A growth model for catastrophic cracking in an RAAF aircraft

✍ Scribed by N.T. Goldsmith; G. Clark; S.A. Barter

• Publisher: Elsevier Science
• Year: 1996
• Tongue: English
• Weight: 774 KB
• Volume: 3
• Category: Article
• ISSN: 1350-6307
• DOI: 10.1016/1350-6307(96)00014-3

✦ Synopsis

The fatigue failure of a training aircraft wing well before it was expected focussed attention on fatigue crack growth in the lower wing spar. To ensure the safety of the remaining fleet required determination of the crack growth rate in service for this aircraft, i.e. it was necessary to develop a crack growth model which could be applied to the rest of the fleet. Such a model was developed, linking the limited load history data for the aircraft with the progression markings on the fracture surface, which were themselves complicated by the presence of stable tensile tearing which often occurs during crack growth. This paper discusses the detailed stages in the development of the crack growth model, and indicates some of the complexities which can become significant. The results of the modelling, applied to the fleet to allow continued operation of the aircraft type, highlighted the sensitivity of aircraft lifting approaches to initial defect size and condition, and, more particularly, the necessity of performing a fatigue test using a truly representative aircraft and loading.