Long range guided waves characterization of defects by two port equivalents

In this paper the effectiveness of a procedure that allows the detection and characterization of defects by the analysis of two port equivalents parameters when a NDT ultrasound guided waves system is investigated. A wavelet expansion and a frequency domain representation of the input (transmitted) and output (reflected) signals have been carried out. A constant coefficient matrix behaving as a transfer function between the input and output port has been defined. The two port equivalent representation correctly simulates the complete system under a wide range of input waveforms in the actual operating condition. The effectiveness of this method to detect and characterize defects in the pipes has been investigated.