Vibro-acoustic modulation technique for micro-crack detection in pipeline

For the poor sensitivity of traditional ultrasonic technique for micro crack detection, a kind of nonlinear ultrasonic technique, vibro-acoustic modulation technique, is used for micro crack detection in pipes. The influence of the frequency and amplitude of vibration on the modulation index (MI) is experimentally investigated. The experiment results prove that the vibro-acoustic modulation technique can be used for crack detection in pipes. The modulation index is influenced by the frequency and amplitude of vibration, therefore it is important to choose the appropriate parameters in order to get higher sensitivity in crack detection.