K. Chandrashekhara, S. Sundararaman, University of Missouri - Rolla, Rolla, MO; T. R. Berkel, G. B. Bilow, The Boeing Company, St.Louis, MO

Summary:

High performance aircraft composite parts have been manufactured using the autoclave process for many years. Now there are some non-autoclave processes that offer the potential for reduced cost and cycle time, especially for complex parts. The goal of the present study is to improve one of the non-autoclave processes called vacuum assisted resin transfer molding (VARTM). This will be accomplished through the development of accurate flow simulation modeling to improve process control and product quality. Stiffened panels will be manufactured using AS4-5HS carbon fabric infused with SI-ZG-5A low viscosity epoxy resin. A three dimensional mathematical model will be developed for flow simulation and implemented in the ABAQUS finite element package code using the user-subroutine to predict and optimize the flow parameters. The model will simulate resin flow through the preform, and viscosity and cure kinetics of the resin. This model will be used to determine the optimum locations of inlet and vacuum ports for the infusion process. The flow front and degree of cure obtained from the flow simulation model will be compared with experimental observations derived from fabrication trials and analytical tests. Mechanical tests such as flexure and impact will be performed on the VARTM stiffened panels and validated with the finite element structural analysis modeling results. Low velocity impact tests will be conducted using the Dynatup 9250 impact testing machine. A three dimensional failure model to account for the impact damage in the specimen due to penetration of the impactor will be developed and implemented in ABAQUS. Physical damage will be assessed using non destructive evaluation techniques such as C-scan and thermography. Progress on all these tasks will be presented.