An analytical method is proposed for determining wave impact "slamming" pressures on all types of ship hulls including advanced vehicles that may travel at speeds up to 100 knots and even higher speeds. The method is based on the Wagner wedge impact theory, the Chuang cone impact theory, and experiments performed at the David W. Taylor Naval Ship Research and Development Center. Determination of the impact pressure is based on the hypothesis that the impact velocity is equal to the relative velocity normal to the impact surface of the moving body and the wave surface. The proposed method has been verified by several model tests in waves and by actual ship trials of the catamaran USNS Hayes. Computer programs are included for the practical use of the method.

Reliability of structures is an overriding consideration in the design of high-performance, weight-critical ships which require design with new materials having high strength-to-weight ratios. These high-strength materials can be susceptible to catastrophic failure in the presence of small flaws, such that the initiation and propagation of cracks by cyclic loading of the structure is of the utmost concern. Techniques for dealing with these problems, as they relate to structural reliability, are discussed, and the close relationship between problems of high-performance ships and aircraft is examined. The current need to rely on large-scale validation testing of vehicle structure and structural details is examined, with particular attention to the requirements for high-performance ship structures."Air Cushion Vehicles have an inherent over-the-beach capability that makes them extremely well suited for amphibious assault or possibly Arctic over-the-ice roles." Rear Admiral N. Sonenshein, former Commander, Naval Ship Systems Command [1].5"Hydrofoils are best suited for high-speed, all-weather missions, such as patrol and interdiction. The demonstrated ability of PCH and the PGH's (Patrol Craft Hydrofoil and Patrol Gunboat Hydrofoil) to maintain speed in extremely high sea states is a proven accomplishment." [1]."To go to the SES (surface effect ship, with rigid sidewalls), the exact mission for these have not been defined because this is new technology" [1]. However, Admiral Elmo R. Zumwalt, former Chief of Naval Operations, has proposed the hard sidewall surface effects vessel that can travel at 80 knots to serve as a small aircraft carrier. A small (2000 ton) SES also offers a platform which could be developed in greater numbers to perform a portion of the ASW surveillance mission [2]. The PURPOSE of this paper is to review the fatigue and fracture aspects of today's ship, submarine, and aircraft structures and, through lessons learned, project the technical needs from these experiences to the design of future high-performance surface ships. The paper synthesizes the overall technical considerations of fatigue and fracture requirements for ships and aircraft structures for the benefit of designers and research managers, and suggests to research scientists areas needing additional research effort. Major attention is given to the application of submarine and aircraft materials and structures technologies to advanced high-performance ships. These structural performance requirements are consolidated in terms of a ‘hull-subsystem’ to (a) relate the structural subsystems to total system program managers, (b) acquaint these system managers with the structural validation tests necessary to assure design of reliable ships for the new types of service called upon by today's commercial and military demands, and (c) make them better aware of available technology and facility resources relevant to validation of structural performance.

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A comprehensive U.S. Navy Development Program is underway to establish a sound and reliable technology base for aluminum ship structures. Central to this effort is an 85‐foot long, 17‐ton Aluminum Ship Evaluation Model (ASEM) which represents approximately a one‐third scale structure model of a conceptual all‐aluminum Destroyer Escort designed by the Naval Ship Engineering Center. The overall approach taken to develop this technology base for aluminum ships is basically similar to that employed in the aircraft structures field over the last two decades, i.e., systematic testing of large‐scale structural components under simulated service loading. Underlying considerations for the design and test of the large‐scale Structural Ship Model (the ASEM) me presented with details both for the static testing and the simulated life‐cycle fatigue testing of this Model. Rational design loads applied to the ASEM were based upon 80% of the highest significant wave for the static tests and on wave spectra expected in 20 years of operation in the North Atlantic for the fatigue tests. Results expected from this overall effort include vurious Mannuals for design, fabrication, inspection, and surveillance and repair of aluminum ship structures. These results are intended to provide a mechanism for technology transfer to industry so that a sound and efficient industrial base will be established for the construction and operation of aluminum ships.