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Polymer composite materials, particularly glass reinforced plastics (GRP), are increasingly being used in the offshore industry and their behaviour in fire is studied using mathematical and numerical modelling. A generalised finite element method is developed to analyse the thermally induced response of a widely used GRP, consisting of polyester resin and glass fibre reinforcement. GRP panels, pipes and joins subject to hydrocarbon fires (i.e. high temperatures) are studied. One- and two-dimensional mathematical models are developed to study the fire performance of: (i) single-skinned GRP panels, (ii) twin-skinned GRP-Vermiculux sandwich panels, and (iii) thin and thick GRP joins (step panels). The models involve thermochemical decomposition of the material (pyrolysis) and include: (i) transient heat conduction, (ii) gas mass movement and internal heat convection of pyrolysis gases, (iii) mass loss and Arrhenius rate decomposition of the resin material into gases and char, and (iv) endothermicity of pyrolysis. The effect of imperfect bonding on heat transfer in sandwich panels and the accumulation of pyrolysis gases and internal pressurisation in thick step panels are also included. The models may be used with any combination of steady or time-dependent boundary conditions including temperature, radiation, chemical reactions, mass diffusion and free and forced convections. Various positions of panels, i.e. vertical, horizontal and inclined are studied. The material is assumed homogeneous and orthotropic with respect to thermal and transport properties which may vary with temperature, pore pressure and moisture. The finite element models use weighted residual approach with linear elements for one- dimensional and quadrilateral elements for two-dimensional. Non-linear terms and coefficients are evaluated explicitly using an iterative-updating method and nodal temperatures and pore pressures implicitly using Crank-Nicolson solution. The classical finite difference time stepping algorithm is used where an efficient solution is achieved using variable time step. Numerical results are presented in the form of temperature versus time, temperature versus distance, pore pressure versus distance, mass loss versus distance and moisture versus distance and compared with experimental data where available. It is shown that the decomposition of the material, endothermicity of pyrolysis and the movement of pyrolysis gases make substantial contributions towards the cooling behaviour and delaying the bum-through. The effect of gas mass movement and surface chemical reactions across the boundary layer adjacent to the fire-exposed surface is very important in introducing a theoretical boundary condition. An investigation into the effect of inclusion the variable thermal properties reveals considerable improvement in thermal predictions. Sandwich panels consisting of GRP/Vermiculux/GRP offer good thermal insulation. Thermal contact resistance at an imperfect bonding is important where an average difference of 12% can be found between the thermal responses of sandwich panels with perfect and imperfect bonding. For thin GRP step panels, a one-dimensional solution is found adequate to predict the fire resistance behaviour of the material. For thick GRP step panels, the effect of internal pressurisation coupled with temperature on the thermal response is considerable.

Interest in evaluating the performance and safety of offshore oil and gas platforms has been expanding due to the growing world energy supply and recent offshore catastrophes. In order to accurately assess the reliability of an offshore platform, all relevant uncertainties must be properly accounted for. This necessitates the development of a probabilistic demand model that accounts for the relevant uncertainties and model errors. In this study, a probabilistic demand model is developed to assess the deformation demand on asymmetric offshore jacket platforms subject to wave and current loadings. The probabilistic model is constructed by adding correction terms and a model error to an existing deterministic deformation demand model. The correction terms are developed to capture the bias inherent in the deterministic model. The model error is developed to capture the accuracy of the model. The correction terms and model errors are estimated through a Bayesian approach using simulation data obtained from detailed dynamic analyses of a set of representative asymmetric offshore platform configurations. The proposed demand model provides accurate and unbiased estimates of the deformation demand on offshore jacket platforms. The developed probabilistic demand model is then used to assess the reliability of a typical offshore platform considering serviceability and ultimate performance levels. In addition, a sensitivity analysis is conducted to assess the effect of key parameters on the results of the analyses. The proposed demand model can be used to assess the reliability of different design options and for the reliability-based optimal design of offshore jacket platforms.

I takt med att det svenska tonnaget flaggas ut och förminskas söker sig allt fler nyexaminerade styrmän till andra marknader. Ett stort sådant segment är den norska offshoreindustrin. Syftet med denna studie var att undersöka nyutexaminerade styrmäns upplevelser av oro och stress under första tiden som yrkesverksamma och om dessa upplevelser skilde sig åt beroende på vilken bransch de var verksamma i. För att undersöka detta användes en kvalitativ metod där personliga intervjuer genomfördes. Åtta styrmän, fyra från den traditionella svenska handelsflottan och fyra som är verksamma inom offshorebranschen, som tagit examen från Sjöfartshögskolan i Kalmar våren 2012, valdes slumpvis ut för intervjuer. Resultatet från intervjuerna visade att styrmännen, oberoende av bransch, upplevde högre nivåer av stress och oro under de första törnarna än senare i karriären. Detta härleddes till oro över den egna arbetsförmågan och det plötsligt ökade ansvarsområdet man som nyutexaminerad upplever. Undersökningen slog även fast att sömnbrist är en betydande faktor i upplevd stress och oro och att detta är vanligt inom offshorebranschen, där det är vanligare att arbeta efter ett tvåvaktsystem. / With an ever decreasing Swedish tonnage more and more maritime graduates seek out other segments than the traditional Swedish trades. A major one of these segments is the Norwegian offshore market. The purpose of this study was to investigate recently graduated maritime officer’s experiences of stress and worries during their first turns as active officers and if these experiences differed depending on which segment they were active in. A qualitative method with personal interviews was used to investigate these questions. Eight recently graduated officers were interviewed, four from the traditional Swedish merchant navy and four from the Norwegian offshore industry. All graduated in the spring of 2012.The results from the interviews showed that the officers, not depending on which segment they were active in, experienced higher levels of stress during their first turns than later in their career. This was due to worry with the graduates about their own professional abilities and the increase in responsibility that graduates experience in the beginning of their careers. The study also found that lack of sleep is a major factor in the stress equation and that this was more common within the offshore industry, due to the extensive use of the two-watch system within that segment.

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This thesis addresses the formulation and assessment of the damage survivability of passenger/RO-RO vessels from a fundamental point of view, whilst accounting for water ingress and taking fully into consideration vessel and flood water dynamics. Following the mathematical formulation, a numerical code was developed in the time domain capable of predicting the dynamic behaviour of the damaged vessel in a realistic environment. The developed model describes a free drifting vessel undergoing extreme motions in six degrees-of-freedom under the action of wind, current and waves of arbitrary direction whilst subjected to progressive flooding. The position and attitude of the vessel are updated continuously in time and consequently all the terms in the vessel/flood water systems. A semi-analytical method is also presented, for the evaluation of the flooding rate as a function of the relative position of the water level on either side of a damage opening. This treatise begins w ith a thorough review of the available literature concerning models and methods proposed to date to assess damaged stability and survivability of passenger ships aiming to identify the strength and weaknesses of the existing theories and determine the key factors involved in the degradation of a vessel's ability to survive damage. Having validated the numerical code to the extent that confidence was gained of its ability to simulate the dynamic behaviour of the damaged vessel meaningfully and to predict her resistance to capsize with acceptable accuracy, a topdown approach was pursued, leading from a comprehensive model - including most of the critical features highlighted by the preliminary investigation - to a simplified one in which only the most relevant elements are retained if the significance of which had been demonstrated through a sensitivity analysis designed for this purpose, thus aiding in the transition of complex models to becoming useful engineering "tools". The mathematical/numerical models described in this thesis represent the most advanced treatment to date of the ability of a damaged vessel to resist capsize in a seaway. The most surprising conclusion of the investigation presented herein is that the damage survivability of a passenger/RO-RO ships can be predicted with sufficient engineering accuracy with the simplest of models, deriving from the fact that at the final stages before capsize, the "fate" of the vessel is governed by quasi-static forces.

Deep-ocean (benthic) landers are free-falling vehicles that are deployed from a ship and descend to the ocean floor by virtue of attached ballast. They carry with them scientific instrumentation to carry out in-situ experiments, and once operation is complete, an acoustic command from the surface vessel causes the lander to release its ballast and allow buoyancy to return it to the surface for recovery. Landers function autonomously, typically under the control of a central micro-controller and data-logger. The extreme environment in which landers operate require that all electronics is contained in special pressure housings and interconnection between modules is made using expensive deep-ocean cables and connectors. This thesis presents the concept of a new Controller Area Network (CAN)-based architecture, and a report is given of the development of a miniature network interface board suitable for use on benthic landers. One application of lander technology is in tracking the movements of abyssal fishes that forage close above the ocean floor. Small acoustic transponders are wrapped in bait and attached to the ballast of the lander. Scavenging fish attracted to the bait consume the transponders, after which a sonar system on the vehicle can track their movements. A new method for tracking these fishes is presented that uses a short-baseline hydrophone array mounted on a specially designed lander, AUDOS II. With no moving parts, this method has many advantages over previous systems that relied on scanning directional sonar. Tracking resolution has been greatly improved, and new software tools allow the movements of tracked fish to be viewed quickly and with ease.

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No description available.