Experimental stress analysis of model of emergency forebody release device used in deep diving research submarines Alvin, Sea Cliff and Turtle

Originally issued as Reference No. 69-68, series later renamed WHOI-Technical Reports

Submitted to the Office of Naval Researchunder Contract Nonr-3484(00); NR 260-107.

Tests were conducted on a full-scale model of the emergencyforebody release used in the deep-diving submarines ALVIN, SEA CLIFFand TURTLE. The model was machined from metal to the same dimensionaltolerances as the prototype. Resistance strain gages, attachedto the model, permitted measurement of forces on component parts ofthe device. Of primary concern was the bending stress which mightbe set up in the release operating shaft when the submarine is submergedin an inclined position. Tests were arranged to simulate three possibleconditions of loading of the release device at a 30 degree vehicle listangle: case (1) righting moment of inclined forebody resisted by release components only; case (2) righting moment resisted by releasewith assistance from lower guides; and (3) righting moment resistedby couple set up by release and rubber support ring. Test results show that shaft bending stresses (for ALVIN) are high (200,000 psi)for the case (1) condition, lower (400,000 - 90,000 psi) for case (2)and essentially zero for case (3). The conclusion is that the presentforebody release design is adequate for all submarine attitudesencounteredin normal operation, provided the vehicle has been assembled sothat contact between sphere and rubber ring is assured at all times.