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Widespread fatigue damage monitoring: Issues and concernsThis paper is intended to illustrate the considerable effect that small in-service undetectable multi-site-damage (MSD) can have on the residual strength capability of aging aircraft structures. In general, very few people in the industry believe that tiny cracks of undetectable size are a problem because they know that many aircraft have been able to survive much larger damage. In fact they have been certified for this large damage capability. However, this is not the issue. The real issue is the effect the tiny cracks, at multiple sites, have on the large damage capability which the industry has become accustomed to expect and which the aircraft have been certified to sustain. The concern is that this message does not appear to be fully understood by many people outside the fracture community. The prime purpose of this paper, therefore, has been to convey this message by describing in simple terms the net section yielding phenomenon in ductile materials which causes loss in lead crack residual strength in the presence of MSD. The explanation continues with a number of examples on complex stiffened structures, using the results of previous finite element analyses, which illustrate that the effect of MSD is extremely sensitive to structural configuration. It is hoped that those members of the aviation community who believe that tiny cracks are not a problem will read this paper very carefully.
Document ID
19950013072
Acquisition Source
Legacy CDMS
Document Type
Conference Paper
Authors
Swift, T.
(Federal Aviation Administration Long Beach, CA, United States)
Date Acquired
September 6, 2013
Publication Date
September 1, 1994
Publication Information
Publication: NASA. Langley Research Center, FAA(NASA International Symposium on Advanced Structural Integrity Methods for Airframe Durability and Damage Tolerance, Part 2
Subject Category
Aircraft Design, Testing And Performance
Meeting Information
Meeting: International Conference on Structural Airworthiness of New and Aging Aircraft
Location: Hamburg
Country: Germany
Start Date: June 16, 1993
End Date: June 18, 1993
Accession Number
95N19488
Distribution Limits
Public
Copyright
Work of the US Gov. Public Use Permitted.
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