Dynamic Response of a Catamaran-Hull Ship Subjected to Underwater Explosions PDF Download
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Author: Hakan Ucar
Publisher:
ISBN:
Category : Mechanical engineering
Languages : en
Pages : 158
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Book Description
Surface Ship Shock trials play an essential role in ship test and evaluation (T & E), and Live Fire Test and Evaluation (LFT & E) requirements for the lead ship of each new construction shock-hardened ship class. While those trials are necessary in order to evaluate the vunerability and survivability of the ship, they are very expensive, require extensive time for planing and coordination, and pose serious danger to the crew, ship and marine environment. Thus, computer modeling of the ship structure, surrounding fluid, and virtual shock environment by utilizing finite element method offers a valuable design tool and an alternative to these tests. This thesis investigates the response of a catamaran-hull ship subjected to an underwater explosion by creating a virtual UNDEX environment based on the modeling and simulation methodology established by the Shock and Vibration Computational Laboratory at the Naval Postgraduate School (NPS). In previous works, all of the structural models were monohull ships and there have been concerns about the feasibility of creating the coupled fluid and catamaran-hull model. This thesis studies the effect of an additional hull and gap between two hulls on the dynamic response of the ship as well as the effect of the charge location.
Author: Hakan Ucar
Publisher:
ISBN:
Category : Mechanical engineering
Languages : en
Pages : 158
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Book Description
Surface Ship Shock trials play an essential role in ship test and evaluation (T & E), and Live Fire Test and Evaluation (LFT & E) requirements for the lead ship of each new construction shock-hardened ship class. While those trials are necessary in order to evaluate the vunerability and survivability of the ship, they are very expensive, require extensive time for planing and coordination, and pose serious danger to the crew, ship and marine environment. Thus, computer modeling of the ship structure, surrounding fluid, and virtual shock environment by utilizing finite element method offers a valuable design tool and an alternative to these tests. This thesis investigates the response of a catamaran-hull ship subjected to an underwater explosion by creating a virtual UNDEX environment based on the modeling and simulation methodology established by the Shock and Vibration Computational Laboratory at the Naval Postgraduate School (NPS). In previous works, all of the structural models were monohull ships and there have been concerns about the feasibility of creating the coupled fluid and catamaran-hull model. This thesis studies the effect of an additional hull and gap between two hulls on the dynamic response of the ship as well as the effect of the charge location.
Author: Defence Research Establishment Atlantic
Publisher: [Dartmouth, N.S.] : Defence Research Establishment Atlantic
ISBN:
Category : Blast effect
Languages : en
Pages : 42
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Book Description
A summary of the bubble pulsation dynamics of an underwater explosion is presented with the aim of establishing the whipping response of a nearby surface ship. The effects of the initial shock front are not considered and the fluid is assumed to be an incompressible medium. The gas bubble volume dynamics can then be related to far field fluid accelerations assuming that a potential flow condition is satisfied. Given the effective mass of the ship comprising the added fluid and bouyancy mass contributions, the forces on the ship resulting from the accelerated flow field can be determined. The theory considers the effects of proximity of the explosion bubble to a free surface, vertical migration of the bubble due to the hydrostatic imbalance, and an energy dissipative mechanism introduced via a pseudo pressure drag coefficient. The theory is applied in analyses of the whipping displacements and stresses induced in the hull of a typical frigate-size warship subjected to underwater blast loading. The response is obtained using a modal superposition of the wet hull modes of a detailed equivalent beam model of the hull.
Author: Chiara Bedon
Publisher: MDPI
ISBN: 3039435698
Category : Technology & Engineering
Languages : en
Pages : 434
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Book Description
Exceptional loads on buildings and structures may have different causes, including high-strain dynamic effects due to natural hazards, man-made attacks, and accidents, as well as extreme operational conditions (severe temperature variations, humidity, etc.). All of these aspects can be critical for specific structural typologies and/or materials that are particularly sensitive to external conditions. In this regard, dedicated and refined methods are required for their design, analysis, and maintenance under the expected lifetime. There are major challenges related to the structural typology and material properties with respect to the key features of the imposed design load. Further issues can be derived from the need for risk mitigation or retrofit of existing structures as well as from the optimal and safe design of innovative materials/systems. Finally, in some cases, no appropriate design recommendations are available and, thus, experimental investigations can have a key role within the overall process. In this Special Issue, original research studies, review papers, and experimental and/or numerical investigations are presented for the structural performance assessment of buildings and structures under various extreme conditions that are of interest for design.
Author: A. H. Keil
Publisher:
ISBN:
Category : Explosions
Languages : en
Pages : 34
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Book Description
Various phases of an underwater explosion are described. Nomograms are given for characteristics parameters of the shock wave and the bubble pulsation. Possible effects of the water surface and the sea bottom are discussed. Characteristic ship-response phases are reviewed and explained. They are demonstrated by actual examples of hull response and hull damage. The shipboard shock environment to which any installation aboard a ship is subjected is presented, and typical cases of shock damage are shown. The significance of the study of ship response to underwater explosions is reviewed. Generalization of the few controlled explosion tests against ships becomes possible by application to loading and response theories. The foundation is thus laid for increasing the combat reliability of ships and their endurance under attack.
Author:
Publisher:
ISBN:
Category :
Languages : en
Pages : 470
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Book Description
The report contains results of studies relevant to the dynamic response of objects subjected to underwater explosions. The kinetics of detonation waves are mathematically evolved.
Author: Ye Pyae Sone Oo
Publisher:
ISBN:
Category :
Languages : en
Pages : 0
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Book Description
Underwater explosions involve many complex physical phenomena such as shock wave propagation, fluid-structure inter actions, cavitation, etc. To model these phenomena as precisely as possible, finite element calculations coupled with the code "Underwater Shock Analysis" (USA) are used nowadays. However, such approaches require a lot of modeling effort and computation time. In this context, the research work carried out within the framework of this thesis has enabled the development of simplified analytical formulations that are both rapid and reasonably accurate. The range of validity of the proposed formulations was examined by comparing the analytical results with numerical simulations (also carried out within the framework of the thesis) and experimental results available from the literature. An office design tool for the analysis of the shock response of submerged composite plates was also developed.
Author: Share Inc
Publisher:
ISBN:
Category : Electronic data processing
Languages : en
Pages : 480
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Book Description
Author:
Publisher:
ISBN:
Category :
Languages : en
Pages :
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Book Description
Author: Dennis J. Fallon
Publisher:
ISBN:
Category : Shock (Mechanics)
Languages : en
Pages : 46
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Book Description
Author: Nathan A. Schneider
Publisher:
ISBN: 9781423501206
Category :
Languages : en
Pages : 184
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Book Description
During World War II many surface combatants were severely crippled by close-proximity underwater explosions from ordnance that had actually missed their target. Since this time, in order to test the survivability of mission essential equipment in a severe shock environment, all new classes of combatants have been required to have shock trial tests conducted on the lead ship of the class. While these tests are extremely important in determining the vulnerabilities of a surface ship, they require an extensive amount of preparation, manhours, and money. Furthermore, these tests present an obvious danger to the crew onboard, the ship itself and any marine life in the vicinity. Creating a virtual shock environment by use of a computer to model the ship structure and the surrounding fluid presents a valuable design tool and an attractive alternative to these tests. This thesis examines the accuracy of shock simulation using the shock trials conducted on USS WINSTON S. CHURCHILL (DDG 81) in 2001. Specifically, all three explosions DDG 81 was subjected to are simulated and the resulting predictions compared with actual shock trial data. The effects of the fluid volume size, mesh density, mesh quality, and shot location are investigated.
