Stachiw 



tion in the liull required for man-sized hatches or windows, while 

 the 8° size insert simulated an electrical wiring or hydraulic 

 piping feed-through on an underwater hull structure of ten to 

 twenty feet in diameter with personnel transfer capability. The 

 most rigid inserts selected were made of steel, while the least 

 rigid inserts were made from polyvinyl chloride plastic; other 

 inserts used were made from aluminum. During the hydrostatic test- 

 ing to destruction of the insert-equipped models, strains were 

 measured around the inserts and compared to strains existing in 

 the same sphere away from the penetration inserts. In such a 

 manner some quantitative measure of the stress concentration factors 

 produced by inserts of different rigidities could be obtained. The 

 comparison of the critical pressures of insert equipped spherical 

 hulls with the critical pressures of identical hull without any 

 penetrations would also be indicative of the effect that penetra- 

 tion inserts have on the overall strength of the spherical concrete 

 pressure hull. 



PHASE III - The design, fabrication, and testing of the 

 spherical habitat model had as its objective proving the feasibil- 

 ity of concrete pressure hulls with usable windows, hatches, and 

 wire feed-throughs for 3500 foot depth service. This concrete 

 habitat model could be considered a typical example of first gener- 

 ation concrete habitats for ocean bottom location. The concrete 

 hull model dimensions, concrete mix composition, and method of 

 casting was selected to be the same as in the previous phases of 

 concrete spherical hull feasibility study. 2 in this manner, the 

 critical pressure of the model with penetrations reinforced by 

 flanges could be directly compared to the critical pressure of 

 models without penetrations. The difference between the critical 

 pressure of the working model and of the concrete spheres without 

 penetrations would serve as a quantitative indicator of hull 

 strength decrease due to use of the particular type of window, 

 hatch, and feed-through flange designs. 



The pressure hull for the ocean bottom habitat was conceived 

 as a monocoque concrete sphere resting on an aluminum cradle 

 supported by three pad equipped legs. Three large window assem- 

 blies placed around the circumference, and one located at the 

 bottom of the sphere would permit television or photographic ca- 

 meras to observe and record the behavior of ocean floor, hydrospace, 

 and its inhabitants. To make the habitat adaptable to different 

 missions, it could be selectively equipped with an array of spe- 

 cialized subassemblies, fitting into typical large window penetra- 

 tions. Such subassemblies, in the form of windows (Figure 8), a 

 glass observation dome (Figure 9), diver transfer chamber, vehicle 

 transfer hatch, or oceanographic instrument tower would make the 

 basic concept of the concrete ocean bottom habitat adaptable to 

 an almost unlimited number of mission requirements. The only re- 

 quirement that would apply to all of them was that their mounting 

 plates fit the penetration opening, and that the plate bearing lip 

 matches the bearing lip on the penetration flange. In order to 



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