The Experts below are selected from a list of 219 Experts worldwide ranked by ideXlab platform
R. A. Ibrahim - One of the best experts on this subject based on the ideXlab platform.
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Overview of structural life assessment and reliability, Part V: Joints and weldments
Journal of Ship Production and Design, 2016Co-Authors: R. A. IbrahimAbstract:Structural life assessment periodically evaluates the state and condition of a structural system and provides recommendations for possible maintenance actions or the end of structural service life. It is a diversified field and relies on the theories of fracture mechanics, fatigue damage process, probability of failure, and reliability. With reference to naval ship Structures, their life assessment is not only governed by the theory of fracture mechanics and fatigue damage process, but by other factors such as corrosion, grounding, and sudden collision. The purpose of this series of review articles is to provide different issues pertaining to structural life assessment of ships and Ocean Structures. Part I deals with the basic ingredients of the theory of fracture mechanics, which is classified into linear elastic fracture mechanics and elastoplastic fracture mechanics. The amount of energy available for fracture is usually governed by the stress field around the crack, which is measured by the stress intensity factor. The value of the stress intensity factor, which depends on the loading mode, is evaluated by different methods developed by many researchers. The applications of the theory of fracture mechanics to metallic and composite Structures are presented with an emphasis to those used in marine Structures. When the inertia of relatively large pieces of a structure is large enough that the correct balancing of the energy of fracture requires the inclusion of kinetic energy, then the dynamic nature of fracture dominates the analysis. For a crack that is already propagating, the inertial effects are important when the crack tip speed is small compared with the stress wave velocities. This fact has been realized in the theory of fracture mechanics under the name of dynamic fracture and peridynamic. In essence, peridynamic replaces the partial differential equations of classic continuum theories with integro-differential equations as a tool to avoid singularities arising from the fact that partial derivatives do not exist on crack surfaces and other singularities. A brief overview of fracture dynamics and peridynamics together with damage mechanisms in composite Structures is presented. The limitations of fracture mechanics criteria are also discussed. Life assessment of ship Structures depends on the failure modes and the probabilistic description of failure, which are addressed in Part II. Life assessment of ship Structures depends on the failure modes and the probabilistic description of failure. In view of structural parameter uncertainties, probabilistic analysis requires the use of reliability methods for assessing fatigue life by considering the crack propagation process and the first passage problem, which measures the probability of the exit time from a safe operating regime. The main results reported in the literature pertaining to ship structural damage assessments resulting from to slamming loads, liquid sloshing impact loads of liquefied natural gas in ship tankers, and ship grounding accidents, and collision with solid bodies are discussed in Part III. Under such extreme loadings, structural reliability will be the major issue in the design stage of Ocean Structures. The treatment of extreme loading on ship Structures significantly differs from those approaches developed by dynamicists. Environmental effects on ship Structures play a major factor in the life assessment of Ocean systems. In particular, these effects include corrosion and hydrogen embrittlement. Part IV is devoted to a ship's life assessment resulting from corrosion and hydrogen embrittlement. Because structural components made from aluminum and its alloys are vital to the ship and aerospace industries, the influence of environment on aluminum Structures and the means of corrosion control and monitoring in both aluminum and nonaluminum metals are presented. Hybrid ships consist of a stainless steel advanced double-hull center section, to which a composite material bow and/or stern is attached. Such Structures require strong joints between the composite and the steel parts. Some of the difficulties with joining composites and metal are related to the large difference in mechanical properties such as stiffness, coefficient of thermal expansion, etc., between the adherents and the large anisotropy of composites. Such differences generally lead to large stress concentrations and weak joints. Fatigue crack growth, stress concentrations resulting from details, joints, and fasteners are addressed in Part V. Fatigue improvement in welded joints is considered one the major tasks of this part. Brittle fracture of hull Structures causes serious structural damage and this motivated the ship structure community to develop some means to prevent brittle cracks from occurring. The basic principle behind the use of a crack arrester is to reduce the crack-driving force below the resisting force that must be overcome to extend a crack. The crack arrestor can be as simple as a thickened region of metal or may be constructed of a laminated or woven material that can withstand deformation without failure. Part VI provides different approaches of passive crack control in the form of crack arresters to stop crack propagation before it spreads over a structure component. Crack arresters used in ship Structures and pipelines are described for both metal and composite materials. This six-part review article is by no means exhaustive and is based on over 1800 references. It does not address the structural health monitoring, which constitutes a major task in the structural diagnostic process.
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Overview of Structural Life Assessment and Reliability, Part VI: Crack Arresters 1
Journal of Ship Production and Design, 2016Co-Authors: R. A. IbrahimAbstract:Structural life assessment periodically evaluates the state and condition of a structural system and provides recommendations for possible maintenance actions or the end of structural service life. It is a diversified field and relies on the theories of fracture mechanics, fatigue damage process, probability of failure, and reliability. With reference to naval ship Structures, their life assessment is not only governed by the theory of fracture mechanics and fatigue damage process, but by other factors such as corrosion, grounding, and sudden collision. The purpose of this series of review articles is to provide different issues pertaining to structural life assessment of ships and Ocean Structures. Part I deals with the basic ingredients of the theory of fracture mechanics, which is classified into linear elastic fracture mechanics and elasto-plastic fracture mechanics. The amount of energy available for fracture is usually governed by the stress field around the crack, which is measured by the stress intensity factor. The value of the stress intensity factor, which depends on the loading mode, is evaluated by different methods developed by many researchers. The applications of the theory of fracture mechanics to metallic and composite Structures are presented with an emphasis to those used in marine Structures. When the inertia of relatively large pieces of a structure is large enough that the correct balancing of the energy of fracture requires the inclusion of kinetic energy, then the dynamic nature of fracture dominates the analysis. For a crack that is already propagating, the inertial effects are important when the crack tip speed is small compared with the stress wave velocities. This fact has been realized in the theory of fracture mechanics under the name of dynamic fracture and peridynamic. In essence, peridynamic replaces the partial differential equations of classic continuum theories with integro-differential equations as a tool to avoid singularities arising from the fact that partial derivatives do not exist on crack surfaces and other singularities. A brief overview of fracture dynamics and peridynamics together with damage mechanisms in composite Structures is presented. The limitations of fracture mechanics criteria are also discussed. Life assessment of ship Structures depends on the failure modes and the probabilistic description of failure, which are addressed in Part II. Life assessment of ship Structures depends on the failure modes and the probabilistic description of failure. In view of structural parameter uncertainties, probabilistic analysis requires the use of reliability methods for assessing fatigue life by considering the crack propagation process and the first passage problem, which measures the probability of the exit time from a safe operating regime. The main results reported in the literature pertaining to ship structural damage assessments resulting from to slamming loads, liquid sloshing impact loads of liquefied natural gas in ship tankers, and ship grounding accidents, and collision with solid bodies are discussed in Part III. Under such extreme loadings, structural reliability will be the major issue in the design stage of Ocean Structures. The treatment of extreme loading on ship Structures significantly differs from those approaches developed by dynamicists. Environmental effects on ship Structures play a major factor in the life assessment of Ocean systems. In particular, these effects include corrosion and hydrogen embrittlement. Part IV is devoted to a ship's life assessment resulting from corrosion and hydrogen embrittlement. Because structural components made from aluminum and its alloys are vital to the ship and aerospace industries, the influence of environment on aluminum Structures and the means of corrosion control and monitoring in both aluminum and nonaluminum metals are presented. Hybrid ships consist of a stainless steel advanced double-hull center section, to which a composite material bow and/or stern is attached. Such Structures require strong joints between the composite and the steel parts. Some of the difficulties with joining composites and metal are related to the large difference in mechanical properties such as stiffness, coefficient of thermal expansion, etc., between the adherents and the large anisotropy of composites. Such differences generally lead to large stress concentrations and weak joints. Fatigue crack growth, stress concentrations resulting from details, joints, and fasteners are addressed in Part V. Fatigue improvement in welded joints is considered one the major tasks of this part. Brittle fracture of hull Structures causes serious structural damage and this motivated the ship structure community to develop some means to prevent brittle cracks from occurring. The basic principle behind the use of a crack arrester is to reduce the crack-driving force below the resisting force that must be overcome to extend a crack. The crack arrestor can be as simple as a thickened region of metal or may be constructed of a laminated or woven material that can withstand deformation without failure. Part VI provides different approaches of passive crack control in the form of crack arresters to stop crack propagation before it spreads over a structure component. Crack arresters used in ship Structures and pipelines are described for both metal and composite materials. This six-part review article is by no means exhaustive and is based on over 1800 references. It does not address the structural health monitoring, which constitutes a major task in the structural diagnostic process.
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Overview of structural life assessment and reliability, part III: Impact, grounding, and reliability of ships under extreme loading
Journal of Ship Production and Design, 2015Co-Authors: R. A. IbrahimAbstract:Structural life assessment periodically evaluates the state and condition of a structural system and provides recommendations for possible maintenance actions or the end of structural service life. It is a diversified field and relies on the theories of fracture mechanics, fatigue damage process, probability of failure, and reliability. With reference to naval ship Structures, their life assessment is not only governed by the theory of fracture mechanics and fatigue damage process, but by other factors such as corrosion, grounding, and sudden collision. The purpose of this series of review articles is to provide different issues pertaining to structural life assessment of ships and Ocean Structures. Part I deals with the basic ingredients of the theory of fracture mechanics, which is classified into linear elastic fracture mechanics and elasto-plastic fracture mechanics. The amount of energy available for fracture is usually governed by the stress field around the crack, which is measured by the stress intensity factor. The value of the stress intensity factor, which depends on the loading mode, is evaluated by different methods developed by many researchers. The applications of the theory of fracture mechanics to metallic and composite Structures are presented with an emphasis to those used in marine Structures. When the inertia of relatively large pieces of a structure is large enough that the correct balancing of the energy of fracture requires the inclusion of kinetic energy, then the dynamic nature of fracture dominates the analysis. For a crack that is already propagating, the inertial effects are important when the crack tip speed is small compared with the stress wave velocities. This fact has been realized in the theory of fracture mechanics under the name of dynamic fracture and peridynamic. In essence, peridynamic replaces the partial differential equations of classic continuum theories with integro-differential equations as a tool to avoid singularities arising from the fact that partial derivatives do not exist on crack surfaces and other singularities. A brief overview of fracture dynamics and peridynamics together with damage mechanisms in composite Structures is presented. The limitations of fracture mechanics criteria are also discussed. Life assessment of ship Structures depends on the failure modes and the probabilistic description of failure, which are addressed in Part II. Life assessment of ship Structures depends on the failure modes and the probabilistic description of failure. In view of structural parameter uncertainties, probabilistic analysis requires the use of reliability methods for assessing fatigue life by considering the crack propagation process and the first passage problem, which measures the probability of the exit time from a safe operating regime. The main results reported in the literature pertaining to ship structural damage assessments resulting from to slamming loads, liquid sloshing impact loads of liquefied natural gas in ship tankers, and ship grounding accidents, and collision with solid bodies are discussed in Part III. Under such extreme loadings, structural reliability will be the major issue in the design stage of Ocean Structures. The treatment of extreme loading on ship Structures significantly differs from those approaches developed by dynamicists. Environmental effects on ship Structures play a major factor in the life assessment of Ocean systems. In particular, these effects include corrosion and hydrogen embrittlement. Part IV is devoted to a ship’s life assessment resulting from corrosion and hydrogen embrittlement. Because structural components made from aluminum and its alloys are vital to the ship and aerospace industries, the influence of environment on aluminum Structures and the means of corrosion control and monitoring in both aluminum and nonaluminum metals are presented. Hybrid ships consist of a stainless steel advanced double-hull center section, to which a composite material bow and/or stern is attached. Such Structures require strong joints between the composite and the steel parts. Some of the difficulties with joining composites and metal are related to the large difference in mechanical properties such as stiffness, coefficient of thermal expansion, etc., between the adherents and the large anisotropy of composites. Such differences generally lead to large stress concentrations and weak joints. Fatigue crack growth, stress concentrations resulting from details, joints, and fasteners are addressed in Part V. Fatigue improvement in welded joints is considered one the major tasks of this part. Brittle fracture of hull Structures causes serious structural damage and this motivated the ship structure community to develop some means to prevent brittle cracks from occurring. The basic principle behind the use of a crack arrester is to reduce the crack-driving force below the resisting force that must be overcome to extend a crack. The crack arrestor can be as simple as a thickened region of metal or may be constructed of a laminated or woven material that can withstand deformation without failure. Part VI provides different approaches of passive crack control in the form of crack arresters to stop crack propagation before it spreads over a structure component. Crack arresters used in ship Structures and pipelines are described for both metal and composite materials. This six-part review article is by no means exhaustive and is based on over 1800 references. It does not address the structural health monitoring, which constitutes a major task in the structural diagnostic process.
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Overview of structural life assessment and reliability, part II: Fatigue life and reliability assessment of naval ship Structures
Journal of Ship Production and Design, 2015Co-Authors: R. A. IbrahimAbstract:Structural life assessment periodically evaluates the state and condition of a structural system and provides recommendations for possible maintenance actions or the end of structural service life. It is a diversified field and relies on the theories of fracture mechanics, fatigue damage process, probability of failure, and reliability. With reference to naval ship Structures, their life assessment is not only governed by the theory of fracture mechanics and fatigue damage process, but by other factors such as corrosion, grounding, and sudden collision. The purpose of this series of review articles is to provide different issues pertaining to structural life assessment of ships and Ocean Structures. Part I deals with the basic ingredients of the theory of fracture mechanics, which is classified into linear elastic fracture mechanics and elasto-plastic fracture mechanics. The amount of energy available for fracture is usually governed by the stress field around the crack, which is measured by the stress intensity factor. The value of the stress intensity factor, which depends on the loading mode, is evaluated by different methods developed by many researchers. The applications of the theory of fracture mechanics to metallic and composite Structures are presented with an emphasis to those used in marine Structures. When the inertia of relatively large pieces of a structure is large enough that the correct balancing of the energy of fracture requires the inclusion of kinetic energy, then the dynamic nature of fracture dominates the analysis. For a crack that is already propagating, the inertial effects are important when the crack tip speed is small compared with the stress wave velocities. This fact has been realized in the theory of fracture mechanics under the name of dynamic fracture and peridynamic. In essence, peridynamic replaces the partial differential equations of classic continuum theories with integro-differential equations as a tool to avoid singularities arising from the fact that partial derivatives do not exist on crack surfaces and other singularities. A brief overview of fracture dynamics and peridynamics together with damage mechanisms in composite Structures is presented. The limitations of fracture mechanics criteria are also discussed. Life assessment of ship Structures depends on the failure modes and the probabilistic description of failure, which are addressed in Part II. Life assessment of ship Structures depends on the failure modes and the probabilistic description of failure. In view of structural parameter uncertainties, probabilistic analysis requires the use of reliability methods for assessing fatigue life by considering the crack propagation process and the first passage problem, which measures the probability of the exit time from a safe operating regime. The main results reported in the literature pertaining to ship structural damage assessments resulting from to slamming loads, liquid sloshing impact loads of liquefied natural gas in ship tankers, and ship grounding accidents, and collision with solid bodies are discussed in Part III. Under such extreme loadings, structural reliability will be the major issue in the design stage of Ocean Structures. The treatment of extreme loading on ship Structures significantly differs from those approaches developed by dynamicists. Environmental effects on ship Structures play a major factor in the life assessment of Ocean systems. In particular, these effects include corrosion and hydrogen embrittlement. Part IV is devoted to a ship’s life assessment resulting from corrosion and hydrogen embrittlement. Because structural components made from aluminum and its alloys are vital to the ship and aerospace industries, the influence of environment on aluminum Structures and the means of corrosion control and monitoring in both aluminum and nonaluminum metals are presented. Hybrid ships consist of a stainless steel advanced double-hull center section, to which a composite material bow and/or stern is attached. Such Structures require strong joints between the composite and the steel parts. Some of the difficulties with joining composites and metal are related to the large difference in mechanical properties such as stiffness, coefficient of thermal expansion, etc., between the adherents and the large anisotropy of composites. Such differences generally lead to large stress concentrations and weak joints. Fatigue crack growth, stress concentrations resulting from details, joints, and fasteners are addressed in Part V. Fatigue improvement in welded joints is considered one the major tasks of this part. Brittle fracture of hull Structures causes serious structural damage and this motivated the ship structure community to develop some means to prevent brittle cracks from occurring. The basic principle behind the use of a crack arrester is to reduce the crack-driving force below the resisting force that must be overcome to extend a crack. The crack arrestor can be as simple as a thickened region of metal or may be constructed of a laminated or woven material that can withstand deformation without failure. Part VI provides different approaches of passive crack control in the form of crack arresters to stop crack propagation before it spreads over a structure component. Crack arresters used in ship Structures and pipelines are described for both metal and composite materials. This six-part review article is by no means exhaustive and is based on over 1800 references. It does not address the structural health monitoring, which constitutes a major task in the structural diagnostic process.
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Overview of structural life assessment and reliability, part IV: Corrosion and hydrogen embrittlement of naval ship Structures
Journal of Ship Production and Design, 2015Co-Authors: R. A. IbrahimAbstract:Structural life assessment periodically evaluates the state and condition of a structural system and provides recommendations for possible maintenance actions or the end of structural service life. It is a diversified field and relies on the theories of fracture mechanics, fatigue damage process, probability of failure, and reliability. With reference to naval ship Structures, their life assessment is not only governed by the theory of fracture mechanics and fatigue damage process, but by other factors such as corrosion, grounding, and sudden collision. The purpose of this series of review articles is to provide different issues pertaining to structural life assessment of ships and Ocean Structures. Part I deals with the basic ingredients of the theory of fracture mechanics, which is classified into linear elastic fracture mechanics and elasto-plastic fracture mechanics. The amount of energy available for fracture is usually governed by the stress field around the crack, which is measured by the stress intensity factor. The value of the stress intensity factor, which depends on the loading mode, is evaluated by different methods developed by many researchers. The applications of the theory of fracture mechanics to metallic and composite Structures are presented with an emphasis to those used in marine Structures. When the inertia of relatively large pieces of a structure is large enough that the correct balancing of the energy of fracture requires the inclusion of kinetic energy, then the dynamic nature of fracture dominates the analysis. For a crack that is already propagating, the inertial effects are important when the crack tip speed is small compared with the stress wave velocities. This fact has been realized in the theory of fracture mechanics under the name of dynamic fracture and peridynamic. In essence, peridynamic replaces the partial differential equations of classic continuum theories with integro-differential equations as a tool to avoid singularities arising from the fact that partial derivatives do not exist on crack surfaces and other singularities. A brief overview of fracture dynamics and peridynamics together with damage mechanisms in composite Structures is presented. The limitations of fracture mechanics criteria are also discussed. Life assessment of ship Structures depends on the failure modes and the probabilistic description of failure, which are addressed in Part II. Life assessment of ship Structures depends on the failure modes and the probabilistic description of failure. In view of structural parameter uncertainties, probabilistic analysis requires the use of reliability methods for assessing fatigue life by considering the crack propagation process and the first passage problem, which measures the probability of the exit time from a safe operating regime. The main results reported in the literature pertaining to ship structural damage assessments resulting from to slamming loads, liquid sloshing impact loads of liquefied natural gas in ship tankers, and ship grounding accidents, and collision with solid bodies are discussed in Part III. Under such extreme loadings, structural reliability will be the major issue in the design stage of Ocean Structures. The treatment of extreme loading on ship Structures significantly differs from those approaches developed by dynamicists. Environmental effects on ship Structures play a major factor in the life assessment of Ocean systems. In particular, these effects include corrosion and hydrogen embrittlement. Part IV is devoted to a ship’s life assessment resulting from corrosion and hydrogen embrittlement. Because structural components made from aluminum and its alloys are vital to the ship and aerospace industries, the influence of environment on aluminum Structures and the means of corrosion control and monitoring in both aluminum and nonaluminum metals are presented. Hybrid ships consist of a stainless steel advanced double-hull center section, to which a composite material bow and/or stern is attached. Such Structures require strong joints between the composite and the steel parts. Some of the difficulties with joining composites and metal are related to the large difference in mechanical properties such as stiffness, coefficient of thermal expansion, etc., between the adherents and the large anisotropy of composites. Such differences generally lead to large stress concentrations and weak joints. Fatigue crack growth, stress concentrations resulting from details, joints, and fasteners are addressed in Part V. Fatigue improvement in welded joints is considered one the major tasks of this part. Brittle fracture of hull Structures causes serious structural damage and this motivated the ship structure community to develop some means to prevent brittle cracks from occurring. The basic principle behind the use of a crack arrester is to reduce the crack-driving force below the resisting force that must be overcome to extend a crack. The crack arrestor can be as simple as a thickened region of metal or may be constructed of a laminated or woven material that can withstand deformation without failure. Part VI provides different approaches of passive crack control in the form of crack arresters to stop crack propagation before it spreads over a structure component. Crack arresters used in ship Structures and pipelines are described for both metal and composite materials. This six-part review article is by no means exhaustive and is based on over 1800 references. It does not address the structural health monitoring, which constitutes a major task in the structural diagnostic process.
Masayoshi Toda - One of the best experts on this subject based on the ideXlab platform.
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Motion control of an oscillatory-base manipulator using sliding mode control via rotating sliding surface with variable-gain integral control
2013 American Control Conference, 2013Co-Authors: Takuya Iwamura, Masayoshi TodaAbstract:In this paper, we present a motion control method of oscillatory-base manipulators, which are associated with mechanical systems installed on vessels or Ocean Structures. The typical property of such systems is strong and persistent disturbance due to the base oscillation to be overcome. Therefore, we attempt to exploit the sliding mode control (SMC) concept which is known to be a powerful tool to develop a robust control system against disturbances and model uncertainties. Specifically, we propose a novel approach based on SMC by introducing a nonlinear sliding surface with variable-gain integral control. We address control system design and stability analysis for the proposed SMC, and demonstrate its control performance by simulations. The results show that the proposed control method can achieve successful control performance for oscillatory-manipulators and further exhibits advantageous features with respect to control performance and control inputs when compared with the conventional SMC.
Masahiro Usami - One of the best experts on this subject based on the ideXlab platform.
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a study on calculation method of antifouling system by sea water electrolysis
Journal of the Society of Naval Architects of Japan, 1998Co-Authors: Masahiro Usami, Y. Huang, K Ueda, M IwataAbstract:The antifouling system for ship hull and Ocean Structures by sea water electrolysis has been developed. In this system, the ClO- ions, which are effective for antifouling, is generated by the sea water electrolysis reaction caused by electric current supplied from electro-conductive coatings on the surface of ship hull or the Ocean structure. In order to design a reasonable antifouling system, therefore, the technique to estimate the polarizing potential distribution and the current density distribution on the interface between sea water and electro-conductive coatings is expected.In report (1), based on the Interface Electro-double Layer theory, a finite element method for the numerical analysis of the potential field caused by the antifouling system was developed, and the validity and usefulness of which was confirmed by its application to a test tank model.For the analysis of the potential field caused by the antifouling system of a ship hull, however, it is very difficult to apply the finite element method to the semi-infinite sea water domain under water surface. Therefore, in this paper a new numerical analyzing technique by using both of finite element method (for electro-conductive coatings and Ti foil potential filed) and boundary element method (for sea water potential field) jointly is developed and the validity of which is verified by its applications to a small-size passenger boat and a steel sea water pipe, for which the antifouling systems were undertaken and the antifouling efficiency tests have been performed.
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a study on cad of antifouling system by sea water electrolysis
Journal of the Society of Naval Architects of Japan, 1995Co-Authors: Y. Huang, Masahiro Usami, M Iwata, K UedaAbstract:The antifouling system for Ocean Structures by sea water electrolysis has been developed. In this system, the ClO- ions effective for antifouling is generated by the sea water electrolysis reaction taking place by electric current supplied from the electro-conductive coatings on the surface of the structure. In order to design the antifouling system, therefore, the current density on the surface of electro-conductive coatings should be able to estimated.In this paper, a numerical method by FEM is developed for the analysis of the potential field including electro-conductive coatings, sea water and the electric double layer formed on the coatings-water interface. The electric behavior of the electric double layer is included in the polarization characteristics. In order to treat the unknown potential distribution on both sides of the electric double layer, plate elements with double nodal points are employed for the discretization of the coatings-water interface.The validity and usefulness of the proposed method are confirmed by comparing with experimental results and by the numerical simulations of some antifouling models.
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a study on cad of antifouling system by sea water electrolysis report 1 development of the analysis method for the potential field
1995Co-Authors: Y. Huang, Masahiro UsamiAbstract:An antifouling system for Ocean Structures by sea water electrolysis has been developed. In the system, the CIO- ions effective for antifouling is generated by the sea water electrolysis reaction taking place by electric current supplied from the electro- conductive coatings on the surface of the structure. In order to design the antifouling system, the current density on the surface of the electro-conductive coatings should be estimable. In this paper, a numerical method by FEM is developed for the analysis of the potential field including electro-conductive coatings, sea water and the electric double layer formed on the coatings-water interface. The electric behaviour of the electric double layer is included in the polarization characteristics. In order to treat the unknown potential distribution on both sides of the electric double layer, plate elements with double nodal points are employed for the discretization of the coatings-water interface. The validity and usefulness of the proposed method are confirmed with experimental results and by the numerical simulations of some antifouling models.
N. Moshchuk - One of the best experts on this subject based on the ideXlab platform.
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Nonlinear Random Response of Ocean Structures Using First- and Second-Order Stochastic Averaging
Nonlinear Dynamics, 1997Co-Authors: M. Hijawi, R. A. Ibrahim, N. MoshchukAbstract:This paper deals with the dynamic response of nonlinear elastic structure subjected to random hydrodynamic forces and parametric excitation using a first- and second-order stochastic averaging method. The governing equation of motion is derived by using Hamilton's principle, taking into account inertia and curvature nonlinearities and work done due to hydrodynamic forces. Within the framework of first-order stochastic averaging, the system response statistics and stability boundaries are obtained. Unfortunately, the effects of nonlinear inertia and curvature are not reflected in the final results, since the contribution of these nonlinearities is lost during the averaging process. In the absence of hydrodynamic forces, the method fails to give bounded response statistics, and the analysis yields stability conditions. It is the second-order stochastic averaging which can capture the influence of stiffness and inertia nonlinearities that were lost in the first-order averaging process. The results of the second-order averaging are compared with those predicted by Gaussian and non-Gaussian closures and by Monte Carlo simulation. In the absence of parametric excitation, the non-Gaussian closure solutions are in good agreement with Monte Carlo simulation. On the other hand, in the absence of hydrodynamic forces, second-order averaging gives more reliable results in the neighborhood of stochastic bifurcation. However, under pure parametric random excitation, the stochastic averaging and Monte Carlo simulation predict the on-off intermittency phenomenon near bifurcation point, in addition to stochastic bifurcation in probability.
Y. Huang - One of the best experts on this subject based on the ideXlab platform.
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a study on calculation method of antifouling system by sea water electrolysis
Journal of the Society of Naval Architects of Japan, 1998Co-Authors: Masahiro Usami, Y. Huang, K Ueda, M IwataAbstract:The antifouling system for ship hull and Ocean Structures by sea water electrolysis has been developed. In this system, the ClO- ions, which are effective for antifouling, is generated by the sea water electrolysis reaction caused by electric current supplied from electro-conductive coatings on the surface of ship hull or the Ocean structure. In order to design a reasonable antifouling system, therefore, the technique to estimate the polarizing potential distribution and the current density distribution on the interface between sea water and electro-conductive coatings is expected.In report (1), based on the Interface Electro-double Layer theory, a finite element method for the numerical analysis of the potential field caused by the antifouling system was developed, and the validity and usefulness of which was confirmed by its application to a test tank model.For the analysis of the potential field caused by the antifouling system of a ship hull, however, it is very difficult to apply the finite element method to the semi-infinite sea water domain under water surface. Therefore, in this paper a new numerical analyzing technique by using both of finite element method (for electro-conductive coatings and Ti foil potential filed) and boundary element method (for sea water potential field) jointly is developed and the validity of which is verified by its applications to a small-size passenger boat and a steel sea water pipe, for which the antifouling systems were undertaken and the antifouling efficiency tests have been performed.
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a study on cad of antifouling system by sea water electrolysis
Journal of the Society of Naval Architects of Japan, 1995Co-Authors: Y. Huang, Masahiro Usami, M Iwata, K UedaAbstract:The antifouling system for Ocean Structures by sea water electrolysis has been developed. In this system, the ClO- ions effective for antifouling is generated by the sea water electrolysis reaction taking place by electric current supplied from the electro-conductive coatings on the surface of the structure. In order to design the antifouling system, therefore, the current density on the surface of electro-conductive coatings should be able to estimated.In this paper, a numerical method by FEM is developed for the analysis of the potential field including electro-conductive coatings, sea water and the electric double layer formed on the coatings-water interface. The electric behavior of the electric double layer is included in the polarization characteristics. In order to treat the unknown potential distribution on both sides of the electric double layer, plate elements with double nodal points are employed for the discretization of the coatings-water interface.The validity and usefulness of the proposed method are confirmed by comparing with experimental results and by the numerical simulations of some antifouling models.
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a study on cad of antifouling system by sea water electrolysis report 1 development of the analysis method for the potential field
1995Co-Authors: Y. Huang, Masahiro UsamiAbstract:An antifouling system for Ocean Structures by sea water electrolysis has been developed. In the system, the CIO- ions effective for antifouling is generated by the sea water electrolysis reaction taking place by electric current supplied from the electro- conductive coatings on the surface of the structure. In order to design the antifouling system, the current density on the surface of the electro-conductive coatings should be estimable. In this paper, a numerical method by FEM is developed for the analysis of the potential field including electro-conductive coatings, sea water and the electric double layer formed on the coatings-water interface. The electric behaviour of the electric double layer is included in the polarization characteristics. In order to treat the unknown potential distribution on both sides of the electric double layer, plate elements with double nodal points are employed for the discretization of the coatings-water interface. The validity and usefulness of the proposed method are confirmed with experimental results and by the numerical simulations of some antifouling models.