Effect of MSD on Large Damage Residual Strength

  • T. Swift


The purpose of this paper is to point out that a need exists to re-visit component test data used to substantiate large damage residual strength capability for those commercial transport aircraft now considered to be aging. Many of these aircraft are operating well beyond their initial design life goals due to the current economic environment and are therefore prone to the formulation of widespread fatigue damage (WFD) which may considerably reduce the large damage tolerance capability used to support initial certification of the aircraft. The purpose of this paper is to re-visit such a component test, as an example, to illustrate the considerable effect that in-service uninspectable multiple-site-damage (MSD), a sub-element of WFD, can have on lead crack residual strength. The stiffened panel test was originally performed to substantiate the residual strength capability in the presence of a two-bay circumferential crack with a broken central stiffener in the most critical location on the crown of a pressurized fuselage. This particular test was chosen because it illustrates the need to consider the non-linear load displacement characteristics of the skin to stiffener rivets as the skin crack approaches the intact crack arresting stiffeners. The results of an elastic/plastic displacement compatibility analysis illustrates that the lead crack tip stress intensity factor becomes non-linear with respect to applied gross stress well before the failure stress due to rivet yielding. The resulting crack tip stress intensity factor, a function of both crack length and applied gross stress, is used with an intuitive lead crack/MSD crack link-up criterion to determine the loss in residual strength caused by in-service uninspectable MSD. The analysis illustrates that residual strength is very sensitive to exact rivet location with respect to the lead crack tip and also to the model used to describe the crack tip plastic zone size. There appears to be an urgent need to conduct further research to determine the effect on plastic zone size of stiffening materials having much higher yield strengths than the cracked skin.


Residual Strength Plastic Zone Size Fast Fracture Half Crack Length Rivet Hole 
These keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.


Unable to display preview. Download preview PDF.

Unable to display preview. Download preview PDF.


  1. [1]
    Swift, T., “Widespread Fatigue Damage Monitoring-Issues and Concerns.” Presented at the 5th International Conference on Structural Airworthiness of New and Aging Aircraft. Hamburg, Germany, June 1993.Google Scholar
  2. [2]
    Swift, T., “Design of Redundant Structures.” Published in Fracture Mechanics Design Methodology, AGARD LS-97, 1978.Google Scholar
  3. [3]
    Swift, T., “Fracture Analysis of Stiffened Structure.” Published in Damage Tolerance of Metallic Structures: Analysis Methods and Application, ASTM STP 842, 1984.Google Scholar
  4. [4]
    Swift, T., “The Application of Fracture Mechanics in the Development of the DC-10 Fuselage.” Published in Fracture Mechanics of Aircraft Structures, AGARD-AG-176, 1974.Google Scholar
  5. [5]
    Swift, T., “Damage Tolerance Capability.” Published in Fatigue of Aircraft Materials, Proceedings of the Specialist’s Conference dedicated to the 65th birthday of J. Schijve, Delft University Press, 1992.Google Scholar
  6. [6]
    Stone, M., “Airworthiness Philosophy Developed From Full-Scale Testing.” Presented to The International Committee on Aeronautical Fatigue, London, England, July, 1973.Google Scholar
  7. [7]
    Swift, T., “The Effects of Fastener Flexibility and Stiffener Geometry on the Stress Intensity in Stiffened Cracked Sheet.” Published in Prospects of Fracture Mechanics, Noordhoff International Publishing, Leydon, Netherlands, 1974, pp. 419–436.Google Scholar
  8. [8]
    Swift, T., “Damage Tolerance Analysis of Redundant Structures.” Published in Fracture Mechanics Design Methodology, AGARD-LS-97, North Atlantic Treaty Organization, London, England, 1979.Google Scholar
  9. [9]
    Westergaard, H.M., “Bearing Pressures and Cracks.” Journal of Applied Mechanics, Vol. 6, No. 1, June 1939, pp A49.Google Scholar
  10. [10]
    Love, A.E.H., “A Treatise on the Mathematical Theory of Elasticity,” Fourth Edition., Dover Publications, 1944, p. 209.MATHGoogle Scholar
  11. [11]
    Irwin, G.R., “Analysis of Stresses and Strains Near the End of a Crack Traversing a Plate.” Journal of Applied Mechanics, Transactions of the American Society of Engineers, Vol. 24, Sept. 1957, pp. 361–364.Google Scholar
  12. [12]
    Paris, P.C., “Application of Muskhelishvili’s Method to the Analysis of Crack Tip Stress Intensity Factors for Plane Problems Part III”, Lehigh University, Bethlehem, PA, 1960.Google Scholar
  13. [13]
    Swift, T., “Damage Tolerance in Pressurized Fuselages.” 11th Plantema Memorial Lecture. Presented at the 14th Sysposium of the International Committee on Aeronautical Fatigue, Ottawa, Canada, June 1987.Google Scholar
  14. [14]
    Broek, D., “The Effects of Multi-Site Damage on the Arrest Capability of Aircraft Fuselage Structures.” FractuResearch TR 9302, June 1993.Google Scholar
  15. [15]
    Broek, D., “Elementary Engineering Fracture Mechanics.” Martinus Nijhoff Publishers, 1983.Google Scholar
  16. [16]
    Moukawsher, J.E., “Fatigue Life and Residual Strength of Panels With Multiple- Site-Damage.” Purdue University Thesis, May, 1993.Google Scholar
  17. [17]
    Bowie, O.L., “Analysis of an Infinite Plate Containing Radial Cracks Originating from the Boundary of an Internal Circular Hole.” Jounal of Matematics and Physics, Vol. 35, 1956.Google Scholar
  18. [18]
    Rooke, D.P., and Cartwright, D.J., “Compendium of Stress Intensity Factors.” Published by Her Majesty’s Stationary Office, London, England, 1976.Google Scholar

Copyright information

© Springer-Verlag Berlin Heidelberg 1995

Authors and Affiliations

  • T. Swift
    • 1
  1. 1.Federal Aviation AdministrationLakewoodUSA

Personalised recommendations