Civil Engineering ETDs

Publication Date

9-3-1974

Abstract

The transient fluid-shell interaction problem is investigated for thin shells constructed of other than linearly elastic materials. Specifically, solutions are developed in terms of elementary functions for the transient responses of impulsively loaded, fluid-surrounded spherical shells constructed of either viscoplastic or viscoelastic materials. In all cases the fluid medium surrounding the shell is taken as inviscid and compressible and only spherically symmetric shell motions and radiation of sound into the surrounding medium are considered. For the viscoplastic (strain rate sensitive) shells considered, two separate elastic-plastic solutions are presented. The first is based upon a shell material exhibiting linear strain hardening and linear strain rate sensitivity. The resulting fluid-shell interaction and radiation of sound is then treated exactly by partitioning the transient response of the shell into a series of phases. The second solution is based upon a more realistic nonlinear strain rate sensitivity assumption, but in this case the presence of the fluid is approximated by use of the plane wave assumption. For the viscoelastic shells considered, two separate solutions are presented, utilizing the Kelvin-Voigt and Maxwell viscoelastic models, respectively. In these cases the influence of the surrounding fluid is again treated exactly. It was found that the influence of material strain hardening and strain rate sensitivity can be significant in reducing fluid-shell displacement response, particularly when the shell is subjected to severe loading well in the plastic range. Further, limited investigations for viscoelastic materials indicate that low loss materials are adequately approximated by linear elastic behavior in problems of fluid-shell interactions. However, for higher loss materials, displacement response of the shell is significantly altered by the inclusion of the viscoelastic behavior. Finally, the well-known plane wave fluid approximation is found to be quite accurate for determining shell displacements and radiated pressure at the fluid-shell interface for thicker shells in seawater. However, for very thin shells, the approximation becomes inadequate.

Sponsors

The U.S. Atomic Energy Commission through the Sandia Laboratories Doctoral Study Program

Document Type

Dissertation

Language

English

Degree Name

Civil Engineering

Level of Degree

Doctoral

Department Name

Civil Engineering

First Committee Member (Chair)

Roy Linton Johnson, Jr.

Second Committee Member

James Auby Ellison

Third Committee Member

Charles Gilbert Richards

Fourth Committee Member

Gerald William May

Fifth Committee Member

Marion Marvin Cottrell

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