ABSTRACT 



The potential of glass as a hull material for hydro- 

 space vehicles was investigated by determining the hydro- 

 static strength of 20 long cylinders of No. 7740 glass. 

 The experimental collapse pressures, which ranged between 

 2000 and 15,000 psi, were in excellent agreement with 

 classical theorj- for elastic buckling of long cylinders . 

 Calculations were based on minimum measured thicknesses . 

 Although all failures appeared to initiate in the elastic 

 buckling range, maximum circumferential, stresses of about 

 100,000 psi were reached. This high strength coupled with a 

 relatively low weight makes glass appear very attractive for 

 some deep-depth applications. Although these tests were con- 

 ducted on long unstif fened cylinders , calculations indicate 

 that glass spheres have a potential- of demonstrating higher 

 strength-to-weight ratios than is attainable by aiw other 

 tjT^e hull using currently available material-S. 



INTRODUCTION 



Anticipating a future requirement of deep-depth capability for 

 underwater vehicles, the David Taylor Model Basin, in 1957, initiated a 

 limited fundamental research program to investigate structures to 

 operate at great depths. The program was divided into two phases, one 

 in which new hull shapes were considered and one in which new hull 

 materials were investigated. Although the limited program was initial-ly 

 sponsored under Project S-ROll 01 01, considerable exploratory work has 

 also been accomplished under direct sponsorships of the Bureau of Ships 

 and the Office of Naval Research. 



Research in the area of hull shapes has been conducted both ana- 

 lytically and experimentally. The material studies have normal.ly 

 involved tests of small models as new materials become available. 

 The analytical and experimental studies of new structural shapes and 

 configurations have dealt with sandwich, composite, multilayer, and 

 membrane cylinders, and oval, spherical, and spheroidal shells. Model 

 studies have been conducted on cylindrical, hulls of HY-150 to HY-220 steel, 

 HY-120 to HY-200 titanium alloys, HY-60 to HY-80 aluminum alloys, and 

 Fiberglas-reinforced plastics with yield strengths of 7 5,000 psi and 

 greater. In addition, cylinders of plastics with reinforcement other 

 than Fiberglas are currently being considered. 



