Coupled Elastic Surface Wave in Curved Structures
Final rept. May 1996-Nov 1999
ILLINOIS UNIV AT URBANA DEPT OF THEORETICAL AND APPLIED MECHANICS
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A mathematical description of coupled. surface-wave propagation in elastic waveguides whose properties change slowly in the lateral or transverse directions has been constructed. This construction includes curved waveguides shells whose radius of curvature is large with respect to thickness. The work was undertaken to explore a nondestructive way to interrogate an inaccessible side of a structure by launching a surface wave on the other accessible side. For flat waveguides plates whose thickness varies slowly in the propagation direction the surface waves couple very efficiently provided the thickness is on the order of a wavelength, but as the waveguide grows in thickness the coupling is quickly lost. The coupling in a curved waveguide occurs provided the ratio thickness to radius of curvature is of the order of 120 and the thickness is on the order of a wavelength.