title: Robust ultrasonic damage detection under complex environmental conditions using singular value decomposition.
abstract: Guided wave ultrasonics is an attractive monitoring technique for damage diagnosis in large-scale plate and pipe structures. Damage can be detected by comparing incoming records with baseline records collected on intact structure. However, during long-term monitoring, environmental and operational conditions often vary significantly and produce large changes in the ultrasonic signals, thereby challenging the baseline comparison based damage detection. Researchers developed temperature compensation methods to eliminate the effects of temperature variation, but they have limitations in practical implementations. In this paper, we develop a robust damage detection method based on singular value decomposition (SVD). We show that the orthogonality of singular vectors ensures that the effect of damage and that of environmental and operational variations are separated into different singular vectors. We report on our field ultrasonic monitoring of a 273.05 mm outer diameter pipe segment, which belongs to a hot water piping system in continuous operation. We demonstrate the efficacy of our method on experimental pitch-catch records collected during seven months. We show that our method accurately detects the presence of a mass scatterer, and is robust to the environmental and operational variations exhibited in the practical system.
authors.affiliation: Department of Civil and Environmental Engineering, Carnegie Mellon University, Pittsburgh, PA, United States.
authors.forename: Chang
authors.initials: C
authors.lastname: Liu
authors.affiliation: Department of Electrical and Computer Engineering, University of Utah, Salt Lake City, UT, United States.
authors.forename: Joel B
authors.initials: JB
authors.lastname: Harley
authors.affiliation: Department of Civil and Environmental Engineering, Carnegie Mellon University, Pittsburgh, PA, United States.
authors.forename: Mario
authors.initials: M
authors.lastname: Bergés
authors.affiliation: Department of Electrical and Computer Engineering, Carnegie Mellon University, Pittsburgh, PA, United States.
authors.forename: David W
authors.initials: DW
authors.lastname: Greve
authors.affiliation: Department of Civil and Environmental Engineering, Carnegie Mellon University, Pittsburgh, PA, United States. Electronic address: ijo@cmu.edu.
authors.forename: Irving J
authors.initials: IJ
authors.lastname: Oppenheim
keywords: Damage detection; Environmental and operational variations; Guided waves; Singular value decomposition; Structural health monitoring