| A new Reconfigurable Tooling System (RTS) is being developed for use in composite repair and prototype manufacturing. The system utilizes a state-change material that can change from a liquid slurry to a hardened solid and back to a liquid. The material in its hardened state consists of hollow glass microspheres held together by a small amount of binder to form a porous solid. Desirable properties for this material in a tooling application include: low thermal expansion coefficient, high strength and stiffness, good thermal conductivity, and high temperature stability. This is a unique material system and there is very little literature available for comparison. The main purpose of this study is to understand the bulk physical and mechanical properties of the standard state-change material and to evaluate variations from the standard that may improve these properties. Properties of interest include density, porosity, compressive strength, flexural strength, flexural stiffness, coefficient of thermal expansion (CTE), and thermal conductivity. The CTE is consistent for all heat treated specimens with an average value of 5.7x10 -06 K-1 and a standard deviation of 8.4%. The average value of the flexural strength and modulus were 3.94 MPa (571 psi) and 3.18 GPa (461 ksi) with a standard deviation of 9% and 13% respectively. Environmental effects such as thermal hardening and humidity were studied. And finally, the properties were used in a computational model to simulate the expansion and stresses generated in a tool-bed during the heating process. |
