abstract
- © 2020 Published by Shahid Chamran University of AhvazA new method is described, allowing to locate and also measure the length and orientation of crack-type damage features in thin-walled composite beams (TWCB), a capability not previously reported. The method is based on a modal-analysis technique and is shown to work on a hollow composite beam, going beyond previous work limited to simple beams and plates. The method is shown to be capable to function down to signal-to-noise ratios (SNR) of about 15, corresponding to far noisier conditions than in most previous work. This capability is achieved by a combination of wavelet de-noising and the use of a 2D Continuous Wavelet Transform (CWT), applied to two modal analysis metrics, COMAC and Mode Shape Differences (MSD). The length and orientation of the crack can be determined accurately using a 2D curve fitting approach. Using either COMAC or MSD produces reliable results, but MSD is found to be somewhat more noise-tolerant. The new method is believed to be useful for the measurement of damage features in a variety of thin-walled composite beams such as aircraft wings and wind turbine blades, among others.