Location

La Jolla ,CA

Start Date

1-1-1989 12:00 AM

Description

Analytical modeling of ultrasound NDE requires understanding of the propagation properties of source-excited high frequency fields in an elastic environment. The sources may be actual, as generated by a transducer, or they may be induced in a fault region that disturbs the unflawed environment. One effective approach to dealing with wave phenomena in the source-excited environment is to decompose the source distribution into basis elements, propagate each basis element from the source region to the receiver, and recombine them to synthesize the total field. Because Gaussian beams have favorable propagation characteristics and represent physically observable entities, they have played a prominent role in many modeling schemes [1,2]. Gaussian beams individually may furnish an approximate replica of fields generated by ultrasonic transducers with smoothly tapered aperture distribution. These beams, because they are highly focused, are normally propagated through the environment by paraxially approximated phases and amplitudes, thereby facilitating description of beam preserving narrow-angle encounters with planar and curved interfaces, etc. [2]. However, scattering from localized fault zones or abrupt terminations is not beam preserving, and the output from many transducers (like flat pistons) gives rise to side lobes and other marked deviations from a well collimated Gaussian.

Book Title

Review of Progress in Quantitative Nondestructive Evaluation

Volume

8A

Chapter

Chapter 1: Fundamentals of Classic Techniques

Section

Elastic Wave Propagation

Pages

149-156

DOI

10.1007/978-1-4613-0817-1_19

Language

en

File Format

application/pdf

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Jan 1st, 12:00 AM

Source Field Modeling by Self-Consistent Gaussian Beam Superposition

La Jolla ,CA

Analytical modeling of ultrasound NDE requires understanding of the propagation properties of source-excited high frequency fields in an elastic environment. The sources may be actual, as generated by a transducer, or they may be induced in a fault region that disturbs the unflawed environment. One effective approach to dealing with wave phenomena in the source-excited environment is to decompose the source distribution into basis elements, propagate each basis element from the source region to the receiver, and recombine them to synthesize the total field. Because Gaussian beams have favorable propagation characteristics and represent physically observable entities, they have played a prominent role in many modeling schemes [1,2]. Gaussian beams individually may furnish an approximate replica of fields generated by ultrasonic transducers with smoothly tapered aperture distribution. These beams, because they are highly focused, are normally propagated through the environment by paraxially approximated phases and amplitudes, thereby facilitating description of beam preserving narrow-angle encounters with planar and curved interfaces, etc. [2]. However, scattering from localized fault zones or abrupt terminations is not beam preserving, and the output from many transducers (like flat pistons) gives rise to side lobes and other marked deviations from a well collimated Gaussian.