For many years, sandwich structures have been utilized throughout the aerospace and shipbuilding industry. One of the efficient configurations of sandwich structures is fiber reinforced polymer (FRP) facings laminated onto a balsa -wood core. This configuration provides both high specific strength and high specific stiffness. The major disadvantage of this system is the flammability of the organic polymers used for binding the fiber facings to the balsa wood core. Balsa wood itself is susceptible to fire but does not generate toxins. The results reported in this paper deal with the fire performance of balsa sandwich panels made using an inorganic polymer matrix known as Geopolymer. This polymer can be formulated to cure at room temperature and is resistant up to 1000°C. By combining this matrix with a lightweight glass powder, a fire-resistant paste was formulated. Two layers of a woven carbon and glass fabric were applied to the balsa core followed by varying thicknesses of a fire-resistant Geopolymer glass paste to serve as a fire barrier. Seventeen sandwich panels were fabricated and tested using the Heat Release Rate Test and the Smoke Test for Cabin Materials to measure the heat release rates and smoke generating characteristics, respectively. The added weight of the insulation was one of the variables since the weight of aerospace composites is a critical design factor. The results indicate that a 2 mm layer of the Geopolymer glass coating is more than sufficient to meet the FAA requirements. The maximum heat release rate of 71 kW/m 2 for plain balsa decreased to 53 kW/m 2, well below the limit of 65 kW/m 2 set forth by the Federal Aviation Administration. The sandwich facings alone were more than adequate in allowing the structure to pass the Smoke Test with a four minute specific optical density of 41, compared to the FAA limit of 200. The system is simple and easy to manufacture, results in very little increase in weight, and provides an effective solution for the protection of flammable materials.
|Original language||English (US)|
|Number of pages||8|
|State||Published - Sep 1 2004|
ASJC Scopus subject areas
- Materials Science(all)
- Mechanics of Materials
- Mechanical Engineering