Ship Deck Research Articles

DIE AKADEMIKUS SE PLEK IN DIE SAW

'Down the streets of Ponsmouth, more than a hundred years ago, walked a sailor with one arm, one eye, a persistent state of nerves and unable to tread a ship's deck without being seasick. Indeed he would probably have been in a home for incurables, were not his name Admiral Lord Nelson. The man's spirit drove the flesh. '

Experimental and numerical analysis of container stack dynamics using a scaled model test

This paper describes an approach to simulate a seven-tier stack consisting of scaled model of a 20 ft ISO freight container and its linking connectors, denominated twist locks, subjected to dynamical load induced by its base. The physical (dimensions, mass, and moments of inertia) and structural (longitudinal, transversal and torsional stiffness) characteristics of the scaled models were decided based on two dimensionless numbers: ratios between gravity force and inertia force, and elastic force divided by inertia force, through experimental and numerical analysis. A series of experiments with controlled parameters were performed using a shaking table test to understand the effects of each variable in the container stack dynamics and present enough data to validate the numerical model. The results of this study indicate that the numerical model built is a promising tool for further study. Moreover, the model is able to predict conditions close to real situations faced by container stacks while storage on a ship's deck.

Modeling Research for Active Control of Coupled Vibration between Multiple CNC Milling Machines and Flexible Foundation

In real life many agencies are using the flexible foundation as a base of support, such as ship hull or deck, the chassis of car, and machine tools work on stairs. With the traditional theory, the mathematical model between machine and based simplified as single-degree-of-freedom, assuming foundation is a rigid, and many investigate for a single machine, ignoring the dynamic coupling of base and the coupling characteristics between vibrators. This paper build a dynamics model with flexible basis and multiple machines, it’s multi-degrees-of-freedom model. The foundation is flexibled. On this basis builiding a model about multiple machines, flexible foundation and vibration isolation system. This paper resolve to the problem of the machine work on stair, research the system include vibrator, actuators, and flexible foundation. Using Lagrange equation deduce dynamics equation. Express every factor in eqution,deduced the state and space expression.Take prepare for optimal and system simulation.

Implementation of knowledge-based engineering methodology in ship structural design

The work presents a knowledge-based engineering (KBE) methodology for ship hull structural member design. In the ship design process, many design tasks need the expertise or design experiences to support them. However, the ship design procedure is a complicated process with many labor-intensive activities. Therefore it is necessary to integrate intelligent design process into ship design. An application developed in a KBE system takes design requirements, applies the knowledge stored in the knowledge base and generates a new design automatically. Knowledge-based engineering methods for ship design are put forward, which combine with the theory of intelligent design. A ship deck design case illustrates the feasibility of the proposed approach. The KBE technology provides appropriate suggestions and support, integrates the information, to avoid conflict and errors. Besides, it also achieves knowledge reuse and accumulation, provides reliable technical support for ship design quality, significantly reduces the design cycle, and promotes working efficiency.

Interaction between web-core sandwich deck and hull girder of passenger ship

Structural response of modern large passenger vessels is fairly complicated due to discontinuities created by open spaces, but also due to balcony openings. These two facts result in non-linear strain distribution along the depth of the hull girder. During recent years steel sandwich panels have been developed to decrease the structural weight, centre of gravity of the ship and also to ease the production of the ships through modularity. In order to make decks, the sandwich panels need to be joined. In order to implement these panels to load carrying deck structures of the modern passenger ship their influence on the structural response of the hull girder needs to be investigated. Therefore, the present investigates the interaction between hull girder of passenger ship and steel sandwich decks. Sandwich decks with both symmetrical and production friendly non-symmetrical joints are considered and compared to the traditional decks made from stiffened plates. Both deflection and normal stresses are considered as the response.

Acoustic observations of dusky dolphins Lagenorhynchus obscurus hunting Cape horse mackerel Trachurus capensis off Namibia

Predator-prey interactions of mammals and their fish prey in marine ecosystems are rarely identified and recorded. We document for the first time the underwater behaviour of hunting dusky dolphins Lagenorhynchus obscurus and the responses of their prey, Cape horse mackerel Tra- churus capensis, observed in open ocean waters off northern Namibia. Predator-prey interactions were monitored acoustically during a continuous period of 2 h with a split-beam scientific echo sounder, and the surface behaviour of the dolphins was observed from the ship's deck. In total 54 predator-prey events were observed (mean, 0.45 events min -1 ). The maximum burst speed during attack was 9.9 m s -1 , while the average attack speed was 3.4 m s -1 (mean swimming speed: 1.4 m s -1 ). Dolphin traces were predominantly located underneath the fish aggregation (63% of the time), as the dolphins attacked the schools from underneath (mean depth: 120 m; maximum depth: 156 m). The dolphin target strength at 38 kHz was, on average, -31.5 dB (95% CI: -33.4 to -30.2 dB). The attacks caused immediate reactions in the Cape horse mackerel aggregations: subschools were forced towards the surface where they were herded into dense aggregations by the dolphins. Observed predator response patterns included 'Vacuole' (n = 21), 'Split' (n = 19), 'Bend' (n = 10) and 'Hourglass' (n = 4). Packing densities changed significantly before (0.4 fish m -3 ), during (2.0 fish m -3 ) and after (0.3 fish m -3 ) the dolphin attacks, and when predators burst into the fish aggregations, mean (±SD) intraschool packing densities of horse mackerel were significantly lower in front of the predators (0.33 ± 0.17 fish m -3 ) than behind (6.65 ± 1.76 fish m -3 ).

Domain-decomposition strategy for marine applications with cavity entrapments

A 2-D domain-decomposition (DD) strategy, developed for marine applications involving gas cavities, is presented. The DD couples a boundary element method with a Navier–Stokes solver using a level-set (LS) technique to handle the evolution of the gas–liquid interface. The deformation of compressible cavities is handled by means of a simplified model assuming uniform pressure and adiabatic conditions. Merging and splitting phenomena are described as isothermal processes without chemical reactions. Benchmark solutions are used for the verification of the LS with compressible cavities. The resulting DD method is applied to study the initial stages of a water-shipping event on the deck of a barge-shaped ship.

UAV landing system simulation model software system

A software system for a simulation model of a UAV's automatic landing system is presented herein. The simulation model allows us to determine the level of influence of different distortions of the observed image on the UAV's landing accuracy. The correlation extremal system of terminal guidance (CESTG) of an unmanned aerial vehicle (UAV) executed on the basis of an optoelectronic sensor has found its application as a tool providing the terminal delivery of UAV's freight to the planned Earth surface area or automatic landing of an unmanned helicopter (UH) on a selected place or on a surface ship deck. In operation, the CESTG carries out a search for a landing place (freight delivery), guidance to the selected landing place (freight delivery) at the UAV's approach and the exact path of the UAV to the selected area in the processing of current information receiving at the discrete moments of time (shot shaping time) about the surveillance area from the optoelectronic sensor.

SPH simulation of green water and ship flooding scenarios

Flooding of a ship's deck (greenwater) or within its internal compartments can severely restrict the operational ability of the vessel, and the safety of its cargo. In severe circumstances such as those produced by freak waves or hull damage, the vessel can become unstable causing it to sink and/or capsize. The flows produced by such events tend to be highly dynamic, with large amounts of free surface deformation. For this reason, SPH is a valuable method for predicting the physics of such flows. In this paper, SPH is used to predict fluid behaviour for two different flooding scenarios. The first is the interaction between a vessel (represented by a rigid body) and undulating travelling waves. The predicted water heights on the deck are compared to experimental results in [1]. The second is the transient flooding behaviour that occurs during, and immediately after a side collision between two vessels. Water heights are measured close to the point of impact within the vessel. The measurements are compared to experimental results in [2].

Notch stress concepts for the fatigue assessment of welded joints – Background and applications

Among modern fatigue design concepts for welded structures, the linear-elastic notch stress concept gains increasing industrial acceptance. There are two variants of this concept, one for thick walled ( t ⩾ 5 mm) welded joints with the reference radius r ref = 1.00 mm, which is already included in the fatigue design recommendations of the IIW and applied for the assessment of big welded structures, and one for thin walled ( t < 5 mm) welded joints with the reference radius r ref = 0.05 mm, which is more and more used in the automotive industry. The concept with r ref = 1.00 mm is based on the micro-support theory of Neuber with the fictitious radius r ref = 1.00 mm, derived by Radaj. The background of the concept with r ref = 0.05 mm is the relationship between the stress-intensity factor and the notch stress according to Creager and Paris as well as Irvin’s theory of crack blunting. Besides these two theories, the definition of both of these radii has also an experimental background; they are observed in many welded joints. In the present paper, first the background and then different applications of both concept variants are described: the application of the reference radius of r ref = 1.00 mm for MAG-welded offshore K-nodes ( t = 30 mm) and sandwich panels for ship decks ( t = 5 mm), and the application of r ref = 0.05 mm for spot-welded automotive doors ( t = 1 mm) and MAG-welded automotive trailing links ( t = 3–4 mm). The sandwich panels were evaluated additionally with r ref = 0.05 mm. Calculations and experimental results are compared and the reliability of the notch stress concept variants underlined. Additionally, recommendations for the slope of design lines distinguishing between thin and thick dimensions are given, i.e. k = 3.0 and 5.0 (normal stress, shear stress) for thick and stiff structures, k = 5.0 and 7.0 for thin and flexible structures.

Determination of oceanic ozone deposition by ship-borne eddy covariance flux measurements

Abstract. A fast response ozone analyzer based on the ozone-nitric oxide chemiluminescence method was integrated into the NOAA-ESRL flux system to achieve the first ship-borne, direct ozone flux measurements over the open ocean. Air was collected from an inlet at 18 m height over the ocean surface mounted to the bow-jackstaff and via a 30 m-long sampling line to the ozone instrument on the ship deck. A "puff" system was used for accurate and regular determination of the sample transport time (lag) between the inlet and the chemical analyzer. A Nafion-membrane dryer facilitated removal of fast water vapor fluctuations, which eliminated the need for quenching and density correction of the ozone signal. The sampling-analyzer system was found to have a ~0.25–0.40 s response time at a sensitivity of ~2800 counts s−1 per ppbv of ozone. Quality control and data filtering procedures for eliminating data that did not meet measurement requirements were critically evaluated. The new ozone flux system was deployed aboard the NOAA Ship Ronald H. Brown, and evaluated using results obtained during several research cruises off the coasts of the North and South America continents, yielding ozone deposition velocities (mean ± standard error) ranging from 0.009±0.001 cm s−1 to 0.24±0.020 cm s−1.

Ultimate strength of orthogonal stiffened plates subjected to axial and lateral loads

Orthogonal stiffened plates present in the ship deck are subjected to axial compression due to hogging and sagging bending moments and, lateral load due to cargo load. The main objective of this investigation is to determine the ultimate load carrying capacity and study the interactive behaviour of orthogonal stiffened plates under axial and lateral loads. Tests were conducted on six stiffened plates with plate slenderness ratios of 80 and 64, and corresponding column slenderness ratios of 24 and 26. Hydraulic jacks and inflatable air balloon with load control mechanism were fabricated to apply axial and lateral loads on the test specimens respectively. All the specimens were tested up to ultimate load and the mode of failure was determined based on the initial yielding observed in the plate and/or stiffener. Nonlinear finite element analysis of test specimens was performed using the general purpose FE software ANSYS®. Both material and geometric nonlinearities were considered in the FE analysis of test specimens. The ultimate loads obtained from the finite element analysis were compared with experimental data and found to be satisfactory. It was also observed that the mode of failure obtained from finite element analysis is similar as observed from experiments. It was concluded that the increase in lateral load beyond two thirds of ultimate lateral load significantly reduces the axial ultimate load carrying capacity of stiffened panels. The interactive effect of stiffened plates subjected to combined action of axial and lateral loads is determined as nonlinear.

The study of the tank cars dynamics in transporting their railway ferry boat in a sea of pitching

The article is dealt with the results of dynamics research of cistern car while transporting it by the railway-ferry ship in conditions of sea rolling and pitching taking into account the incomplete filling of boiler by the bulk cargo and different wave route movement in relation to the ferry ship body. The acceleration values, which appear in the given conditions of its operation and make impact on the car strength and stability relative to the ship deck, have been determined.

The modeling of seakeeping qualities of Floating Production, Storage and Offloading (FPSO) sea-going ships in preliminary design stage

This paper presents an analysis of a presently applied approach to accounting for seakeeping qualities of FPSO sea-going ships and possible using it in preliminary design stage. Approximations of heaving, pitching, green water ingress on the deck and slamming of FPSO ships, based on main ship design and wave parameters, are presented. The approximations were elaborated with the use of the linear regression method and theory of artificial neural networks for a very wide range of FPSO ship dimensions and hull forms. In the investigations ship operational conditions were limited to those occurring in real service of FPSO ships, described by means of the so called operational scenario. Such approach made it possible to reach simultaneously high approximation accuracy and simple structure of mathematical model.

The Spectrum Dip of Deck Mounted Systems

In this paper, a detailed model of a ship deck and attached dynamic systems was developed and subjected to dynamic studies using two different shock inputs: a triangular shaped velocity pulse and the vertical motion of the innerbottom of the standard Floating Shock Platform (FSP). Two studies were conducted, one considering four single degree-of-freedom systems attached at various deck locations and another considering a three-mass system attached at one location. The two shock inputs were used only for the multi-mass system study. The triangular pulse was used for the four single degree-of-freedom systems study. For the single degree-of-freedom systems study, shock spectra were first calculated at the four mounting locations assuming the oscillators were not present. Then the oscillator systems were added to these grid points to determine the change in the shock spectra. First, the oscillators were added one at a time, and then all the oscillators were added to the deck. The multi-mass system was analyzed using both shock inputs. First, the fixed-base modal masses and frequencies were determined. Then, the system as a whole was attached to the deck and the spectrum values at the base point were determined and compared to those for the free deck case. In the last step each mode of the multi-mass system, represented by a single degree-of-freedom system with the modal mass and appropriate spring stiffness, was considered individually to determine the spectrum responses. Results of the free deck, the entire system and individual modal responses are compared.

The Spectrum Dip of Deck Mounted Systems

In this paper, a detailed model of a ship deck and attached dynamic systems was developed and subjected to dynamic studies using two different shock inputs: a triangular shaped velocity pulse and the vertical motion of the innerbottom of the standard Floating Shock Platform (FSP). Two studies were conducted, one considering four single degree-of-freedom systems attached at various deck locations and another considering a three-mass system attached at one location. The two shock inputs were used only for the multi-mass system study. The triangular pulse was used for the four single degree-of-freedom systems study. For the single degree-of-freedom systems study, shock spectra were first calculated at the four mounting locations assuming the oscillators were not present. Then the oscillator systems were added to these grid points to determine the change in the shock spectra. First, the oscillators were added one at a time, and then all the oscillators were added to the deck. The multi-mass system was analyzed using both shock inputs. First, the fixed-base modal masses and frequencies were determined. Then, the system as a whole was attached to the deck and the spectrum values at the base point were determined and compared to those for the free deck case. In the last step each mode of the multi-mass system, represented by a single degree-of-freedom system with the modal mass and appropriate spring stiffness, was considered individually to determine the spectrum responses. Results of the free deck, the entire system and individual modal responses are compared.

Occupations and Lung Cancer: A Population-Based Case-Control Study in British Columbia

An investigation based on a large population-based case-control study in British Columbia, Canada, was conducted to identify high-risk occupations for lung cancer by histological subtypes. Subjects were 14,755 male incident cancer cases for whom lifetime occupational histories and information on smoking and relevant covariates were collected. Occupational associations for 2998 lung cancer cases, including histological subtypes, were assessed by logistic regression using other cancer cases, excluding smoking-related cancers, as controls. An excess risk of lung cancer was found among workers in metal processing, bakers, and ship deck crew for all histological subtypes, and construction workers, chefs and cooks, and medical workers for specific histological subtypes. Occupational associations that are unique to histological subtypes of lung cancer were identified. Owing to a scarcity of literature in this area, future research needs to focus on confirming these histological associations, and identifying the risk from key exposures found within these occupations (e.g., medical radiation, electromagnetic fields, and cooking fumes).

A Novel Setup for Testing of Ship Deck Stiffened Panels under Axial and Lateral Loads

Abstract A novel setup for testing of stiffened panels in ship decks subjected to axial and lateral loads is developed in the Department of Ocean Engineering, IITMadras. The entire setup consists of self-straining test rig, imperfection measuring device, displacement controlled hydraulic jacks, rigid grillage, inflatable air balloon with and without opening, and a data acquisition system. The fabricated deformable test rig replicates similar boundary conditions along the loaded and unloaded edges of stiffened panels in between transverse stiffeners of a ship deck. An imperfection measuring device located on the test rig is designed and fabricated to measure geometrical initial imperfections on the plate and stiffener. A unique displacement controlled twin hydraulic jack system is developed to apply axial load on the panel. A rigid grillage connected to the bottom of the test rig to act as reactive support for the application of lateral load on the panel is fabricated by performing static nonlinear analysis using ANSYS. An inflatable air balloon with and without opening is fabricated to simulate constant cargo (lateral) load acting on the panels. The applied axial load and produced axial deformation measured by load cells and LVDT, respectively, is plotted simultaneously while testing using an integrated data acquisition system. Nonlinear finite element analysis of tested specimens is performed using ANSYS to compare the ultimate load obtained from experiments. A close agreement between the experimental data and finite element analysis results indicates realistic simulation of truly combined axial and lateral loads with deformable supports acting on stiffened panels as in ship decks achieved in the laboratory and numerically.

The effect of additional hand contact on postural stability perturbed by a moving environment

Additional hand contact of external objects has been shown to reduce postural instability caused by a deficiency of one or more senses. Little is known, however, if additional contact can help in an environment where the senses are available but conflicting. This question was investigated by analyzing the effect of different types of hand contact on postural stability perturbed by the moving visual scene. While standing for 1 min on a rocker board in front of a screen, eight healthy young subjects observed a projection of a virtual ship rocking on water to simulate standing on the ship's deck. In randomly assigned trials subjects were asked (a) to stand with arms at sides (with no contact); (b) to hold a standard cane parallel to the ground; (c) to lightly touch a rocker cane handle with their index finger; or (d) touch a standard quad cane handle with their index finger. Based on the kinematic data collected, the displacement of the center of mass (COM) and angular displacements in the hip and ankle joints were computed. Results showed that the moving visual scene perturbed body stability. However, additional contact with support of varying stability reduced the destabilizing effect. The results can be potentially used for practical purposes; when in an environment with visual perturbations simply holding an object in hand may help stabilize the body when at risk for a fall.

Experimental Study on the Behavior of a Swimming Pool Onboard a Large Passenger Ship

The water in a swimming pool on the top deck of a large passenger ship can be excited to a resonant motion, even in a moderate sea state. The motion of the water in the pool is mainly caused by longitudinal acceleration, resulting from the ship's pitch and surge motions. At resonance, there can be high waves in the pool and splashing of water. In this study the behavior of the Solarium Pool of the Freedom of the Seas was examined in various sea states and operating conditions. The motions of the pool were calculated on the basis of a linear seakeeping method, and the behavior of the water in the pool was studied with experimental model tests. A large-scale model of the pool was constructed and fitted to a purpose-built test bench that could be axially moved by a computer-controlled hydraulic cylinder. Water elevation in the pool was measured, and all tests were video recorded. Different modifications of the pool were tested to improve the behavior of the pool. A strong correlation between the longitudinal motion and the behavior of the water in the pool was found.