ANALYZING THE THIRD HARMONIC OF THE SH0 ULTRASONIC GUIDED WAVE MODE FOR EARLY DAMAGE DETECTION
Open Access
Author:
Woelkers, Eric Ferguson
Area of Honors:
Mechanical Engineering
Degree:
Bachelor of Science
Document Type:
Thesis
Thesis Supervisors:
Clifford Jesse Lissenden III, Thesis Supervisor Dr. Jacqueline Antonia O'Connor, Thesis Honors Advisor Guhaprasanna Manogharan, Faculty Reader
Keywords:
Ultrasonic Guided Wave Nonlinear
Abstract:
Structural components degrade with time and stress, causing concern for both cost-effective design and safety. Structural health monitoring (SHM) and nondestructive testing (NDT), which both can be described as the evaluation of structural components during their service life without causing damage, are used often in the transportation and infrastructure industries to detect structural degradation before failure occurs. The research team for this project addresses whether or not the third harmonic of the SH0 ultrasonic guided wave mode is sensitive enough to microstructural changes to characterize a component as damaged earlier than current methods allow. To do so, finite element analysis (FEA) simulations and nonlinear ultrasonic tests were conducted on long samples of aluminum 2024-T3 to determine the waves’ responses to the samples’ geometries and degree of fatigue damage. After adjusting and refining several different variables critical to experimentation, such as mid-section thickness and ultrasonic wave frequency, the team cyclically loaded the samples and discovered that, using the methods and parameters selected, the third harmonic of the SH0 mode is less sensitive to microstructural changes than hypothesized. While seemingly contradictory to previous results, this result may be due to using lower frequency waves than is required to obtain the desired effects.
