Lamb Wave Ultrasonic Detection of Barely Visible Impact Damages of CFRP

Results of applying a Lamb-wave-based ultrasonic technique to detect impact damages to a CFRP honeycomb panel are presented. The technique is based on analyzing changes in wave propagation due to defects and makes use of a network of piezoelectric transducers adhesively bonded to the panel surface. Preliminary experiments and tests have been carried out in which defect simulators (metal discs attached at various points of the CFRP panel) and low energy impact damages inflicted by drop-weight operation were detected. Results of defect location (calculated coordinates) are considered, as well as a damage index. A detailed analysis of the results has made it possible to identify the specific features and shortcomings of the technique. Possible ways are proposed for eliminating these shortcomings and upgrading the methodology of ultrasonic data processing in general.