Impact Tests of Aircraft Aluminums and Composites for Uncontained Engine Fragment Modeling

Transport aircraft design requires that manufacturers minimize the risk of a catastrophic failure resulting from an uncontained engine failure. This happens when one of the turbine engines rotating components fails, usually due to fatigue, and passes through the engine containment structure. While the loss of one engine is not enough to cause the complete failure of the commercial aircraft, the subsequent loss of critical components, such as the hydraulic or fuel lines, could result in losing control of the aircraft. Redundancy is a primary design feature that allows for the loss of an engine or major system without causing a catastrophic event. Separation of redundant systems is also a vital part of the design process. In cases where a critical component is vulnerable, shielding may be used to protect the component. To reduce the weight and operating cost for shielding, lightweight materials, such as aluminum, titanium, high-strength fabric, composites, and other materials, are being considered to act as barriers against engine fragments on critical aircraft systems. In developing a barrier, it is necessary to characterize the ballistic performance of these materials, which is typically done through testing. This report describes the tests performed at the University of California at Berkeley to aid in this characterization. In the experiments, 1/16-inch-thick 2024-T3 aluminum, 5/64-inch-thick 7075-T73 aluminum, and 8- and 16-ply unidirectional carbon fiber composite panels were impacted with 1/2-inch-diameter spheres, flat-ended cylinders, and hemispherically ended cylinders shot from a pneumatic gun. Impact curves were generated, and failure methods were observed. The composite panels failed by fracture, delamination, and plugging, depending on conditions such as projectile velocity, projectile tip shape, and target thickness. Projectile shape also affected the amount of energy required for a projectile to pass through the aluminum plates. For all materials tested, an assumption of constant projectile energy loss, independent of initial projectile speed, seemed valid.

• Record URL:
  http://www.tc.faa.gov/its/worldpac/techrpt/ar0846.pdf
• 
• Corporate Authors:

  University of California, Berkeley

  Berkeley, CA  United States  94720

  Federal Aviation Administration

  800 Independence Avenue, SW
  Washington, DC  United States  20591
• Authors:
  • Donovan, K
  • Johnson, G
  • Zohdi, T
• Publication Date: 2008

Language

• English

Media Info

• Media Type: Print
• Edition: Final Report
• Pagination: 58p

Subject/Index Terms

• TRT Terms: Air transportation crashes; Aircraft; Aluminum alloys; Carbon fibers; Finite element method; Impact tests; Rotor blades; Turbine engines
• Uncontrolled Terms: Engine failure
• Subject Areas: Aviation; Design; Vehicles and Equipment; I91: Vehicle Design and Safety;

Filing Info

• Accession Number: 01120400
• Record Type: Publication
• Files: TRIS, USDOT
• Created Date: Jan 30 2009 7:38AM