Open AccessElastic Radiation From Explosively‐Loaded Axisymmetric Cavities
Author(s) -
Glenn L. A.,
Moran B.,
Ladd A. J. C,
Wilson K. A.,
Rial J. A.
Publication year - 1986
Publication title -
geophysical journal of the royal astronomical society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.302
H-Index - 168
eISSN - 1365-246X
pISSN - 0016-8009
DOI - 10.1111/j.1365-246x.1986.tb01076.x
Subject(s) - ellipsoid , rotational symmetry , spheres , physics , cylinder , decoupling (probability) , mechanics , classical mechanics , finite element method , radiation , cavity wall , optics , geometry , materials science , mathematics , astronomy , control engineering , engineering , composite material , thermodynamics
Our earlier calculations of the radiation spectra from explosively‐driven ellipsoidal cavities in an unbounded medium have been extended to axisymmetric cavities of a more general shape. These calculations are based on a finite element description of conditions on the cavity surface, together with a numerical implementation of the elastodynamic integral representation theorem to determine the far field. In addition, a simple, analytical model was developed which provides very good agreement with the numerical results. Elongated cavities are found to be effective low‐pass filters for seismic radiation in the direction parallel to the long axis. For the cylinder, the ‘corner’ frequency varies inversely with length or, relative to a sphere with the same volume, with the 2/3‐power of the aspect ratio. Ellipsoidal cavities behave similarly. Separated spheres, cylinders connected to spheres and annular configurations were also investigated. Most of the calculations were for an unbounded medium, but free surface effects were studied as well for ellipsoidal cavities. The significance of the results is discussed in connection with the potential use of large cavities for decoupling underground nuclear explosions.