Adhesive Bonded Joint With Improved Cyclic Fatigue Life for Alumina-Ceramic Cylinders and Hemispheres. Fourth Generation Housings.

摘要

A series of 20-inch-diameter monocoque cylinders of 94-percent alumina-ceramic have been pressure tested to determine their structural performance under repeated pressurizations to 9,000 psi external design pressure when their ends are encapsulated in epoxy-filled Mod 1 titanium or aluminum end caps. Naval Ocean Systems Center (NOSC) Type Mod 1 titanium end caps provided an order-of-magnitude improvement in cyclic fatigue life for the ceramic cylinders over previously tested Mod 0 end caps. The cyclic fatigue life of 20-inch OD by 18.63-inch ID by 30-inch L by 0.685-inch t ceramic cylinders with 0.5-inch weight/displacement ratio, the ends of which were encapsulated with epoxy adhesive in Mod 1 titanium end caps, exceeded 400 cycles to 9,000 psi that generated inside the cylinder compressive membrane stresses of 136,000 psi magnitude in hoop and 68,000 psi in axial direction. At these stress levels, the shell of the monocoque cylinder can tolerate imperfections in the shape of spherical 0.063-inch) and oblong cavities (<= 0.063-inch by <= 0.187-inch) located below, or on, the shell surface, provided that they are at least two inches away from the ends. The payload-carrying ability of 94-percent alumina-ceramic monocoque cylinders with above dimensions is approximately four-times larger, then, of rib-stiffened titanium cylinders with the same external dimensions and pressure rating. Ceramics, External pressure housing, Ocean engineering.