Combined vibration and guided wave-based approach for composite panels health assessment
Various non-destructive testing (NDT) methods have been developed to extract information about state of a structure. Two of them: vibration-based and guided wave-based techniques are one of the most commonly used and well developed. Both approaches can be implemented using Scanning Laser Doppler Vibrometer measurements and excitation by means of piezoelectric transducer. In this paper authors present a combined approached for NDT using successive and simultaneous measurement of both mode shapes and guided waves. Vibration-based damage detection is focused on detection of mode shape singularity, created by material discontinuity. This method utilizes wavelet transform and Teager energy operator for damage indication. Guided wave-based damage detection uses propagating elastic wave energy variation on the specimen surface as well as any changes in wave propagation pattern due to its interaction with material discontinuity as a tool for structural health assessment. Combining this two different techniques can give higher accuracy in defect detection. At the same time any additional specimen preparation are necessary, any set-up changes are required and the all the data can be registered in the same amount of time (simultaneous excitation). To confirm proposed technique a honeycomb core sandwich aluminum plate with debonding is tested. A results obtained with both techniques and combined approach are presented.
