The Influence of Finite-Size Sources in Acousto-Ultrasonics

TITLE AND SUBTITLE:
The Influence of Finite-Size Sources in Acousto-Ultrasonics

AUTHOR(S):
Brian N. Pavlakovic and Joseph L. Rose

REPORT DATE:
August 1994

FUNDING NUMBERS:
WU-505-90-51
C-NAG3-1365

PERFORMING ORGANIZATION NAME(S) AND ADDRESS(ES):
The Pennsylvania State University
Department of Engineering Science and Mechanics
114 Hallowel Building
University Park, Pennsylvania

PERFORMING ORGANIZATION REPORT NUMBER:
E-9061

SPONSORING/MONITORING AGENCY NAME(S) AND ADDRESS(ES):
National Aeronautics and Space Administration
Lewis Research Center
Cleveland, Ohio 44135-3191

REPORT TYPE AND DATES COVERED:
Final Contractor Report

SPONSORING/MONITORING AGENCY REPORT NUMBER:
NASA CR-195374

SUPPLEMENTARY NOTES:
Project Manager Alex Vary, Structures Division, Lewis Research Center, organization code 5250, (216) 433-6019.

ABSTRACT:
This work explores the effects that the finite normal axisymmetric traction loading of an infinite isotropic plate have on wave propagation in Acousto-Ultrasonics (AU), in which guided waves are created using two normal incidence transducers. Although the work also addresses the effects of the transducer pressure distribution and pulse shape, this thesis concentrates on two main questions: how does the transducer's diameter control the phase velocity and frequency spectrum of the response?, and how does the plate thickness relate to the plate's excitability? The mathematics of the time-harmonic solution and the physical principles and the practical considerations for AU wave generation are explained. Transient sources are modeled by the linear superposition of the time-harmonic solutions found using the Hankel transform and they are then compared to experimental data to provide insight into the relation between the size of the transducer and the preferred phase velocity.

SUBJECT TERMS:
Nondestructive testing (NDT); Nondestructive evaluation (NDE); Ultrasonics; Plate waves; Lamb waves; Composites

NUMBER OF PAGES:
107

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