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Flow Control in Vacuum Assisted Resin Transfer Molding

Rahmanian, Vahid | 2015

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  1. Type of Document: M.Sc. Thesis
  2. Language: Farsi
  3. Document No: 46770 (06)
  4. University: Sharif University of Technology
  5. Department: Chemical and Petroleum Engineering
  6. Advisor(s): Shojaei, Akbar; Pishvaie, Mahmoud Reza
  7. Abstract:
  8. Vacuum assisted resin transfer molding (VARTM) is one of the most efficient and low cost process in composite industries. In this process, the preform is covered by a flexible vacuum bag and resin flows into the mold with applying vacuum pressure at the vent. The main objective in VARTM process is preventing voids and dry spots formation in final composite part because these defects may significantly deteriorate the mechanical properties of a structure. Flow front is an important parameter in this process which have a high influence on the void formation. Resin flow control is required to prevent dry spots or micro voids during the VARTM process. In general, the flow control is classified into passive (or off-line) and active (or on-line) control. Passive flow control is performed before the actual molding process by optimizing mold design or gate location using numerical flow simulation and an optimization scheme. Active flow control, on the other hand, is employed to monitor the impregnation state and can react to unexpected resin flow. In recent years, structures with complex shapes have been integrally molded by VARTM to reduce the number of parts and time required. Since these structures will have multiple preform alignment, warped preform, part-to-part joints, and vacuum bag wrinkling, the resin flow is often unpredictable. Thus, active flow control is essential for manufacturing such complex structures by VARTM with high quality. Flow simulation in order to forecasting flow front and control it is an important method which prevents void formation. In this investigation, flow simulation for a rectangular mold with different injection lines is already done. After that, an active flow control approach is applied by monitoring flow front and actuating flow rate in order to flow front modification. Results shows that flow front became smoother in the case with flow control approach in comparison with the case without flow control
  9. Keywords:
  10. Flow Patterns ; Simulation ; Control ; Vacuum Asisted Resin Transfer Molding (VARTM)

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