Ultrasonic guided wave inspection in large composite plate

• Main Author: Sakthivel Tamilarasam
• Other Authors: Fan Zheng David
• Format: Theses and Dissertations
• Language: English
• Published: 2017
• Subjects: DRNTU::Engineering::Aeronautical engineering
• Online Access: http://hdl.handle.net/10356/72478
• Institution: Nanyang Technological University

Ultrasonic Guided wave testing is acknowledged as one of the prominent tools in identifying damages in composite structures. Elastic waves that propagate in thin-walled structures are called as Guided waves or Lamb waves and their propagation follows the structure curvature. The main aim of this research work is to investigate the propagation of lamb waves over the thin composite plate of a large area. This study is essential in order to improve the understanding of lamb waves in a large composite plate. A large thin GFRP (Glass Fibre Reinforced Polymer) composite plate is manufactured by using the autoclave and analyzed for defects. Piezoelectric transducers are used to transmit different wave modes and the displacement in signals due to disturbances is captured by Laser vibrometer for high precision to eliminate unwanted disturbances. The excitation signal is five cycle hanning windowed tone burst and based on the vibration signal captured in Laser vibrometer, the interactions between lamb waves and the composite plate are studied. Dispersion curve for the particular composite specimen is extrapolated to discuss the characteristics of the lamb wave. Keywords: ultrasonic, lamb waves, GFRP, laser vibrometer, dispersion curve.