Front cover image for Flanged Acrylic Plastic Hemispherical Shells for Undersea Systems

Flanged Acrylic Plastic Hemispherical Shells for Undersea Systems

The effects of an equatorial flange and a nonuniform wall thickness upon the critical pressure and stress distribution in acrylic plastic hemispheres were investigated by experimental and analytical methods. Forty acrylic hemispheres were fabricated and tested to destruction under short-term hydrostatic pressure applied on the convex surface. Dome apex displacements were obtained from each specimen and strains were obtained from a selected few. A finite-element elastic analysis was performed on one window configuration for two different boundary conditions and the experimentally derived stresses were used to determine which assumed boundary condition was best for analysis. It appears that in acrylic plastic hemispheres with t/R sub i = or <0.200 an integral equatorial flange has no deleterious effect on the critical pressure of the hemisphere. Reduced wall thickness at the apex, however, significantly reduces the critical pressure of flanged and flangeless hemispheres. Critical pressures of hemispheres with varying wall thickness correlate well with the mean wall thickness. Axial displacements of the apex under hydrostatic loading were found to be approximately of the same magnitudes for both flanged and flangeless shells of constant thickness. The displacements of flanged shells with variable thickness were significantly higher than of flanged shells with constant thickness when the comparison was made at the same nominal t/R sub i ratio. (Author)
Print Book, English, SEP 1973
Defense Technical Information Center, Ft. Belvoir, SEP 1973