction of the preform.…”

Section: Introductionmentioning

confidence: 99%

“…Although these methods yielded notable improvements in fiber volume fraction, utilization of special tools and fixtures would often require high initial investment and skilled labor. On the other hand, consolidation of the preform by using pressurized air could eliminate the use of special tools, and yet significantly increase the fiber volume fraction by ~25% to above 60% even at a moderate pressure level of 138 kPa .…”

Section: Introductionmentioning

confidence: 99%

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Dynamic pressure control in VARTM: Rapid fabrication of laminates with high fiber volume fraction and improved dimensional uniformity

2018

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The compaction pressure on the fibrous preform is one of the most critical parameters in vacuum assisted resin transfer molding (VARTM), which significantly affects the preform permeability, mold filling time, and final thickness of the fabricated composite. In this study, the compaction pressure on the vacuum bag was controlled during and after the mold filling to achieve rapid impregnation and improve the fiber volume fraction of the laminate. It was shown that the dynamic pressure control (1) enabled the manipulation of the fabric permeability and faster distribution of the resin to decrease the mold filling time, (2) improved the dimensional uniformity of the laminate by reducing the thickness variation, and (3) increased the fiber volume fraction by further consolidating the preform and removing the excess resin. One of the most essential and prominent features of the process was shown to be the resin removal from the inlet by applying external pressure, which reduced the thickness variation in laminates from 15 to 1%. The mold filling time was reduced by 48% compared with conventional VARTM, while achieving a high fiber volume fraction up to 64% and a low void content of below 1%.• The two main components of the experimental setup were the bottom aluminum mold and pressure chamber.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Dynamic pressure control in VARTM: Rapid fabrication of laminates with high fiber volume fraction and improved dimensional uniformity

2018

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“…The application of a high consolidation pressure during the cure of a composite laminate is particularly important for manufacturing a high-quality composite part 47 . If the external pressure is not applied and the laminate is cured only under vacuum, the final part will generally contain high void content, possibly exceeding 5% by volume, and undesirable resin rich regions 48 .…”

Section: Discussionmentioning

confidence: 99%

Magnet Assisted Composite Manufacturing: A Flexible New Technique for Achieving High Consolidation Pressure in Vacuum Bag/Lay-Up Processes

Pishvar

Amirkhosravi

Altan

2018

JoVE

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This work demonstrates a protocol to improve the quality of composite laminates fabricated by wet lay-up vacuum bag processes using the recently developed magnet assisted composite manufacturing (MACM) technique. In this technique, permanent magnets are utilized to apply a sufficiently high consolidation pressure during the curing stage. To enhance the intensity of the magnetic field, and thus, to increase the magnetic compaction pressure, the magnets are placed on a magnetic top plate. First, the entire procedure of preparing the composite lay-up on a magnetic bottom steel plate using the conventional wet lay-up vacuum bag process is described. Second, placement of a set of Neodymium-Iron-Boron permanent magnets, arranged in alternating polarity, on the vacuum bag is illustrated. Next, the experimental procedures to measure the magnetic compaction pressure and volume fractions of the composite constituents are presented. Finally, methods used to characterize microstructure and mechanical properties of composite laminates are discussed in detail. The results prove the effectiveness of the MACM method in improving the quality of wet lay-up vacuum bag laminates. This method does not require large capital investment for tooling or equipment and can also be used to consolidate geometrically complex composite parts by placing the magnets on a matching top mold positioned on the vacuum bag.

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“…The CFRP layers were connected with TST shells using the vacuum-assisted resin transfer molding (VaRTM) method. The VaRTM method has many advanced characteristics, such as being cost-effective, easy to mold for many kinds of shapes, and having no complicated steel surface preparations needed [34,[40][41][42]. In addition, one of the most outstanding advantages of the VaRTM method is that this method can create a thin lamination with a high fiber content.…”

Section: Molding Processmentioning

confidence: 99%

Experimental Investigations of the Strengthening Effects of CFRP for Thin-Walled Storage Tanks under Dynamic Loads

2020

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In this study, the strengthening effects of different lamination conditions on carbon fiber reinforced polymers (CFRPs) for thin-walled storage tanks (TSTs) subjected to internal pressure under dynamic loads were experimentally investigated. A total of three small-scale models of TSTs were used for the investigation, including non-strengthened specimens, specimens strengthened with 0° CFRP layers, and specimens strengthened with 0°/90° CFRP layers. There were two types of tests for every specimen: the static and dynamic tests. A new experimental method using small steel balls was applied to create internal pressure in the TSTs. The results show that small steel balls could be used to increase the internal pressure compared to a normal liquid. Furthermore, the similarity rules for small-scale TSTs with small steel balls inside were also studied to consider the applicability of the models. The experimental results indicated that the CFRP layer could effectively restrain both static and dynamic hoop strains in the TSTs. Moreover, the CFRP layer could also remarkably reduce the impact of sloshing on the TST shells. The 0° CFRP layer proved to have better effects than the 0°/90° CFRP layers on the strengthening of the TSTs against dynamic loads.

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Fabrication of high quality composite laminates by pressurized and heated-VARTM

Cited by 53 publications

References 49 publications

Dynamic pressure control in VARTM: Rapid fabrication of laminates with high fiber volume fraction and improved dimensional uniformity

Dynamic pressure control in VARTM: Rapid fabrication of laminates with high fiber volume fraction and improved dimensional uniformity

Magnet Assisted Composite Manufacturing: A Flexible New Technique for Achieving High Consolidation Pressure in Vacuum Bag/Lay-Up Processes

Experimental Investigations of the Strengthening Effects of CFRP for Thin-Walled Storage Tanks under Dynamic Loads

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