AN INVESTIGATION OF STRAIN MEASUREMENT VIA EMBEDDED FIBER BRAGG GRATING STRAIN GAUGES FOR CONDITION MONITORING IN ADDITIVELY MANUFACTURED HYDROTURBINES
Open Access
Author:
Hunt, Cory Douglas
Graduate Program:
Mechanical Engineering
Degree:
Master of Science
Document Type:
Master Thesis
Date of Defense:
March 27, 2017
Committee Members:
Dr. Timothy Simpson, Thesis Advisor/Co-Advisor Dr. Karl Reichard, Committee Member Dr. Nicholas Meisel, Committee Member
Machine health monitoring, also referred to as condition monitoring or condition-based maintenance, presents an effective way to reduce long-term service costs for expensive or remotely-located equipment. The addition of sensors with abilities to monitor key functional components can provide necessary data to better inform maintenance schedules. A successful condition monitoring solution addresses the most costly failures through the addition of robust sensors that can function throughout the equipment’s lifetime. This thesis investigates the viability of fiber Bragg grating, or FBG, strain gauges for condition monitoring in an additively-manufactured low-head hubless hydroturbine, specifically for the purpose of detecting or predicting blade failures. The validation process began by comparing FBG performance alongside traditional metal foil strain gauges to build confidence in the sensor’s performance. Next, a process similar to vacuum-assisted resin transfer molding, or VARTM, was developed for embedding fibers in polymer additively manufactured, or AM, parts. Reliable surface measurements and a repeatable embedding process were combined to quantify the reliability of embedded FBG strain gauges in fully dense metal AM parts. Although it was shown that accurate strain measurement requires further development of a calibration process, FBG strain gauges can be embedded to provide valuable data that supports a successful condition monitoring solution.
