SYMPOSIA PAPER Published: 01 January 1995
STP13052S

Early Stages of Fatigue Damage of Fastener Holes Monitored by Laser Speckle

Source

The present work confines itself to the study of the initiation and early propagation of fatigue cracks emanating from simulated fastener holes using a laser speckle method that is a noncontact, nondestructive, and remote sensing technique. When illuminated by a narrow laser beam, the fatigue-induced surface roughness causes the laser beam to diffract into a halo modulated by a random speckle pattern. The fatigue damage information is contained in the speckle diffraction pattern. The half width and cross correlation coefficient of a speckle pattern are chosen to quantify this information. Two kinds of specimens, a thin plate with an open hole in the center and a thin plate with an oversized pin impacted into a central hole, were tested. The fatigue process was monitored by the laser speckle patterns. After crack propagation, the specimens were examined under a scanning electron microscope and their fractographic features correlated with the fatigue process.

Author Information

Chiang, F-P
Laboratory for Experimental Mechanics Research, Department of Mechanical Engineering, State University of New York at Stony Brook, Stony Brook, NY
Du, M-L
Laboratory for Experimental Mechanics Research, Department of Mechanical Engineering, State University of New York at Stony Brook, Stony Brook, NY
Li, S
Laboratory for Experimental Mechanics Research, Department of Mechanical Engineering, State University of New York at Stony Brook, Stony Brook, NY
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Details
Developed by Committee: E08
Pages: 143–154
DOI: 10.1520/STP13052S
ISBN-EB: 978-0-8031-5300-4
ISBN-13: 978-0-8031-2017-4