Bending complex curved steel plates for constructing ship hull has long been a challenge in shipbuilding industry. This paper presents a novel incremental bending process to obtain complicated curved steel plates by a series of sequential and layered punches. Taking advantage of this process, the blank plate that is fixed and held by a flexible supporting system can incrementally be bent into the target shape by a press tool along a planned tool path step by step and layer by layer. Acting as a “lower die,” the flexible supporting system can provide flexible and multifunctional supports for the work piece during the forming process, whose four general motion modes are demonstrated in this paper. Meanwhile, the procedures of tool path planning and forming layering are also explained in detail. In addition, aiming at different motion modes of the flexible supporting system, two springback compensation methods are given. Furthermore, according to the forming principle presented in this paper, an original incremental prototype equipment was designed and manufactured, which is mainly composed of a three-axis computer numerical control (CNC) machine, a flexible supporting system, and a three-dimensional (3D) scanning feedback system. A series of forming experiments focusing on a gradual curvature shape were carried out using this prototype to investigate the feasibility and validity of this forming process.

A new design for a urethane cylinder is presented which exhibits very high energy absorption for a given maximum compressive force and for a given amount of urethane. These characteristics are obtained by altering the buckling response of the cylinder by casting in place equally spaced annular steel rings along the cylinder’s length and by introducing a small concave curvature to the cylinder’s walls. This geometry has been analyzed using nonlinear finite element analysis and confirmed with experiment for up to a 50 percent decrease in the cylinder’s original length. The comparison between theory and experiment is good.

The simple exponential capstan equation relating output tension to back tension is valid for most cable applications. However, when the capstan is small and the back tension is low, the bending resistance of the cable reduces its conformity to the capstan, and thereby reduces the effectiveness of the capstan. The conditions under which a cable will not conform to a capstan are worked out. These conditions can be expressed as a minimum back tension required for the capstan to work. Two applications are considered. For a typical coaxial cable on the ship cable machine at a back tension of 5000N (1124 lbf), the effect of bending resistance is negligible. For a different cable on a captain-pair at a back tension of 100N (22.5 lbf), the effect is important. The equations used here are also applicable to other cases where a cable is pulled and bent.

An axial flow hydraulic transmission is being investigated when using such a transmission in conjunction with ship propulsion driving a propeller. The investigation covers the procedure to discern the theoretical and predicted operating points for an axial flow hydraulic transmission. Theoretical performance characteristics of the primary and secondary units are determined and actual performance is predicted based on design and fluid losses. The performance curves of each component are then overlayed, and the intersection of these curves represents the transmissions’ operating point. Since actual performance curves are highly non-linear, graphic representations provide the best way to predict actual operating points.

Vibration isolators of machines installed on ships are subject to both dynamic forces involved with the working of these machines and inertia forces resulting from the rolling of the ship. In order to illustrate this better, a solution of the vibration equation of a single mass system has been analyzed, the system being excited simultaneously by a dynamic force and a motion of foundation. It has been found that the larger the ratio of rotation speed is to natural frequency of vibration, the larger is the relative displacement of a machine mounted on vibration isolators. To obtain as small as possible a value of this ratio it might be necessary to use “hard” isolators, but such a solution is not one of the best, because forces transmitted to the foundation would then be larger than the dynamic forces causing the vibration of this machine. Thus the author recommends employing “soft” isolators, on condition, however, that the frequency ratio mentioned previously be chosen such that the elastic deformation of the isolators be within allowable limits.

This study deals with the development of an orientation device that enables the working diver to control and maintain automatically his spatial orientation underwater. The device can be useful during welding or grinding of ship hulls, salvaging operations, and any underwater activity when a specific special orientation improves the diver’s performance. The device utilizes the natural forces of buoyancy and gravity in its operation to reduce the power requirements and to assure stable performance. Underwater evaluation of an optimally designed prototype of the system shows good potential for the device as a useful tool for the working diver.

Assessing the impact of Navy shipboard sanitary waste discharges within the contiguous zone of the United States requires generation of data, not available so far, on the dispersion and fate of pollutants from shipboard sources. To generate data applicable to the 3–12-mi coastal zone, studies were conducted by the Naval Ship Research and Development Center using Naval facilities in the Norfolk, Va. area. Controlled releases were made of sanitary waste water and tracer dye mixtures. Dispersion of waste/dye patches was monitored through aerial reconnaissance, precise radio-navigational information, and seawater sample collection. It was demonstrated that pollution from controlled releases of sanitary waste can be detected above background concentrations for a brief span of time using conventional methods for determining effluent water quality (5-day biochemical oxygen demand, total suspended solids, ammonia-nitrogen, total acid-hydrolizable phosphate, coliform bacteria). A mathematical model for the dispersion of pollutants discharged from ships in the coastal zone was developed from these data. An assessment was then made of the concentration of pollutants after discharge from Navy ships during normal operation. Seawater samples were collected from the wakes of ships in transit and from the water around ships anchored for an amphibious operation in the coastal zone. It was determined that pollutants discharged from the transiting ships were not measurable above background concentrations, and only slight coliform bacteria population increases were detected in the amphibious operations area. These increases were still well within those prescribed as safe for bathing beaches and fisheries. Findings of this study specifically refer to the Navy ships and the geographic locations involved. They may be used for estimating effects of sanitary waste releases by non-Navy ships and in other areas.

The inclined pipeline is modeled as a Bernoulli-Euler beam with an initial static deflection due to self-weight, end loads, and external drag forces. Pipeline stability and transient responses are determined for a constant flow rate suddenly imposed on the contained fluid mass. Effects of the following dimensionless system parameters are studied: ratio of pipe mass to contained mass; ratio of flow frequency to a reference pipeline frequency; axial loads including line pressure, self-weight and added weight; external drag and linear, viscous damping. Results can be used in the design of oil-conveying pipelines and of dredge pipes used to convey mineral deposits to ships from the ocean floor.

Data acquired in the years 1958 to 1960 at the Naval Ship Engineering Center under sponsorship of the American Society of Mechanical Engineers are used to derive semiempirical equations for the performance of two variable area meters with both liquid and gas flow. As the measurements are put to a useage for which they were not intended, the data treatment is considered illustrative of the application of a flow equation derived by an analysis based upon a force and momentum balance. The hydraulic flow coefficient is expressed in terms of a function of (a) pressure drop divided by float weight and of (b) a dimensionless length ratio β for float position. Density ratio is used to modify the function of β to derive the expansion factor Y for gas flow as suggested by the analysis. Reasonable agreement between measured and derived values of Y is demonstrated, and approximate measures of the velocity profiles in the meter are derived from the correlation equations. One set of air tests at one float position in which the viscous influence number N was changed from 500,000 to 783,000 indicated (within this range) a possible insensitivity of the derived function of β to change of N.

User demands for higher performance from today’s clamshell unloaders have led to a critical examination of the operator himself. In order to reduce dependency on this unpredictable individual, it becomes desirable to automate the unloading cycle as much as possible to achieve maximum efficiency. This paper discusses some of the computer simulation which has been done to determine an automated cycle, and the electrical controls involved in implementing the automation.

A major construction program, including a computerized automatic control system, was initiated to improve the ore handling and ship docking facilities at Sparrows Point. Although the basic concept for the handling of ore has not changed, many innovations have been implemented.

Underwater plate vibration and its associated noise are of interest for the analysis of ship structures, propeller blades, and other areas of underwater acoustics. In order to analyze the relationship between a plate vibrating underwater and the acoustic pressure in the near-field, optical interferometric holography, using a blue-green laser beam, was used to determine surface displacement for the vibrating plate, which was excited through a fluid-coupled system. Acoustic measurements of the same source were made in a water tower concurrently with the holography and later at a precision acoustic testing facility. This method permits prediction of underwater plate modal frequencies and shapes with high accuracy.

Recent increases in bulk material tonnage being transported throughout the world are requiring the planning of many new ship and barge unloading installations, as well as the renovation and updating of a number of existing facilities. For many years, the clamshell unloader has been the heart of the typical unloading facility, and in spite of new unloading techniques, it will continue to play a major role in years to come. Since today’s high performance, high capacity unloader can represent an investment of several million dollars, it is important that the operation of this machine be well understood and appreciated by all those involved. The purpose of this presentation is to discuss the various types of reeving systems that are available, their major advantages and limitations, and the features that are essential to any system to insure smooth and trouble free operation.

The S 3 semisubmerged ship concept consists basically of two parallel torpedo-like hulls, submerged to a depth of about two diameters and attached to an above-water platform by means of four vertical struts. Horizontal fins and control surfaces attached to the hulls provide dynamic stability and permit full automatic control over pitch, heave, and roll. The anticipated advantages of the S 3 over conventional ships are greatly improved seaworthiness, high-speed potential, large internal volume and deck area, controllability, and many aspects of its unusual hydrodynamic form. The S 3 concept appears to be most applicable to small ships (100 to 15,000 tons) having missions associated with the use of sonar—the handling of aircraft, weapons, or submersibles—and for missions requiring a high degree of seaworthiness and stability.

The transmission of sound and vibration through structures is of interest in many noise control problems, including architectural acoustics, sound transmission through aircraft, spacecraft and ships, and the transmission of noise through machinery and engine enclosures. Statistical energy analysis provides a simple and accurate method of approaching these problems. In this paper, theory is examined for the transmission of acoustic energy through single panels, independent double panels, and double panels connected with tie beams. In the single panel case, the theoretical model consists of three linearly coupled oscillators; room-panel-room. The independent double panel case consists of five oscillators; room-panel-cavity-panel-room. In the connected double panel case, the tie beams must be accounted for as the sixth oscillator. A coupling loss factor is determined for the ties by considering the transmission of longitudinal waves, bending waves, and lateral shear waves in the ties. Both resonant and nonresonant transmission are included in the theory. It is shown that for a single panel, the experimental sound transmission loss, panel radiation resistance, and vibration amplitude are all well predicted by the theory. The experimental sound transmission loss is also well predicted in the independent double panel and coupled double panel cases.

An equation of motion for a drill string, considering elastic, dynamic, and drag forces, is derived. This equation is then applied to two types of drill-string behavior; i.e., a beam having constant axial tension and a perfectly flexible cable under variable tension. A drill string is then synthesized by subdivision into short beam sections at the top and bottom, joined by a flexible cable in the center. The lateral deflection of the drill string is obtained by joining the beam and cable solutions, subject to boundary conditions at each junction. The drill string is considered built-in at the ocean floor and is displaced harmonically at the surface by the ship. An example is discussed and results are compared with experimentally measured values. The effect of roll will be considered in a subsequent paper; as the governing equations have been linearized, these solutions may be superimposed.

An equation of motion for a drill string, considering elastic, dynamic, and drag forces, was derived in a previous paper and was applied to two types of beam behavior: A beam having constant axial tension and a perfectly flexible cable. A drill string was then considered as consisting of short beam sections at the top and bottom, joined by a perfectly flexible cable. The lateral deflection of the drill string was obtained by joining the beam and cable solutions subject to boundary conditions at each junction. In this paper, the drill string is considered built-in at the ocean floor and to be experiencing a harmonic change of slope at the ocean surface imposed by roll (or pitch) of the ship, the ship remaining stationary vertically above the point of entry at the ocean floor. Examples are discussed and results are compared with experimentally measured values. The combined effects of roll and displacement are obtained by superposition of the two solutions.