Open Access

ARTICLE

Crack Detection in High Strain Aerospace Applications¹

by

1 The views expressed in this article are those of the authors and do not reflect the official policy or position of the Air Force, Department of Defense or the U.S. Government
2 Department of Systems Engineering and Management, U.S. Air Force Institute of Technology, Wright-Patterson AFB, OH, USA.
3 Department of Aeronautics and Astronautics, U.S. Air Force Institute of Technology, WrightPatterson AFB, OH, USA.
4 U.S. Air Force Non-Destructive Inspection Program Office, Tinker AFB, OK, USA.

Structural Longevity 2009, 2(2), 63-79. https://doi.org/10.3970/sl.2009.002.063

Abstract

Detecting through-thickness fatigue cracks in a geometrically constrained structure is a challenging structural health monitoring (SHM) problem due to potentially degraded sensor performance. Fatigue cracks are typically found in aircraft structures during visual inspections and non-destructive testing (NDT); however, there exists a real need to detect damage between NDT intervals. Over the last decade, a significant amount of research effort has been focused on developing “hot spot” approaches to monitor areas of structures known to have damage using Lamb waves generated from surface-mounted lead zirconate titanate (PZT) transducers. This research is focused on evaluating an SHM approach for detecting fatigue cracks in a “hot spot” that takes into account tight geometric constraints and changes in sensor performance due to high strain levels and high-cycle fatigue, so as to maintain a high probability of damage detection. In order to account for changes in PZT performance due to high-cycle fatigue and static loads, relative changes in signals from a reference pair of PZTs mounted in close proximity are removed from measured test signals. These relative changes indicate that fatigue cracks can in many cases be sensed under various loads even after considerable sensor degradation.

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Keywords

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