Remotely Operated Underwater Vehicles (ROV) currently have been utilized for scientific and commercial applications. Many industries are involved in developing robots in order to reduce human effort as well as increase productivity, efficiency, and monitoring. That said, the need to optimize the cost for design of ROVs became popular. In the present work, a simplified design procedure of a low cost-light-weight ROV is proposed. The design overview includes a description of the three thrusters operated by bilge pump electric motors. The ROV contains only a camera, an IMU and a GPS sensor. The ROV is wired to a control station that is equipped with a screen with a GUI, a joystick and a keyboard to monitor and control the ROV. The design is optimized to achieve a neutral buoyancy force in order to reduce the stabilizing effort during operation, hence reducing energy consumption. The drag force, lift force, drag center, lift center and fluid velocity contours are predicted using a CFD tool. Dynamic analysis including thrust and drag forces in longitudinal, vertical and yaw directions of motion are investigated to facilitate selection of the prime movers. Finally, the control strategy and electrical system description is presented. The proposed methodology proved that a satisfactory performance with an optimized design is achievable. The ROV design presented could be used in quick and low cost inspection of ships.

In the preliminary design of merchant ships, shipbuilders generally modify some of the standard specifications to fulfill shipowner needs, which is time-consuming owing to the complex techno-economic constraints of ship design. Therefore, an appropriate standard specifications formulation method is necessary to improve the efficiency of the preliminary design. In this study, we performed genetic algorithm-based clustering to determine the subtypes of a specific type of merchant ship and formulated the standard specification for each subtype. To demonstrate the effectiveness of the proposed method, experiments were performed using 98 specification documents to formulate the standard specifications. The results showed that feature relations among each determined subtype were significantly simpler than those of the main type; thereby, the formulated standard specifications were desirable in the preliminary design of merchant ships.

Optimal 3D spatial packaging of interconnected systems with physical interactions (thermal, hydraulic, electromagnetic, etc.), or SPI2, plays a vital role in the functionality, operation, energy usage, and life cycle of practically all engineered systems, from 3D chips to ships to aircraft. These highly-nonlinear SPI2 problems, involving tightly constrained component packing, governed by coupled physical phenomena transferring energy and material through intricate geometric interconnects, have largely resisted design automation for decades, and can quickly exceed human cognitive abilities at even moderate complexity levels. Existing design methods treat the pieces of this problem separately without a fundamental systems approach and are sometimes too slow to evaluate various possible designs. Hence, there exists an emergent need to develop efficient SPI2 design automation frameworks for two reasons: 1) to enable the rapid generation and evaluation of candidate SPI2 design solutions; and 2) for the development of newer complex engineering systems. In this paper, the holistic 3D-SPI2 design problem with its attributes is defined, previous research efforts in various individual SPI2 related areas are reviewed, some existing critical gaps are outlined, and associated challenges are identified. Finally, a vision for fundamental research in SPI2 design based on the authors’ experience in this topic is presented through a set of new exciting opportunities at the intersection of several engineering domains.

An expert system is developed for engineering design based on object-oriented knowledge representation concept. The design process is understood as determining design variables and their relationships which compose design model. The design model is represented as a network in the computer system using the object-oriented knowledge representation. The system built with the above concept provides the following abilities: 1) flexible model building and easy modification, 2) effective diagnosis of the design process, 3) supporting method for redesign, 4) a hybrid function with numerical computations and graphics, and 5) applicability for various design problems. Finally, it is applied to the basic design of a ship.

Dynamic frequency response of mechanical and structural systems is of interest in design problems that are subjected to harmonically varying external loads caused by the reciprocating power train or other rotating machineries such as motors, fans, compressors, and forging hammers [1]. For example, airplane body and wing structures are subjected to a harmonic load transmitted from the propulsion system. Also, ship vibrations resulting from the propeller and engine excitation can cause noise problem, cracks, fatigue failure of tailshaft, and discomfort to crew. When a machine or any structure oscillates in some form of periodic or random motion, the motion generates alternating pressure waves that propagate from the moving surface at the velocity of sound. For instance, the interior sound pressure in an automobile compartment can occur when the input forces transmitted from road and power train excite the vehicle compartment boundary panels. These motions with frequencies between 20 Hz and 20 KHz stimulate the hearing mechanism of human [2].

This paper discusses the development of a set of algorithms for the automatic nesting of ship/offshore structural plates. The algorithms are developed to take advantage of the peculiarity of most ship/offshore structural plates with the aims of optimising material usage and minimising computer search time. The parts to be nested are first processed by a shape processing routine which employs a simple feature extraction approach to classify the plates according to predefined rules specially adopted for ship/offshore structural shapes. The most appropriate search path for each class of plates is used to obtain the best enclosing rectangle for similar shapes. The search paths are based on heuristics developed to simulate the manual method used by the human operator. Finally, all the plates are laid out on the stock sheet using a “rectangle packing” approach. A computer package, Patnest-Ship was developed to demonstrate the efficiency of the algorithms and very encouraging results are achieved. The input and output files to and from Patnest-Ship are described in DXF format so that it can be integrated with existing CAD/CAM systems. Pre- and post-processors for this package have been implemented on AutoCAD to permit the user to define the plates and interactively improve on the solutions provided by Patnest-Ship, if necessary.

The loss of dynamic stability and the resulting large-amplitude roll of a vessel in a head or following sea were studied theoretically and experimentally. A ship model with three degrees of freedom (roll, pitch, heave) was considered. The governing equations for the heave and pitch modes were linearized and their harmonic solutions were coupled with the nonlinear equation governing roll. The resulting equation, which has time-varying coefficients, was used to predict the response in roll. The principal parametric resonance was considered in which the excitation frequency is twice the natural frequency in roll. Force-response curves were obtained. The existence of jump phenomena and multiple stable solutions for the case of subcritical instability was observed in the experiments and found to be in good qualitative agreement with the results predicted by the theory. The experiments also revealed that the large-amplitude roll is dependent on the location of the model in the standing waves.

The response of a single-degree-of-freedom system to a nonstationary excitation is investigated by using the method of multiple scales as well as analog- and digital-computer simulations. The unexcited system has one focus and two saddle points. The system can be used to model rolling of ships in head or follower seas. The method of multiple scales is used to derive equations governing the modulation of the amplitude and phase of the response. The modulation equations are used to find the stationary solutions and their stability. The response to nonstationary excitations is found by integrating the original governing equation as well as the modulation equations. There is good agreement between the results of both approaches. For some frequency and amplitude sweeps, the nonstationary response found from integrating the original governing equation exhibits behaviors that are analogous to symmetry-breaking bifurcations, period-doubling bifurcations, chaos, and unboundedness present in the stationary case. The maximum response amplitude and the excitation amplitude or frequency at which the response becomes unbounded are found as functions of the sweep rate. The results of the digital-computer simulations are verified with an analog computer.

In this work, global analysis of ship rolling motion as effected by parametric excitation is studied. The parametric excitation results from the roll restoring moment variation as a wave train passes. In addition to the parametric excitation, an external periodic wave excitation and steady wind bias are also included in the analysis. The roll motion is the most critical motion for a ship because of the possibility of capsizing. The boundaries in the Poincaré map which separate initial conditions which eventually evolve to bounded steady state solutions and those which lead to unbounded capsizing motion are studied. The changes in these boundaries or manifolds as effected by changes in the ship and environmental conditions are analyzed. The region in the Poincaré map which lead to bounded steady state motions is called the safe basin . The size of this safe basin is a measure of the vessel’s resistance to capsizing.

Responses of panel structures on board ships and aerospace systems under point and in-plane intensive transient excitations, originating, primarily, from near-mixed explosion and impact upon the ships are investigated and presented in this paper. The panel structures are idealized by finite elements while the intensive transient in-plane and point loads are modelled as nonstationary random processes. The latter are treated as products of modulating functions and Gaussian white noise processes. The focus of the paper is the comparison of results obtained by employing the three nodes, eighteen degree-of-freedoms (DOF) triangular bending plate element (the explicit element stiffness, mass and stability matrices of which have been derived by the authors) and the four nodes, twelve DOF Melosh-Zienkiewicz-Cheung (MZC) rectangular bending plate element. The isssues addressed are: (a) convergence and reduction of computational time by applying the eighteen DOF plate element in comparison to the MZC element, (b) the contribution of the in-plane nonstationary random excitation on the response of the discretized structures, and (c) the influence of the number of modes included in the response computation.

In this paper a new approach in the global transient analysis of nonlinear systems is presented; it has the advantages of being conceptually simpler and at the same time more relevant than one based soley on a stability analysis of the steady-state motions. We address the problem of analysing the global transient stability of nonlinear systems in terms of basins of attraction. We show that at a forcing level that is considerably smaller than that at which the steady state attractor loses its stability, there may exist a rapid erosion and stratification of the basin, signifying a global loss of engineering integrity of the system. This conclusion is reinforced by the fact that basin boundaries can become fractal , resulting in chaotic transients , adding a new degree of uncertainty in the response. The techniques developed are then applied to a ship roll model with cubic and quintic nonlinearities as well as linear plus cubic damping characteristics.

Flexible Computer Integrated Manufacturing (FCIM) technology existing today in industry, combined with modern repair processes, can be used to address erosion and corrosion inherent in submarine and surface ship fluid systems. Commander Submarine Force Atlantic Fleet (COMSUBLANT) will implement in the near future a Pump and Valve Repair System in the Trident Refit Facility (TRF), Submarine Base, Kings Bay, Georgia. The system will support the repair of submarine and surface ship components such as valve bodies, valve tailpieces, and pump casings. It will replace metal lost by erosion and corrosion using repair processes such as automated welding and epoxy spray and reliably return these components to original specification with computer numerical control (CNC) machining.

The DDG 51 Class of AEGIS guided missile destroyers is the Navy’s premier surface combatant. Named for famed World War II hero. Admiral Arleigh Burke, these ships represent state-of-the-art technology. This 504 foot, 8,300 ton destroyer has been designed with improved seakeeping and survivability characteristics and carries the sophisticated AEGIS Weapon System. Derived from the Greek word meaning “shield”, AEGIS ships are the “shield of the fleet”. The Navy has commissioned the first two ships of the class. They have performed beyond expectation in rigorous at-sea trials designed to fully test combat capability. The DDG 51 Class ships are replacing retiring fleet assets. In a decreasing Department of Defense (DoD) budget environment, however, acquisition costs must be reduced to continue to build capable warships. The Navy’s Destroyer Program Office is pursuing the implementation of Computer Aided Design (CAD) and Computer Aided Manufacturing (CAM) technology to reduce costs without reducing ship’s capability. Under Navy direction, the ship construction yards, Bath Iron Works and Ingalls Shipbuilding, are aggressively pursuing the transition to CAD-based design, construction, and life cycle support This effort also involves General Electric, the Combat System Engineering Agent. Building a three dimensional (3D) computer model of the ship prior to construction will facilitate the identification and resolution of interferences and interface problems that would otherwise go undetected until actual ship construction. This 3D database contains geometry and design data to support system design. Accurate construction drawings, fabrication sketches, and Numerical Control (NC) data can be extracted directly from the database to support construction at each shipyard. At completion of construction, a model representing the “as built” configuration will be provided as a lifetime support tool for each ship’s projected 40 year life. The transition to CAD-based design and construction has applied fundamental concepts of the DoD’s Computer Aided Acquisition and Logistic Support (CALS) initiative. In addition to creating a 3D database representing ship design, the shipyards have developed a neutral file translator to exchange this data between Computervision and Calma CAD systems in operation at Bath Iron Works and Ingalls Shipbuilding respectively. This object oriented transfer capability ensures data is shared rather than duplicated. The CALS concepts of concurrent engineering and computer aided engineering analysis are being applied to design an upgrade to the ship that features the addition of a helicopter hanger. The CAD models are used as an electronic baseline from which to assess proposed modifications. Optimizing the design before the first piece of steel is cut will reduce construction costs and improve the quality of the ship.

Nonstationary response of a two-degrees-of-freedom system with quadratic coupling under a time varying modulated amplitude sinusoidal excitation is studied. The nonlinearly coupled pitch and roll ship model is based on Nayfeh, Mook and Marshall’s work for the case of stationary excitation. The ship model has a 2:1 internal resonance and is excited near the resonance of the pitch mode. The modulated excitation (F 0 + F 1 cos ωt) cosQt is used to model a narrow band sea-wave excitation. The response demonstrates a variety of bifurcations, loss of stability, and chaos phenomena that are not present in the stationary case. We consider here the periodically modulated response. Chaotic response of the system is discussed in a separate paper. Several approximate solutions, under both small and large modulating amplitudes F 1 , are obtained and compared with the exact one. The stability of an exact solution with one mode having zero amplitude is studied. Loss of stability in this case involves either a rapid transition from one of two stable (in the stationary sense) branches to another, or a period doubling bifurcation. From Floquet theory, various stability boundary diagrams are obtained in F 1 and F 0 parameter space which can be used to predict the various transition phenomena and the period-2 bifurcations. The study shows that both the modulation parameters F 1 and ω (the modulating frequency) have great effect on the stability boundaries. Because of the modulation, the stable area is greatly expanded, and the stationary bifurcation point can be exceeded without loss of stability. Decreasing ω can make the stability boundary very complicated. For very small ω the response can make periodic transitions between the two (pseudo) stable solutions.

For ships, rolling motion is the most critical due to the possibility of capsizing. In a regular (periodic) sea, if no bounded steady state solutions exist, then capsizing may be imminent. Determining for exactly which wave amplitude and frequency the steady-state solutions disappear or become unstable is of great practical importance. In previous works (Falzarano, Esparza, and Taz Ul Mulk, 1994) and abstracted presentations (Falzarano, 1993), the global transient dynamics of large amplitude ship rolling motion was studied. The effect on the steady-state solutions of changing wave frequency for a fixed wave amplitudes was studied. It was shown how the in-phase and out-of-phase solutions evolve as the frequency passes through the linear natural frequency. For small wave amplitudes (external forcing) there exists a single steady-state throughout the frequency range, for moderate wave amplitudes there exists a frequency range where multiple steady state harmonic solutions exists. As the wave amplitude was increased further there existed a frequency range where no steady-state harmonic solution existed. In the present work, the very large amplitude ship rolling motion in the region where no steady-state solutions exist will be studied in more detail. Moreover, the mechanisms (bifurcations) that cause this type of behavior to evolve from more simple behavior will be studied using a combination of both frequency response curves and Poincaré maps. It is expected that global chaotic bifurcations such as those previously described (e.g., Thompson and Stewart, 1989) will be identified.

Reliability theory analyzes failure phenomena in systems, leading to maintenance and replacement schedules as well as risk assessment and other topics. Dynamic reliability takes into account the (possibly nonlinear) dynamics of the system and of the random excitation that may lead to failure. It is shown, how some of the concepts of reliability theory can be interpreted in the dynamical systems context. Analytical results are derived for failure probabilities, for life time distributions, asymptotic damage accumulation rates, and other relevant concepts. The Takens-Bogdanov oscillator and a model for ship roll motion are analyzed in detail, together with a thorough description of the numerical methods that are available for dynamic reliability studies.

The study of motion of ships or similar slender offshore structures in irregular seas has, in recent years, gathered sufficient interest due to the fact that experimental data and various approximate techniques are readily available, and that ship safety is a much more expensive issue. Central to the study is the problem of predicting ship rolling motion due to random waves. In this paper a method, employing the statistical non-linearization technique that was developed by the author, is applied to evaluate the joint stationary probability density of response of a model proposed by Roberts and associates for the analysis of nonlinear ship rolling in random seas. For small nonlinear damping and small intensity of excitation the result is identical to that obtained with the generalized stochastic averaging method of energy envelope presented earlier by the author.

A prototype concurrent design optimization tool, named CELS for Concurrent Engineering of Layered Structures, has been developed. This tool can be used to analyze and/or optimize the conceptual design of a composite panel for Naval ship topside structures. CELS integrates five technology modules: (1) electromagnetic interference, (2) radar cross section, (3) structures, (4) cost, and (5) weight. Two optimization methods drive the integration of the technology modules. These methods include: (i) a local optimizer based on feasible sequential quadratic programming, and (ii) a global optimizer based on an exhaustive search. To obtain an objectively balanced design, “goodness” measures are allocated for each objective or constraint function. These measures, via a graphical user interface, allow topside designers to easily and quickly assess the impact of their decisions on various technologies. The utility and capability of CELS are demonstrated via the design of a topside composite panel. The design study shows that CELS can be easily adapted to different topside conceptual design problems, and that design tradeoffs can be performed quickly and used in decision making.

The current trend of CAD system is to make the system intelligent. CAD systems need to be intelligent in the sense that they must be able to use knowledge to achieve the designer’s goal. In the early stages of ship design, more experienced and higher level knowledge is required rather than that of detail design. The existing CAD systems have several limitations in terms of satisfying the requirements of real design. Accordingly, a more powerful and capable CAD system is required to support the activities in the early stage of design. Recently the application of expert systems has been considered as a tool for extending the capability of existing CAD systems. In this paper, we present an approach to implement a practical knowledge-based system for the machinery layout design of a ship engine room. The knowledge-base is implemented and verified in the actual CAD environment of a ship engine room, named MADES, which we develop in this study. The approaches presented in this paper provide a practical example of a knowledge-based system for complex design problems, and can also provide guidance on implementing an integrated design expert system that extends the capability of existing CAD systems.

A multi-cylinder engine is a cluster of slider-crank linkages. Presently used conventional pure torsional shaft models predict results far from the results predicted considering actual three-dimensional linkage and crankshaft geometries. Pure torsional model doesn’t sense the variation in frequency with the variation in engine geometry. It predicts one constant frequency value for each mode; it does not permit the use of flexible bearings. Article offers a finite element method for performing frequency and critical speed analysis of multi-cylinder engines considering three-dimensional geometries of the linkage loops, crankshaft, and the crankshaft throws, as a spatial elastic mechanism system. Any number of cylinders in any angular orientations with respect to each other may be considered. A three-dimensional flexural finite-line element with isoparametric joint freedom irregularity is developed and used to formulate the eigenvalue equations of motion for the system. Consistent mass matrix as well as lumped mass matrix methods can be used. The element can be restrained to perform coupled torsional and flexural or pure torsional frequency analysis of geared rotor model of engines and shafts on many rigid or flexible bearings. Geared connections can also be considered flexible. A generalized computer program is made available for industrial use. It determines frequencies, mode shapes and critical speed bands of an engine for complete crankshaft rotation for as many modes as desired. The frequency and critical speed analysis of a four-cylinder MGB automobile engine with in-plane crank throws, with and without bearing flexibilities, is performed and the results are compared with those obtained using the conventional pure torsional shaft model. Geared tandem ship drive system is studied to test the reliability of the developments.