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Access Type

WSU Access

Date of Award

January 2021

Degree Type


Degree Name



Electrical and Computer Engineering

First Advisor

Xiaoyan Han


Sonic IR (SIR) is a relatively new thermal NDE method which has received considerable acceptance in the NDE community. SIR has shown the capability of detecting surface and subsurface defects in a wide range of materials including metal alloys, ceramics, and composites. Most of the research conducted aimed to improve the method’s detectability and optimizing the inspection process to improve the inspection outcome; less attention was devoted to extracting further information that would help characterize defects quantitatively.In this study, we developed an analytical model of a subsurface circular heat source that can be used to characterize interplay delaminations in composites. The model is used to map some aspects of the temperature-time curve with a defect’s depth. Three points are used for depth profiling: Half maximum power time, peak slope time, and the second derivative peak time. In addition to material properties, the model considers the defect’s depth, defect size, and ultrasonic excitation duration. The model suggests that a linear relationship between these features and the depth squared can be established. The agreement between the theoretical calculations and the experimental results validated the model over a broad range of defect depths, sizes, and heating durations. The diversity of features allows for the choice of the feature that fits best the application of interest.

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