Theoretical and Experimental Studies of Longitudinal Guided Wave Generation in Hollow Cylinders by Multielement Transducers

Numerical simulation and experimental investigation on defect detection in pipes using ultrasonic guided waves are carried out in the paper. In theoretical analysis, normal mode expansion method is used to quantify the coupling between the applied boundary loadings and acoustic field. The general results are specialized to the loading configuration of multielement transducers. Several important conclusions can be drawn about the design of transducers to generate guided wave modes in pipes. The importance of design parameters such as the number of elements, the ratio of gap width to element width, and the length of each element is discussed in detail. The experimental study demonstrates the use of practical axisymmetric loading in generating axisymmetric longitudinal guided waves, which is particularly useful in the inspection of tubing or piping.