| | STATEMENT OF INTENT: This topic holds the greatest potential for meeting the technical needs of our warfighters supported by PEOs and Centers.
| Objective: | Provide a low cost, frangible composite structure.
| Description: | FAA regulation requires any structure located within 250 feet of runway centerline has to be frangible, which means the structure needs to break away when hit by an aircraft to minimize damages to the aircraft and its pilot. Many structures located at our nation airports (including Hill AFB) do not meet this frangible requirement.
The use of composites in the construction of towers, lends the possibility of frangibility to towers. Due to their composition, composites not only do not corrode in highly humid environments, they can break away when struck by an aircraft without extensive damage to the aircraft. Due to the close proximity these towers have to an air field, they can not be guyed, but should be sufficiently stiff without the use of guy wires. The development of an economically viable composite tower with a special emphasis on frangibility is desired. A lower cost alternative consists of composite pultruded I-beams and tubes designed for use in a limited number of structural applications.
This project seeks a low cost composite solution achieved through an improvement in material properties. A primary objective will be a 100% frangible tower that will create little to no damage when struck by an airplane. A second objective will be to investigate a low cost manufacturing process. The final goal will be to validate the structural strength and economic viability with an economic cost equivalent to steel.
| | PHASE I: Design a frangible composite tower with the following target capabilities: (i) When struck with a small plane the tower will break away with minimal damage to the plane, (ii) Tower will not require guy wires for stability.
| | | PHASE II: Develop a commercially viable process for manufacturing the towers. Based on Phase 1 design, build a frangible composite tower proposed for a tall tower or platform. Test the specimens for deflection, strength, fatigue and frangibility in accordance with ASTM standards. In addition, test specimens for degradation associated with moisture absorption and UV resistance.
| | DUAL USE COMMERCIALIZATION: The proposed product will have numerous benefits to the military and civil infrastructure communities such as civilian airports. The material will be valuable for use as roadside reflector stands, road signs, and electric and light poles that now are responsible for the damage, injuries, and deaths from autos impacting these structures.
| References: | ASTM Standard D2990-01, Standard Test Method for Tensile, Compressive, and Flexural Creep and Creep-Rupture of Plastics. Web site www.astm.org
2. ASTM Standard D790, Standard Test Method for Flexural Properties of Unreinforced and reinforced Plastics. Web site www.astm.org
3. Composite Tower System Requirement Document, AF Tactical Shelter & Radome Program Office, Dec 2002.
4. FAA E-2702, Low Impact Resistant Support Structures (LIRS).
5. AFMAN 32-1076, Run Way Lighting Structure Requirements.
| | Keywords: | Composite, frangible, deflection, stiffness, tall structures, tower, platform, low cost |