Orthotropic shell analysis of a ship's bottom section
Johnson, G. L.
Evans, J. Harvey
MetadataShow full item record
In the interest of developing more thorough methods of analyzing ship structures, an entire bottom section extending from side to side and from one bulkhead to another is analyzed as an orthotropic shell of variable curvature. The longitudinally framed destroyer type ship is studied under hydrostatic loading and longitudinal bending stress. Specific consideration is given to the orthotropy of the structure and its curvature. As a result of the combined analysis of the shell and its associated stiffener system, partial differential equations are developed which define the behavior of the stiffened shell. The inherent complexity of the developed equations precludes an analytic solution. An approximate solution could be obtained, however, by the use of difference equations and digital machine computation. An application of membrane theory to an equivalent orthotropic shell provides a means of determining direct stresses and extensional rigidities. A comparative study of two existing destroyer types using developed theory reveals that membrane theory with corrective iterations is of value in preliminary analysis. The sensitivity of the variation of hull curvature from the analytic curvature is also demonstrated. The use of the midship section coefficient as a design parameter for the structural designer should be encouraged and exploited. If the midship section area is kept constant the curvature can be varied to the advantage of the structure with no effect on speed. The relatively high bending stiffness in the girthwise direction of current designs merits a reevaluation of transverse strength requirements. Structural design procedures employing orthotropic rigidity coefficients in combination with either the solution to the above differential equations or a modified membrane theory, have been outlined by the author.
This thesis document was issued under the authority of another institution, not NPS. At the time it was written, a copy was added to the NPS Library Collection for reasons not now known. It has been included in the digital archive for its historical value to NPS. Not believed to be a CIVINS (Civilian Institutions) title.
Showing items related by title, author, creator and subject.
Giraldo, F.X. (2001);The spectral element method for the two-dimensional shallow water equations on the sphere is presented. The equations are written in conservation form and the domains are discretized using quadrilateral elements obtained ...
Cosmological models with weakly turbulent fluctuations of the metric superimposed on a homogeneous and isotropic background metric Jackson, John Philip (Monterey, Calif. : Naval Postgraduate School, 1972);Uniform and isotropic mathematical models of the expanding universe usually predict an initial singularity of infinite mass density and space curvature. To study possible mechanisms which would avoid the occurance of ...
Danielson, D. A. (Donald A.) (Monterey, California. Naval Postgraduate School, 1988); NPS-53-88-003The subject of this paper is the buckling behavior of thin bar stiffeners attached to plates which are subjected to normal pressure loadings. The stiffeners are mathematically modeled by a nonlinear beam theory recently ...