Vibrations of complete spherical shells with imperfections.
- Thomas A.
- Jason E.
- Amy N.
- Michael L.
Numerous theoretical investigations on the natural frequencies for complete spherical shells have been reported over the past four decades. However, attempts at correlating the theoretical results with either experimental or simulated results (both for axisymmetric and non-axisymmetric modes of vibration) are almost completely lacking. In this paper, natural frequencies and mode shapes obtained from axisymmetric and nonaxisymmetric theories of vibration of complete spherical shells and from Finite Element computer simulations of the vibrations, with and without geometrical imperfections, are presented. Modal tests reported elsewhere on commercially available, thin spherical marine floats (with imperfections) are utilized as a basis for comparison of frequencies to both the theoretical and numerical results. In addition, comparisons with 'whole field' measurements on one of the imperfect shells using dynamic holography are presented. Because of the imperfections present, 'splitting' of frequencies of non-axisymmetric modes is anticipated. Correlations of recorded natural frequencies of the spherical shells with earlier theoretical results and with finite element simulations for the first few modes are good, and the presence of the frequency splitting phenomenon is demonstrated.
- Research Organization:
- Los Alamos National Laboratory
- Sponsoring Organization:
- DOE
- OSTI ID:
- 977882
- Report Number(s):
- LA-UR-04-6904
- Country of Publication:
- United States
- Language:
- English
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