A Comb Transducer Model for Guided Wave Mode Control

Abstract

<p>A variety of ultrasonic transducers can be used for quantitative NDE. One commonly used is a comb transducer [1–5]. Design of this probe involves a detailed consideration of its physical and geometrical parameters. These design parameters should provide the best capability for generation and selection of a particular guided wave mode. The comb sizing (element width plus gap) determines the length of the generating wave. Parameter characterization of the comb transducer without time delay features was performed in [1]. A diverse discussion of techniques for transducer design is described in [4] and some practical NDE applications in guided wave generation are described in [5]. Unfortunately, practical considerations make it difficult to alter a comb’s geometry, consequently, restricting the ability to generate an arbitrary point on the dispersion curve. The goal of the current study is to overcome this restriction without adjustment or building another probe, by introducing a time delay profile. This means that each transducer element is excited with some time delay. An arbitrary phase velocity for the excitation of a desired point on the dispersion curve is then selected by determining the appropriate time delay value.</p>