Photoelastic Analysis of Undersea Structures

Stress distributions in sphere-cylinder transition regions of externally pressurized thick-walled vessels are studied. Data determined by two different approaches, photoelasticity and finite element computer programs, are compared. These approaches afford a capability for analyzing complicated deep ocean structures that are of considerable interest to the U.S. Navy. Two small-scale epoxy models of the prototype structures were loaded by external pressure and stress frozen. The first model had a cylinder radius-to-wall thickness ratio = 8 and incorporated 60% balanced opening reinforcement at the transition. The second had a cylinder radius-to-wall thickness ratio of 2.5 and 65% balanced reinforcement. After stress freezing, tie models were sliced longitudinally and transversely; meridional and circumferential stresses were determined photoelastically in a diffused-light polariscope. The experimental solutions verified stresses calculated by finite element computer programs.