Defect Detection In Carbon Fiber Composites by Partially Embedded Magnetostrictive Transducers

Open Access
Author:
Dickerson, Clayton Joseph
Area of Honors:
Engineering Science
Degree:
Bachelor of Science
Document Type:
Thesis
Thesis Supervisors:
  • Clifford Jesse Lissenden Iii, Thesis Supervisor
  • Gary Gray, Honors Advisor
  • Thomas David Juska, Thesis Supervisor
  • Judith A Todd, Faculty Reader
Keywords:
  • Carbon Fiber
  • Composites
  • Magnetostrictive
  • Transducers
Abstract:
Glass reinforced and carbon reinforced polymers are widely used across many industries. Both glass fibers and carbon fibers are measured in micrometers in diameter, and can be molded into many different shapes when combined with resin. Fiber reinforced polymers have a very high strength to weight ratio, making them very useful in the aircraft industry, sports industry, and infrastructure; however, as the fiber reinforced products are manufactured and are used in service, defects can occur that will compromise the strength and the life of the product. There are currently several nondestructive evaluation techniques to provide quality assurance in industry today. These techniques include C-Scans and Acoustic Emission testing. Both methods can accurately predict if flaws are present within a fiber-reinforced composite; however, there are several disadvantages to either method of nondestructive evaluation. This work performed in this study evaluated a new method of nondestructive testing using magnetostrictive transducers as a tool for ultrasonic wave propagation. The iron-cobalt foil component of the magnetostrictive transducer was embedded in both glass fiber reinforced polymer and carbon fiber reinforced polymer. While no usable signals were gathered from the embedded foils within the glass fiber reinforced polymer, many usable signals were obtained from the carbon fiber reinforced polymer. Experiments continued with testing embedded foils in a carbon fiber plate with manufacturer-induced flaws. The flaws were a wrinkle defect and a ply-backing defect. The flaws were identifiable using the magnetostrictive testing indicating that it is a viable method to detect flaws within carbon fiber reinforced polymer. The effectiveness of magnetostrictive transducers on other types of flaws and carbon fiber requires further investigation.