The Experts below are selected from a list of 26196 Experts worldwide ranked by ideXlab platform
Ravi Penmetsa - One of the best experts on this subject based on the ideXlab platform.
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multidisciplinary optimization of a lightweight Torpedo structure subjected to an underwater explosion
Finite Elements in Analysis and Design, 2006Co-Authors: Rajesh Kalavalapally, Ravi Penmetsa, Ramana V GrandhiAbstract:Undersea weapons, including Torpedoes need to be designed to survive extreme loading conditions such as underwater explosions (UNDEX). In this work, a multidisciplinary optimization problem is solved for a lightweight Torpedo model subjected to UNDEX. A Torpedo configuration with least possible weight for a given level of safety from an explosion at a critical distance is obtained. The Torpedo is modeled using both metallic and composite material models. The similitude relations are used to model the pressure wave resulting from an explosive, which is assumed as a spherical wave. The response of the composite flat plate is obtained prior to the Torpedo for validating the analysis routine and determining the stress levels in each of the layers. The response of a composite lightweight Torpedo model is also obtained and structural optimization is performed to achieve the minimum weight subject to the required safety levels. Similar analysis and optimization was performed for a stiffened metallic Torpedo. The optimal designs for both models are compared and it is observed that the composite Torpedo model is stronger and lighter than the metallic design when subjected to an UNDEX at a given standoff distance.
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optimum design of a supercavitating Torpedo considering overall size shape and structural configuration
International Journal of Solids and Structures, 2006Co-Authors: Edward Alyanak, Ramana V Grandhi, Ravi PenmetsaAbstract:Abstract A supercavitating Torpedo is a complex high speed undersea weapon that is exposed to extreme operating conditions due to the weapon’s speed. To successfully design a Torpedo that can survive in this environment, it is necessary to consider the Torpedo shell as a critical component. The shell of a supercavitating Torpedo must be designed to survive extreme loading conditions (depth pressure and thrust loading), meet frequency constraints, and fit inside the cavity generated by the cavitator. In this research, an algorithm to determine the optimal configuration of the Torpedo is presented. This method formulates an optimization problem that determines the general shape of the Torpedo in order to satisfy the required performance criteria. Simultaneously, a method to determine the optimal stiffener configuration in the Torpedo structure is also presented. A Torpedo configuration for a desired speed is obtained and the details of the process are thoroughly discussed.
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structural response and optimization of a supercavitating Torpedo
Finite Elements in Analysis and Design, 2005Co-Authors: Edward Alyanak, Ramana V Grandhi, Vipperla Venkayya, Ravi PenmetsaAbstract:A conceptual supercavitating Torpedo model is developed and the weapon structure is designed to satisfy potentially conflicting performance criteria from multiple disciplines. These disciplines include static strength, dynamic, and buckling analyses that require extensive computer simulation. Therefore, a high fidelity finite element model of the supercavitating Torpedo was developed in order to make the complex task of analyzing multiple configurations feasible. Using this model, an initial parametric investigation was performed to determine the effect of multiple structural members on the performance of the Torpedo with respect to the disciplines investigated. Static analysis was performed to determine the effect of depth pressure, cavitator forces, and fin forces. Using information obtained from these analyses, it was determined that the preliminary Torpedo design was not sufficiently meeting the performance criteria, such as minimum stress requirements. Therefore, multi-disciplinary optimization of the Torpedo structure was performed to determine the optimal configuration of the stiffeners, stiffener dimensions, and shell thickness of the Torpedo. The design strategy developed in this work can be extended with minimal effort to multiple configurations that might be dictated by the cavity shape requirements in the future.
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Shape optimization of the cavitator for a supercavitating Torpedo
Structural and Multidisciplinary Optimization, 2005Co-Authors: J.h. Choi, Ravi Penmetsa, Ramana V GrandhiAbstract:The Torpedo is a vital component of the naval arsenal, and efforts are continually directed toward improving the technology to make the Torpedo more lethal and more stealthy. Recently, a new direction of research is considering the high-speed Torpedo, which is capable of reaching up to 200 mph underwater. When a Torpedo travels at this speed, the flow around the body separates and a cavity is formed. This cavity generation due to high speeds is called supercavitation. And the drag force acting on this supercavitating Torpedo dictates the thrust requirements for the propulsion system, to maintain a required cavity at the operating speed. Therefore, any reduction in the drag force, obtained by modifying the shape of the cavitator or the nose of the Torpedo, would result in lower propulsion requirements. In this work, shape optimization techniques were employed to determine the optimum (minimum-drag) shape of the cavitator given certain operating conditions. Shape optimization was also used to determine the shape of the cavity for any given cavitator, using potential flow theory. Analytical sensitivities were derived for various parameters in order to implement a gradient-based optimization algorithm. The developed methodology is an optimization process where the cavity and cavitator shapes are determined simultaneously. The cavitator shape that induces minimum drag and the corresponding cavity shape can be used to model a supercavitating Torpedo that fits in the generated cavity and satisfies the required performance characteristics.
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Structural Response of a Supercavitating Torpedo Shell
45th AIAA ASME ASCE AHS ASC Structures Structural Dynamics & Materials Conference, 2004Co-Authors: Edward Alyanak, Ramana V Grandhi, Vipperla Venkayya, Ravi PenmetsaAbstract:A conceptual supercavitating Torpedo model is developed and the vehicle structure is designed to satisfy potentially conflicting performance criteria from multiple disciplines. These disciplines include static, dynamic, and buckling analyses that require extensive computer simulation. Therefore, a high fidelity finite element model of the supercavitating Torpedo was developed in order to make the complex task of analyzing multiple configurations feasible. Using this model an initial parametric investigation was performed to determine the effect of multiple structural members on the performance of the Torpedo with respect to the disciplines investigated. Static analysis was performed to determine the effect of depth pressure, cavitator forces, and fin forces. Using information obtained from these analyses, it was determined that the preliminary Torpedo design was not sufficiently meeting the performance criteria, such as minimum stress requirements. Therefore, multi-disciplinary optimization of the Torpedo structure was performed to determine the optimal configuration of the stiffeners, stiffener dimensions, and shell thickness of the Torpedo. The design strategy developed in this work can be extended with minimal effort to multiple configurations that might be dictated by the cavity shape requirements in the future.
Ramana V Grandhi - One of the best experts on this subject based on the ideXlab platform.
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multidisciplinary optimization of a lightweight Torpedo structure subjected to an underwater explosion
Finite Elements in Analysis and Design, 2006Co-Authors: Rajesh Kalavalapally, Ravi Penmetsa, Ramana V GrandhiAbstract:Undersea weapons, including Torpedoes need to be designed to survive extreme loading conditions such as underwater explosions (UNDEX). In this work, a multidisciplinary optimization problem is solved for a lightweight Torpedo model subjected to UNDEX. A Torpedo configuration with least possible weight for a given level of safety from an explosion at a critical distance is obtained. The Torpedo is modeled using both metallic and composite material models. The similitude relations are used to model the pressure wave resulting from an explosive, which is assumed as a spherical wave. The response of the composite flat plate is obtained prior to the Torpedo for validating the analysis routine and determining the stress levels in each of the layers. The response of a composite lightweight Torpedo model is also obtained and structural optimization is performed to achieve the minimum weight subject to the required safety levels. Similar analysis and optimization was performed for a stiffened metallic Torpedo. The optimal designs for both models are compared and it is observed that the composite Torpedo model is stronger and lighter than the metallic design when subjected to an UNDEX at a given standoff distance.
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optimum design of a supercavitating Torpedo considering overall size shape and structural configuration
International Journal of Solids and Structures, 2006Co-Authors: Edward Alyanak, Ramana V Grandhi, Ravi PenmetsaAbstract:Abstract A supercavitating Torpedo is a complex high speed undersea weapon that is exposed to extreme operating conditions due to the weapon’s speed. To successfully design a Torpedo that can survive in this environment, it is necessary to consider the Torpedo shell as a critical component. The shell of a supercavitating Torpedo must be designed to survive extreme loading conditions (depth pressure and thrust loading), meet frequency constraints, and fit inside the cavity generated by the cavitator. In this research, an algorithm to determine the optimal configuration of the Torpedo is presented. This method formulates an optimization problem that determines the general shape of the Torpedo in order to satisfy the required performance criteria. Simultaneously, a method to determine the optimal stiffener configuration in the Torpedo structure is also presented. A Torpedo configuration for a desired speed is obtained and the details of the process are thoroughly discussed.
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structural response and optimization of a supercavitating Torpedo
Finite Elements in Analysis and Design, 2005Co-Authors: Edward Alyanak, Ramana V Grandhi, Vipperla Venkayya, Ravi PenmetsaAbstract:A conceptual supercavitating Torpedo model is developed and the weapon structure is designed to satisfy potentially conflicting performance criteria from multiple disciplines. These disciplines include static strength, dynamic, and buckling analyses that require extensive computer simulation. Therefore, a high fidelity finite element model of the supercavitating Torpedo was developed in order to make the complex task of analyzing multiple configurations feasible. Using this model, an initial parametric investigation was performed to determine the effect of multiple structural members on the performance of the Torpedo with respect to the disciplines investigated. Static analysis was performed to determine the effect of depth pressure, cavitator forces, and fin forces. Using information obtained from these analyses, it was determined that the preliminary Torpedo design was not sufficiently meeting the performance criteria, such as minimum stress requirements. Therefore, multi-disciplinary optimization of the Torpedo structure was performed to determine the optimal configuration of the stiffeners, stiffener dimensions, and shell thickness of the Torpedo. The design strategy developed in this work can be extended with minimal effort to multiple configurations that might be dictated by the cavity shape requirements in the future.
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Shape optimization of the cavitator for a supercavitating Torpedo
Structural and Multidisciplinary Optimization, 2005Co-Authors: J.h. Choi, Ravi Penmetsa, Ramana V GrandhiAbstract:The Torpedo is a vital component of the naval arsenal, and efforts are continually directed toward improving the technology to make the Torpedo more lethal and more stealthy. Recently, a new direction of research is considering the high-speed Torpedo, which is capable of reaching up to 200 mph underwater. When a Torpedo travels at this speed, the flow around the body separates and a cavity is formed. This cavity generation due to high speeds is called supercavitation. And the drag force acting on this supercavitating Torpedo dictates the thrust requirements for the propulsion system, to maintain a required cavity at the operating speed. Therefore, any reduction in the drag force, obtained by modifying the shape of the cavitator or the nose of the Torpedo, would result in lower propulsion requirements. In this work, shape optimization techniques were employed to determine the optimum (minimum-drag) shape of the cavitator given certain operating conditions. Shape optimization was also used to determine the shape of the cavity for any given cavitator, using potential flow theory. Analytical sensitivities were derived for various parameters in order to implement a gradient-based optimization algorithm. The developed methodology is an optimization process where the cavity and cavitator shapes are determined simultaneously. The cavitator shape that induces minimum drag and the corresponding cavity shape can be used to model a supercavitating Torpedo that fits in the generated cavity and satisfies the required performance characteristics.
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Structural Response of a Supercavitating Torpedo Shell
45th AIAA ASME ASCE AHS ASC Structures Structural Dynamics & Materials Conference, 2004Co-Authors: Edward Alyanak, Ramana V Grandhi, Vipperla Venkayya, Ravi PenmetsaAbstract:A conceptual supercavitating Torpedo model is developed and the vehicle structure is designed to satisfy potentially conflicting performance criteria from multiple disciplines. These disciplines include static, dynamic, and buckling analyses that require extensive computer simulation. Therefore, a high fidelity finite element model of the supercavitating Torpedo was developed in order to make the complex task of analyzing multiple configurations feasible. Using this model an initial parametric investigation was performed to determine the effect of multiple structural members on the performance of the Torpedo with respect to the disciplines investigated. Static analysis was performed to determine the effect of depth pressure, cavitator forces, and fin forces. Using information obtained from these analyses, it was determined that the preliminary Torpedo design was not sufficiently meeting the performance criteria, such as minimum stress requirements. Therefore, multi-disciplinary optimization of the Torpedo structure was performed to determine the optimal configuration of the stiffeners, stiffener dimensions, and shell thickness of the Torpedo. The design strategy developed in this work can be extended with minimal effort to multiple configurations that might be dictated by the cavity shape requirements in the future.
Edward Alyanak - One of the best experts on this subject based on the ideXlab platform.
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optimum design of a supercavitating Torpedo considering overall size shape and structural configuration
International Journal of Solids and Structures, 2006Co-Authors: Edward Alyanak, Ramana V Grandhi, Ravi PenmetsaAbstract:Abstract A supercavitating Torpedo is a complex high speed undersea weapon that is exposed to extreme operating conditions due to the weapon’s speed. To successfully design a Torpedo that can survive in this environment, it is necessary to consider the Torpedo shell as a critical component. The shell of a supercavitating Torpedo must be designed to survive extreme loading conditions (depth pressure and thrust loading), meet frequency constraints, and fit inside the cavity generated by the cavitator. In this research, an algorithm to determine the optimal configuration of the Torpedo is presented. This method formulates an optimization problem that determines the general shape of the Torpedo in order to satisfy the required performance criteria. Simultaneously, a method to determine the optimal stiffener configuration in the Torpedo structure is also presented. A Torpedo configuration for a desired speed is obtained and the details of the process are thoroughly discussed.
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structural response and optimization of a supercavitating Torpedo
Finite Elements in Analysis and Design, 2005Co-Authors: Edward Alyanak, Ramana V Grandhi, Vipperla Venkayya, Ravi PenmetsaAbstract:A conceptual supercavitating Torpedo model is developed and the weapon structure is designed to satisfy potentially conflicting performance criteria from multiple disciplines. These disciplines include static strength, dynamic, and buckling analyses that require extensive computer simulation. Therefore, a high fidelity finite element model of the supercavitating Torpedo was developed in order to make the complex task of analyzing multiple configurations feasible. Using this model, an initial parametric investigation was performed to determine the effect of multiple structural members on the performance of the Torpedo with respect to the disciplines investigated. Static analysis was performed to determine the effect of depth pressure, cavitator forces, and fin forces. Using information obtained from these analyses, it was determined that the preliminary Torpedo design was not sufficiently meeting the performance criteria, such as minimum stress requirements. Therefore, multi-disciplinary optimization of the Torpedo structure was performed to determine the optimal configuration of the stiffeners, stiffener dimensions, and shell thickness of the Torpedo. The design strategy developed in this work can be extended with minimal effort to multiple configurations that might be dictated by the cavity shape requirements in the future.
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Structural Response of a Supercavitating Torpedo Shell
45th AIAA ASME ASCE AHS ASC Structures Structural Dynamics & Materials Conference, 2004Co-Authors: Edward Alyanak, Ramana V Grandhi, Vipperla Venkayya, Ravi PenmetsaAbstract:A conceptual supercavitating Torpedo model is developed and the vehicle structure is designed to satisfy potentially conflicting performance criteria from multiple disciplines. These disciplines include static, dynamic, and buckling analyses that require extensive computer simulation. Therefore, a high fidelity finite element model of the supercavitating Torpedo was developed in order to make the complex task of analyzing multiple configurations feasible. Using this model an initial parametric investigation was performed to determine the effect of multiple structural members on the performance of the Torpedo with respect to the disciplines investigated. Static analysis was performed to determine the effect of depth pressure, cavitator forces, and fin forces. Using information obtained from these analyses, it was determined that the preliminary Torpedo design was not sufficiently meeting the performance criteria, such as minimum stress requirements. Therefore, multi-disciplinary optimization of the Torpedo structure was performed to determine the optimal configuration of the stiffeners, stiffener dimensions, and shell thickness of the Torpedo. The design strategy developed in this work can be extended with minimal effort to multiple configurations that might be dictated by the cavity shape requirements in the future.
Joel L Sussman - One of the best experts on this subject based on the ideXlab platform.
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molecular dynamics simulations of the interaction of mouse and Torpedo acetylcholinesterase with covalent inhibitors explain their differential reactivity implications for drug design
Chemico-Biological Interactions, 2019Co-Authors: Nellore Bhanu Chandar, Irena Efremenko, Israel Silman, Jan M L Martin, Joel L SussmanAbstract:Abstract Although the three-dimensional structures of mouse and Torpedo californica acetylcholinesterase are very similar, their responses to the covalent sulfonylating agents benzenesulfonyl fluoride and phenylmethylsulfonyl fluoride are qualitatively different. Both agents inhibit the mouse enzyme effectively by covalent modification of its active-site serine. In contrast, whereas the Torpedo enzyme is effectively inhibited by benzenesulfonyl fluoride, it is almost completely resistant to phenylmethylsulfonyl fluoride. A bottleneck midway down the active-site gorge in both enzymes restricts access of ligands to the active site at the bottom of the gorge. Molecular dynamics simulations revealed that the mouse enzyme is substantially more flexible than the Torpedo enzyme, suggesting that enhanced ‘breathing motions’ of the mouse enzyme relative to the Torpedo enzyme may explain why phenylmethylsulfonyl fluoride can reach the active site in mouse acetylcholinesterase, but not in the Torpedo enzyme. Accordingly, we performed docking of the two sulfonylating agents to the two enzymes, followed by molecular dynamics simulations. Whereas benzenesulfonyl fluoride closely approaches the active-site serine in both mouse and Torpedo acetylcholinesterase in such simulations, phenylmethylsulfonyl fluoride is able to approach the active-site serine of mouse acetylcholinesterase, but remains trapped above the bottleneck in the Torpedo enzyme. Our studies demonstrate that reliance on docking tools in drug design can produce misleading information. Docking studies should, therefore, also be complemented by molecular dynamics simulations in selection of lead compounds. An animated Interactive 3D Complement (I3DC) is available in Proteopedia at http://proteopedia.org/w/Journal:CHEMBIOINT:2 .
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molecular dynamics simulations of the interaction of mouse and Torpedo acetylcholinesterase with covalent inhibitors explain their differential reactivity implications for drug design
bioRxiv, 2019Co-Authors: Nellore Bhanu Chandar, Irena Efremenko, Israel Silman, Jan M L Martin, Joel L SussmanAbstract:Abstract Although the three-dimensional structures of mouse and Torpedo californica acetylcholinesterase are very similar, their responses to the covalent sulfonylating agents benzenesulfonyl fluoride and phenylmethylsulfonyl fluoride are qualitatively different. Both agents inhibit the mouse enzyme effectively by covalent modification of its active-site serine. In contrast, whereas the Torpedo enzyme is effectively inhibited by benzenesulfonyl fluoride, it is completely resistant to phenylmethylsulfonyl fluoride. A bottleneck midway down the active-site gorge in both enzymes restricts access of ligands to the active site at the bottom of the gorge. Molecular dynamics simulations revealed that the mouse enzyme is substantially more flexible than the Torpedo enzyme, suggesting that enhanced ‘breathing motions’ of the mouse enzyme relative to the Torpedo enzyme might explain why phenylmethylsulfonyl fluoride can reach the active site in mouse acetylcholinesterase, but not in the Torpedo enzyme. Accordingly, we performed docking of the two sulfonylating agents to the two enzymes, followed by molecular dynamics simulations. Whereas benzenesulfonyl fluoride closely approached the active-site serine in both mouse and Torpedo acetylcholinesterase in such simulations, phenylmethylsulfonyl fluoride was able to approach the active-site serine of mouse acetylcholinesterase - but remained trapped above the bottleneck in the case of the Torpedo enzyme. Our studies demonstrate that reliance on docking tools in drug design can produce misleading information. Docking studies should, therefore, also be complemented by molecular dynamics simulations in selection of lead compounds. Author summary Enzymes are protein molecules that catalyze chemical reactions in living organisms, and are essential for their physiological functions. Proteins have well defined three-dimensional structures, but display flexibility; it is believed that this flexibility, known as their dynamics, plays a role in their function. Here we studied the neuronal enzyme acetylcholinesterase, which breaks down the neurotransmitter, acetylcholine. The active site of this enzyme is deeply buried, and accessed by a narrow gorge. A particular inhibitor, phenylmethylsulfonyl fluoride, is known to inhibit mouse acetylcholinesterase, but not that of the electric fish, Torpedo, even though their structures are very similar. A theoretical technique called molecular dynamics (MD) shows that the mouse enzyme is more flexible than the Torpedo enzyme. Furthermore, when the movement of the inhibitor down the gorge towards the active site is simulated using MD, the phenylmethylsulfonyl fluoride can reach the active site in the mouse enzyme, but not in the Torpedo enzyme, in which it remains trapped midway down the gorge. Our study emphasizes the importance of taking into account not only structure, but also dynamics, in designing drugs targeted towards proteins.
Wang Zhengyu - One of the best experts on this subject based on the ideXlab platform.
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The Surface Ship Torpedo Defense Simulation System
2018 IEEE 3rd International Conference on Image Vision and Computing (ICIVC), 2018Co-Authors: Dong Xiaoheng, Zhang Yiqi, Li Minghang, Wang ZhengyuAbstract:Surface ship Torpedo defense simulation system plays a guiding role in the development of new surface ships underwater acoustic warfare system. Through the study of the functional analysis of the simulation system, the surface ship Torpedo defense simulation system is proposed and the hardware composition, topological structure, data structure, data transmission method of the surface ship Torpedo defense simulation system is determined. According to the role of combat maneuvers, the Torpedo defense simulation evaluation system is divided into attack, defense and public parts, and surface ship Torpedo defense system simulation running instance is given, which verified the feasibility of the surface ship Torpedo defense system simulation.