INTRODUCTION 



A preliminary hull design for an oceanographic vehicle intended for 

 operation at 15, 000 ft was submitted^ to the David Taylor Model Basin by 

 the Bureau of Ships for evaluation and recommendation for possible re- 

 design, if this proved necessary. A web-stiffened sandwich cylinder with 

 a weight-displacement ratio of approximately 63 percent, to be fabricated 

 of a-titanium having a yield strength of 120, 000 psi, constitutes the basic 

 hull design. The nninimum specified design collapse pressure is 10,000 

 psi. A schematic of the proposed design is shown in Figure 1 . 



The Bureau of Ships preliminary design was arrived at by using an 

 engineering-type analysis based primarily on previous test results of web- 

 stiffened sandwich cylinders; however, these cylinders were intended for 

 a collapse depth of about 6000 ft. A description of this procedure is out- 

 lined in the next section of this report. 



To evaluate the static strength of the proposed hull design, five 

 structural models were designed and tested to collapse under external 

 hydrostatic pressure. Two of these models were one-diameter-long cylin- 

 ders fabricated from HY-100 steel plating which was available at the time. 

 Three other models were machined from bar stock of titanium alloy; one 

 model was one diameter long and two models were four diameters long. 



In this report, construction details of the models are presented, the 

 test procedures used are described, the experimental and the theoretical 

 strength data are compared, and certain extrapolations are ventured as 

 to the structural behavior of the prototype hull. 



DESIGN AND DESCRIPTION OF MODELS 



Three different designs of a web-stiffened, sandwich-type pressure 

 hull were investigated. The titanium hulls were designed to have the same 

 weight, the same outside diameter, and the same design collapse strength 

 (10,000 psi) for the fabricated prototype structure. Figure 2 shows the 



References are listed on page 35. 



