Expansion and refinement of out-of-autoclave curing/consolidation methods for advanced composites

Abstract

Specialized Elastomeric Tooling (SET) technology, a patented process, has been shown to effectively replicate properties of composite parts formed by autoclaving while reducing the necessary energy, cost and waste by orders of magnitude. The process involves using a heated tool mold and insulative mold covered with an algorithm-generated elastomeric mask to ensure uniform temperature and pressure in a highly localized consolidation and curing process for advanced composite parts. SET was invented to help answer the high demand for out-of-autoclave curing and consolidation processes for advanced composite materials.

Future work will focus on further development of modeling to better integrate the pressure modeling and elastomer design software. Moreover, with the expansion of Vistex Composites, LLC, SET technology will be applied to include more diverse part shapes and various composite materials.

The third area of SET expansion is process combination with other processes used in the fabrication of composite parts. This thesis will focus on the integration of resin transfer molding (RTM) into the SET process. Parts formed through typical vacuum-assisted resin transfer molding are compared to those formed through vacuum-assisted resin transfer molding and cured with SET. Finally, the fourth main area of expansion is the up-scaling of SET to further certify it as a viable manufacturing process.

Expansion of SET has been focused on four main areas. The first area is the modeling capability of SET. Pressure distribution modeling with FEA software as well as initial tool design has begun for new part geometries, including a nose cone for an underwater power turbine from Verdant Power. In so doing, the algorithm used for elastomeric shape synthesis has been improved to allow for more complex geometries and increased control while modeling, as well as improved user interface. Heat transfer simulations have been performed to better aid in the design of tooling to further reduce wasted costs and energy.

The second main area of growth is the breadth of materials used in the process. While previous parts have been limited to thermoset "prepreg" materials, prototypes have successfully been formed using thermoplastic materials, establishing these materials for use in later, complex parts. The ability to successfully cure thermoplastic parts are elevated temperatures and pressures establishes is one which SET boasts over many curing processes currently available.

Work featured in this thesis has been concentrated on refinement and growth of SET. Improvement of the process has been focused on better characterization of component materials with an ultimate focus on reliability and modeling accuracy. Properties of the elastomer used in the pressing process have been tested under conditions which more closely resemble the curing process for more accurate modeling and reliability. Properties tested include compression, tension, friction, and fatigue. Additionally, brief surveys were conducted for various tooling boards and rubbers to use in SET.