Study on excitation frequency of longitudinal and torsional guided waves

Guided ultrasonic wave is a new non-destructive pipe inspection method for rapid, long distance inspection. It can be used to inspect pipes, especially those buried underground or difficult to access using other conventional NDT methods. In this paper, the excitation frequency of two most commonly used ultrasonic guided waves, longitudinal wave and torsional wave were researched, and the lower and upper frequency limit were discussed in detail. Furthermore, factor that may affect the selection of experimental frequency was studied and optimum frequency of guided wave for a carbon steel experimental pipe was selected.