Periodic overloads have shown pronounced improve ments in the fatigue endurance of wire rope, typicall;y limited in servi~e use to loads one-fifth of static breaking strength. This enhanced life is attributed to overload crack retardation and to readjustment-or stresses within the rope by movement of contact points between wires during overloads. The optimum overload is thought to be that which just begins to result in rope yield. To optimize rope life one must also look at number of overload cycles, frequency of overload application and rope material and construction as well.
Ballistic evaluations of beryllium, beryllium-Doron, alumina-Doron and alumina-beryllium-Doron were conducted with caliber 0.22inch and/or caliber 0.30-inch missiles at normal incidence. Fhe areal densities of the targets extended from 1.5 to 10 lbs/ft. The beryllium-Doron composites exhibited excellent fragment armor characteristics while the alumina-Doron composites provided outstanding protection against a single hit type impact by an AP-M2 projectile. The three-phase composite exhibits an improved ballistic limit over either of the two-phase composites at the same areal density against caliber 0.30-inch projectiles. Variations in target composition, structure and support had little if any effect upon the ballistic limit velocities determined on the alumina-Doron composites except that a minimum thickness of about 0.25 inches of alumina is required to cause sufficient core blunting and breakup of the AP-M2 projectile to result in a good armor.
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