Response of Marine Structures to Underwater Explosions PDF Download
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Author: Y. S. Shin
Publisher:
ISBN:
Category : Hydrodynamics
Languages : en
Pages :
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Book Description
Author: Y. S. Shin
Publisher:
ISBN:
Category : Hydrodynamics
Languages : en
Pages :
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Author: Siddharth Avachat
Publisher:
ISBN:
Category : Blast effect
Languages : en
Pages :
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Book Description
The need to protect marine structures from the high-intensity impulsive loads created by underwater explosions has stimulated renewed interest in the mechanical response of sandwich structures. The objective of this combined numerical and experimental study is to analyze the dynamic response of composite sandwich structures and develop material-structure-property relations and design criteria for improving the blast-resistance of marine structures. Configurations analyzed include polymer foam core structures with planar geometries. A novel experimental facility to generate high-intensity underwater impulsive loads and carry out in-situ measurements of dynamic deformations in marine structures is developed. Experiments are supported by fully dynamic finite-element simulations which account for the effects of fluid-structure interaction, and the constitutive and damage response of E-glass/polyester composites and PVC foams. Results indicate that the core-density has a significant influence on dynamic deformations and failure modes. Polymeric foams experience considerable rate-effects and exhibit extensive shear cracking and collapse under high-magnitude multi-axial underwater impulsive loads. In structures with identical masses, low-density foam cores consistently outperform high-density foam cores, undergoing lesser deflections and transmitting smaller impulses. Calculations reveal a significant difference between the response of air-backed and water-backed structures. Water-backed structures undergo much greater damage and consequently need to absorb a much larger amount of energy than air-backed structures. The impulses transmitted through water-backed structures have significant implications for structural design. The thickness of the facesheets is varied under the conditions of constant material properties and core dimensions. The results reveal an optimal thickness of the facesheets which maximizes energy absorption in the core and minimizes the overall deflection of the structure.
Author: Srinivasan Gopalakrishnan
Publisher: Springer
ISBN: 9811071705
Category : Science
Languages : en
Pages : 477
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Book Description
This book primarily focuses on methodologies to enable marine structures to resist high velocity impact loadings. It is based on invited talks presented at the recent India–USA workshop on “Recent Advances in Blast Mitigation Strategies in Civil and Marine Composite Structures” The book comprises content from top researchers from India and the USA and covers various aspects of the topic, including modeling and simulation, design aspects, experimentation and various challenges. These failure modes significantly reduce the structural integrity of the marine structures unless they are designed to resist such harsh loadings. Understanding the mechanics of these structures under harsh loadings is still an open area of research, and the behavior of these structures is not fully understood. The book highlights efforts to reduce the effects of blast loadings on marine composite structures. Intended for researchers/scientists and practicing engineers, the book focuses not only the design and analysis challenges of marine composite structures under such harsh loading conditions, but also provides new design guidelines.
Author: Luigi Emanuele Perotti
Publisher:
ISBN:
Category : Blast effect
Languages : en
Pages : 248
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Book Description
Fiber composite material panels and sandwich panels possess both a high resistance to weight ratio and a high stiffness to weight ratio. Due to these features, fiber composite panels are used widely in aeronautic and marine structures, where the improvement of the structural performance while keeping a low weight is crucial. Sandwich structures, consisting of a foam core enclosed by two external layers of fiber reinforced material, seem to be promising in minimizing the total weight, maintaining structural rigidity and improving the resistance under exceptional loads, such as those due to explosions. Full scale experiments to test the performance of real fiber composite sandwich structures subjected to underwater explosions would be very complex and expensive. Therefore, the capability to numerically simulate the response of sandwich structures undergoing explosive loading will provide a powerful and unique tool to analyze and optimize their design by investigating the influence of different parameters. Obviously, small scale laboratory tests will still be essential to validate and calibrate the computational model before its use. The present research focuses on the development of a computational scheme to model the behavior of large sandwich panels subjected to underwater explosions. The description of the sandwich requires the definition of the material behavior of the components, i.e., the foam core and the external sheets, of the structural behavior of the thin shell structure, and of the interaction with the surrounding fluid. Several finite kinematics material models taken from the recent literature have been used, and a new simple model for fiber reinforced composites has been developed and validated. The thin shell structure is modeled with an existing in-house built non-local shell finite element code (SFC), equipped with fracturing capabilities. The coupling between the behavior of the shells and the action of the fluid as a consequence of an underwater explosion is modeled here with the aid of an existing fluid-solid interaction (FSI) code. In this study, the FSI code has been expanded in order to include the possibility of simulating fiber composite materials. New algorithms and new control indicators, such as global measures of energy dissipation, have also been developed. The new capabilities of the fluid-solid coupled solver have been verified and validated before applying the solver to realistic problems. In the applications part of the present research, two different methods for applying the pressure load due to an underwater explosion are compared. The first method is simpler, and consists in applying a prescribed pressure profile without considering FSI. In the second method, the explosive charge is modeled as a spherical energy deposition and the full FSI is considered. The simpler method is used to assess the role of different design parameters of the face sheets on the overall response of sandwich panels when subjected to impulsive loads. Subsequently, the best sandwich design obtained from these initial simulations is used for the evaluation of the mechanical performance of the hull section of an existing Argentinean navy vessel. The final application of the proposed computational scheme is a parametric analysis of the hull section, considering different weights of the explosive charge and different distances of the explosion location from the hull wall. Finally, with awareness of the limits of the adopted approach, several alternative schemes to improve the dynamical analysis of sandwich panels impulsively loaded are presented and discussed. In particular, two different kinds of shell finite elements are introduced. The proposed shell elements are based on alternative approximation schemes, which may model in a more realistic way the behavior of sandwich structures under extreme loads.
Author: Jorgen Amdahl
Publisher: CRC Press
ISBN: 1000533832
Category : Technology & Engineering
Languages : en
Pages : 1274
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Book Description
Developments in the Analysis and Design of Marine Structures is a collection of papers presented at MARSTRUCT 2021, the 8th International Conference on Marine Structures (by remote transmission, 7-9 June 2021, organised by the Department of Marine Technology of the Norwegian University of Science and Technology, Trondheim, Norway), and is essential reading for academics, engineers and professionals involved in the design of marine and offshore structures. The MARSTRUCT Conference series deals with Ship and Offshore Structures, addressing topics in the fields of: - Methods and Tools for Loads and Load Effects; - Methods and Tools for Strength Assessment; - Experimental Analysis of Structures; - Materials and Fabrication of Structures; - Methods and Tools for Structural Design and Optimisation; and - Structural Reliability, Safety and Environmental Protection. The MARSTRUCT conferences series of started in Glasgow, UK in 2007, the second event of the series took place in Lisbon, Portugal in March 2009, the third in Hamburg, Germany in March 2011, the fourth in Espoo, Finland in March 2013, the fifth in Southampton, UK in March 2015, the sixth in Lisbon, Portugal in May 2017, and the seventh in Drubovnik, Croatia in May 2019. The ‘Proceedings in Marine Technology and Ocean Engineering’ series is dedicated to the publication of proceedings of peer-reviewed international conferences dealing with various aspects of ‘Marine Technology and Ocean Engineering’. The Series includes the proceedings of the following conferences: the International Maritime Association of the Mediterranean (IMAM) conferences, the Marine Structures (MARSTRUCT) conferences, the Renewable Energies Offshore (RENEW) conferences and the Maritime Technology (MARTECH) conferences. The ‘Marine Technology and Ocean Engineering’ series is also open to new conferences that cover topics on the sustainable exploration and exploitation of marine resources in various fields, such as maritime transport and ports, usage of the ocean including coastal areas, nautical activities, the exploration and exploitation of mineral resources, the protection of the marine environment and its resources, and risk analysis, safety and reliability. The aim of the series is to stimulate advanced education and training through the wide dissemination of the results of scientific research.
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.
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: Kishan Gopal Ramawat
Publisher: CRC Press
ISBN: 1138000450
Category : Medical
Languages : en
Pages : 606
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Book Description
Forest trees cover 30% of the earth's land surface, providing renewable fuel, wood, timber, shelter, fruits, leaves, bark, roots, and are source of medicinal products in addition to benefits such as carbon sequestration, water shed protection, and habitat for 1/3 of terrestrial species. However, the genetic analysis and breeding of trees has lagged behind that of crop plants. Therefore, systematic conservation, sustainable improvement and pragmatic utilization of trees are global priorities. This book provides comprehensive and up to date information about tree characterization, biological understanding, and improvement through biotechnological and molecular tools.
Author: Carlos Guedes Soares
Publisher: CRC Press
ISBN: 1351653415
Category : Technology & Engineering
Languages : en
Pages : 952
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Book Description
Progress in the Analysis and Design of Marine Structures collects the contributions presented at MARSTRUCT 2017, the 6th International Conference on Marine Structures (Lisbon, Portugal, 8-10 May 2017). The MARSTRUCT series of Conferences started in Glasgow, UK in 2007, the second event of the series having taken place in Lisbon, Portugal in March 2009, the third in Hamburg, Germany in March 2011, the fourth in Espoo, Finland in March 2013, and the fifth in Southampton, UK in March 2015. This Conference series deals with Ship and Offshore Structures, addressing topics in the areas of: - Methods and Tools for Loads and Load Effects - Methods and Tools for Strength Assessment - Experimental Analysis of Structures - Materials and Fabrication of Structures - Methods and Tools for Structural Design and Optimisation, and - Structural Reliability, Safety and Environmental Protection Progress in the Analysis and Design of Marine Structures is essential reading for academics, engineers and all professionals involved in the design of marine and offshore structures.
Author: W. W. Webbon
Publisher:
ISBN:
Category :
Languages : en
Pages : 26
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Book Description
This interim report summarizes results obtained in conjunction with continuing work toward extension of the Navy's Dynamic Design Analysis Method (DDAM) to multiple foundation motion. A dynamic model of a hull section containing simulated internal equipment with two supports was analyzed using the Variable Geometry Submarine Model (VGSM) for response to underwater explosions with varying charge standoffs. Charge weights were also varied such that the shock factor component normal to the hull was maintained constant for each standoff. Both symmetric and unsymmetric charge geometries with respect to the simulated equipment were examined. Results show that there is a trend toward reduced severity of shock predicted by this simulation for this equipment is the standoff is increased for constant shock factor. The unsymmetric loading resulting in different foundation motions of the two equipment supports shows a trend toward reduced severity of shock for many locations when the foundation motions are uncorrelated (small standoff). However, some locations, particularly those excited by unsymmetric modes of vibration, experience a significant increase in severity. As the unsymmetric charge geometry becomes more approximately symmetric for larger standoffs, the foundation motions become more correlated and the shock response approaches the symmetric case.
