Unclassified 



DOCUMENT CONTROL DATA -R&D 1 



(St-ctinly rifliaifirafion ol liltc. body of ,i6sfr/irf ond indexdifc' .tnnolt^lion niu^l be entered wlien the overall report rs rf.iisified) | 



t ORIGINATING 4 c T 1 V 1 T Y (-Corpofaf e au fhorj 



Naval Civil Engineering Laboratory 

 Port Hueneme, California 93041 



Unclassified 



26. GROUP 



STRUCTURAL DESIGN OF CONICAL ACRYLIC VIEWPORTS 



4. DESCRIPTIVE NOTES (Type ot raport and inctumivo dmtea) 



Final; April 1967-April 1969 



9 A>j THORl» (FIrtI nmirte, mitldit Inlllml, /••! >iam«; 



M. R. Snoey and M. G. Katona 



June 1970 



57 



14 



„. PROJECT NO YF 38.535.005.01.005 



d. 



TR-686 



9b. OTHER REPORT NOISJ (Any Other r^untbora th»t may bo aaslgned 

 this report) 



This document has been approved for public release and sale; its distribution is unlimited. 





Naval Facilities Engineering Command 

 Washington, D. C. 20390 



The purpose of this report is to establish a rational engineering approach for the design of 

 conical acrylic viewports. To achieve this goal, a time-dependent, yield-failure criterion was devel- 

 oped and utilized in the analysis of a variety of viewport configurations. Specifically, a range of 

 thickness/minor diameter (t/d) ratios from 0.25 to 1.75 and included angles from 60° to 120° 

 were analyzed by the finite element technique. Using the viewport structural analysis in con- 

 junction with the yield-failure criterion for acrylic, time-dependent operating depths were 

 determined as a function of viewport configuration. 



Paralleling the above, an experimental investigation was performed to validate the analytical 

 results. Six full-scale viewports were tested for a year under simulated operational conditions that 

 included simultaneous cycling of pressure and temperature, to 4,000 psi and 70 to 35°F, respec- 

 tively. 



Comparison of analytical and experimental results indicated excellent agreement for the 

 physical location of viewport failure at specified loading histories. 



Design recommendations are presented in the form of design curves which enable the design 

 of a conical acrylic viewport for a specified operating pressure and duration under load. To com- 

 plete the recommendations, design information is given also on sealing with a conventional O-ring, 

 as well as guidelines for elevating a viewport in its flange. 



DD 



e,1473 



S/N 0101.807.680 1 



Unclassified 



irilv Classificatic 



