Location

Seattle, WA

Start Date

1-1-1996 12:00 AM

Description

The signal-to-noise penalty of air or gas-coupled ultrasonics has so far limited its application principally to feasibility demonstration experiments and qualitative assessments of material condition [1–3]. In most cases to date, use of air-coupled ultrasound to estimate material properties has been performed by observing the phase-matched transmitted signal amplitude and correlating this occurrence with the plate wavespeed. While this approach has approximate validity, other experimental conditions, including geometry and frequency, as we have shown [4], can significantly alter the estimate of material properties made only on the basis of phase-matched amplitude extrema. In addition, since the acoustic impedance mismatch is so large in air-coupled measurements, material damping plays a greatly enhanced role in determining the nature of the transmitted or reflected field.

Volume

15A

Chapter

Chapter 4: NDE Sensors

Section

Ultrasonic Transducers (Air Coupled)

Pages

1067-1074

DOI

10.1007/978-1-4613-0383-1_139

Language

en

File Format

application/pdf

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Jan 1st, 12:00 AM

Quantitative Materials Characterization of Elastic Plates Using Air-Coupled Leaky Lamb Waves

Seattle, WA

The signal-to-noise penalty of air or gas-coupled ultrasonics has so far limited its application principally to feasibility demonstration experiments and qualitative assessments of material condition [1–3]. In most cases to date, use of air-coupled ultrasound to estimate material properties has been performed by observing the phase-matched transmitted signal amplitude and correlating this occurrence with the plate wavespeed. While this approach has approximate validity, other experimental conditions, including geometry and frequency, as we have shown [4], can significantly alter the estimate of material properties made only on the basis of phase-matched amplitude extrema. In addition, since the acoustic impedance mismatch is so large in air-coupled measurements, material damping plays a greatly enhanced role in determining the nature of the transmitted or reflected field.