On the pipe’s investigation by means of the asymmetric radiated/received Lamb waves

Abstract

The pipe research method by means of Lamb waves is described. The waves were excited and received with longitudinal wave transducers lodged near the wall. Their contact area can be treated as a point. The amplitude-frequency response is analyzed when exciting and receiving transducers are fastened asymmetrically (at one side). It is shown that when the receiver is in the surrounding of the node, some peaks disappear or become very small. Peaks become a little smaller and their form remains unchanged if the receiver is in the surrounding of the antinode. It is proposed to skip from the measurement the frequencies where the transducer falls into a node. It was modeled by summing in vector form the complex amplitudes of the waves that came to the receiver from the left and right and are running many times around the pipe. The results of modeling and experimental results coincide well.