Open Access

ARTICLE

Damage Detection in z-Fiber Reinforced, Co-Cured Composite Pi-Joint Using Pitch-Catch Ultrasonic Analysis and Scanning Laser Vibrometry

Hitesh Kapoor¹, James L. Blackshire², Som R. Soni³

1 Aerospace and Ocean Engineering Dept., Virginia Tech, Blacksburg, VA-24060
2 Air Force Research laboratory, AFRL/RXLP, WPAFB, Ohio-45433
3 Dept. of System & Engineering Management, AFIT, 2950 Hubson Bay, WPAFB, Ohio-45433

Structural Longevity 2010, 3(3), 221-238. https://doi.org/10.3970/sl.2010.003.221

Abstract

Damage detection in constrained geometry structures like z-pinned, co-cured composite pi-joints is established using pitch-catch ultrasound and scanning laser vibrometry measurements. Ultrasonic pitch-catch measurements consisted of a network of PZT (Lead Zirconate Titanate) sensors placed on the specimen and sensing Lamb waves at each sensor location, where measurements were taken at symmetric top and bottom sensor locations for healthy and damaged pijoint specimens. Results showed the presence of fatigue-induced bend damage of the joint as a reduced peak-to-peak amplitude response across the joint. Scanning laser vibrometry measurements were used to study the propagation of Lamb waves within the narrow, constrained geometry pi-joint structure, where the reflection and superposition of propagating Lamb waves was studied using time-resolved image analysis. The presence of delamination and hidden damage was visualized as changes in the propagating Lamb wave characteristics, where a reduction in propagating energy levels and dispersive wave characteristics were observed due to delamination and thinning of the composite plies.

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