Signal processing for ultrasonic NDT on aerospace structures

• Main Author: Tan, Heng Chian.
• Other Authors: Anamitra Makur
• Format: Final Year Project
• Language: English
• Published: 2009
• Subjects: DRNTU::Engineering::Electrical and electronic engineering::Electronic systems::Signal processing
• Online Access: http://hdl.handle.net/10356/16691
• Institution: Nanyang Technological University

Composite structures are increasing being used in the aerospace industry because of their strong mechanical properties such as high strength-to-light weight ratio and stiffness. Even so, they are still susceptible to defects, such as delaminations between two adjacent layers within the structure. It is thus imperative to be able to detect these defects to ensure material reliability and safety. Ultrasonic non-destructive testing (NDT) has always been the commonly used effective method in defect detection within structure. However, the study of ultrasonic NDT (at low ultrasonic frequencies) of composites is still a relatively new area. Thus, development in the understanding of how such ultrasonic NDT will response to defects within composites is still being pursued. This project is an industrial collaboration between Nanyang Technological University and Singapore Institute of Manufacturing Technology (SIMTech) which forms a constituent part of a larger aerospace project. It seeks to identify and characterize defects in the given composite structure (fiberglass specimen) using various signal processing and the pitch-catch probe. This is done so as to acquire further understanding of low-frequency ultrasonic NDT on composite structures. Four Test Systems (TS) – TS 1, TS 2, TS 3 and TS 4 using the pitch-catch probe have been developed to facilitate the study. The test setup and testing procedure for the four TSs can be found in the report. Observations and results obtained from the testing are presented and analyzed in this report. Recommendation for further study in this area and development are also available at the end of the report.