Detection of composite damage by IR NDT using ultrasonic and optic excitation

The submitted paper presents experience with detection of damaged composites by means of an ultrasonic excitation system in comparison with an optic system of excitation. In case of the ultrasonic excitation system is a high-frequency signal modulated by lock-in frequency. For a selection of the carrier signal we measured a response of a sample to sweep excitation and a sample resonance was defined by means of STFT. Consequently, the method lock-in was applied for detection. In case of the optic excitation system we applied several suitably selected frequencies with an aim to obtain information from various depths of the measured object. Results of measurements are presented in composite samples of CFRP.