Event Title

Energy Velocity and Group Velocity for Guided Waves Propagating Within an Absorbing or Non-Absorbing Plate in Vacuum

Location

Snowbird, UT, USA

Start Date

1-1-1999 12:00 AM

Description

Non destructive evaluation techniques often use ultrasonic guided waves in order to inspect different structures such as plates or cylinders. These waves are confined inside the material in which they propagate and can in general travel over long distances if they are not significantly attenuated. Hence, the knowledge of their properties is of prime interest for the inspection of the state of the material being tested. The waves are characterized by a frequency, a phase velocity and an attenuation factor. The attenuation factor is due to the material damping and/or to the spatial leakage (real frequency) [1] and/or to the temporal leakage (complex frequency) [2]. A particularly interesting feature of guided waves is the velocity of the envelope of a pulse or wave packet, usually known as the group velocity, which represents the velocity of the energy carried by the pulse. This velocity is widely used in NDE and allows quick and simple measurements provided that the signal is non dispersive. However, although the definition of the phase velocity is well established whatever the geometry being studied is, the definition of the group velocity is not.

Book Title

Review of Progress in Quantitative Nondestructive Evaluation

Volume

18A

Chapter

Chapter 1: Elastic Waves and Ultrasonic Techniques

Section

Guided Waves and Applications

Pages

183-190

DOI

10.1007/978-1-4615-4791-4_22

Language

en

File Format

application/pdf

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Jan 1st, 12:00 AM

Energy Velocity and Group Velocity for Guided Waves Propagating Within an Absorbing or Non-Absorbing Plate in Vacuum

Snowbird, UT, USA

Non destructive evaluation techniques often use ultrasonic guided waves in order to inspect different structures such as plates or cylinders. These waves are confined inside the material in which they propagate and can in general travel over long distances if they are not significantly attenuated. Hence, the knowledge of their properties is of prime interest for the inspection of the state of the material being tested. The waves are characterized by a frequency, a phase velocity and an attenuation factor. The attenuation factor is due to the material damping and/or to the spatial leakage (real frequency) [1] and/or to the temporal leakage (complex frequency) [2]. A particularly interesting feature of guided waves is the velocity of the envelope of a pulse or wave packet, usually known as the group velocity, which represents the velocity of the energy carried by the pulse. This velocity is widely used in NDE and allows quick and simple measurements provided that the signal is non dispersive. However, although the definition of the phase velocity is well established whatever the geometry being studied is, the definition of the group velocity is not.