Dissertations / Theses on the topic 'Ship and Platform Structures'
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1
Largiadèr, Caspar Andri 1965. "Modular platform based surface ship design." Thesis, Massachusetts Institute of Technology, 2001. http://hdl.handle.net/1721.1/91331.
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Thesis (S.M. in Naval Architecture and Marine Engineering)--Massachusetts Institute of Technology, Dept. of Ocean Engineering, 2001.Includes bibliographical references (leaves 97-99).
by Caspar Andri Largiadèr.
S.M.in Naval Architecture and Marine Engineering
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Cannon, Stuart Martin. "Materials selection for ship structures." Thesis, Brunel University, 1995. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.294827.
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Yu, Lei. "Fatigue reliability of ship structures." Thesis, University of Glasgow, 2010. http://theses.gla.ac.uk/2259/.
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Today we are sitting on a huge wealth of structural reliability theory but its application in ship design and construction is far behind. Researchers and practitioners face a daunting task of dove-tailing the theoretical achievements into the established processes in the industry. The research is aimed to create a computational framework to facilitate fatigue reliability of ship structures. Modeling, transformation and optimization, the three key elements underlying the success of computational mechanics are adopted as the basic methodology through the research. The whole work is presented in a way that is most suitable for software development. The foundation of the framework is constituted of reliability methods at component level. Looking at the second-moment reliability theory from a minimum distance point of view the author derives a generic set of formulations that incorporate all major first and second order reliability methods (FORM, SORM). Practical ways to treat correlation and non- Gaussian variables are discussed in detail. Monte Carlo simulation (MCS) also accounts for significant part of the research with emphasis on variance reduction techniques in a proposed Markov chain kernel method. Existing response surface methods (RSM) are reviewed and improved with much weight given to sampling techniques and determination of the quadratic form. Time-variant problem is touched upon and methods to convert it to nested reliability problems are discussed. In the upper layer of the framework common fatigue damage models are compared. Random process simulation and rain-flow counting are used to study effect of wide-banded non-Gaussian process. At the center of this layer is spectral fatigue analysis based on SN curve and first-principle stress and hydrodynamic analysis. Pseudo-excitation is introduced to get linear equivalent stress RAO in the non-linear ship-wave system. Finally response surface method is applied to this model to calculate probability of failure and design sensitivity in the case studies of a double hull oil tanker and a bulk carrier.
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Keller, Joe, James Ivey, Antonios Dalakos, Orhan Okan, Ryan Kuchler, Rabon Cooke, Brad Stallings, et al. ""SEA ARCHER" Distributed Aviation Platform." Thesis, Monterey, California. Naval Postgraduate School, 2001. http://hdl.handle.net/10945/7277.
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Includes supplemental material.This report outlines the results of a two quarter Total Ship Systems Engineering (TSSE) Capstone design project undertaken by the students at the Naval Postgraduate School. The project was under the direction of Professors C.N. Calvano and R.Harney.
Currently, no system exists that provides a sea-based distributed aviation platform capability. The emergence of Unmanned Air Vehicles (UAVs) / Unmanned Combat Air Vehicles (UCAVs), the continued U.S. Navy focus on the littorals, the desire for force distribution, the need for operational cost reductions, and the advent of Network Centric Warfare (NCW) all continue to support the requirement to re-evaluate how littoral operations will be conducted in the future. Given this background, a bottom-up design of a ship supporting a primarily UAV/UCAV air wing in a low to medium threat environment is of significant interest. SEA ARCHER meets this interest. This report outlines a design that meets the future needs for distributed aviation with a high-speed, highly automated platform. Large gains in reduced manning through automated systems for both operation and damage control helpmeet the demanding needs for the future of the Navy at reduced operational costs. The report will outline both the Mission Needs Statement (MNS) and Operational Requirements Document (ORD) for the ship that was developed. The analysis of alternatives that was conducted to determine relative size requirements for the ship in presented in the next section. The concept design that resulted as a result of the Total Ship Systems Engineeing process in then presented. Finally, a detailed look at the analysis and trade studies that were conducted in presented in order to show the more detailed analysis that was conducted in designing the ship.
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Lin, Tian Ran. "Vibration of finite coupled structures, with applications to ship structures." University of Western Australia. School of Mechanical Engineering, 2006. http://theses.library.uwa.edu.au/adt-WU2006.0093.
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[Truncated abstract] Shipbuilding is fast becoming a priority industry in Australia. With increasing demands to build fast vessels of lighter weight, shipbuilders are more concerned with noise and vibration problems in ships than ever. The objective of this thesis is to study the vibration response of coupled structures, in the hope that the study may shed some light in understanding the general features of ship vibration. An important feature characterizing the vibration in complex structures is the input mobility, as it describes the capacity of structures in accepting vibration energy from sources. The input mobilities of finite ribbed plate and plate/plate coupled structures are investigated analytically and experimentally in this study. It is shown that the input mobility of a finite ribbed plate is bounded by the input mobilities of the uncoupled plate and beam(s) that form the ribbed plate and is dependent upon the distance between the source location and the stiffened beam(s). Off-neutral axis loading on the beam (point force applied on the beam but away from the beam’s neutral axis) affects the input power, kinetic energy distribution in the component plates of the ribbed plate and energy flow into the plates from the beam under direct excitation ... solutions were then used to examine the validity of statistical energy analysis (SEA) in the prediction of vibration response of an L-shaped plate due to deterministic force excitations. It was found that SEA can be utilized to predict the frequency averaged vibration response and energy flow of L-shaped plates under deterministic force (moment) excitations providing that the source location is more than a quarter of wavelength away from the plate edges. Furthermore, a simple experimental method was developed in this study to evaluate the frequency dependent stiffness and damping of rubber mounts by impact test. Finally, analytical methods developed in this study were applied in the prediction of vibration response of a ship structure. It was found that input mobilities of ship hull structures due to machinery excitations are governed by the stiffness of the supporting structure to which the engine is mounted. Their frequency averaged values can be estimated from those of the mounting structure of finite or infinite extents. It was also shown that wave propagation in ship hull structures at low frequencies could be attenuated by irregularities imposed to the periodic locations of the ship frames. The vibration at higher frequencies could be controlled by modifications of the supporting structure.
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Lin, Tian Ran. "Vibration of finite coupled structures, with applications to ship structures /." Connect to this title, 2005. http://theses.library.uwa.edu.au/adt-WU2006.0093.
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Beson, Simon Derek. "Progressive collapse assessment of lightweight ship structures." Thesis, University of Newcastle upon Tyne, 2011. http://hdl.handle.net/10443/1445.
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This thesis investigates the progressive collapse behaviour of lightweight ship hull girders including the effects of compartment level buckling modes. An extension to the progressive collapse methodology is proposed, which has capabilities to predict the compartment strength of a lightweight aluminium midship section. Nonlinear finite element analysis is used to validate both the progressive collapse methodology and the analytical approach proposed for determining the buckling capacity of orthogonally stiffened substructures within the hill girder compartment. The research has been undertaken due to the continued growth in the size of large lightweight craft in both commercial and naval vessels, combined with increasing operability requirements for these vessels. The development of large and lightweight marine structures, predominantly built from aluminium alloy, has raised important issues regarding the response of the hull girder under primary hull girder bending.
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Underwood, J. "Strength assessment of damaged steel ship structures." Thesis, University of Southampton, 2013. https://eprints.soton.ac.uk/355704/.
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In 2012 106 vessels over 100 gross tonnes were lost. During the damage incidents many of these vessels required assistance from shore based emergency response services with regards to their damaged strength to stabilise the situation, preserve life, prevent environmental disaster and limit financial costs to owners and insurers. The research work presented in this Engineering Doctorate Thesis surrounds the strength assessment of damaged steel ship structures, the influence of damage on the strength of steel-plated structures and methods for assessing the residual strength of a vessel in an emergency. The focus of the work is to improve the modelling of damaged steel ship structures within an emergency situation, in order to improve guidance provided to a stricken vessel during a damage incident or salvage process. Literature study has shown that structural idealisation through the use of interframe progressive collapse analysis, to be the current state of the art method for the rapid assessment of intact and damaged ship structures. However, a number of weaknesses have been identified in the method when applied to damage assessment. The literature study has also shown a lack of understanding of the effect of damage on steel-plated structures as specific analysis has not been performed previously. Significant research has been undertaken into the influence of damage, in the form of a hole, on the ultimate collapse strength of steel-plated structures. Three levels of structural modelling have been used, stiffened-plate, stiffened panel and grillage. Comparison of the predicted ultimate collapse strength by finite element analysis (FEA) with predictions using the interframe progressive collapse idealisation, has shown the calculated results to be conservative for the assessment of damaged structure when the failure mode remains in the interframe collapse form. However, changes in the failure mode lead to the interframe progressive collapse method over predicting the ultimate collapse strength. The analysis shows that even small damage events can lead to significant changes to the failure mode and resulting ultimate collapse strength of the structure. Such influences must be accounted for in any simplified method. A new method for the assessment of damaged ship structures is proposed that is capable of modelling a damage scenario more accurately. Demonstration of the method has shown the results to be less conservative than the current state of the art, when compared to FEA, for local analysis of damaged steel-plated structure. The ability of the method to account for the influence of damage, and the resulting failure modes, that may significantly influence the ultimate bending strength of the structure has also been demonstrated. The method implements a compartment level progressive collapse analysis with structural data captured through the use of the response surface method ‘kriging’, using data points provided from FEA. This method allows the critical damage variables to be captured and strength data accessible quickly for use in the analysis. The time to provide a solution to the damage scenario is equivalent to the existing interframe progressive collapse method. Therefore, the method is suitable for application within an emergency response or salvage service.
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Asadi, Ghasem Vaez-Zadeh. "Dynamic response of ship structures to impact loads." Thesis, University of British Columbia, 1989. http://hdl.handle.net/2429/29310.
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In this study the dynamic response of a ship structure to impact loads is investigated. The ship motion is fully three-dimensional and the ship structure is modeled as a three-dimensional elastic beam. Finite element methods are used to digitize the equations of motion of the system. The forces on the ship are interactive with the ship motion and position so that a full dynamic analysis is essential.
Two main problems are considered: i) Estimation of hull damage when a ship collides with another ship, floating structure or fixed installation. A particular aspect of this analysis which has not previously been examined analytically involves estimating damage to the bottom of ship when it runs aground. Depending on the nature of the ground the ship may be pierced and significant amounts of steel may be torn, or the ship may ride over a sand bar without tearing but with noticeable denting and bending. In such grounding studies it has been necessary to introduce certain strength coefficients, realistic values of which have not been determined, but for which sensible estimates have been made. The results of a numerical study into grounding and collision damage illustrate clearly that ship speed is the major variable in the damage process. In particular the effect of subsequent angular motions incurred during a high speed collision can cause secondary but also significant collisions further aft. It is believed that these aspects of collision and grounding, and the related problems associated with collision whilst maneuvering, have not been investigated previously. ii) Bending stresses induced in ice-breaking ships during operation in ice. In this second class of problems two modes of operations are considered; continuous operation in level ice without loss of speed, and high speed ramming of ice ridges in which the ship is brought to rest.
In the continuous ice breaking mode, the impulse loads are relatively low but periodic. The period of the impulse loads varies linearly with ship speed and also depends on the hardness and thickness of the ice. Since the ship is an elastic system with natural frequencies of the same order as impact frequency, some interesting response conditions have been identified leading to large flexural bending stresses in the ship.
In the ramming mode,' two response states are of importance., The initial impulse at the bow of the ship, when contact is first made, causes the ship to respond primarily in its first flexural mode with possibly large bending stresses developing during the first second after impact. The ship then rides onto the ice in a "beaching mode" causing large quasi-static bending stresses in the hull which reach a peak after five seconds or so. Both of these peak bending situations have been investigated and their dependence on speed, hull" stiffness, bow angle, and ship speed has been established. In the past few years some data obtained from ships operating in the Beaufort sea has been released, both for continuous ice-breaking and for ramming. Whenever possible those data have been compared with the results predicted by the numerical method developed here. The agreement is shown to be very good.Applied Science, Faculty of
Mechanical Engineering, Department of
Graduate
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Han, Yongqing. "Crack arrest toughness of weldments for ship structures." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1999. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape8/PQDD_0005/MQ43341.pdf.
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繆泉明 and Quanming Miao. "Effect of submerged vertical structures on ship waves." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2001. http://hub.hku.hk/bib/B3025176X.
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Han, Yongqing Carleton University Dissertation Engineering Civil and Environmental. "Crack arrest toughness of weldments for ship structures." Ottawa, 1999.
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Miao, Quanming. "Effect of submerged vertical structures on ship waves /." Hong Kong : University of Hong Kong, 2001. http://sunzi.lib.hku.hk/hkuto/record.jsp?B23765902.
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Phillips, Holly Jacqueline. "Assessment of damage tolerance levels in FRP ship structures." Thesis, University of Southampton, 1997. https://eprints.soton.ac.uk/361131/.
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This work is concerned with the damage tolerance assessment of laminated composite structures used in ship structures. An intensive review has been carried out with regard to current experimental, analytical and numerical work on both laminates and structural elements. Particular attention has been focused on the problem of damage due to delamination and its structural consequences. Strength assessments of top hat stiffeners and tee joints has been carried out with a view to identifying regions most susceptible to delaminations. It has been shown that such regions are contained within the curved region of the overlaminate in both types of structural elements. Strain energy release rates and J-integral values have been calculated for specific cracks to determine their likelihood of propagation under a variety of loading conditions. Overall, a number of conclusions have been drawn with regard to single-skin marine FRP structures. For example, both the strength - and the energy - based approaches have predicted that a tee joint subjected to a 45 degree pull-off load, delaminations which are deep within the overlaminate are more likely to propagate than those close to the surface.
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Liu, Zhenhui. "Analytical and numerical analysis of iceberg collisions with ship structures." Doctoral thesis, Norges teknisk-naturvitenskapelige universitet, Institutt for marin teknikk, 2011. http://urn.kb.se/resolve?urn=urn:nbn:no:ntnu:diva-15790.
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The scope of the present Ph.D. thesis was to investigate the mechanics of collisions between icebergs and ship structures. Large reservoirs of oil and gas and new sailing routes in the Arctic area are two large motivations for the present research. Human activity in the Arctic demands well-designed naval architectures for facing different kinds of ice loads. According to modern design codes, ship and offshore structures are usually designed under the ultimate limit state (ULS) methods and checked with the accidental limit state (ALS) methods. The methods and assumptions presented in this thesis are only valid for ALS design. This thesis considers three topics related to the iceberg collisions with ship structures: external mechanics, internal mechanics and residual strength assessments. Collisions between icebergs and ship structures are quite complicated processes. For simplicity, this problem was split into its external and internal mechanics. External mechanics talks about the translational and rotational momentum balance. It is believed that the impact mechanics of iceberg collisions with ship structures should be presented in three dimensions. Thus, a new formulation of impact mechanics was proposed that describes the impact in three dimensions. All forces except for impact force are neglected. This new three-dimensional method degrades to existing two dimension (2D) method. It was successfully applied to the calculation of the demanded dissipated energy for iceberg and ship collisions. Internal mechanics deal with both deformations of icebergs and ship structures. Nonlinear finite-element analysis (NLFEA) was used in this research. The commercial code LS-DYNA 971 was used to assess the internal mechanics of both icebergs and ship structures. Deformations of both icebergs and ship structures should be well captured by numerical simulations. However, due to the difficulties of simulating ice, NLFEA is not straightforward. To facilitate such simulations, a plasticity-based material model for icebergs was developed in this thesis. Iceberg crack propagation was simulated by element erosion. An empirical failure criterion for detecting those failed ice elements is proposed. Numerical examples showed that the new iceberg model gives good results. The model was successfully implemented in LS-DYNA 971 through a user-defined subroutine. Subsequently, the integrated numerical analysis of iceberg-ship collisions was then successfully performed. Efforts were made to investigate the internal mechanics of both icebergs and ship structures during collision, such as local structural behaviours and ice failure. Two scenarios of iceberg-ship collisions were investigated: iceberg collisions with foreship and side-ship structures. In the first scenario, efforts focused on the investigation of the detailed internal mechanics of the icebergs and ship structures. The strength of ship structures was varied by adjusting the parameters of the steel material model, thereby varying the relative strength of icebergs and ship structures. A comprehensive discussion is based on the simulation results. The discussion addresses contact pressure, iceberg shapes and collision locations. In the second scenario, investigations focused on the influences of the iceberg shapes. Simple iceberg shapes representing “sharp” and “blunt” icebergs were used. The results show that “blunt” icebergs may behave as rigid bodies. Finally, the residual strengths of the ship structures after impact, which may be caused by the icebergs, was assessed. A simple plasticity method and a single stiffener model were developed to quantify the residual strengths of the damaged ship structures. In the simple plasticity method, elastic and rigid-plastic methods were combined to derive the end-shortening curve for damaged stiffeners. In the single stiffener model, proper boundary conditions were proposed. Both methods were verified against numerical simulations. Generally, good results were obtained. From this work, a rapid method to assess the residual strength of damaged ship structures is suggested.
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Barber, Matthew Edward. "Experimental and computational determination of global resonances in ship structures." Thesis, Springfield, Virginia: Available from National Technical Information Service, 1991. http://hdl.handle.net/10945/28198.
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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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Zoet, Petrus Gosse. "Component mode synthesis for ship structures : investigation into an alternative approach." Thesis, University of Strathclyde, 2013. http://digitool.lib.strath.ac.uk:80/R/?func=dbin-jump-full&object_id=24881.
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The main aim of this work is to help the shipbuilder to effectively assess a ships' structural design for its vibratory behaviour. For that purpose state of the art structural modelling techniques are reviewed for the validity of their basic principles, accuracy, practicality and required computation time when applied on typical marine structures. Full finite element modelling has been applied on a part of the structure of an LNG carrier on board which the author has taken vibration and noise measurements. Also fixed interface (Craig-Bampton) and free interface (Rubin's method) component mode synthesis sub structuring techniques have been applied. The aim of the analysis is to evaluate the effectiveness of finite element modelling through evaluation with measurement results, evaluate the accuracy of the sub structuring modelling techniques and to identify short comings of any of the tested methods. Two alternative component synthesis modelling sub structuring techniques are proposed in order to reduce required computation time; Zoet's method and the Rubin Zoet method. The Zoet method is tested using a section of the LNG carrier's structural model. The method is evaluated for accuracy (comparing obtained results with the results obtained through the full harmonic finite element analysis) and required computation time through comparison with the required computation time for: - full harmonic analysis - the classical modal reduction and mode superposition technique - the classical Rubin free interface component mode synthesis - and Rubin's method with interface reduction according to the IRS method (see section 6.5.3) - the Rubin-Zoet technique.
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Maneepan, Komsan. "Genetic algorithm based optimisation of FRP composite plates in ship structures." Thesis, University of Southampton, 2007. https://eprints.soton.ac.uk/52012/.
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Composite materials (herein means Fibre Reinforced Plastic, FRP) are increasingly usedin the construction of marine vehicles because of their outstanding strength, stiffness and light weight properties. However, the use of FRP comes with difficulties in the design process as a result of the large number of design variables involved: composite material design, topologies and laminate schemes. All variables are related to each other leading to a high dimensional and flexible design space. It is hard to use traditional design methods in order to gain solutions for an initial design stage in a short time. Hence, this thesis deals with the presentation of a structural synthesis (optimisation framework) for plate components of composite ship structures. The framework broadly consists of an optimisation technique and structural analytical methods. To make the framework compatible with the nature of composite ship structural design problems, the Genetic Algorithm (GA) is selected as the optimisation tool because of its robustness, its ability in dealing with both continuous and discrete variables and its excellent searching for a global optimum. The typical plate types in a ship structure are the stiffened and unstiffened plates. For a stiffened plate, the combination of the grillage analysis of energy method based on Navier solution and an equivalent elastic properties approach are introduced. Using this, it is possible to produce layer by layer optimisation results for the base plate, web and crown of the stiffened plate. Unfortunately, solutions of the adopted grillage analysis do not cover the mechanical behaviour of the plate between stiffeners so the Higher-Order Shear Deformation Theory (HSDT) must be employed. This method provides accurate solutions for thin to moderately thick plates with a compromised computational time. Then stiffness, strength and stability can be considered in the design problem. In addition, to achieve the program of the structural synthesis, various computational modules are implemented according to the evaluation of composite micromechanics properties, maximum stress failure criteria and structural weight function. Then the main modules are validated with available resources. The usefulness of the program has been proved by comparing it with the optimal solutions from finite element software. Finally, many application examples of secondary and tertiary composite ship structures are presented. The optimal results prove the success of the optimisation framework. This could be evidence for further improvement to obtain a valuable structural optimisation tool.
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Balaji, R. "Collisions of tension leg platforms with ships." Thesis, University of Southampton, 1987. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.380192.
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Kumar, Anil. "Estimation and Mapping of Ship Air Wakes using RC Helicopters as a Sensing Platform." Diss., Virginia Tech, 2018. http://hdl.handle.net/10919/82910.
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This dissertation explores the applicability of RC helicopters as a tool to map wind conditions. This dissertation presents the construction of a robust instrumentation system capable of wireless in-situ measurement and mapping of ship airwake. The presented instrumentation system utilizes an RC helicopter as a carrier platform and uses the helicopter's dynamics for spatial 3D mapping of wind turbulence. The system was tested with a YP676 naval training craft to map ship airwake generated in controlled heading wind conditions. Novel system modeling techniques were developed to estimate the dynamics of an instrumented RC helicopter, in conjunction with onboard sensing, to estimate spatially varying (local) wind conditions. The primary problem addressed in this dissertation is the reliable estimation and separation of pilot induced dynamics from the system measurements, followed by the use of the dynamics residuals/discrepancies to map the wind conditions.
This dissertation presents two different modelling approaches to quantify ship airwake using helicopter dynamics. The helicopter systems were characterized using both machine learning and analytical aerodynamic modelling approaches. In the machine learning based approaches, neural networks, along with other models, were trained then assessed in their capability to model dynamics from pilot inputs and other measured helicopter states. The dynamics arising from the wind conditions were fused with the positioning estimates of the helicopter to generate ship airwake maps which were compared against CFD generated airwake patterns. In the analytical modelling based approach, the dynamic response of an RC helicopter to a spatially varying parameterized wind field was modeled using a 30-state nonlinear ordinary differential equation-based dynamic system, while capturing essential elements of the helicopter dynamics. The airwake patterns obtained from both types of approach were compared against anemometrically produced wind maps of turbulent wind conditions artificially generated in a controlled indoor environment.
Novel hardware architecture was developed to acquire data critical for the operation and calibration of the proposed system. The mechatronics design of three prototypes of the proposed system were presented and performance evaluated using experimental testing with a modified YP676 naval training vessel in the Chesapeake Bay area. In closing, qualitative analysis of these systems along with potential applications and improvements are discussed to conclude this dissertation.Ph. D.
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Zubaydi, Achmad. "Use of neural networks for the identification of damage in ship structures." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 2001. http://www.collectionscanada.ca/obj/s4/f2/dsk3/ftp05/NQ62462.pdf.
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Yang, Park Dal Chi. "Energy absorption and collapse of ship structures with particular reference to collisions." Thesis, University of Newcastle Upon Tyne, 1987. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.339754.
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Blinn, Bart A. "Flexlab a flexible structure controls test platform." Ohio : Ohio University, 1997. http://www.ohiolink.edu/etd/view.cgi?ohiou1177609627.
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Smit, Philip Ethelbert. "Development of a 3-DOF motion simulation platform." Thesis, Stellenbosch : University of Stellenbosch, 2010. http://hdl.handle.net/10019.1/4155.
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Thesis (MScEng (Electrical and Electronic Engineering))--University of Stellenbosch, 2010.ENGLISH ABSTRACT: The successful development of a three degree of freedom motion simulation platform, capable of simulating a vessel’s flight deck at sea, is presented. The motion simulation platform was developed to practically simulate and test an unmanned aerial vehicle’s capability of landing on a moving vessel, before practically being demonstrated on an actual vessel. All aspects of the motion simulation platform’s development are considered, from the conceptual design to its practical implementation. The mechanical design and construction of a pneumatic motion simulation platform, as well as the electronics and software to enable the operation of this motion simulation platform, are presented. Mathematical models of the pneumatic process and platform orientation are developed. A controller architecture capable of regulating the pneumatic process, resulted in the successful control of the motion simulation platform. Practical motion simulation results of one of the South African Navy Patrol Corvettes, demonstrate the motion simulation platform’s success. The successful development of the motion simulation platform can largely be attributed to extensive research, planning and evaluation of the different development phases.
AFRIKAANSE OPSOMMING: In hierdie studie word die suksesvolle ontwikkeling van ’n drie-grade-van-vryheid bewegingsimulasieplatform, wat in staat is daartoe om ’n skip se vliegdek ter see te simuleer, aangebied. Die bewegingsimulasieplatform is ontwikkel om ’n onbemande lugvaartuig se vermoë om op ’n bewegende skip te land, te simuleer en te toets, voor dit op ’n werklike skip gedemonstreer word. Alle aspekte van die ontwikkeling van die bewegingsimulasieplatform word in ag geneem – van die konsepontwerp tot die praktiese implementering daarvan. Die meganiese ontwerp en konstruksie van ’n pneumatiese bewegingsimulasieplatform word bespreek, sowel as die elektronika en programmatuur wat die werking van hierdie bewegingsimulasieplatform bemoontlik. Wiskundige modelle van die pneumatiese proses en platformoriëntering word ontwikkel. ’n Beheerderargitektuur wat in staat is daartoe om die pneumatiese proses te reguleer, lei tot die suksesvolle beheer van die bewegingsimulasieplatform. Praktiese resultate van die bewegingsimulering van een van die Suid-Afrikaanse Vloot se patrolliekorvette wys daarop dat die bewegingsimulasieplatform wel suksesvol is. Die geslaagde ontwikkeling van die bewegingsimulasieplatform kan grootliks toegeskryf word aan omvangryke navorsing, beplanning en evaluering van die onderskeie ontwikkelingsfases.
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Mohammed, Abuu Khalifa. "Nonlinear Shell Finite Elements for Ultimate Strength and Collapse Analysis of Ship Structures." Doctoral thesis, Norwegian University of Science and Technology, Faculty of Engineering Science and Technology, 2001. http://urn.kb.se/resolve?urn=urn:nbn:no:ntnu:diva-79.
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The present thesis deals with ultimate strength and collapse analysis of ship structures. Within this are, the attention is directed towards simple and efficient nonlinear finite element models for stiffened plate panels in ship structures. Several types of Morley elements are investigated and two are selected for further development. These triangular elements assume constant stress distribution over the element area.
The first element considered is a nonlinear facet shell element which is valid within moderate rotations. Its elastic formulation has been proposed earlier. In this work, the element matrices are extended to account for material plasticity. The second element, is a displacement-based curved element which undergoes arbitrary large displacements and rotations. The discrete equilibrium equations for this element are re-derived so as to make them more efficient with standard Newton-Raphson solution procedures.
Material plasticity formulation using through-the thickness integration as well as resultants plasticity is presented. The evolution laws are derived from the natural laws of thermodynamics, and a return mapping algorithm with a backward Euler difference scheme is used for a solution of the evolution equations. The plasticity computations involve a solution of a single scalar yield surface for the plasticity multiplier. By performing the matrix algebra analytically, simple and explicit expressions are derived. These equations reduce the computational costs remarkably.
Numerical examples, mostly selected from well-know benchmark problems, are presented to demonstrate the performance of the proposed formulations. Very good agreement is obtained when compared with published results. In addition, typical problems for ultimate strength and collapse analysis of ship hull-girder are analyzed. These include plate girders, stiffened plate panels, as well as a cruciform element. The results show good agreement not only with those obtained from commercial finite element programs, but also from the experimental observations. For stiffened plate panels, comparison is made with DNV design rules, which is found to give non-conservative estimates for some load conditions.
Finally, a study on multi-span stiffened panels is performed so as to compare the estimates provided by the conventional single span model. It is observed that the conventional model provides conservative estimates, and the effect of transverse frames is especially significant on the finite element model of stiffened panels.
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Glenwright, David George. "An experimental and finite element investigation of added mass effects on ship structures." Thesis, University of British Columbia, 1987. http://hdl.handle.net/2429/26701.
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The Experimental and Finite Element Investigation of Added Mass Effects on Ship Structures comprised three phases : 1) investigation of the fluid modelling capabilities of the Finite Element Program VAST, 2) experimental investigation to determine the effect of the fluid on the lowest natural frequencies and mode shapes of a ship model, and 3) comparison of these experimental results with numerical results obtained from VAST. The fluid modelling capabilities of VAST were compared with experimental results for submerged vibrating plates, and the effect of fluid element type and mesh discretization was considered. In general, VAST was able to accurately predict the frequency changes caused by the presence of the fluid. Experimental work both in air and water was performed on a ship model. The lowest four modes of vertical, horizontal, and torsional vibration were identified, and the effect of draught on the frequencies and mode shapes was recorded. When the experimentally obtained frequencies and mode shapes for the ship model were compared with the numerical predictions of VAST, good agreement was found in both air and water tests for the vertical vibration modes.Applied Science, Faculty of
Mechanical Engineering, Department of
Graduate
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Pahos, Spiro J. "Reliability-based vulnerability requirements for asymmetric threats in the design of ship structures." Thesis, University of Strathclyde, 2009. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.570447.
Full textAbstract:
This thesis investigates the structural response of modem ship structures under the effect of premeditated blast loads from acts of terrorism and extremism. The escalation of maritime terrorism and piracy has given the impetus to this study to take an introspective look into the details of ship structural performance under a series of design threats. Knowledge gained in studying the vulnerability of merchant ship structures is important in identifying the area to focus further work. As soon as the vulnerability of a typical ship structure is identified, a more detailed study on the most contributive structural members is carried out. Then, a rational increase of the highlighted members raises the reliability index of the subject panel, and proposes a target reliability index for blast-loaded stiffened panels. The benefit from meeting the suggested reliability-based vulnerability requirements is assessed in terms of a series of identified metrics of benefit for the considered design threats
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Aksu, Seref. "Steady state and transient responses of flexible ship structures travelling in irregular seaways." Thesis, University of Southampton, 1993. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.334385.
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McGowan, David. "Ultimate capacity of offshore platform conductor strings." Thesis, Virginia Tech, 1991. http://hdl.handle.net/10919/41703.
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The ultimate capacity of offshore platform conductor strings is studied. The unique way in which conductors are loaded is described and the various design methods that exist are presented. Previous research in the field of tubular member behavior is also reviewed.
The results of seven experimental tests are evaluated and compared with the existing conductor design criteria. The test matrix calls for various amounts of lateral loading to be imposed on the conductor system. Axial load, applied to simulate the weight of inner casings, is then applied until failure.
Results indicate that internally applied axial loads do not induce stability related failure in the outer conductor. Additionally, the design internal moment, which is based on an inner casing being as eccentric as possible, accurately represents the upper limit for the bending moment observed in the experimental tests. The flexural stiffness of the inner casing serves to strengthen the conductor system. Therefore, a design method that considers the strength of the outer conductor and the inner casings is recommended.Master of Science
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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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McCoy, Kevin Michael. "Identification and alteration of global resonance modes in ship structures to reduce sound radiation." Thesis, Massachusetts Institute of Technology, 1989. http://hdl.handle.net/10945/42110.
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Approved for public release, distribution unlimitedA ship hull and foundation structure will have many vibratory resonance modes. During the shipbuilding process on land or in a drydock, it would be highly advantageous to determine which of these modes have a potential for strong sound radiation when the ship is waterborne. This research employs an experimental model of a submarine hull and foundation. Small masses are placed on the foundation and hull, and the effects on the vibration spectra of the structure are studied. Based on spectra response, modes are classified as hull modes, foundation modes, or "global" modes. Global modes are well coupled hull and foundation mode pairs which are closely spaced in frequency. Waterbome testing reveals that global mode pairs are strong waterbome sound radiators. Additionally, the application of small masses is shown to perturb the coupling between the global mode pairs and yield dramatic changes in the radiated sound. Four foundations of differing size are tested and repeatability of the experimental results is confirmed. As the foundation size increases, global modes are identified on the basis of foundation drive point vibration spectra alone, hull vibration data is not required.
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Syrigou, Maria. "Progressive collapse assessment of intact and damaged ship structures under combined bending and torsional loading." Thesis, University of Newcastle upon Tyne, 2017. http://hdl.handle.net/10443/3793.
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The Simplified Progressive Collapse Method is a quick and well‐established method recommended by International Association of Classification Societies (IACS) for the evaluation of a ship’s ultimate strength due to longitudinal bending. However, in the case which the torsional rigidity of the structure is reduced i.e. containerships, longitudinal bending may not be the dominant reason for failure. Torsion and shear forces may influence the global strength and therefore the effect of combined loading needs to be investigated. The current research aims to understand hull girder failure modes under these combined loads both for intact and damage case scenarios and incorporate torsional loading effect into the existing method. A hull girder which is subjected to longitudinal bending moment and torsional loading generates compressive/tensile and shear stresses on its plates and stiffened panels. Therefore, a thorough investigation of plates under these combined loads has been carried out. The outcome of this study is interaction diagrams of compression/tension and shear for steel and aluminium plates. The ultimate strength of the structure is then estimated for an applied amount of torsion calculating the shear flow distribution of the plates in the cross section and using the results of the previous study. The same procedure is repeated for different amounts of torsion and the interaction diagram of vertical/horizontal bending moment and torsional moment is derived. For validation, the proposed method is applied to a number of different intact box girders and to a hull girder of a 10000 TEU containership. The effect of damage on the ultimate strength is examined only under bending due to the current representation of damage in the simplified method. The results are compared with the results of non‐linear finite element models which have been generated and analysed for this purpose. The results for all studies show very good correlation, however the simplified method provides a sufficient advantage of time estimation and simplicity in comparison with the existing methods. It can be used in both concept and preliminary design to provide accurate estimation of hull girder strength. This extension of the Simplified Progressive Collapse Method, which accounts for combined load effects, is particularly useful in cases which require quick estimate of ultimate strength.
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Vishnubhotla, Srinivas. "A New Method to Predict Vessel Capsizing in a Realistic Seaway." ScholarWorks@UNO, 2007. http://scholarworks.uno.edu/td/588.
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A recently developed approach, in the area of nonlinear oscillations, is used to analyze the single degree of freedom equation of motion of a oating unit (such as a ship) about a critical axis (such as roll). This method makes use of a closed form analytic solution, exact upto the rst order, and takes into account the the complete unperturbed (no damping or forcing) dynamics. Using this method very-large-amplitude nonlinear vessel motion in a random seaway can be analysed with techniques similar to those used to analyse nonlinear vessel motions in a regular (periodic) or random seaway. The practical result being that dynamic capsizing studies can be undertaken considering the shortterm irregularity of the design seaway. The capsize risk associated with operation in a given sea state can be evaluated during the design stage or when an operating area change is being considered. Moreover, this technique can also be used to guide physical model tests or computer simulation studies to focus on critical vessel and environmental conditions which may result in dangerously large motion amplitudes. Extensive comparitive results are included to demonstrate the practical usefulness of this approach. The results are in the form of solution orbits which lie in the stable or unstable manifolds and are then projected onto the phase plane.
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Bellstedt, Philip. "The design, implementation of a moving platform landing algorithm for an unmanned autonomous helicopter." Thesis, Stellenbosch : Stellenbosch University, 2015. http://hdl.handle.net/10019.1/96780.
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Thesis (MSc)--Stellenbosch University, 2015.ENGLISH ABSTRACT: With a view to future ship deck landings, a moving platform landing algorithm for an unmanned autonomous helicopter was successfully designed and a number of systems were developed in order to implement the landing algorithm. Through a combination of an MCA-based ship motion prediction algorithm and the appropriate analysis of platform motion criteria, a system was developed which can identify valid landing opportunities in real ship motion data recorded at sea state 4 for up to 5 s into the future with a 75% success rate. The bandwidth of the heave motion estimator and controller of the helicopter were increased by the implementation of GPS latency compensation, and velocity and acceleration feed forward terms respectively. The resulting bandwidth of at least 0.2 Hz is sufficient to track the heave motion of a platform which is simulating the motion of a ship at sea state 4 or lower. After the various systems were integrated they were coordinated in a landing state machine. A stationary platform landing was demonstrated successfully during flight tests, verifying the functionality of the landing state machine and the integration of the system. Landings on a platform simulating the motion of a ship at sea state 4 were demonstrated successfully in hardware-in-the-loop simulations.
AFRIKAANSE OPSOMMING: Met die oog op toekomstige skip dek landings, is 'n bewegende platformlandingsalgoritme vir 'n onbemande outonome helikopter suksesvol ontwerp en 'n aantal stelsels ontwikkel om die landingsalgoritme te implementeer. Deur 'n kombinasie van 'n MCA-gebaseerde skipbewegingvoorspellingsalgoritme en die toepaslike ontleding van platformbewegingkriteria, is 'n stelsel ontwikkel wat geldige landingsgeleenthede in realeskipbewegingsdata kan identifiseer. Vir skipbewegingsdata wat by seetoestand 4 opgeneem is kan landingsgeleenthede 5 s in die toekoms met ‘n 75% sekerheid identifiseer word. Die bandwydte van die afgeebewegingafskatter en beheerder van die helikopter is deur die implementering van GPS vertragingkompensasie, en snelheid en versnelling vorentoe-voer terme onderskeidelik verhoog. Die gevolglike bandwydte van minstens 0.2 Hz is voldoende om die afgeebeweging van 'n platform te volg wat die beweging van 'n skip by seetoestand 4 of laer simuleer. Nadat die stelsels geïntegreer is is hulle gekoördineer in 'n landingtoestandsmasjien. 'n Stilstaande platform landing is suksesvol gedemonstreer tydens vlugtoetse, wat die funksionaliteit van die landingtoestandsmasjien en die integrasie van die stelsel bewys. Landings op 'n platform wat die beweging van 'n skip by seetoestand 4 simuleer is suksesvol in hardeware-in-die-lus simulasies gedemonstreer.
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Qian, Liyuan. "An interwoven visualization platform for assessing : the restoration of fragmented landscape structures." Doctoral thesis, Universitat Politècnica de Catalunya, 2016. http://hdl.handle.net/10803/404379.
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The process of landscape restoration in highly polluted areas is influenced by complex interactions between a variety of environmental elements; these are interconnected through the comprehensive medium of the landscape structure which is made up of patches, corridors and matrices. In this study, I research landscape structure using an environmental monitoring model, configured with high-definition real-time visualization, to assess the process of controlling pollution and top-soil restoration in both restored and un-restored sites. Using a unique visual environmental impact assessment platform, I evaluate a simulation from July 1999 to July 2014. I conclude that, at 5m X 5m resolution from the Unmanned Aerial Vehicle (UAV), and 30 m X 30 m resolution from the Landsat satellite (combining GIS, ENVI, Rhino and Grasshopper software), the model captures the main features of observed surface temperature, vegetation and the hydrology variation in the research site. The finer visual representation of the complex surface temperature, vegetation variables and explicit hydrology simulation at different resolutions, significantly improves the efficient and comprehensive assessment of the restoration process, in particular with regard to the visualization analysis of the structure of the damaged landscape eco-system. The change in this during the restoration process is noteworthy; the growth of the vegetation patch and the trend of the surface temperature matrix for each five years are included in the new hydrology corridor. I conclude that there is great potential for improving the precision of the environmental impact assessment platform in restoration through using high-visualization models to develop such studies in the future.
1)I first discuss an insight into the current global conditions of severely fragmented landscape structures before researching restoration of the damage caused by different disturbance conditions. Therefore, in chapter 1, the themes of fragmented patch, corridor and matrix are discussed as cases which analyze the current heavily fragmented conditions of the landscape structure, which will enable the correct environmental index to be selected for each of the different fragmented structure assessments in Chapter 3.
2)Second, I research a number of restoration responses applied to different sites, different fragmented structures and different degrees and types of disturbance. The following restoration cases in Chapter 2 show that similar types of fragmentation can result in different conditions or statuses. These include restoring fragmented areas either back to their original natural status, or to a new modified status, or in other cases using no restoration, but just applying to them a new status and consideration as works of art. In brief, I find that rules for landscape restoration may appear through experience, or even through failure, from which the right direction for future restorations may be learnt.
3)Third, for finding the right approach to landscape restoration in different cases of fragile areas affected by the growing and transformation of cities, I need to build a comprehensive visualization platform, Environmental Impact Assessment (EIA), which we can apply not only to restored areas -to assess and control the effectiveness and evolution of the actions taken and of those in progress, but also to help find out the best alternatives for those sites where no action is taken so far. and un-restored sites. Therefore, in Chapter 3, we present two practical cases where we use our visualization platform to assess and control the situation in two landfill zones both of great landscape significance and both also quite close to important cities which have lately been through intense transformation processes: the Garraf landfill landscape restoration, near Barcelona, and the monitoring and assessment of the un-restored landscape of the landfill area near Lhasa, capital of Tibet.El proceso de restauración del paisaje en zonas altamente contaminadas se ve influido por las interacciones complejas entre varios elementos del medio ambiente; estos están interconectados a través del medio integral de la estructura del paisaje que se compone de corredores, pasillos y matrices. En este estudio, investigo la estructura del paisaje con un modelo de monitorización del medio ambiente, configurado con visualización en tiempo real de alta definición, para evaluar el proceso de control de la contaminación y la restauración de la capa superior del suelo en ambas zonas, restauradas y no restauradas. Usando una plataforma de evaluación del impacto ambiental visual unificada, evalúo una simulación a partir de julio de 1999 y julio de 2014. Llego a la conclusión de que, con 5m X 5m de resolución del vehículo aéreo no tripulado (VANT), y 30 m X 30 m de resolución del satélite Landsat (combinando SIG, ENVI, Rhino y Grasshopper), el modelo capta las principales características de temperatura de la superficie observada, la vegetación y la variación de la hidrología en la zona investigada. La representación visual más precisa de la temperatura en superficies complejas, las variaciones de la vegetación y la simulación de la hidrología explícita en diferentes grados de resolución, mejoran significativamente la evaluación eficiente e integral del proceso de restauración, en particular, en relación con el análisis de la visualización de la estructura del ecosistema del paisaje dañado. Llego así a la conclusión de que existe un gran potencial para mejorar la precisión de esta plataforma infográfica de evaluación del impacto ambiental en la restauración a través del uso de modelos de alta capacidad de visualización para desarrollar este tipo de estudios en el futuro. 1) Esta es la primera vez que se aborda en su conjunto el estado de las condiciones existentes de las estructuras del paisaje severamente afectadas, antes de investigar como reparar los daños causados por las diferentes condiciones de perturbación. Por lo tanto, en el capítulo 1, los temas del mosaico fragmentado, los corredores y la matriz se examinan como casos con los que analizar las condiciones existentes de fuerte fragmentación de la estructura del paisaje, lo que permitirá hallar el índice ambiental correcto para cada una de las diferentes evaluaciones de la estructura fragmentada en el Capítulo 3. 2) En segundo lugar, investigo una serie de las respuestas de restauración que se han aplicado a distintos lugares, estructuras fragmentadas y diferentes grados y tipos de perturbación. Los siguientes casos de restauración en el Capítulo 2 muestran que el mismo tipo de fragmentación puede dar lugar a condiciones o estados diferentes. Estos incluyen la restauración de áreas fragmentadas ya sea de vuelta a su estado natural original, o a un nuevo estado modificado, o en otros casos utilizando no la restauración sino meramente la aplicación a las mismas de un nuevo estatus como obras de arte. En resumen, me encuentro con que los criterios aplicables a la restauración del paisaje pueden aparecer a través de la experiencia, o incluso a través del fracaso, a través del cual podemos hallar la dirección correcta a seguir en futuras restauraciones. 3) En el Capítulo 3, presentamos dos casos prácticos de utilización de nuestra plataforma de visualización para evaluar la situación en dos zonas de vertedero situadas ambas en lugares de gran relevancia desde el punto de vista paisajístico y, también en los dos casos, próximos a dos ciudades importantes que han experimentado en los últimos años intensos procesos de transformación: la restauración paisajística del vertedero del Garraf, cerca de Barcelona, y la monitorización de la evolución de la zona de vertedero, aun no restaurada, en las proximidades de la ciudad de Lhasa, capital de Tibet
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Yucel, Kivanc. "3d Modeling Of Salt Related Structures In The Friesland Platform, The Netherlands." Master's thesis, METU, 2010. http://etd.lib.metu.edu.tr/upload/12612240/index.pdf.
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Southern North Sea Basin is one of the mature hydrocarbon basins in NW Europe and is shaped by a number of phases of tectonic deformations during the Phanerozoic. In addition, mobilization and halokinesis of thick Permian Zechstein Salt has enhanced and contributed to the deformation of the region since Triassic, which further complicated the geology of the region. The Friesland Platform, which is a stable platform area located in northern Netherlands, experienced the main deformation phases that Europe has been endured together with the deformation of Permian Zechstein salt.
In this study a computer based 3D modeling has been carried out within the Friesland Platform with the use of 3D seismic and borehole data in order to delineate structural elements and geological development of the area with special emphasis on the salt tectonic deformation.
The model was constructed by picking key horizons and major faults from the seismic sections in time domain and then migrated into depth domain. The stratigraphy of the
area is correlated with horizons by well-seismic matching. The model includes major structures and seismostratigraphic units of Permian to recent, revealing salt and salt induced structures formed during the periods of active salt movements. Thick Zechstein salt layers deposited in N-S-oriented grabens and half grabens of South Permian Basin acted as the primary control for the location of salt diapirs and are reflected on the overburden without a direct continuation (unlinked) of the basement faults into the overburden. The mapped N-S oriented salt-cored anticline and a convergent conjugate transfer zone between a pair of segmented normal growth faults at the crest of the anticline are controlled by the ascent of the Zechstein salt.
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Moatsos, Ioannis. "Ultimate strength of ship structures including thermal and corrosion effects : a time variant reliability based approach." Thesis, University of Glasgow, 2005. http://theses.gla.ac.uk/5326/.
Full textAbstract:
On December 17th 2002 the World Meteorological Organization issued a statement according to which the global mean surface temperature has risen and consequently 2002 was the warmest year in the 1961-2002 period. Positive sea surface temperature anomalies across much of the land and sea surface of the globe in general contributed to the near record temperature ranking for the year along with climate anomalies in many regions across the globe. Climate change as a result of global warming is a worldwide occurring phenomenon which the experts have only recently started to understand and which affects and significantly will affect us in the near future. The effects of climate change have been somehow neglected by the ship and offshore related academic and research communities. In the case of thermal effects on ships structures, unless the problem solved is temperature dependent, this type of stress has often been neglected and not been taken into account in most types of analysis. The most likely reason behind this would seem to be that the stresses produced from temperature changes would be too small to be taken into account compared with still water loads or wave bending stresses. This is not the case though. Records exist of ships having broken in half while moored in still water and major hull factures occurred in still water while the temperature was changing as it can be seen from the relevant published literature. Very little work on thermal stress on ship structures has been published since the 1950s and 1960s and no work has been done that considers temperature effects on ultimate strength. Research undertaken aims to incorporate temperature effects on existing ultimate strength formulation by using a thermal stress approach, compare and use recently proposed corrosion models to model corrosion effects on ultimate strength and provide a foundation on which reliability analysis could then be performed for Tanker/FPSO structures operating in the North Sea. After comparing a number of possible approaches that would enable to loading components to be combined in a stochastic fashion, the loading part of the reliability analysis is handled using extreme wave statistics and the Ferry Borges-Castanheta load combination method. Annual reliability indices and probabilities of failure are calculated for hogging and sagging conditions using both time-variant and time-invariant approaches and a variety of reliability analysis approaches showing the effects of temperature along with partial Safety Factors for all variables taken into account.
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Brunner, Dominik. "Fast boundary element methods for large-scale simulations of the vibro-acoustic behavior of ship-like structures." Tönning Lübeck Marburg Der Andere Verl, 2009. http://d-nb.info/99703128X/04.
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Shang, Jie. "Development of an Open Source Platform for Monte Carlo Simulation of Paper Structures." Thesis, Uppsala University, Department of Information Technology, 2009. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-103034.
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Paper is a very complex optical material, and for optimization of the optical properties of paper, different advanced models of the interaction of light with complex structures have been studied. Among these models, the Monte Carlo model has been chosen and its routines have been developed for different purposes in previous projects. In order to make this type of simulations more accessible, and future contributions from the scientific communities easier to apply, the main goal of this project is to develop an open source simulation platform named OpenPaperOpt for light scattering simulation from fiber networks. As part of this project, this thesis aims to integrate the P3D model which was previously implemented and tested on the OpenPaperOpt. After the integration, the OpenPaperOpt platform has a general lights scattering process on the static fiber network. The thesis then gives guidelines for further development of different network models.
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Smithwick, Daniel J. II (Daniel John). "Architectural Design 2.0 : An online platform for the mass customization of architectural structures." Thesis, Massachusetts Institute of Technology, 2009. http://hdl.handle.net/1721.1/57554.
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Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Architecture, June 2010.This electronic version was submitted by the student author. The certified thesis is available in the Institute Archives and Special Collections.
Cataloged from student-submitted PDF version of thesis.
Includes bibliographical references (p. 111-112).
Not only are there incredible inefficiencies in the current practice of design, fabrication and construction of architecture, but, until now these processes have been limited to costly design professionals, wasteful manufacturing facilities and labor-intensive site work. Architectural Design 2.0 is a vision for rethinking these processes in order to empower consumers and users of architecture with the tools and resources necessary that will enable them to design and produce their own mass customized architectural structures. Such a change will be achieved by integrating digital fabrication technologies with the massive shift in Internet usage behavior commonly known as Web 2.0. This thesis begins with an historical framework of user-generated design and production in architecture and follows with an introduction to a digital-to-physical translation procedure that harnesses digital fabrication with an online open-source design platform. Finally, this thesis provides evidence of a working model for Architectural Design 2.0 by delivering a set of user-generated, full-scale prototypes.
by Daniel J. Smithwick.
S.M.
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Wu, Xiong-Jian. "Motion and wave load analyses of large offshore structures and special vessels in waves." Thesis, Brunel University, 1990. http://bura.brunel.ac.uk/handle/2438/7865.
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Predictions of the environmental loading and induced motional and structural responses are among the most important aspects in the overall design process of offshore structures and ships. In this thesis, attention is focused on the wave loads and excited bodily motion responses of large offshore structures and special vessels. With the aim of improving the existing theoretical methods to provide techniques of theoretical effectiveness, computational efficiency, and engineering practicality in marine and offshore applications, the thesis concentrates upon describing fundamental and essential aspects in the physical phenomenon associated with wave-structure interactions and deriving new methods and techniques to analyse offshore structures and unconventional ships of practical interest. The total wave force arising from such a wave-structural interaction is assumed to be a simple superposition of the potential and the viscous flow force components. The linear potential forces are solved by the Green function integral equation whilst the viscous forces are estimated based on the Morison's damping formula. Forms of the Green function integral equation and the associated Green function are given systematically for various practical cases. The relevant two-dimensional versions are then derived by a transformation procedure. Techniques are developed to solve the integral equation numerically including the interior integral formulation and, in particular, to tackle the mathematical difficulties at irregular frequencies. In applying the integral equations to solve problems with various offshore structures and special vessels, some modified, improved or simplified methods are proposed. At first, simplified method is derived for predictions of the surge, sway and yaw motions of elongated bodies of full sectional geometry or structures with shallow draft. Then, a new shallow draft theory is described for both three- and two-dimensional cases with inclusion of the finite draft effect. Furthermore, a three-dimensional strip method is formulated where the end effects of the body are fully taken into account. Finally, an approximation to the horizontal mean drift forces of multi-column offshore structures are presented. Some new findings are also discussed including the multiple resonances occurring in the motions of multi-hulled marine structures due to the wave-body interaction, the mutual cancellation effect of the diffraction and the radiation forces arising from a full shaped slender body, and so on. Further to those verification studies for individual methods developed, more comprehensive example investigations are given related to two industrial applications. One is a derrick barge semi-submersible with zero forward speed; and the other, a SWATH ship with considerable speed. By correlation of all the proposed approaches with available analytical, numerical and experimental data, the thesis tries to demonstrate a principle that as long as principal physical aspects in the wave-structure interaction problem are properly treated, an appropriately modified or simplified method works, performs well and, sometimes, even better.
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Acosta, Capilla Laura Karen. "Engineering of photonic structures based on nanoporous anodic alumina as an optical sensing platform." Doctoral thesis, Universitat Rovira i Virgili, 2021. http://hdl.handle.net/10803/672982.
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S'ha demostrat que les propietats òptiques de l'alúmina nanoporosa depenen intrínsecament de la seva arquitectura, el que fa possible modular la seva índex de refracció per fabricar materials avançats amb propietats òptiques úniques com les estructures fotòniques. Aquesta tesi té com a objectiu principal, la fabricació d'estructures fotòniques basades en Alúmina nanoporosa. Les estructures Fotonicas van ser fabricades amb alúmina nanoporosa (NAA-PSS) mitjançant l'anodització d'alumini amb diferents perfils de anodització (sinusoïdal i gaussià) així com la fabricació de microcavitats òptiques. Es van estudiar les seves propietats òptiques i la seva influència quan la mida de porus és més gran. Un cop fabricades i caracteritzades, les NAA-PSS van ser avaluades com a plataformes per desenvolupar sensors òptics mitjançant la tècnica d'espectroscòpia interferomètrica reflectant (rifs). Les estructures van ser analitzades utilitzant diferents concentracions de glucosa, solucions d'alcohols i clorur de sodi. Es van provar amb diferents mides de porus així com amb diferents tipus d'estructures modificant els paràmetres de fabricació. Amb els resultats obtinguts en aquesta tesi doctoral, es va demostrar que les estructures Fotonicas basada en alúmina nanoporosa tenen la capacitat de ser usades com una plataforma amb potencial per desenvolupar sensors òptics.Se ha demostrado que las propiedades ópticas de la alúmina nanoporosa dependen intrínsecamente de su arquitectura, lo que hace posible modular su indice de refracción para fabricar materiales avanzados con propiedades ópticas únicas como las estructuras fotónicas. Esta tesis tiene como objetivo principal, la fabricación de estructuras fotónicas basadas en Alúmina Nanoporosa. Las estructuras fotonicas fueron fabricadas con alúmina nanoporosa (NAA-PSs) mediante la anodización de aluminio con diferentes perfiles de anodización (sinusoidal y gaussiano) así como la fabricación de microcavidades ópticas. Se estudiaron sus propiedades ópticas y su influencia cuando el tamaño de poro es mayor. Una vez fabricadas y caracterizadas, las NAA-PSs fueron evaluadas como plataformas para desarrollar sensores ópticos mediante la técnica de espectroscopia interferométrica reflectante (RIfs). Las estructuras fueron analizadas usando diferentes concentraciones de glucosa, soluciones de alcoholes y cloruro de sodio. Se probaron con diferentes tamaños de poro así como con diferentes tipos de estructuras modificando los parámetros de fabricación. Con los resultados obtenidos en esta tesis doctoral, se demostró que las estructuras fotonicas basada en alúmina nanoporosa tienen la capacidad de ser usadas como una plataforma con potencial para desarrollar sensores ópticos.
The optical properties of nanoporous alumina have been shown to be intrinsically dependent upon its architecture, making it possible to modulate its refractive index to fabricate advanced materials with unique optical properties such as photonic structures. This thesis has as its main objective, the manufacture of photonic structures based on Nanoporous Alumina. The photonic structures were fabricated with nanoporous alumina (NAA-PSs) by anodizing aluminum with different anodizing profiles (sinusoidal and Gaussian) as well as the fabrication of optical microcavities. Its optical properties and its influence when the pore size is larger were studied. Once manufactured and characterized, the NAA-PSs were evaluated as platforms to develop optical sensors using the reflective interferometric spectroscopy (RIfs) technique. The structures were analyzed using different concentrations of D-glucose, alcohol solutions and sodium chloride. They were tested with different pore sizes as well as with different types of structures by modifying the fabrication parameters. With the obtained results in this doctoral thesis, iwas demonstrated that photonic structures based on nanoporous alumina have the ability to be used as a potential platform to develop optical sensors.
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Sönmez, Nurcan. "Investigating Wind Data and Configuration of Wind Turbines for a Turning Floating Platform." Thesis, KTH, Mekanik, 2014. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-148957.
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Wake interactions on a floating platform for offshore wind energy applications were investigated.The study is performed in collaboration with Hexicon AB which has a patent family for innovative floating platforms, which are able to turn automatically. The Jensen model is used for wake effect calculations and the simulations were performed in MATLAB. The present study starts with wind speed and wind direction data analysis for the specific site that Hexicon AB plans to construct its first platform. Data analysis is followed by wake interaction studies for H4-24MW type Hexicon AB platform. Wake interaction simulations were performed for three different cases. Fixed turbine and platform, Nacelle yawing and fixed platform and Nacelle yawing and turned platform. Different cases were investigated in order to see wake interactions for different wind directions. Wind direction effect on wake interactions were performed between _90_ and 90_ with an increment of 10_. After having the simulation results for Nacelle yawing and turned platform case the results were compared with ANSYS - CFX simulations results. The results didn’t match exactly but they were very close, which is an indicator to the validity of the Jensen Model. After finding out the possible behavior of wake interactions for different wind directions, power calculations were performed for the same three cases. In order to perform the power calculations the wake interactions for different wind directions were taken into account. In case of platform turning it was assumed that power losses were caused both by wake interactions and in case of thrusters activation. The losses that would be caused by different thrust forces on the turbine blades were not included. The last study was performed to suggest different layouts. In the second case, Nacelle yawing and fixed platform, it was found out that nacelle yawing for most of the angles is not possible because it creates wake regions in front of the rotor area. It was decided to propose new turbine configurations on the platform which are tolerant to different nacelle yawing angles. The simulations were run without considering any constructions limitations, meaning that the availability of platform structure was not included. The study is ended by performing some probabilistic results for platform turning behavior.
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Tsarouchas, Ioannis. "Through life reliability of a bulk carrier." Thesis, University of Glasgow, 2001. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.368736.
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Piglionica, Andrea. "Structural analysis and re-design of SPM platform in the Adriatic sea." Master's thesis, Alma Mater Studiorum - Università di Bologna, 2019.
Find full textAbstract:
Fixed offshore platforms, especially jacket type platforms, are the most common offshore structures used for Oil & Gas industry in the Adriatic Sea. In fact these structural typologies are suitable for relative shallow water depth, usually up to 250 m, and flat sandy sea floors. Most of them have been built in the last 50 years, some of them are also older, and for instance they have been designed when technological tools were not available and all the calculations were computed by antique machines or by hand.
In lieu with the actual international regulations, the following report will present the technical analysis for the design of such platform. More specifically, it has selected as model example one of the platforms designed more than 50 years ago and a complete stability verification has been computed with modern tools. Furthermore a proposal of new design of the base of this structure has been reported together with specific analysis.
The examined structure is the SPM Mooring Tower, placed in the offshore area of Falconara Marittima (AN), and owned by Api Refinery Spa.
The documents relative to the environmental and geotechnical features of the site in object, the original project documents and drawings, and other documentations have been provided by Tecon Srl Engineering Company, perhaps all the rights about this document are reserved.
Structural stability calculations have been carried out according the actual International Code ‘API Recommended Practice for Planning, Designing and Constructing Fixed Offshore Platforms 2A-WSD’.
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Madhani, Jehangir T. "Sloshing motion of water in a moonpool." Thesis, University of Strathclyde, 1985. https://eprints.qut.edu.au/41649/1/Sloshing_Motion_of_water_in_a_moonpool.pdf.
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This thesis is concerned with the sloshing motion of water in a moonpool. It is a relatively new problem, that is particularly predominant in moonpools with relatively large
dimensions. The problem is further complicated by the additional behaviour of vertical oscillation. It is inevitable that large moonpools will be needed as offshore
technology advances, therefore making a problem an important
one. The research involves two parts, the theoretical and
experimental study. The theoretical study consists of idealising the moonpool to a two dimensional system, represented by two surface piercing parallel barriers at a distance 2a apart. The barriers are forced to undergo roll motion which in turn generates waves. These travelling waves are travelling in opposite directions to each other and have the same amplitude and period, and thus can be expressed in terms of a standing wave. This is mathematically achieved by applying the theory of wavemaking, and therefore the wave amplitude at the side wall can be evaluated at near resonant conditions. The experimental study comprises of comparing the results obtained from the tank and moonpool experiments. The rolling
motion creates the sloshing waves in both cases, in addition
the vertical oscillation in the moonpool is produced by
generating waves at one end of the towing tank. Apart from
highlighting influencing parameters, the resonant frequencies obtained from these experiments are then compared with the theoretical values. Experiments in demonstrating the effect of increasing damping with the aid of baffles are also conducted. This is an important aspect which is very necessary if operations in launching and retrieving are to be carried out efficiently and safely.
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Mathiowetz, Sebastian [Verfasser], Michael [Akademischer Betreuer] Möser, and Andrew [Akademischer Betreuer] Moorhouse. "Prediction of structure-borne sound power injection by vibrational sources with a focus on ship structures / Sebastian Mathiowetz. Gutachter: Michael Möser ; Andrew Moorhouse." Berlin : Technische Universität Berlin, 2014. http://d-nb.info/1066550654/34.
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Oberhagemann, Jan [Verfasser], and Bettar O. el [Akademischer Betreuer] Moctar. "On Prediction of Wave-Induced Loads and Vibration of Ship Structures with Finite Volume Fluid Dynamic Methods / Jan Oberhagemann ; Betreuer: Bettar O. el Moctar." Duisburg, 2017. http://d-nb.info/1125371374/34.
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Zhang, Jian. "Hydrodynamic behavior of packed-bed reactors on a floating platform : liquid distribution and drainage dynamics." Doctoral thesis, Université Laval, 2021. http://hdl.handle.net/20.500.11794/68634.
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Pour combler l'écart entre l'augmentation de la demande énergétique et l'épuisement de la production d'hydrocarbures onshore, l'exploitation des hydrocarbures offshore est de plus en plus envisagée, en particulier les gisements de gaz / pétrole dans les eaux plus profondes. En attendant, un grand nombre d'unités de traitement déployées pour la production d'hydrocarbures doivent respecter les contraintes environnementales conçues pour la protection maritime. Les systèmes tels que les réacteurs et les épurateurs à lit fixe embarqués deviennent inévitablement l'une des options les plus prometteuses pour atteindre ces deux objectifs. De nombreux efforts dans la littérature pour dévoiler l'hydrodynamique de l'écoulement multiphasé dans les lits garnis révèlent que des défis persistent soit dans leur conception / mise à l'échelle, soit dans leurs opérations. De plus, exposer ces réacteurs à des conditions marines difficiles telles que la convolution de la dynamique des navires et de l'hydrodynamique à l'intérieur des réacteurs à lit fixe conduit à des situations encore plus compliquées pour maintenir des performances de fonctionnement acceptables dans les conditions flottantes. Un grand nombre de preuves issues de la littérature a jusqu'à présent mis en évidence l'échec des colonnes garnies avec des garnissages aléatoires, des garnissages structurés ou des mousses à alvéoles ouvertes, pour empêcher la maldistribution des liquides dans les lits fixes destinés à fonctionner à bord de navires ou de platesformes flottantes. Les efforts de recherche doivent donc se poursuivre dans le but de trouver des composants internes robustes et capables de résilience contre la maldistribution des liquides dans les réacteurs / unités de séparation gaz-liquide. Ce projet de doctorat s’est proposé des recherches visant dans un premier temps de tester des internes disponibles commercialement pouvant préserver des performances similaires à celles des unités terrestres classiques. Au meilleur de notre connaissance, la sensibilité et la susceptibilité des réacteurs monolithes à une mauvaise distribution soumis à des conditions offshore n'ont pas encore été étudiées. Plutôt que de se concentrer uniquement sur une étude des lits monolithiques, le chapitre 1 opte pour une campagne expérimentale plus large comprenant un garnissage aléatoire et un garnissage en mousse à cellules ouvertes pour des comparaisons systématiques de la distribution des liquides en conditions flottantes. La distribution liquide des colonnes embarquées garnies de divers garnissages et pour une large plage de débit gaz / liquide est systématiquement comparée à l'aide d'un capteur à treillis métallique (WMS) et d'un émulateur hexapode à six degrés de liberté. La vraisemblance de conditions météorologiques extracôtières rudes pourrait menacer la sureté de l'exploitation des lits fixes, en particulier dans des situations extrêmes telles que des cyclones, des épisodes d'icebergs, etc. Pour assurer la sécurité du personnel et des installations, l’opération des colonnes garnies à bord doit être immédiatement interrompue pour éviter des problèmes de sécurité critiques sous de telles circonstances. Par conséquent, la base de connaissances sur la dynamique de drainage des liquides dans les lits flottants est iv essentielle pour assurer une vidange rapide du liquide. Néanmoins, l'étude de la dynamique du drainage liquide des lits fixes en conditions flottantes est à tout le moins rare. Par conséquent, le chapitre 2 se propose de comparer expérimentalement le drainage du liquide dans des colonnes garnies dans les conditions marines à celui observé dans une colonne statique verticale à l’instar des applications terrestres. En dehors de cela, l'influence des mouvements du navire (par exemple, cavalement, embardée, pilonnement, roulis, tangage, et lacet) à différentes amplitudes et périodes d'oscillation sur la dynamique de drainage des liquides est étudiée pour approfondir nos connaissances. Parallèlement à l'étude expérimentale, un modèle numérique Euler-Euler transitoire et en trois dimensions est utilisé en complément pour tenter de prédire la dynamique du drainage des liquides dans les lits flottants. D'autres facteurs susceptibles d'affecter la dynamique de drainage sont analysés par la simulation numérique. Ainsi, le chapitre 3 met en évidence l'influence globale des propriétés des liquides, de la structure du lit et des types de mouvement associé à la sollicitation marine. Par ailleurs, la campagne expérimentale en fournissant des données mesurables a permis de valider le modèle dans les conditions de roulis et de tangage testées au laboratoire.To fill the gap between increasing energy demand and depletion of onshore hydrocarbon production, offshore hydrocarbon exploitation is increasingly contemplated especially the gas/oil fields in the deeper water. Meantime, large amount of deployed processing units for hydrocarbon productions must comply with the environmental codes designated for maritime protection. Systems such as embarked packed-bed reactors and scrubbers inevitably become one of the most promising options to achieve both purposes. Numerous efforts in literature to unveil the hydrodynamics of multiphase flow in packed beds reveal that challenges persist either in their design/scale-up or during the operations. Moreover, exposing these reactors to harsh marine conditions such as the convolution of ship dynamics and hydrodynamics inside packed-bed reactors leads to even more complex situations to maintain the proper operation performance of packed-bed reactors under floating conditions. A lot of evidence from literature has pointed out the failure of random and structured packings and open-cell foams, to prevent liquid maldistribution in packed beds destined to operate on-board sailing ships and floating platforms. Research efforts must therefore continue in the quest for robust internals capable of resilience against liquid maldistribution in gas-liquid reactors/separation units. The proposed Ph.D. research aims at firstly following a sound path to adapt commercially existing internals being capable of preserving performance similar to landbased packed beds. To the best of literature exploring, the sensitivity and susceptibility of monolith reactors to maldistribution subjected to offshore conditions have yet to be investigated. Rather than focusing on a study of monolith beds alone, Chapter 1 opts for a broader experimental campaign including a random packing and an open-cell foam packing for the sake of systematic comparisons of the liquid distribution under floating conditions. Liquid distribution of embarked columns packed with various internals under wide gas/liquid flow range is systematically compared with the assistance of wire mesh sensor (WMS) and six-degree-of-freedom emulator hexapod. Severe offshore weather conditions threaten the operation safety of floating packed beds especially encountering extreme situations such as cyclone, iceberg episodes and so forth. To ensure the safety of staff and facilities, the onboard packed columns must be immediately shutdown to avoid critical safety concerns under such circumstances. Therefore, knowledgebase of liquid draining dynamics in floating packed beds is the essence to ensure timely discharge of liquid. Nevertheless, the study regarding liquid drainage dynamics of packed beds under floating conditions is scarce to say the least. Then, Chapter 2 compares liquid draining of packed columns embarking on floating platforms with static land-based one experimentally. Other than that, the influence of ship motions (e.g., roll, roll & pitch, heave etc.) with different oscillation amplitudes and periods on liquid draining dynamics is investigated to deepen the insights. vi In parallel with the experimental study, a 3D transient Euler-Euler CFD model is employed as a supplementary analysis to further deepen the understanding of liquid drainage dynamics in floating packed beds. More factors possibly affecting the draining dynamics are exploited by numerical simulation. Consequently, Chapter 3 highlights the comprehensive influence of liquid properties, bed structure and moving types instead of focusing on impact of movements alone. Meanwhile, with sufficient body of experimental campaign, the validity and accuracy of model are strongly endorsed.