Accession Number:

ADA492287

Title:

Measurement of the Shear Wavespeed in an Isotropic Elastomeric Plate

Descriptive Note:

Technical rept.

Corporate Author:

NAVAL UNDERSEA WARFARE CENTER DIV NEWPORT RI

Personal Author(s):

Report Date:

2008-10-10

Pagination or Media Count:

33.0

Abstract:

A method to estimate the shear wavespeed in an isotropic, thick, elastomeric plate is demonstrated in this report. A point force is applied to the plate and a scanning laser vibrometer is used to measure normal velocity on one surface. The temporal domain measurements are transformed into the frequency domain using a Fourier transform, then, the spatial domain measurements are transformed into the kx, ky wavevector domain using two Fourier transforms. Once the data are in the wavevector-frequency domain, the propagation wavenumbers for specific Lamb waves can be estimated from the peaks within the kx,ky spectra. Using the estimated values of the propagation wavenumbers, a Newton-Raphson gradient method is applied to the Raleigh-Lamb dispersion curve equations to obtain an estimate of the shear wavespeed, a quantity that is generally difficult to measure. A simulation and an experiment are included to illustrate the method, and the accuracy of the measurement process is discussed.

Subject Categories:

  • Mechanics

Distribution Statement:

APPROVED FOR PUBLIC RELEASE