Abstract

Long pipes and circular bars are common structural elements. The ability to conduct nondestructive evaluation of such structural elements is thus a critical in maintaining the safe operation of the structures containing such elements. However, such pipes and bars are typically very long, and access to the entire pipe/bar is usually not available. Thus, nondestructive evaluation of local damage along the length direction is a major challenge. To overcome this difficulty, we propose in this paper a method based on the one-way mixing of guided waves to detect the localized damage in pipes/bars. In the experiment, a torsional mode is first generated from one end of a solid bar. After a time-delay, the first symmetric longitudinal mode is also generated from the same end of the bar. Since the longitudinal mode propagates faster, it will catch up with the torsional mode at a location that can be easily calculated based on the group velocities of these two modes and the time-delay between them. When the two primary modes mix, their nonlinear generates a secondary torsional mode, which propagates backwards towards the end of the bar where the two primary waves were generated. This mixed shear wave contains the acoustic nonlinearity parameter of the material in the mixing zone. Therefore, by measuring this mixed shear wave, microstructural damage within the mixing zone can be obtained. Thus, this technique is capable of nondestructively evaluating the material damage along the bar far away from the end where the interrogation signals are injected into the bar.

How to Cite:

Sun, M. & Qu, J., (2019) “An experimental study of one-way mixing of guided waves in circular cylinders”, Review of Progress in Quantitative Nondestructive Evaluation .