Dissertations / Theses: 'Ship hull'

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Voxakis, Petros. "Ship hull resistance calculations using CFD methods." Thesis, Massachusetts Institute of Technology, 2012. http://hdl.handle.net/1721.1/74895.

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Thesis (Nav. E. and S.M.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 2012.
Cataloged from PDF version of thesis.
Includes bibliographical references (p. 77-78).
In past years, the computational power and run-time required by Computational Fluid Dynamics (CFD) codes restricted their use in ship design space exploration. Increases in computational power available to designers, in addition to more efficient codes, have made CFD a valuable tool for early stage ship design and trade studies. In this work an existing physical model (DTMB #5415, similar to the US Navy DDG-51 combatant) was replicated in STAR-CCM+, initially without appendages, then with the addition of the appendages. Towed resistance was calculated at various speeds. The bare hull model was unconstrained in heave and pitch, thus allowing the simulation to achieve steady dynamic attitude for each speed run. The effect of dynamic attitude on the resistance is considered to be significant and requires accurate prediction. The results were validated by comparison to available data from tow tank tests of the physical model. The results demonstrate the accuracy of the CFD package and the potential for increasing the use of CFD as an effective tool in design space exploration. This will significantly reduce the time and cost of studies that previously depended solely on physical model testing during preliminary ship design efforts.
by Petros Voxakis.
Nav.E.and S.M.

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Xu, Jinsong. "Estimation of wave-induced ship hull bending moment from ship motion measurements." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 2000. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape4/PQDD_0029/NQ62460.pdf.

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Fredriksen, Ørjan. "Ice-Induced Loading on Ship Hull During Ramming." Thesis, Norges teknisk-naturvitenskapelige universitet, Institutt for marin teknikk, 2012. http://urn.kb.se/resolve?urn=urn:nbn:no:ntnu:diva-18423.

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As a result of the steadily increasing activities related to marine technology in Arctic regions, Det Norske Veritas has launched an ice load monitoring project to gather knowledge of the ice conditions and prevailing ice-induced actions in the region. The intention of the following thesis is to study different aspects related to design of ice-going vessels, in particular the design scenario where a vessel impacts an ice ridge.The introductory part of the thesis gives an overview of important aspects related to sea ice, including different types of ice features and their physical and mechanical properties. The microstructure of pure ice and formation mechanisms of sea ice are briefly described, and mechanical properties such as elasticity and compressive strength are discussed. Further, a study of existing models for estimation of ice-induced loading on ships is carried out, with focus on local hull plating pressure and global loading due to ice ridge impact.A comparative study of design rules developed by Det Norske Veritas and the International Association of Classification Societies is conducted, and important differences between the two separate rules are identified. The subdivision of class notations is described, and differences in definition of design loads and corresponding requirements are presented. A general conclusion is that the rules developed by Det Norske Veritas are more specific when it comes to governing design scenarios, while rules set forth by the International Association of Classification Societies are more universal in terms of vessel type and prevailing ice conditions.Two separate finite element models based on coastguard vessel KV Svalbard are developed, including a simplified beam element model and a detailed shell element model. Quasi-static and dynamic response analyses for ice ridge impact loading are carried out, where the duration of the load pulse is varied systematically from 0.25~s to 2.0~s. The simplified finite element model is seen to give larger overall maximum response compared with the detailed model, but the difference decreases as the pulse duration is increased.It is observed that quasi-static response is overall larger than dynamic response for both finite element models within the defined pulse duration range. However, the ratio of maximum dynamic to maximum quasi-static response is seen to be positively correlated with the load pulse duration, and a close-to-linear relationship is observed.A study of different parameter variations is performed in order to investigate the importance of various pulse shapes, mass models, damping models and solution methods. Variations are only performed using the simplified beam model. It can be concluded that the shape of the load pulse is of minor importance for dynamic response when the pulse duration is short. However, the pulse shape becomes increasingly important for longer load pulses.An opposite trend is observed when varying the mass model, where a negligible difference in dynamic response is seen for longer load pulses. The difference increases somewhat for shorter load pulses, but can be considered unimportant for dynamic response within the investigated duration interval.It is further observed that the choice of damping model is of significant importance compared with other investigated parameters, and the difference in predicted response remains constant within the investigated pulse duration interval. The choice of solution method is however unimportant for analysis using the simplified beam model.In order to verify the applicability of the finite element models, full scale sea trial measurements of global motions from KV Svalbard are analysed and compared with finite element results. Difference between measured and calculated response during ice ridge impact is seen to be significant, where the calculated maximum response is close to 4 times larger than the maximum measured response. Iterative modifications of the load pulse shape are performed in order to reproduce the measured response history following ice ridge impact, and quite strong agreement is obtained between measured and calculated response.

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Misirlis, Konstantinos. "Progressive collapse analysis of composite ship hull sections." Thesis, University of Newcastle Upon Tyne, 2012. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.576656.

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This thesis presents the development and validation of a progressive collapse methodology for composite structures based on advanced nonlinear finite element analysis (FEA). The method is applied to parametric studies in order to investigate the influence of boundary conditions, material configurations and geometric imperfections on the response of individual structural members that form a composite ship hull. Effects on the analysis from the type and size of finite elements adopted in the FE discretisation scheme are also considered by conducting mesh refinement studies. In terms of material nonlinear behaviour, failure and progressive collapse of the composite section is performed at ply level. Alternative failure theories are compared for accuracy over a wide range of material, geometric and loading configurations. Good correlation between numerical and experimental results is identified from failure theories that accommodate interaction between failure modes and adopting an instantaneous degradation approach for the damaged properties. Failure of the bond region between plate and stiffener is also being considered in the analysis by adapting cohesive zones which also performs well against a variety of physical tests. Parametric studies are performed on square and long plates in compression for a wide range of slenderness ratios. Effects from the shape, size and location of geometric imperfections are also considered. As a result, a set of data is produced that can be used as an initial basis for design curves. This includes failure initiation and ultimate strength for the range of layup configurations under consideration. These studies are repeated for alternative boundary conditions in order to demonstrate their effect on the panel response. An application example for the ultimate longitudinal strength of a GRP hull girder is provided at the end from the progressive collapse analysis at a global level. This is compared against solutions from simplified methodologies that are based on simple beam theory and demonstrates the necessity for considering interaction effects between local and global panel deformations in the strength assessment of the hull girder.

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Hoque, Md Emdadul. "Dynamic Response of Ship Hull due to Slamming." Thesis, Norges teknisk-naturvitenskapelige universitet, Institutt for marin teknikk, 2014. http://urn.kb.se/resolve?urn=urn:nbn:no:ntnu:diva-25270.

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In this thesis full-fledged Finite Element Analysis is done for Free vibration analysis and Dynamic Forced Response Analysis of ship hull due to the slam induced load in sea way. This topic is of concern for ships and offshore structures in terms of safety, serviceability assessment including habitability. The aim is to investigate the validation available of dynamic response prediction methods. Three-dimensional Finite Element model is developed according to the ship (135m dry cargo vessel) particulars provided by the ISSC committee II.2 Dynamic Response. Preliminary model was developed in SESAM/GeniE and later this model is used for Hydrodynamic Analysis in SESAM/HydroD and Finite Element Analysis in ABAQUS/CAE. Mass data and Bottom pressure time traces were also provided by the committee which was used for further model development and input for slamming load respectively. Committee was also provided the estimated characteristics sea state. Added mass matrices and Total damping matrices has been calculated in HydroD which was introduced in ABAQUS for Wet mode models. Low frequency natural hull girder frequencies with associated vibration modes for Dry-mode and Wet-mode models (Lightship condition, Ballast condition, Fully Loaded condition) were determined. The validity of the frequency analysis results were verified through the further investigations involving study of Classification society and ISO rules and regulations. Implicit dynamic analysis was done for the Acceleration and Strain time traces in the specified location of the ship due to the impulse load. Calculated response data will be compared to the measured data on the actual ship while at sea. The result from free vibration analysis and forced dynamic response analysis were in agreement with the accepted knowledge. A number of approximations made in the phase of model development and calculations of hydrodynamic parameter were done assuming zero forward speed which has influence on the results. In order to realize the true potential value of this work it would be necessary to compare actual ship response data to calculated data and sorting out the possible disagreements. This work is a possible source to demonstrate the adequacy of hull structural analysis tool which can potentially leading to future design improvements.

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Lin, Ying-Tsair. "Ship longitudinal strength modelling." Thesis, University of Glasgow, 1985. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.320513.

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Peng, Hongxuan. "Numerical computation of multi-hull ship resistance and motion." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 2001. http://www.collectionscanada.ca/obj/s4/f2/dsk3/ftp05/NQ63482.pdf.

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Vålandsmyr, Anders. "Stress Analysis of Turret Interacting with Ship Hull Structure." Thesis, Norges teknisk-naturvitenskapelige universitet, Institutt for marin teknikk, 2010. http://urn.kb.se/resolve?urn=urn:nbn:no:ntnu:diva-11628.

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The trend in offshore oil and gas industry has been that new oil and gas fields are more remote in terms of water depth and in distance from existing infrastructure. The high price for oil and gas drives the industry to develop fields in harsh environment and record breaking water depths. Fixed offshore structures are not feasible for ultra deep water depths and may also be less profitable or unprofitable for moderate depths. This is due to the high cost of laying export pipelines in remote areas or because marginal fields only requires production facilities for a few years. Floating production storage and offloading systems, FPSOs, has been used by the offshore industry since the late 1970s but the usage has rapidly increased over the last two decades. One of the benefits of using FPSO‘s is that export can be done by shuttle tankers, thus no pipeline infrastructure is required. The FPSO itself are not depth sensitive and the challenges related to greater water depths are mainly considering the riser and mooring system. The use of FPSO‘s for marginal fields are also beneficial because of short installation time and mobility. Therefore it can also easily be reused for new fields. The methods for designing the hull of an FPSO has been somewhat mixed between design rules for ships and design rules for offshore structures. Since the ship rules are not based on specific site parameters and the design rules for offshore structures has mainly been focusing on fixed, tension leg systems or semi submersible platforms, neither one of the two methods has addressed the whole aspect of designing an FPSO. It is actually just recently that several of the main class societies and international standards have released new design codes for floating production systems. Based on the requirements in DNV-OS-C102 and the results available from Wamit a worksheet has been made in Mathcad. The worksheet sums the contribution from each panel and gives the resulting bending moment and shear forces as a hydrodynamic transfer function for the wanted section. Further a structural model with the extent of tank 1 and 2 has been made in Ansys. The sea pressures established in the Mathcad spreadsheet (based on Wamit results), are transferred onto the Ansys model. ULS analysis in Ansys of full load and ballast condition has been preformed for a selected ULS design wave.

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Tregde, Vidar. "Aspects of ship design: optimization of aft hull with inverse geometry design." Doctoral thesis, Norwegian University of Science and Technology, Faculty of Engineering Science and Technology, 2003. http://urn.kb.se/resolve?urn=urn:nbn:no:ntnu:diva-134.

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The main contribution of this thesis is on the study of optimization methods in aft hull design. The optimization methods are inverse geometry design methods to find an aft hull with the flow velocities we specify. The analytic foundation for the flow is given by Stratford in [31], and gives a prescribed velocity distribution on the aft body. With the parameter β we have adjusted this flow to have a certain margin to separation along the pressure recovery region.

This principle and optimization method are successfully applied to design of ships with pram-type aft hull. The 2D optimized profiles corresponds to centerline buttock, and 3D hull sections are extended from this centerline buttock with a bilge radius.

Stratfords original pressure distribution for pressure recovery region were meant for Reynolds numbers up to 107. We have extended Stratfords formula to yield for ship full scale Reynolds numbers to 109.

Different optimization methods were programmed and tested. The best routine for our optimization of aft hull with Stratford flow, was when the offset y-value were the optimization parameter to be changed. When we tried to optimize a complete 2D profile with a given pressure distribution, it worked best to use the variables in a B-spline as the optimization parameter.

Extensive windtunnel tests and towing tank tests are carried out. The tests verified the hydrodynamic properties of the hulls.

Towing tests indicates that the optimized hull lines have lower total resistance than conventional ships with the same main dimensions. Both the frictional, viscous pressure resistance and wave making resistance are significantly lower. Further we can increase cargo capacity with the same power consumption, and achieve a more favourable distribution of the displacement in the aft hull.

This study has shown us that the slant angle for the bottom of the aft hull should not excess 15º with horizontal plane due to danger of separation over the bilge, and longitudinal vortices forming.

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Chun, Ho Hwan. "Theoretical and experimental studies on the resistance of SWATH ships." Thesis, University of Glasgow, 1988. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.237814.

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Harrington, K. "Concrete as a fabrication material for simple hulls : A marine innovation study." Thesis, University of Sunderland, 1987. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.378997.

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Dey, Swapan Kumar. "Parametric representation of hull painted surfaces and the correlation with fluid drag." Thesis, University of Newcastle Upon Tyne, 1989. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.328120.

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Utama, I. Ketut Aria Pria. "Investigation of the viscous resistance components of catamaran forms." Thesis, University of Southampton, 1999. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.297613.

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Weaver, M. Cameron. "Ship hull plating weld misalignment effects when subjected to tension." Thesis, Springfield, Va. : Available from National Technical Information Service, 2001. http://handle.dtic.mil/100.2/ADA393173.

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Thesis (M.S. in Naval Architecture/Marine Engineering and M.S. in Mechanical Engineering) Massachusetts Institute of Technology, June 2001.
Includes bibliographical references (p. 43). Also available online.

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Koh, Leong. "Large and fast ship applications of deep-vee hull forms." Thesis, University of Newcastle Upon Tyne, 2006. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.427327.

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Toscano, David (David P. ). Carleton University Dissertation Engineering Civil and Environmental. "Post yield behaviour of transversely loaded icebreaking ship hull structures." Ottawa, 1995.

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Price, Stephen Rodgers. "Plastic sheer buckling of ship hull plating induced by grounding." Thesis, Cambridge, Massachusetts : Massachusetts Institute of Technology, 1992. http://handle.dtic.mil/100.2/ADA255254.

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Thesis (Naval Engineer and M.S. in Mechanical Engineering)--Massachusetts Institute of Technology, June 1992.
"June, 1992." Description based on title screen as viewed on April 16, 2009. Includes bibliographical references Also available in print.

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Weaver, M. Cameron (Myron Cameron) 1962. "Ship hull plating weld misalignment effects when subjected to tension." Thesis, Massachusetts Institute of Technology, 2001. http://hdl.handle.net/1721.1/91335.

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Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Ocean Engineering; and, (S.M.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 2001.
Includes bibliographical references (leaf 43).
by M. Cameron Weaver.
S.M.

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19

Godaliyadde, Darshana. "Application of formal safety assessment for ship hull vibration modelling." Thesis, Liverpool John Moores University, 2008. http://researchonline.ljmu.ac.uk/5898/.

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This research has evaluated the rules, guidelines and regulations related to ship vibrations. A historical failure data analysis is carried out to identify associated components, equipment and the areas of defects related to ship vibration problems. Ship Hull Vibration (SHV) is recognised as a major problem onboard ships and the propulsion system is identified as the major contributor to SHV. The current status of ship vibrations is reviewed and possible sources which create SHV are recognised. The major problems identified in this research are associated with risk modelling under circumstances where high levels of uncertainty exist. Following the identification of research needs, this PhD thesis has developed several analytical models for the application of Formal Safety Assessment (FSA). Such mode quently demonstrated by their corresponding case sti vith regard to application of FSA for SHV modelling. Firstly, in this research a generic SHV model is constructed for the purpose of risk estimation based on the identified hazards. The hazards include the SHV effects induced by ship design criteria, failure of components, and different patterns associated with the ship propulsion system (propeller system and machinery) as the major contributors to SHV. Then risk estimation bn is carried out utilising Evidential Reasoning (ER) and a fuzzy rule base. Secondly, ship selection (decision making) is investigated to to select the best ship design based on the risk estimation results of SHV. The risk estimation is carried out using ER, a fuzzy rule base and continuous fuzzy sets. The best ship design is selected by taking into account an ER-based utility ranking approach. Thirdly, combining discrete fuzzy sets and an Analytical Hierarchy Process (AHP) risk estimation is conducted in terms of four risk parameters to select the major causes of component failure and then SHV.

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McCulloch, Thomas L. "Feasible Form Parameter Design of Complex Ship Hull Form Geometry." ScholarWorks@UNO, 2018. https://scholarworks.uno.edu/td/2552.

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This thesis introduces a new methodology for robust form parameter design of complex hull form geometry via constraint programming, automatic differentiation, interval arithmetic, and truncated hierarchical B- splines. To date, there has been no clearly stated methodology for assuring consistency of general (equality and inequality) constraints across an entire geometric form parameter ship hull design space. In contrast, the method to be given here can be used to produce guaranteed narrowing of the design space, such that infeasible portions are eliminated. Furthermore, we can guarantee that any set of form parameters generated by our method will be self consistent. It is for this reason that we use the title feasible form parameter design. In form parameter design, a design space is represented by a tuple of design parameters which are extended in each design space dimension. In this representation, a single feasible design is a consistent set of real valued parameters, one for every component of the design space tuple. Using the methodology to be given here, we pick out designs which consist of consistent parameters, narrowed to any desired precision up to that of the machine, even for equality constraints. Furthermore, the method is developed to enable the generation of complex hull forms using an extension of the basic rules idea to allow for automated generation of rules networks, plus the use of the truncated hierarchical B-splines, a wavelet-adaptive extension of standard B-splines and hierarchical B-splines. The adaptive resolution methods are employed in order to allow an automated program the freedom to generate complex B-spline representations of the geometry in a robust manner across multiple levels of detail. Thus two complementary objectives are pursued: ensuring feasible starting sets of form parameters, and enabling the generation of complex hull form geometry.

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Hittel, Steven George. "An experimental analysis of the hydrodynamic characteristics of the monoform: a novel hull form." Thesis, Virginia Polytechnic Institute and State University, 1985. http://hdl.handle.net/10919/91119.

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This thesis presents the results of an experimental investigation of the hydrodynamic characteristics of the Monoform hull in calm water. The forces acting on a 1.7 meter model were measured as the model was held captive and towed in calm water. The model was tested at speeds up to three meters per second. The rudders were held straight during one part of the study and were deflected during another to test both their ability to correct for pitching moment and to create yaw moments. The draft of the model was also varied during this study and included drafts of 1.90, 2.21, and 2.42 hull diameters. All three forces and all three moments were measured. The model was tested in a 31 meter towing basin located at Virginia Polytechnic Institute and State University. The results are presented in Figure form in the thesis body and in numerical form in an appendix. Recommendations for future work and improvements to the instrumentation are presented along with conclusions at the end of the thesis.
M.S.

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Ucar, Hakan. "Dynamic response of a catamaran-hull ship subjected to underwater explosions." Thesis, Monterey, Calif. : Naval Postgraduate School, 2006. http://bosun.nps.edu/uhtbin/hyperion.exe/06Dec%5FUcar.pdf.

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Thesis (M.S. in Mechanical Engineering)--Naval Postgraduate School, December 2006.
Thesis Advisor(s): Young S. Shin, Jarema M. Didoszak. "December 2006." Includes bibliographical references (p. 137-138). Also available in print.

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Park, Jong Jin. "Modelling trailing vortices from a slender ship hull for manoeuvring calculations." Thesis, University of Newcastle Upon Tyne, 2001. http://hdl.handle.net/10443/895.

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A particular problem that has been encountered in modelling the forces and moment acting on a manoeuvring ship, has been the correct estimation of the distribution of side force along its length. If traditional slender body theory is used, reasonable agreement can be obtained between theoretical and experimental result over the forebody of the ship. However, moving aft, the two increasingly diverge until there are significant differences at the stem. For this reason manoeuvring coefficients cannot be accurately predicted by this approach. In a number of studies, the reason for the discrepanciesh as been attributed to the influence of trailing vortices that develop along the hull. The conclusion is consistent with sensitivity analyses carried out with augmented slender body theory incorporating vortices of specified location and strength along the ship. The present thesis is concerned with modelling trailing vortices along a ship in drift motion so that they can be used in the calculation of the associated distribution of forces and manoeuvring coefficients. A numerical model based on the Discrete Vortex Method has been developed for the analysis of vortex flow around the ship which is representedb y slender body approximation. The trailing vortices are modelled by a series of transverse two-dimensional multi-vortex solutions marching longitudinally down the hull. Results are presented for six different hull types; a flat plate, the Wigley hull, a block hull, a Series 60 hull, the British Bombardier and the British Bombardier with a pram stem. The effects of varying drift angles are also investigated for each hull types. Good qualitative agreement is shown between the predicted velocity and vorticity fields and results from experimental studies. The distribution of side forces and yaw moments along the hull is also well predicted. The results explain manoeuvring phenomena occurring for the hull forms considered that have been observed experimentally and at full scale.

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Sarioz, Kadir. "A hydrodynamic hull form design procedure in conceptual and preliminary ship design." Thesis, University of Newcastle Upon Tyne, 1993. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.332816.

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Mehdipour, Reza. "Simulating propeller and Propeller-Hull Interaction in OpenFOAM." Thesis, KTH, Marina system, 2014. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-159275.

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This is a master’s thesis performed at the Department of Shipping and Marine Technology research group in Hydrodynamics at Chalmers University of Technology and is written for the Center for Naval Architecture at the Royal Institute of Technology, KTH.In order to meet increased requirements on efficient ship propulsions with low noise level, it is important to consider the complete system with both the hull and the propeller in the simulation.OpenFOAM (Open Field Operation and Manipulation) provides different techniques to simulate a rotating propeller with different physical and computational properties. MRF (The Multiple Reference Frame Model) is, perhaps, the easiest way but is a computationally efficient technique to model a rotating frame of reference. The sliding grid techniques provide the more complex way to simulate the propeller and its surrounding region, rotating and interpolate on interface for transient effects. AMI, Arbitrary Mesh Interface, is a sliding grid implementation which is available in the recent versions of OpenFOAM, introduced in the official releases after v2.1.0.In this study, the main objective is to compare these two techniques, MRF and AMI, to perform the open water characteristics of the propeller with the Reynolds-Averaged Navier-Stokes equation computations (RANS) and study the accuracy in parallel performance and the benefits of each approach.More specifically, a self-propelled ship is simulated to study the interaction between the hull and propeller. In order to simplify and decrease the computational complexity the free surface is not considered. The ship under investigation is a 7000 DWT chemical tanker which is subject of a collaborative R&D project called STREAMLINE, strategic research for innovative marine propulsion concepts. In self-propelled condition, the transient forces on the propeller shall be evaluated. This study investigates the results of the experimental work with advanced CFD for accurate analysis and design of the propulsion. In this thesis, all simulations are conducted by using parallel computing. Therefore, a scalability analysis is studied to find out how to affect the average computational time by using different number of nodes.

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Vassilikos, Markos Nicolaos. "A comparative analysis of small advanced naval vehicles and displacement-hull naval ship design." Thesis, Massachusetts Institute of Technology, 1989. http://hdl.handle.net/1721.1/31014.

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Hifi, Nabile. "Decision support system for risk-based inspection and maintenance planning for ship hull structures." Thesis, University of Strathclyde, 2013. http://oleg.lib.strath.ac.uk:80/R/?func=dbin-jump-full&object_id=25552.

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This thesis aims to develop a decision support system for inspection and maintenance planning of ship hull structures considering the effects of repair activities performed during the different periodical inspection events through the service life of a ship. Because of the severe environmental conditions in which ships operate, their structure is continually subjected to fatigue and corrosion degradation and as a result of that their strength is reduced. Corrosion and fatigue cracking represent the most aggressive types of structural damage faced by ship structures, either of which, if not properly repaired or adjusted, can potentially lead to leakage, pollution, fire, critical failures or unanticipated out of service time and economic costs. For an economic design to be achieved, the ship structures need to be maintained during their life. Building a ship with enough safety margins so that repairs would not be required during its life would be uneconomical and not technically feasible. From the viewpoint of survey and inspection of ship hull structures, improvements in inspection planning, safety and reduction of maintenance costs are the most needed. These issues are addressed in the newly developed decision support system described in this thesis. Inspection planning may be based on experience (determined by Class Society guidelines), which generally treat all ships with the same inspection program or based on a risk-based maintenance planning program. In the first case, only some of the knowledge that could be used to predict structural problems, in the case of ship-to-ship variation (construction or use), is gained from the data gathered, while in the second case, risk based maintenance methods can deal with any individual structural component or with overall ship structural integrity. To bridge the gap between these two approaches, this thesis combines the knowledge gained from currently used practice in ship inspection and maintenance and from risk-based methods which have already been proven as a good practice in several industrial applications. The newly developed decision support system is employed to calibrate the results of prediction models based on the collected data. To assist in the prediction of structural degradation of ships, a new structural connections catalogue, an inspection oriented ship defects database and a calibration methodology for structural degradation prediction models are developed. The new system is designed to improve risk-based ship inspection and maintenance planning programs. Application of the newly developed system will benefit inspection companies, class surveyors, ship managers and ship designers by providing a mechanism for the calibration of risk based inspection planning activities. The decision support system developed in this thesis is inherently adaptable and can be applied to many other applications that require a cost effective maintenace, e.g. renewable energy devices, offshore platforms, machinery systems, large structures such as bridges and other transport systems.

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Medhurst, John Stephen. "The systematic measurement and correlation of the frictional resistance and topography of ship hull coatings, with particular reference to ablative antifoulings." Thesis, University of Newcastle Upon Tyne, 1989. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.346447.

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Carrell, Toni L. "From forest to fairway : hull analysis of 'La belle', a late seventeenth-century French ship." Thesis, University of St Andrews, 2003. http://hdl.handle.net/10023/2798.

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This thesis is a comprehensive analysis of the hull remains of La Belle, a ship wrecked off the coast of Texas in 1684 during the failed attempt by Robert Cavelier Sieur de La Salle to establish a colony at the mouth of the Mississippi River. The analysis of La Belle's hull focused on five research goals. The first was to reconstruct the conception and design of the hull. Because La Belle was built on France's Atlantic coast, it was expected that the ship would fit into Atlantic traditions of shipbuilding. Instead, it exhibits an ancient Mediterranean method known only from Renaissance manuscripts. Until La Belle's discovery no archaeological example associated with this method had been identified. Reconstruction of the lines also revealed the unexpected use of surmarks that reflect a transition from a largely empirical approach to the architecturally-based ship plan. The second goal was the documentation of a previously unstudied ship type, the barque longue, through an analysis and description of the hull's assembly and its comparison to contemporary shipbuilding practices. The third goal was an analysis of newly discovered registries, letters, and documents specific to La Belle that raised fundamental questions regarding the ship's genesis and typological identification. The fourth goal was species identification of the timbers to provide a more detailed picture of forest exploitation and to identify whether Old or New World timbers were used in the repairs noted in the hull. The fifth goal was to obtain information on the origin of the wood through dendrochronological analysis. That analysis raised unexpected questions regarding dating and the possibility of re-use of whole frame sets. Because there are no other investigated late 17th-century shipwreck sites from the Rochefort region with species and dendrochronology data, La Belle has provided a benchmark for these two analyses. These five research foci provide a unique picture of late 17th-century shipbuilding in French Atlantic shipyards and contribute to the study of hull design, ship typology, construction and assembly, wood species use and origin, dendrochronological dating, and timber reuse.

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Mennitt, Stuart Hayden. "The effects of ship load variations and seastate on hull girder deflection and combat system alignment." Thesis, Massachusetts Institute of Technology, 1990. http://hdl.handle.net/1721.1/32578.

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Morgan, Harith. "Design of a mechanism to increase lateral force resistance of an autonomous ship hull cleaning robot." Thesis, Massachusetts Institute of Technology, 2020. https://hdl.handle.net/1721.1/127897.

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Thesis: S.B., Massachusetts Institute of Technology, Department of Mechanical Engineering, May, 2020
Cataloged from the official PDF of thesis.
Includes bibliographical references (page 27).
Marine biofoul accrues on ship hulls and increases the resistance of a ship during voyage. This is a widespread issue within the shipping an industry -- which supports the vast majority of global trade. To address this problem, we are developing Bio-Inspired HullCrawler -- an autonomous robot capable of cleaning ship hulls while a ship is underway. The novelty of our design centers on the bio-inspired suction cups that are cast as composite silicon elastomer. The purpose of this thesis is to look specifically at the lateral force resistance of elastomeric suction cup mechanisms. Here we propose new design concepts for the attachment system to improve on the drag force resistance of the HullCrawler device.
by Harith Morgan.
S.B.
S.B. Massachusetts Institute of Technology, Department of Mechanical Engineering

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32

Badoe, C. "Design practice for the stern hull of a future twin-skeg ship using a high fidelity numerical approach." Thesis, University of Southampton, 2015. https://eprints.soton.ac.uk/376987/.

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The ability to predict the powering performance of twin skeg LNG ship is a complex endeavour requiring appraisal of operating conditions and hydrodynamic analysis to arrive at a suitable stern design solution. Inherently coupled with the stern design process is the design optimization, namely the selection of most suitable geometrical parameters of the propulsor, control surface and their arrangements with respect to the hull. An approach to the stern design may commence with the prediction of general ship stern flow, hence its resistance and self-propulsion capabilities. Almost a century of experience exists regarding how to predict the resistance and powering capabilities of the twin skeg LNG ship. Despite this, improvement in numerical methods is still in high demand. A RANS based numerical approach is presented in this thesis to predict the resistance and powering performance of future twin skeg ships. This is supported by a meshing approach which easily blends the hull-skeg boundary layer to the free surface. Predicting the non-uniform wake in the propeller plane due to the hull-skeg and control surface interaction was identified as one of the main challenges in the stern design and powering assessment. To predict this within acceptable cost a sectorial approach was developed as part of the numerical method which discretizes the propeller plane into a series of radial and circumferential subdivisions. The local axial and tangential inflow conditions at each location can then be considered. This was coupled to a blade element momentum theory propeller code. The two-way coupling was found to be a computationally efficient tool for studying the powering performance of ships. To demonstrate the pertinence of the RANS based numerical approaches developed in this work a series of case studies has been analysed. These include: skeg-rudder-propeller interaction studies, propulsive characteristic of the KCS ship, and the resistance and self-propulsion characteristics of a future twin skeg LNG ship. These highlight the roles of the numerical approaches in the stern design process for future twin skeg ships. The techniques developed in this work enable the designer to predict the powering performance of future twin skeg LNG ships at a cost effective manner in the initial design stage.

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Berger, Stephan [Verfasser], and Moustafa [Akademischer Betreuer] Abdel-Maksoud. "Numerical analysis of propeller-induced higher-order pressure fluctuations on the ship hull / Stephan Berger ; Betreuer: Moustafa Abdel-Maksoud." Hamburg : Universitätsbibliothek der Technischen Universität Hamburg-Harburg, 2018. http://d-nb.info/115523782X/34.

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Henning, H. L. "A numerical investigation into the heave, sway and roll motions of typical ship like hull sections using RANS numerical methods." Thesis, Stellenbosch : Stellenbosch University, 2011. http://hdl.handle.net/10019.1/18033.

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Thesis (MScEng)--Stellenbosch University, 2011.
ENGLISH ABSTRACT: The hydrodynamic characteristics of three typical ship-like hull sections, in different motions, are numerically investigated using FLUENT, 2009. These simple shapes, namely a v-bottom (triangle) hull, a at-bottom (square) hull and a round-bottom (semi-circle) hull, are investigated in uncoupled heave, sway and roll. The problem is described in two dimensions. A combination of numerical methods and models, found in literature, are used to conduct this investigation. Hull characterisation is achieved through the use of hull mass and damping coe cients. These numerically determined coe cients are compared to experimental work conducted by Vugts (1968). A good correlation between the numerical and experimental results exists for the heave and sway cases. By normalising the coe cients, different hulls are comparable to one another. The numerical models used are validated and veri ed. Roll motion remains largely unsolved for very large angles of roll (in excess of 11°). Different uid ow phenomena occurring around the hull sections have varying degrees of in uence on the motions of a hull. It is found that not one of the turbulence models investigated can be employed to globally solve each type of hull-motion case. Also, forced oscillations in computational simulations require considerably more computational time than free-decay oscillating hull simulations.
AFRIKAANSE OPSOMMING: Die hidrodinamiese karakteristieke van verskillende skeepsrompvorms, in verskeie bewegingswieë, is numeries ondersoek met behulp van FLUENT, 2009. Drie eenvoudige vorms ('n v-bodem (driehoek), plat-bodem (reghoek) en rondebodem (semi-sirkel) romp) is onderskeidelik ondersoek in opwieg, dwarswieg en rol. Die probleem is twee-dimensioneel. Daar is gebruik gemaak van 'n kombinasie van numeriese metodes en modelle, uit die literatuur, om die ondersoek uit te voer. Die rompe is gekarakteriseer met behulp van massa- en dempingskoëffi siënte. Hierdie numeries bepaalde koë ffisiënte is vergelyk met die eksperimentele werk van Vugts (1968). Daar bestaan 'n goeie korrelasie tussen die numeriese en eksperimentele resultate vir die opwieg en dwarswieg gevalle. Die koë ffisiënte is genormaliseer om die verskeie rompvorms te vergelyk. Die numeriese modelle is geverifi eer en valideer. Rolbewegings is onopgelos vir groot rolhoeke (groter as 11°). Die mate waartoe die romp se beweging beïnvloed word deur die verskillende vloei verskynsels wat om die rompe ontstaan, verskil. Daar is bevind dat geen van die turbulensie modelle gebruik kan word om alle skeepsbeweging-gevalle op te los nie. Gedwonge-ossilasie numeriese simulasies benodig meer berekeningstyd as vrye-verval ossilasie gevalle.

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Elder, David James, and d. elder@crc-acs com au. "Optimisation of parametric equations for shock transmission through surface ships from underwater explosions." RMIT University. Aerospace, Mechanical and Manufacturing Engineering, 2006. http://adt.lib.rmit.edu.au/adt/public/adt-VIT20080212.105012.

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Currently shock effects on surface ships can be determined by full scale shock trials, Finite Element Analysis or semi empirical methods that reduce the analytical problem to a limited number of degrees of freedom and include hull configurations, construction methods and materials in an empirical way to determine any debilitating effects that an explosion may have on the ship. This research has been undertaken to better understand the effect of hull shape on surface ships' shock response to external underwater explosions (UNDEX). The study is within the semi empirical method category of computations. A set of simple closed-form equations has been developed that accurately predicts the magnitude of dynamic excitation of different 2- D rigid-hull shapes subject to far-field UNDEX events. This research was primarily focused on the affects of 2-D rigid hull shapes and their contribution to global ship motions. A section of the thesis,

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36

Gudaitė, Ernesta. "Eko-inovatyvių technologijų taikymas KU mokslinių tyrimų laivo statyboje." Master's thesis, Lithuanian Academic Libraries Network (LABT), 2014. http://vddb.library.lt/obj/LT-eLABa-0001:E.02~2014~D_20140616_154827-64131.

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Šiame magistriniame darbe nagrinėjama gyvavimo ciklo metodika, kuri pritaikoma KU statomo Mokslinių tyrimo laivo korpuso suvirinimo metu išsiskiriančių emisijų skaičiavimui GaBi 6 programinės įrangos pagalba. Nagrinėjami du suvirinimo būdai, kurie buvo naudojami statant KU Mokslinių tyrimo laivą, t. y. lankinis suvirinimas po fliusu (SAW) ir lankinis suvirinimas lydžiuoju elektrodu apsauginėse dujose (MIG, MAG).
This master thesis examines the life cycle methodology that adjusts constructed KU research vessel shell weld calculation of emissions released from 6 GaBi software. Analyzed two welding techniques that have been used in the construction of KU research vessel - submerged arc welding (SAW) and arc welding electrode deposits for gas shielded (MIG, MAG).

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Schattschneider, Robert. "Accurate high-resolution 3D surface reconstruction and localisation using a wide-angle flat port underwater stereo camera: towards autonomous ship hull inspection." Thesis, University of Canterbury. Computer Science and Software Engineering, 2014. http://hdl.handle.net/10092/10063.

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The goal of this thesis is to scan a ship hull with high 3D accuracy and resolution using an underwater stereo camera so as to enable the future autonomous detection of invasive biofouling organisms with autonomous underwater vehicles (AUVs). However, turbidity in most harbours necessitates being within a metre of the hull and thus requires ultra wide-angle camera lenses. But such ultra wide-angle lenses embedded in an underwater housing with a flat port lead to significant distance dependent image distortions. Prior research in this area has only considered narrower fields of view and so has not solved for the significant image distortions arising from wide-angle high resolution flat port underwater cameras. This thesis proposes a solution to modelling and calibrating the underwater camera for accurate 2D imaging and 3D reconstruction, and additionally demonstrates an accurate underwater real-time pose estimation system required for future ship hull relative AUV navigation. In this thesis an ultra wide-angle, short-baseline stereo camera is used, which is embedded in a flat port underwater housing. Flat port underwater housings represent a cost efficient way to use arbitrary in-air cameras underwater. However, the flat port of the underwater housing is subject to light refraction and causes distance dependent distortion, which is particularly visible at the large angles of the ultra wide-angle stereo camera used. To incorporate the effects of refraction, the thesis uses the well-known and accurate physics-based refractive underwater camera model. In contrast to the perspective camera-based underwater camera model, the refractive underwater camera model accurately describes the distance dependency of distortion. In the beginning of this thesis, the effects of refraction caused by a thick flat port underwater housing are summarised and extended. In this context, the fundamental magnification function is proposed, which enables the description of numerous known and also newly discovered effects. An additional quantitative analysis is carried out in which the importance to model the thickness of the port and the wavelength of light is revealed. In refractive geometry with a thick flat port, refractive forward projection represents a fundamental operation and describes where a 3D object point is observed in a 2D camera image. Refractive forward projection is required in numerous applications, such as refractive calibration, bundle adjustment, simultaneous localisation and mapping (SLAM) or image restoration. Unlike perspective projection in air, this operation is non-linear and computationally more expensive. This thesis compares existing and proposes new refractive forward projection methods and shows in contrast to previous research that refractive forward projection is efficient enough for real-time applications. The thesis also investigates the impact of the port and the impact of the indices of refraction on the camera's projection and reconstruction accuracy. A novel investigation shows that the water pressure, water salinity, water temperature, air pressure and the wavelength of light significantly affect the projection and reconstruction accuracy of wide-angle flat port underwater stereo cameras and should not be neglected by standard refractive indices. Moreover, this thesis proposes an accurate and efficient calibration method for thick flat port underwater stereo cameras. The proposed calibration method mainly achieves its high accuracy by the use of a significantly higher number of calibration images. In contrast to prior research, the computation of the reprojection error does not represent a bottleneck if the proposed refractive forward projection method is used. In this way, the calibration is similar to standard in-air camera calibration techniques and minimises the reprojection error. In combination with the proposed more accurate indices of refraction and refractive calibration, the underwater reconstruction accuracy of the novel configuration of a wide-angle flat port underwater short baseline stereo camera is evaluated under real-world conditions. In this context, a method is proposed, which enables the evaluation of the accuracy of the reconstructed 3D object space. Both chromatic aberration and pincushion distortion are effects of refraction and are particularly visible at the large angles of wide-angle underwater cameras. In order to obtained distortion-free images with minimised chromatic aberration to texturize reconstructed 3D ship hull surfaces, this thesis proposes accurate real-time methods to minimise chromatic aberration and to correct the distortion in the underwater camera images. The refractive camera model is based on image coordinates of images, which are distortion-free in air. But these in-air undistorted images are strongly distorted in-water by refraction, particularly at the large angles of wide-angle flat port underwater cameras. Image correspondence in these images is difficult. For that reason, this thesis proposes pseudo rectified images in which these distortions are minimised. Moreover, an accurate and efficient representation of epipolar curves is presented, which enables, for example, real-time constrained correspondence search or dense stereo. This thesis concludes with the demonstration of a pose estimation system for future ship hull relative navigation. The proposed pose estimation system is the first underwater SLAM and visual odometry system, which is based on the more accurate refractive underwater camera model. This thesis shows that the proposed pose estimation system is very accurate in a water tank experiment and efficiently works in real-time, and thus is superior to prior underwater SLAM research, which is based on the less accurate perspective camera-based underwater camera model.

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38

Grinberg, Marcelo. "Medição de superfície submersa de embarcação com sistema ótico de precisão a laser." Universidade de São Paulo, 2013. http://www.teses.usp.br/teses/disponiveis/3/3135/tde-27122013-105602/.

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A medição de superfícies através de sistemas óticos de precisão é aplicável em diversas áreas da engenharia naval e oceânica: levantamento de geometria de casco para a determinação da estabilidade estática de embarcações in loco, verificação de processos construtivos, recuperação de planos de linha originais perdidos, arqueologia naval, inspeção de cabos e estruturas submersas, planejamento de rota de mergulho, entre outras. Os dispositivos óticos de precisão disponíveis são de alto custo, e a necessidade de se desenvolver um dispositivo de baixo custo se faz presente. O propósito deste trabalho é a criação de metodologia de obtenção de superfície através de procedimento prático experimental. A varredura tridimensional de superfície é feita experimentalmente através da utilização de leitor tridimensional a laser. A contribuição deste trabalho é de promover um conceito teórico a uma prova experimental do conceito, utilizando-se de recursos da automação e robótica, e programação com linguagem e software aplicativo de baixo custo e largamente disponível.
The surface measurement using precision optics is applicable in many areas of naval engineering: survey of hull geometry to determine the static stability of vessels on the spot, verification of construction processes, recovery of lost original hull plans, naval archeology, inspection of underwater structures and cables, route planning diving, among others. The precision optical devices available are expensive, and the need to develop a low-cost device is present. The purpose of this work is to create a methodology for obtaining surfaces through practical experimental procedure. The three-dimensional scan surface is made experimentally by using three-dimensional laser reader. The contribution of this work is to promote a theoretical concept to an experimental proof of concept, using the resources of automation and robotics, and software programming language and application of lowcost and widely available.

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Alvarez, Rodrigo Loureiro Prado. "Otimização das formas de cascos de deslocamento em relação a sua resistência ao avanço." Universidade de São Paulo, 2008. http://www.teses.usp.br/teses/disponiveis/3/3135/tde-31032008-171045/.

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Devido à constante necessidade de construções de novas embarcações, quer seja pela demanda do mercado, quer seja pela renovação da frota, o desenvolvimento de programas computacionais que auxiliem na fase inicial de projeto torna-se bastante útil. Assim, o desenvolvimento de um procedimento de análise que permita obter formas de melhor desempenho vem a agregar valor nesta etapa de conceituação da geometria do navio. O trabalho aqui apresentado tem como objetivo discorrer sobre um método capaz de otimizar a geometria de um casco de deslocamento conhecido em relação a sua resistência ao avanço, sem perder, porém, as suas características principais, como corpo paralelo médio, por exemplo. Para tanto, dentro deste processo de otimização já estão inseridas algumas restrições que garantem a viabilidade da solução final, tais como variação máxima no comprimento, no volume total e na estabilidade do navio. A modelagem da embarcação pode ser feita através de funções B-Splines cúbicas de superfície, cujos pontos de controle (parâmetros inerentes à função) podem ser modificados de tal sorte a atingir um valor ótimo para a resistência ao avanço. Esta, por sua vez, será obtida através da soma de duas parcelas, sendo uma referente ao atrito e outra à geração de ondas pelo casco. Como a maior parte da resistência provém desta segunda parcela para a velocidade de projeto a ser considerada (alto número de Froude), a redução da resistência total pode ser assumida como conseqüência da diminuição da resistência devido à geração de ondas, a qual pode ser obtida através da formulação apresentada por Michell, em 1898. O cálculo das propriedades hidrostáticas como deslocamento, estabilidade ( KM transversal) e superfície molhada, usada para cálculo da resistência ao avanço, pode ser encontrado fazendo-se uso do cálculo vetorial. O procedimento a ser descrito foi desenvolvido em linguagem C++ (modelagem do casco) e com o auxílio do MATLAB® (método de otimização). Este trabalho foi realizado no Dep. de Eng. Naval e Oceânica da USP.
Due to an increasing necessity of building new vessels, whether by new orders or fleet renewal, the development of computational programs that could allow optimization of hull shapes is always helpful, saving project time and ensuring better performance at sea. Thus, the development of a synthesis procedure that allows obtaining shapes with better performance adds value to the initial phase of the ship geometry concept. The work to be presented herein objectives the presentation of a methodology to achieve optimal shapes for displacement hulls in relation to the total resistance, starting from an initial geometry given, describing hull form and applying specific constraints to optimization problem with the purpose of guarantee a reliable solution. Therefore, inside this optimization process there are included some constraints that ensure a feasible final solution, as maximum variation of ship length, total volume and stability. Hull geometry is described by using B-Spline surface functions and the ship wave resistance is calculated using Michell\'s formulation as a first approximation of the total resistance for high Froude numbers. Once vessel surface is well defined, B-Spline parameters are varied until an optimal form is attained and the minimum resistance is achieved. It can take a little time to calculate, depending on ship definition (number of buttocks and waterlines) and the problem complexity (number of constraints and variables). Ship displacement and other hydrostatic properties as stability, given by transversal KM , wetted surface, used for calculating ship resistance, can be obtained using the vectorial calculus. This work has been developed using C++ language, except the optimization process which makes use of a MATLAB® function called fmincon. This study has been held at the Department of Naval and Ocean Engineering of the University of São Paulo, Brazil.

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40

Kokkonen, Toni. "CFD analysis of stepped planing vessels." Thesis, KTH, Mekanik, 2018. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-250023.

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High speed planing hulls are currently widely used for example in recreational and emergency vessel applications. However, very little CFD research has been done for planing vessels, especially for those with stepped hulls. A validated CFD method for planing stepped hulls could be a valuable improvement for the design phase of such hulls. In this thesis, a CFD method for stepped hulls, with a primary focus on two-step hulls, is developed using STAR-CCM+. As a secondary objective, porpoising instability of two-step hulls is investigated. The simulations are divided into two parts: In the first part a method is developed and validated with existing experimental and numerical data for a simple model scale planing hull with one step. In the second part the method is applied for two two-step hulls provided with Hydrolift AS. A maximum two degrees of freedom, trim and heave, are used, as well as RANS based k-w SST turbulence model and Volume of Fluid (VOF) as a free surface model. The results for the one-step hull mostly corresponded well with the validation data. For the two-step hulls, validation data did not exists and they were first simulated with a fixed trim and sinkage and compered between each other. In the simulations with free trim and heave both hulls experienced unstable porpoising behavior.

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41

Veelo, Bastiaan Niels. "Variations of Shape in Industrial Geometric Models." Doctoral thesis, Norwegian University of Science and Technology, Department of Product Design, 2004. http://urn.kb.se/resolve?urn=urn:nbn:no:ntnu:diva-240.

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This thesis presents an approach to free-form surface manipulations, which conceptually improves an existing CAD system that constructs surfaces by smoothly interpolating a network of intersecting curves. There are no regularity requirements on the network, which already yields superior modelling capabilities compared to systems that are based on industry-standard NURBS surfaces.

Originally, the shape of such a surface can be modified only locally by manipulating a curve in the network. In this process there is an inherent danger that the curve is being pulled away from intersections that it has with other curves. When this happens, the network is invalidated as a surface representation, and many curves may have to be adjusted to restore network consistency and surface quality. This thesis contributes a method that solves these problems by propagating changes that are made in one curve to curves in its vicinity. How and to what extent curves react to changes is controlled by two parameters that can be varied along the curve that is being manipulated. Any curve may be constrained in one or more degrees of freedom. The integrity of the curve network is implicitly conserved, as well as the geometric continuity of the surface.

The result is a tool for the modification of curve-interpolating surfaces, which can easily be applied to large areas on models with any level of detail. This allows designers to concentrate on the creative process, rather than on planning chains of actions. They can explore different design variations, optimise shapes further, and generally be more productive.

Dette doktorgradsarbeidet presenterer en fremgangsmåte for formgivning og modifisering av datamaskinbaserte, skulpturerte flater. Metoden forbedrer et eksisterende system for data-assistert konstruksjon (DAK) som bygger dobbeltkrummede flater ved å interpolere et nettverk av skjærende kurver. Nettverket trenger ikke være regelmessig, noe som allerede gir bedre modelleringsmuligheter sammenliknet med systemer som er basert på standard NURBS flater.

En slik flate kan opprinnelig bare endres lokalt ved å dra i en kurve. I denne prosessen er det fare for at kurven blir dratt fra skjæringspunkter den har med andre kurver. Hvis dette skjer, representerer ikke nettverket en flate lenger, og mange kurver må justeres for å få tilbake integriteten i nettverket og kvaliteten i formen. Denne avhandlingen bidrar med en metode som løser disse problemene ved å spre endringer som blir gjort i en kurve til andre kurver i nærheten. Hvordan og i hvilken utstrekning kurvene reagerer på endringen styres av to parametre som kan varieres langs kurven som blir endret. Enhver kurve kan låses i en eller flere frihetsgrader. Integriteten til nettverket samt glattheten i formen blir bevart automatisk.

Resultatet er et redskap for modifikasjon av kurve-interpolerende flater som med letthet kan brukes på større områder av modeller med hvilken som helst grad av detalj. Dette gir designere muligheten til å konsentrere seg om det kreative, istedenfor å planlegge handlingsrekker. De kan utforske forskjellige designvariasjoner, optimalisere former ytterligere, og i det hele tatt være mer produktive.

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42

Panasiuk, IRINA. "Laivo korpuso detaliu gamybos optimizavimas." Master's thesis, Lithuanian Academic Libraries Network (LABT), 2013. http://vddb.laba.lt/obj/LT-eLABa-0001:E.02~2011~D_20130301_093814-47775.

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Laivų projektavimo ir statybos magistrantūros studijų programa / darbo vadovas doc. dr. L. Turkina; Klaipėdos universitetas, Jūrų technikos fakultetas. – 2011. – 45 p. Baigiamajame magistro darbe nagrinėjama galimybė optimizuoti laivo korpuso kreivalinijinių detalių gamybą. Tradiciškai laivų statyboje sunkiausia optimizuoti korpuso gamybos technologinį procesą. Tačiau būtent korpuso gamybos kaina sudaro 30 % laivo savikainos. Todėl darbe buvo nuspręsta išanalizuoti UAB Vakarų Baltijos laivų statyklos (VBLS) detalių gamybos technologinį procesą ir pasiūlyti laivo korpuso kreivalinijinių detalių gamybos optimizavimo metodą. Mūsų šalyje lakštinio metalo apdirbimo automatizavimo lygis yra aukštas. Tačiau kalbant apie kreivalinijinių profilių gamybos procesą, mūsų gamyklos ženkliai atsilieka nuo pirmaujančių pasaulio laivų statyklų. Taip kiekviename gamybos etape kaupiasi formų ir matmenų nukrypimai. Defektų taisymas yra daug brangesnis nei gamybos savikaina, tačiau iki šiol net 35 % sekcijų gamybos apimties sudaro defektų taisymo ir tvarkymo darbai. Darbo imlumo sumažinimas ir gaminamų laivų korpuso konstrukcijų tikslumo padidinimas yra pagrindinis optimizavimo uždavinys, nuo kurio priklauso šiuolaikinės laivų statybos konkurencingumas. Darbą sudaro įvadas, 3 skyriai, išvados ir rekomendacijos, literatūros sąrašas. Atskirai pridedami darbo priedai.
Panasiuk I. Optimization of ship hull production: Master of naval architecture and marine engineering/ reseach advisor PhD, assoc. prof. L.Turkina; Klaipeda University, the Faculty of Marine Engineering. – 2011. – 45p. The final master paper deals with the possibility of ship hull’s curvilinear profile production optimization. Traditionally in shipbuilding the hardest to optimize is the hull construction, but it is 30% of ship price. In this paper was analyzing the VBLS technological process of profile production and offer a method to improve the curvilinear profile production. There is the high autoimmunization technological level of steel plate production in VBLS, but curvilinear profile production is not effective. In the every part of ship hull production are concentrate defects. The repairs cost are highly than production and now it is 35% of ship sub-assembly work. The aim of the research was to rationalize manufacturing and improve shipbuilding productivity. Work consists of introduction, 3 parts, conclusions and suggestions, references. Appendixes included.

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Aas-Hansen, Mads. "Monitoring of hull condition of ships." Thesis, Norges teknisk-naturvitenskapelige universitet, Institutt for marin teknikk, 2010. http://urn.kb.se/resolve?urn=urn:nbn:no:ntnu:diva-11665.

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In this thesis five bulk ships from Kristian Gerhard Jebsen Skipsrederi AS has been monitored over time in order to discover the increase in resistance due to fouling on the hull and propeller. Each ship has reported weather and ship data twice a month. These reports have been used to discover the resistance due to fouling by correcting all other added resistances from each measurement in the given time period. When all other resistance types are corrected for, each measurement is as if the ship travelled in calm weather. Then these results can be compared. The resistance types that are corrected for in this thesis are: Added resistance in waves Added resistance in wind Added resistance due to steering Speed loss due to shallow water When each measurement has been corrected for these resistance types, they are corrected to a reference speed and draft to be able to compare the results properly. In addition, the extent of the added resistance due to yaw angle because of lift forces from the rudder has been investigated and found to be neglectable. It has been found that the increase in resistance due to fouling is relatively linear the first two-three years. After three years the increase in resistance gets exponential.

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Harper, Justin A. 1975. "Hull form optimization for monohull ships." Thesis, Massachusetts Institute of Technology, 2003. http://hdl.handle.net/1721.1/91798.

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Thesis (S.M. in Naval Architecture)--Massachusetts Institute of Technology, Dept. of Ocean Engineering, 2003.
"June 2003."
Includes bibliographical references (leaves 128-132).
by Justin A. Harper.
S.M.in Naval Architecture

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Holm, Herman. "Ice-Induced Loads on Ship Hulls." Thesis, Norges teknisk-naturvitenskapelige universitet, Institutt for marin teknikk, 2012. http://urn.kb.se/resolve?urn=urn:nbn:no:ntnu:diva-18651.

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The calculation of ice-induced loads on ships is still mainly based on empirical models. In order to gain a better physical understanding of the loading on ice-going vessels, Det Norske Veritas launched an <i>ice load monitoring<i> project involving full scale trials with the coastguard vessel KV Svalbard during the winters 2006, 2007 and 2011. The results from the full scale measurements conducted with KV Svalbard has been topic of several earlier master's thesis at NTNU,The master thesis consists of four parts. The first part is a literature review of the mechanical and physical properties of sea ice.The second part is a review of the rule sets developed by DNV and the IACS regarding vessels operating in ice infested waters. Both design principles and numerical values have been evaluated. The main difference between the designs principles used, is that IACS base their rules on a plastic method of approach, while DNV uses an elastic method. Despite the difference in the design principles, when comparing their numerical values turned out to be quite similar. The DNV rules are in general most conservative for the smaller vessels and the IACS rules the most conservative for large vessels. The third part consists of a finite element study of a part of the bow on KV Svalbard. A systematic load scheme is used, consisting of 102 load cases. For each of the stress factors there where made graphs that showed the stress at the sensor location when moving the patch load. The sensor mounted on the frame were able to measure load that was within the frame loading area and sensor mounted on the stringer could measure stress for all of the load cases in the horizontal directions. One of the explanations for this is that the stringer transfers stress from the load patch area that could be measured by the sensors.The last part consists of a comparison between measurements from the full scale trials and the results from the 102 load cases. This comparison is done through a weighted summation method where 5 different load cases are combined to represent the measured result, and a load factor is calculated for each load case for its contribution of the measured results. The stress component used in this comparison is the shear stress tau xy The load cases were tested against the 11 measurements from the full scale trials. There were in total 11 load cases that gave positive factors for all of the 11 measurements at the same time. A figure was made to show which load cases were likely to contribute in the solution of the load cases. Load cases inside the frame loading area have the largest load factors for the solution of measurements.This load decision scheme is very sensitive to the selection of load cases and boundary conditions. A change of the boundary conditions for the model was tried out for 7 load cases, and with changed boundary conditions, only 5 gave positive load factors.The results of this thesis shows that is possible to find many solution to the measured result by combining many load case, but is it not possible to decide <i>the<i> solution.

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Dimitroglou, Panagiotis 1967. "Performance of high speed multi-hull ships." Thesis, Massachusetts Institute of Technology, 1998. http://hdl.handle.net/1721.1/49667.

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Thesis (M.S. and Nav.E.)--Massachusetts Institute of Technology, Dept. of Ocean Engineering, 1998.
Includes bibliographical references (leaves 110-112).
by Panagiotis Dimitroglou.
M.S.and Nav.E.

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Tober, Hampus. "Evaluation of drag estimation methods for ship hulls." Thesis, KTH, Mekanik, 2020. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-277843.

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This study aims to evaluate to which degree CFD can complement traditional towing-tank experiments, and to develop a computationally cheap and robust methodology for these type of simulations. Two radically different surface ship hulls were chosen for the trials: a capesize bulk carrier and a fast displacement hull. A bare submarine hull was also used to benchmark the software in the early stages of the study. All simulations were Reynolds–Averaged Navier–Stokes (RANS) simulations using the k-w-SST turbulence model. The chosen software was OpenFOAM 5.x and foam-extend 4.1 coupled with the commercial expansion Naval Hydro Pack, which is supposed to handle high Courant numbers well. Producing a high-quality mesh which is able to capture both the free surface and the boundary layers proved to be of utmost importance and the meshing procedure is thus discussed in detail. A majority of the surface ship simulations suffered from a phenomenon known as numerical ventilation. The effect seemed to be much worse for the fast-displacement hull and the drag estimates for this hull deviated around 16.1% from experimental data. The bulk carrier was less affected and the drag estimates for this hull only deviated around 6.3% from experimental data. In order to reduce the computational cost, all surface ship simulations were run with a maximum Courant number of 25 and some consequences of this are also discussed.

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Thorsen, Ingvill Bryn. "Estimation and Computation of Ice-Resistance for Ship Hulls." Thesis, Norges teknisk-naturvitenskapelige universitet, Institutt for marin teknikk, 2012. http://urn.kb.se/resolve?urn=urn:nbn:no:ntnu:diva-18757.

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The oil price continues to increase while oil companies search for oil in new areas. There is assumed that 25% of the world’s hydrocarbons are located in the arctic area. Operating in these areas will be a huge challenge due to extreme low temperatures and ice condition Today one can predict with good accuracy how a ship will manage in different ice condition. Research on ship operating in ice the last decades has resulted in many different formulas for predicting ice resistance on a ship hull. Analytical and numerical methods are developed to estimate the resistance working on the ship hull under different ice conditions. Model test will still be the most accurate prediction, but the other methods may give you some guidelines on what to expect. This thesis contain a theoretically study of ice physics and mechanics. The formation and development of sea ice has been reviewed. The Ice Load Monitoring system tested on the Norwegian coast guard vessel KV Svalbard is described. Three different analytical ice resistance calculation methods are described. The three methods are Lindqvist (1989), Keinonen et al. (1996) and Riska et al. (1997). Data obtained from the Ice Load Monitoring system are used to estimate the full scale ice resistance on KV Svalbard. The three analytical methods are calculated with KV Svalbard as a reference ship to be able to compare with the full scale measurements. MATLAB is used for the calculations.

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Kokko, Michael A. (Michael Andrew). "Range-based navigation of AUVs operating near ship hulls." Thesis, Massachusetts Institute of Technology, 2007. http://hdl.handle.net/1721.1/40292.

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Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 2007.
This electronic version was submitted by the student author. The certified thesis is available in the Institute Archives and Special Collections.
Includes bibliographical references (p. 107-109).
In-water ship hull inspection is essential for both routine preventative maintenance as well as for timely detection and neutralization of limpet mines planted on military and commercial vessels. While a host of inspection methods have been proposed for this task, Autonomous Underwater Vehicles (AUVs) are particularly well-suited for such missions as they require neither constant human supervision nor a restrictive tether as do Remotely Operated Vehicles (ROVs). MIT and Bluefin Robotics have jointly developed a Hovering AUV (HAUV) for the inspection of ship hulls and other submerged marine structures which has been successfully demonstrated to achieve a coverage rate on the order of 700m2/hour with centimeter-scale resolution for a variety of hull types. AUV navigation often involves dead reckoning based on velocity measurements from an acoustic Doppler Velocity Log (DVL) sensor. As this strategy is inherently susceptible to drift, related efforts seek to generate vehicle position updates through either Simultaneous Localization and Mapping (SLAM) or the use of external sensor networks. In this work we propose a unique localization approach which relies on range measurements taken to surfaces of known curvature.
(cont.) The algorithm is developed for navigating relative to simple parabolic curvatures and is tested both in simulation and on a floating raft robot. Localization and servoing are demonstrated in real-time to achieve estimated position deviations within millimeters of their expected values. In addition to exploring other facets of hull-relative navigation, this thesis also documents a significant mechanical redesign of certain HAUV components.
by Michael A. Kokko.
S.M.

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Vinamata, Xavier F. "Development of a noise rejecting sensor for conformal hull arrays." Thesis, Georgia Institute of Technology, 2001. http://hdl.handle.net/1853/17226.

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Dissertations / Theses on the topic 'Ship hull'

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