Sizing of Interface Delamination in a Composite T-Joint Using Time-of-Flight of Lamb Waves

The quantitative evaluation of the size of interface delamination in a glass/epoxy (GFRP) composite T-joint is discussed here. An expression was derived to estimate the size of interface delamination from Time-of-Flight and group velocities of the fundamental anti-symmetric Lamb mode, A(o). Numerical simulations were carried out on [0(2)/90(2)](s) GFRP T-joint with different size of interface delaminations and validated with air-coupled ultrasonic experiments. The proposed methodology requires a baseline signal from a healthy region. Supplementary equations were presented to determine the error induced in the estimation of size of the interface delamination, due to mis-alignment during data collection.