As a part of the design program of the McDonnell Douglas DC-10 fuselage, experiments were performed on unstiffened and stiffened shells with longitudinal cracks. The shells were loaded under internal pressure. In these experiments, flapping of the cracks was observed. Above a certain length, the cracks no longer propagated in longitudinal direction but they turned towards a circumferential line. In an aircraft, this type of U-shaped crack would form a much larger outlet in the pressurized fuselage than a straight crack would do. The larger hole would allow a more rapid decompression before catastrophic damage could occur, especially since the decompression relieves the main load on the pressurized fuselage. In e.g. the Boeing 737-200, cracks have indeed been found to flap. If one would rely on flapping for the safety of the aircraft, it is essential that one must be certain that a crack will flap. Instead of relying on flapping for the primary damage tolerance of a pressurized fuselage, flapping can always be used as an additional safety precaution. Then, besides the normal damage tolerance of the fuselage, the flapping can form an additional safety precaution.
Survey of Crack Path Stability Criteria and Their Application to Crack Flapping Phenomena in Stiffened Structures
1992
168 pages
Report
Keine Angabe
Englisch
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