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A New Approach to Overcoming Spatial Aliasing in Structural Damage DetectionAircraft, reusable launch vehicles,unmanned aircraft, and other advanced structures are being built using lightweight composite materials/metals with design safety factors as low as 1.25. These advanced structures operate in uncertain and severe environments and are susceptible to damage such as delamination, fiber/matrix damage, hydrothermal strain in composite materials, and fatigue and cracking in metals. To ensure human safety and load-bearing integrity these structures must be inspected to detect and locate often invisible damage and faults before they become catastrophic. Conventional methods of non-destructive evaluation sometimes miss significant damage and are time consuming and expensive to perform. In contrast, vibrometry or vibration signature techniques are a global method of structural integrity monitoring that potentially can efficiently detect damage on large structures, including damage that is away from sensor locations, and in the interior of structures. However, a barrier problem in damage detection using vibration measurements is the need to measure the vibration response at a large number of points on the structure. Typically, model reduction or expansion procedures such as Guyan reduction or dynamic expansion are attempted to overcome the problem of insufficient measurements or spatial aliasing. These approaches depend on using information from the healthy model, and thus put error into the reduction used to represent the damaged structure. In this paper, a Frequency Response Function technique is used to detect damage to a fixed-free beam. The technique uses measured frequency response functions from the healthy structure as reference data, and then monitors vibration measurements during the life of the structure to detect damage. In an analytical simulation using a finite-element model of a beam, damage was located using only sparse measurements because the technique uses both rotation and translation measurements from the damaged structure.
Document ID
20000032294
Acquisition Source
Langley Research Center
Document Type
Conference Paper
Authors
Schulz, Mark J.
(North Carolina Agricultural and Technical State Univ. Greensboro,NC United States)
Naser, Ahmad S.
(North Carolina Agricultural and Technical State Univ. Greensboro,NC United States)
Thyagarajan, Sunil K.
(North Carolina Agricultural and Technical State Univ. Greensboro,NC United States)
Mickens, Travluss
(North Carolina Agricultural and Technical State Univ. Greensboro,NC United States)
Pai, Frank
(Missouri Univ. Columbia, MO United States)
Date Acquired
August 19, 2013
Publication Date
February 22, 1998
Publication Information
Publication: NASA University Research Centers Technical Advances in Aeronautics, Space Sciences and Technology, Earth Systems Sciences, Global Hydrology, and Education
Volume: 2 and 3
Subject Category
Composite Materials
Report/Patent Number
98URC143
Funding Number(s)
CONTRACT_GRANT: NCC1-255
Distribution Limits
Public
Copyright
Work of the US Gov. Public Use Permitted.
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