Citation

Carney KS, Pereira JM, Revilock DM, Matheny P. Int. J. Impact Eng. 2009; 36(5): 720-728.

Copyright

(Copyright © 2009, Elsevier Publishing)

DOI

10.1016/j.ijimpeng.2008.10.002

PMID

unavailable

Abstract

In order to insure passenger and crew safety, international aviation regulatory bodies, such as the Federal Aviation Administration in the United States and the Joint Aviation Authorities in Europe require that in commercial jet engines a system must exist which will not allow any compressor or turbine blade to perforate the engine case in the event that it is released from a disk during engine operation Federal Aviation Administration. Federal aviation regulation part 33, Section 33.94. 1984. Due to this requirement the fan case is the heaviest single component of a jet engine. The Federal Aviation Administration further requires that jet engine manufacturers demonstrate, through a certification test, that the most critical blade be contained within the engine when a blade is released while the engine is running at full rated thrust. The most critical blade in the engine, in terms of maximum kinetic energy, is invariably the fan blade, and the system designed to prevent it from penetrating the engine is called the fan containment system.

With a goal of reducing jet engine weight, simulations of a fan blade containment system with an alternate geometry were tested and analyzed. A projectile simulating a fan blade was shot at two alternate geometry containment case configurations using a gas gun. The first configuration was a flat plate representing a standard case configuration. The second configuration was a flat plate with a radially convex curve section at the impact point. The curved surface was designed to force the blade to deform plastically, dissipating energy before the full impact of the blade is received by the plate. The curved case was able to tolerate a higher impact velocity before failure. The computational model was developed and correlated with the tests and a weight savings assessment was performed. For the particular test configuration used in this study the ballistic impact velocity of the curved plate was approximately 60 m/s (200 ft/s) greater than that of the flat plate. For the computational model to successfully duplicate the test, the very high strain rate behavior of the materials had to be incorporated.