Advertisement

Fracture Mechanics and Fail-Safe Design for Helicopter Rotor Structures

  • M. J. Rich
Part of the Sagamore Army Materials Research Conference Proceedings book series (SAMC)

Abstract

Fracture mechancis analysis is the key for design of fail-safe structures. Controlled fracture offers a substantial improvement for the design goal of increased safety and reliability of helicopter rotor system components. However, to achieve an overall gain the system must be inspectable and the fail-safe and safe-life features must be integrated. Fracture mechanics analysis is currently being used for many of the metallic rotor components with crack propagation time being the most important factor. The new advanced composites offer a substantial improvement in crack time but the emphasis may well now be in static fracture strength. By proper consideration of trade-offs in fail-safe and safe-life aspects lighter weight and increased safety can be achieved.

Preview

Unable to display preview. Download preview PDF.

Unable to display preview. Download preview PDF.

References

  1. 1.
    Jensen, H.T., “The Evolution of Structural Fail-Safe Concepts — Rotorcraft”, in Fatigue Design Procedures, ed. by E. Gassner and W. Schütz. New York: Pergamon Press (1969), 433–86.Google Scholar
  2. 2.
    McBreaty, J., “Fatigue and Fail-Safe Airframe Design”, SAE Trans., 64 (1956), 427–36.Google Scholar
  3. 3.
    Stratton, W.K. and White, R.F., “Fail Safety — What Is It?”, Vertiflite, 14, no. 8 (1968), 4–10.Google Scholar
  4. 4.
    Thompson, G. and Weiss, W., “Fail-Safety for the H-46 Rotor Blade”, Preprint No. 551, American Helicopter Society, May 1971.Google Scholar
  5. 5.
    Weiss, W. and Zola, J., “The Application of Fracture Mechanics to the Design of Damage Tolerant Components for the UTTAS Helicopter”, Preprint No. 882, American Helicopter Society, May 1974.Google Scholar
  6. 6.
    Jensen, H., “The Application of Reliability Concepts to Fatigue Loaded Helicopter Structures”, paper presented at the 18th Annual Forum of the American Helicopter Society, Washington, D.C., May 1962.Google Scholar
  7. 7.
    Jacoby, G. and Nowack, H., “Comparison of Scatter Under Program and Random Loading and Influencing Factors”, in Probabilistic Aspects of Fatigue, Special Technical Publication 511. Philadelphia: Am. Soc. for Testing and Materials (1972), 61–74.CrossRefGoogle Scholar
  8. 8.
    Degnan, W.G., Dripchak, P.D. and Matusovich, C.J., “Fatigue Crack Propagation in Aircraft Materials”, Sikorsky Aircraft Div., United Aircraft Corp., Stratford, Conn., Army Aviation Material Laboratories Contract Report No. USAAVLABS-TR-66–9, March 1966. (AD 630 926)Google Scholar
  9. 9.
    Rich, M.J., “Crack Propagation in Helicopter Rotor Blades”, in Damage Tolerance in Aircraft Structures, Special Technical Publication 486. Philadelphia: Am. Soc. for Testing and Materials (1971), 243–51.CrossRefGoogle Scholar
  10. 10.
    Pociluyko, S., Griffen, C., Figge, I. and Blad, L., “Composite Material Geodesic Structures — A Structural Concept for Increased Helicopter Blade Survivability”, Preprint No. 884, American Helicopter Society, May 1974.Google Scholar
  11. 11.
    Salkind, M., “The Twin Beam Composite Rotor Blade”, Preprint No. 782, American Helicopter Society, May 1973.Google Scholar
  12. 12.
    Rich, M.J. and Linzeil, L.E., “Damaged Static and Fatigue Stress Analysis of VTOL Structures”, AIAA Paper 69–214, February 1969.Google Scholar
  13. 13.
    Barrett, L. and Mack, J., “Evaluation of Rotor Controls Designed for Increased Safety”, Preprint No. 550, American Helicopter Society, May 1971.Google Scholar
  14. 14.
    Rich, M.J., “Vulnerability Considerations in the Design of Rotary Wing Structures”, in Proceedings of the Air Force Conference on Fatigue and Fracture of Aircraft Structures and Materials, held at Miami Beach, Fla., 15–18 December 1969, Air Force Flight Dynamics Laboratory, Wright-Patterson AFB, Ohio, Report No. AFFDL-TR-70–144 (September 1970), 635–51. (AD 719 756)Google Scholar
  15. 15.
    Pian, T., Tong, R. and Luk, C.H., “Elastic Crack Analysis by A Finite Element Hybrid Method”, Massachusetts Institute of Technology, Cambridge, Air Force Office of Scientific Research Contract Report No. AFOSR-TR-72–0752, December 1971. (AD 739 988)Google Scholar
  16. 16.
    Mandell, J., McGarry, F., Wang, S. and Im, J., “Stress Intensity Factors for Anisotropic Fracture Test Specimens of Several Geometrics”, J. Composite Mater., 8 (1974), 106–15.CrossRefGoogle Scholar
  17. 17.
    Holdsworth, A. and Owen, H., “Macroscopic Fracture Mechanics of Glass Reinforced Polyester Resin Laminates”, J. Composite Mater., 8 (1974), 117–29.CrossRefGoogle Scholar
  18. 18.
    Phillips, D., “The Fracture Mechanics of Carbon Fibre Laminates”, J. Composite Mater., 8 (1974), 130–41.CrossRefGoogle Scholar
  19. 19.
    Durchlaub, E. and Freeman, R., “Design Data for Composite Structure Safe-Life Prediction”, Boeing Vertol Co., Philadelphia, Pa., Air Force Materials Laboratory Contract Report No. AFML-TR-73–225-Vol-1, March 1974. (AD 918 496L)Google Scholar

Copyright information

© Springer Science+Business Media New York 1979

Authors and Affiliations

  • M. J. Rich
    • 1
  1. 1.Sikorsky Aircraft DivisionUnited Technologies CorporationStratfordUSA

Personalised recommendations