SYNTACTIC-FOAM, FILAMENT-WOUND COMPOSITE PRESSURE HULLS.

External hydrostatic pressure tests were conducted on 12 fiberglass filament-wound cylinders, each 12 in. long with an ID of 5 in. Six of these had a wall thickness of 0.210 in., designed to fail by buckling at 2000 psi the other six had a wall thickness of 0.305 in., designed to fail by buckling at 5000 psi. Three of each type were covered with an external coating of INLYTE a buoyant syntactic foam previously developed by the contractor in an effort to stabilize the G. R. P. against buckling. The syntactic foam density was 44 lbcu. ft. The six uncoated cylinders were used as controls. Long cylinders of fiberglass exhibit collapse characteristics under external hydrostatic pressures. The compressive stresses are not developed to their full potential. The tests were conducted to determine if a coating of syntactic foam would stabilize the units to allow more efficient use of the compressive stress. Conclusions By coating cylinders with a layer of low-density syntactic foam, such as INLYTE, the unit is stabilized in the buckling mode, and a great increase in strength is achieved before rupture from externally-applied hydrostatic pressure. Also, the buoyancy of the composite structure is significantly increased. Author