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| 2. |
- Ahuja, Gaurav, 1978, et al.
(författare)
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Sandwich Construction - Application on a superstructure
- 2005
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Ingår i: INMAT 2005. ; , s. 11-
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Konferensbidrag (refereegranskat)abstract
- The use of light weight materials is increasing at a rapid pace in the present day industry. Automobiles, aircrafts, ships and several other fields are increasingly finding large potential in using lighter materials for construction. In the past few years a number of water borne means of transportation have been moulded from composites. For ships, this leads to reducing the light weight and thus an increase in the capacity of the payload. A reduction in the light weight of the ship implies more cargo and more revenue generation for the ship owner. Over an average lifetime of 25 years, the amount of revenue generated could be significant, due to which a number of ship owners are giving a serious thought to the usage of light weight materials in shipping. Stena Line, a Swedish shipping company has a number of passenger ferries running in the European region. They are also the proud owners of the HSS series of ships, which are unique as they are catamarans made completely in aluminium. Being the pioneers in the shipping industry, they have considered the possibility of having a sandwich superstructure for one of their ferries, HSS 900. This paper looks into the preliminary design of the structure under DNV regulations. While fire safety is also part of the project, this paper focuses on the structure. Different kinds of fibres, resins and cores could be used for making the sandwich construction. The fibre making the faces could be E-glass, S-glass, carbon fibre etc, the resin systems also provide a variety of options like the polyesters, vinyl esters and phenolics. Similarly the core material could be honeycomb, PVC or PU. In this paper, possibilities of using these materials for the making the superstructure has been looked into. A preliminary calculation shows how much in terms of light weight of the vessel could be saved if sandwich construction is used. As it is weight critical approach that is the driving factor in using light weight materials, an optimization of the structure by breaking it up into sandwich panel, spacing of the transverses and longitudinal has also been performed. While optimizing the sandwich panel, four major criteria of maximum normal stress, maximum shear stress, wrinkling stress and maximum allowed deflection have been explored. The limit point where all the four requirements are met and the weight is minimum possible has been considered as the optimum point. All in all it is a sandwich superstructure, which has been optimized for weight.
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| 3. |
- Jia, Junbo, 1979, et al.
(författare)
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A parametric study for the structural behaviour of a lightweight deck
- 2004
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Ingår i: Engineering Structures. - : Elsevier BV. - 1873-7323 .- 0141-0296. ; 26:7, s. 963-977
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Tidskriftsartikel (refereegranskat)abstract
- Lightweight structures are increasingly used for high-speed ships. Research of fatigue and stability of the highly stressed thin plate structures is an ongoing activity, which produces valuable information for the structural engineers. One topic that should be an integrated part of these studies is the dynamic behaviour of lightweight deck structures. When the deck structures are made extremely lightweight, the natural frequencies of the structures as such may increase while the loaded decks will most likely deflect more than conventional decks do. It is then expected that the natural frequencies of the decks will decrease and new problems of vibration and damping will appear. There is concern for resonance with propeller blade frequencies but also with the wave responses of these high-speed ships.The subject of this paper is to study the static and dynamic behaviour of a lightweight ship deck. A theoretical model was made in order to study the interaction between the car and the deck. The model indicates that the car chassis is a significant part of the problem and influences the solution. A finite element model of the ship deck was generated and special parameters, such as material of the panels, numbers and locations of loaded cars were studied. The speed of running cars on the deck during loading and the frequencies of the propeller excitation were varied in order to understand their influences on the structural response. Based on the results from finite element analysis obtained, it is shown how a conventional steel structure is improved by introducing lightweight material. The structural behaviour is significantly influenced from both a static and dynamic point of view.
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| 4. |
- Jia, Junbo, 1979, et al.
(författare)
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A systematic approach towards the structural behaviour of a lightweight deck–side shell system
- 2005
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Ingår i: Thin-Walled Structures. - : Elsevier BV. - 0263-8231. ; 43:1, s. 83-105
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Tidskriftsartikel (refereegranskat)abstract
- Lightweight structures are increasingly used for high-speed ships. This paper presents a systematic approach to analyse the structural behaviour of a lightweight deckside shell system using high strength steel. An analytical model of the deckside shell system was first given, which includes the effects of stiffeners for the deck and side shell, the support conditions of the centreline girder (CL-girder), the influence of transverse beams, and the interaction between the side shell and the lightweight deck as parts of problems to the solution. By changing several geometric parameters, the sensitivity of both overall and local stress and deflection for the deckside shell system was investigated. The different geometric parameters analysed comprise the influence for variation in the thickness of the web for transverse beams, longitudinal stiffeners and the CL-girder, the thickness of lower flange for the transverse beam and, the thickness for the panel. Furthermore, the influence of the lightweight deck and loads from the deck above on the side shell, the effects of the side shell and loads from top deck on the deck, the support conditions for the CL-girder, and the influence of deck loads on the eigenmodes were also analysed. By evaluating the results obtained from FE simulation, the support conditions of the CL-girder, the thickness of the panels and the lower flange of the transverse beams were found to be the most relevant parameters affecting both the stress and the deflection distribution of the structure. The dynamic characteristics of the structure were also analysed. The FE analysis concerning buckling of the structure was present. The results enable naval architects and structural engineers to design new extreme lightweight deck structure more reliable and economical. And some suggestions for future research are also given.
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| 5. |
- Jia, Junbo, 1979, et al.
(författare)
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Dynamic analysis of vehicle-deck interactions
- 2006
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Ingår i: Ocean Engineering. - : Elsevier BV. - 0029-8018. ; 33:13, s. 1765-1795
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Tidskriftsartikel (refereegranskat)abstract
- This paper presents the review and studies at various levels of problems concerning the authors' previous research on the dynamics of vehicle-deck interactions. The various levels of study include the dynamic structural behavior of vehicle-deck systems, vehicle vibrations, damping effects of vehicles on structural systems, dynamic interactions between tire and deck surface, and vehicle securing on decks during ship motions, etc. The study includes analytical, numerical and experimental analysis. Practical problems encountered by Ro-Ro ship designers are addressed by discussing those analysis. It is shown that influences from the dynamics of vehicle-deck interactions are relevant to a number of aspects of issues, such as the excitation frequency range, how detailed information of the structural system response is required, the structure characteristics, and positions and orientations of vehicles on decks, etc. The study contributes to the knowledge for the naval architect and vehicle engineer on how significant the dynamics of vehicle-deck interactions are when dealing with relevant problems.
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| 6. |
- Jia, Junbo, 1979, et al.
(författare)
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Modal Testing and Finite Element Calculations for Lightweight Aluminum Panels in Car Carriers
- 2006
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Ingår i: Marine Technology. - 0025-3316. ; 43:1, s. 11-21
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Tidskriftsartikel (refereegranskat)abstract
- Due to their characteristics and lower maintenance cost, lightweight aluminum structures have been widely used for manufacturing deck structures. When this type of structure is developed, the natural frequencies for the unloaded deck may increase, while the natural frequencies for loaded decks are most likely to decrease and new problems of vibration and damping may appear. In addition, it has already been shown by the authors that compared to the load effects of normal cargo, the dynamic structural behavior of a vehicle-loaded deck is different due to the participation of vehicle vibrations. The current paper presents a modal analysis by both testing and finite element (FE) calculation for a lightweight deck using aluminum panels. By comparing the results between the unloaded and car-loaded cases, it is shown how vehicle loading influences the dynamic structural behavior of the deck structures. The authors report that an aluminum panel mechanically connected to a steel frame may participate in some mode shapes of vibrations that significantly increase the corresponding damping ratio. The reasonably good agreement between modal testing results and FE calculations validates the finite element model, which may then be used for further dynamic analysis. The authors found that the spring-damping systems of car suspension and tires can interfere in the dynamic transmission of the vehicle mass into the deck structure. The study enables structural engineers interested in the design of car carriers to have a better understanding of how the vehicles parked on decks can influence the dynamic characteristics of the vehicle deck systems.
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| 7. |
- Jia, Junbo, 1979, et al.
(författare)
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Structural behaviour of a high tensile steel deck using trapezoidal stiffeners and dynamics of vehicle–deck interactions
- 2005
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Ingår i: Marine Structures. - : Elsevier BV. - 0951-8339. ; 18:1, s. 1-24
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Tidskriftsartikel (refereegranskat)abstract
- As an early part of a large design and fabrication-oriented project FasdHTS funded by the GROWTH programme of the European Commission, an exotic concept ship was designed in very high tensile steel (EHS690) with the purpose of finding out consequences for design and production. The project has already produced a considerable bank of knowledge for design and shipyard production in this material.This paper presents analysis and discussions on static and dynamic behaviour of a high tensile steel deck designed with trapezoidal stiffeners. First, a finite element model of the deck structure is created. The influence of support condition for the longitudinal girders, and the contact area between the vehicle tyre and panel were analysed. The results from modal analysis of the structure under different load conditions are presented. The different load conditions comprise the unloaded and loaded deck, and the load type, i.e. cargo loads or vehicle loads (car loads or truck loads). From the frequency response analysis under harmonic excitation, it shows how the locations and numbers of cars parked on the deck influence the dynamic response of the structure. Furthermore, by studying the cardeck interaction, it is found that the effects of normal cargo loads are quite different from the vehicle loads due to the spring/damping effects of the vehicles. It is suggested that the carloads have a similar mechanism to that of tuned mass dampers. Finally, two transient analyses of the structure due to excitations transferred from deck supports and lorry braking-induced loading are performed. It is suggested that the deck structure and vehicle design could have more interactions with each other.
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| 8. |
- Jia, Junbo, 1979, et al.
(författare)
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The Friction Between Car Tires and Decks Under Ship Motions
- 2006
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Ingår i: Marine Technology. ; 43:1, s. 27-39
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Tidskriftsartikel (refereegranskat)abstract
- For roll-on/roll-off (RO/RO) ships, when transporting more cars within the same deck area on board, it is necessary to adjust or take away the current lashing system. Furthermore, this operation may also decrease the cost and time of operation as well as cargo damages due to lashing. This requirement, combined with the safety consideration on cargo shifting, may lead to concepts of lashing-free deck design. One of the lashing-free concepts suggests that in some conditions cars can be secured without using lashings, mainly depending on the friction between the tire and the deck without lashings. By doing a series of parametric studies of vehicle securing without lashings under roll and pitch motions, it was found that the value of the maximum required friction coefficient between the tires and the deck is highly relevant to the roll and pitch amplitude, pitch period, orientation of vehicles on decks, and the vertical location of vehicles from the baseline of the vessel.
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| 9. |
- Jia, Zhibin, 1974, et al.
(författare)
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A return period based plastic design approach for ice loaded side-shell/bow structures
- 2009
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Ingår i: Marine Structures. - 0951-8339. ; 22:3, s. 438-456
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Tidskriftsartikel (refereegranskat)abstract
- Based on the design ice load that corresponds to a certain return period, a practical approach for designing the frames behind the side-shell or the bow of a ship subject to ice loading is proposed. Four typical types of section profiles have been selected for modelling and numerical analysis. Nonlinear finite element analyses that involve both the geometric and material nonlinearity were performed. From the analyses, the relationships between the loads and the beam’s cross-section properties were obtained for different permanent set requirements. These relationships were then used for finding the section modulus from which the cross-section of the beam can be decided. Finally, a design example is presented for illustration.
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| 10. |
- Karlsson, Ulf, 1965, et al.
(författare)
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Experimental and numerical investigation of bulb impact with a ship side-shell structure
- 2009
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Ingår i: Marine Technology. - 0025-3316. ; 46:1, s. 16-26
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Tidskriftsartikel (refereegranskat)abstract
- The finite element (FE) method is suitable as a numerical tool in the numerical analysis of, for example, ship collision scenarios. It is feasible to simulate and compare different collision scenarios by parameter variations. The objective with this investigation was to establish a reliable and robust FE modeling procedure for ship-ship collision simulations, using the commercial FE software Abaqus/Explicit, by means of parameter sensitivity and experimental analyses. Four types of experiments are presented that have supported the development of the FE models and simulations with sufficient information for representation of material characteristics and for validation of models: (i) uniaxial tensile tests, (ii) friction tests, (iii) bulb impact with a steel-sheet test and, finally (iv) a bulb impact with a side-shell ship structure. The outcome of the parameter study after calibration against test results was two validated FE models: one of the bulb-sheet test and one of the bulb-structure test.
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