Lamb Waves for Detection of Delamination in Composite Plates

Lamb waves for health monitoring purposes of carbon based plate like composites using ultrasonic PZT (Piezoelectric Transducers) sensors and signal processing technics. Two approaches are introduced, a passive detection of impact location on an anisotropic composite and delamination detector using induced guided Lamb waves. Both approaches utilizes the Wavelet transform along with other technics to analyze the received signal by the sensors and extract different wave propagation modes. Impact location detection is based on error minimization of TOA (time of arrival) differences between a measured and a simulated TOA differences and produces good results and enable automatic calibration of velocity for different plates. Delamination detection is done using SVM (support vector machine) methods on our develop feature based on the wavelet transform this approach enables a detection without any prior knowledge of the composite characteristics and can be highly specialized for each composite type. The reported result lay an excellent infrastructure for further development and produced and accurate C-scan of the delaminated area.