Defect Growth Detection Potential Using Guided Waves

Open Access
Author:
Waller, Matthew David
Graduate Program:
Engineering Mechanics
Degree:
Master of Science
Document Type:
Master Thesis
Date of Defense:
July 11, 2016
Committee Members:
  • Joseph Lawrence Rose, Thesis Advisor
  • Clifford Jesse Lissenden III, Committee Member
  • Bernhard R Tittmann, Committee Member
Keywords:
  • SHM
  • NDT
  • NDE
  • structural health monitoring
  • guided waves
  • ultrasonics
  • crack detection
Abstract:
Modern society relies on vast networks of infrastructure such as bridges, pipelines, railroads, and electric generating stations to name a few. Keeping infrastructure operating reliably and safely requires inspection and maintenance. In the United States, inspection and maintenance is especially important for aging infrastructure which is often kept in service beyond its intended lifespan. Inspection is carried out via a range of nondestructive evaluation (NDE) techniques depending on the application. Ultrasonic guided wave testing is a popular NDE technique because of its versatility and ability to quickly inspect large structures and to detect hidden defects. However, ultrasonic guided wave propagation is complex and requires an understanding of wave mechanics for effective inspection. In this thesis, different guided wave modes and frequencies are tested for tracking simulated crack growth in a steel pipe, based on the hypothesis that the effectiveness of the mode and frequency combinations will differ based on the wave structure. Along the way, many concepts relevant to NDE and ultrasonic guided waves such as maintenance philosophies, defect growth and fracture mechanics, guided wave excitation, dispersion principles, source influence, wave structure, noise, and variability in results are discussed.