The Experts below are selected from a list of 315 Experts worldwide ranked by ideXlab platform

Mahmoud Helal - One of the best experts on this subject based on the ideXlab platform.

  • multi objective optimization of an intersecting elliptical Pressure Hull as a means of buckling Pressure maximizing and weight minimization
    Materials Testing-Materials and Components Technology and Application, 2019
    Co-Authors: Mahmoud Helal, Elsayed Fathallah
    Abstract:

    Abstract Pressure Hulls are one of the keys in the design of submarines. In order to improve the accuracy and efficiency of Pressure Hull structure, methods of optimizing it were studied. In the pr...

  • numerical analysis of sandwich composite deep submarine Pressure Hull considering failure criteria
    Journal of Marine Science and Engineering, 2019
    Co-Authors: Mahmoud Helal, Huinan Huang, Defu Wang, Elsayed Fathallah
    Abstract:

    The Pressure Hull is the primary element of submarine, which withstands diving Pressure and provides essential capacity for electronic systems and buoyancy. This study presents a numerical analysis and design optimization of sandwich composite deep submarine Pressure Hull using finite element modeling technique. This study aims to minimize buoyancy factor and maximize deck area and buckling strength factors. The collapse depth is taken as a base in the Pressure Hull design. The Pressure Hull has been analyzed using two composite materials, T700/Epoxy and B(4)5505/Epoxy, to form the upper and lower faces of the sandwich composite deep submarine Pressure Hull. The laminated control surface is optimized for the first ply failure index (FI) considering both Tsai–Wu and maximum stress failure criteria. The results obtained emphasize an important fact that the presence of core layer in sandwich composite Pressure Hull is not always more efficient. The use of sandwich in the design of composite deep submarine Pressure Hull at extreme depths is not a safe option. Additionally, the core thickness plays a minor role in the design of composite deep submarine Pressure Hull. The outcome of an optimization at extreme depths illustrates that the upper and lower faces become thicker and the core thickness becomes thinner. However, at shallow-to-moderate depths, it is recommended to use sandwich composite with a thick core to resist the shell buckling of composite submarine Pressure Hull.

  • optimal structure design of elliptical deep submersible Pressure Hull
    Materials Science Forum, 2015
    Co-Authors: Fathallah Elsayed, Hui Qi, Lili Tong, Mahmoud Helal
    Abstract:

    Geometric configurations such as Hull shape, shell thickness, stiffener layout, and type of materials are the key factors influencing the structural performance of Pressure Hulls. The aim of this study is to maximize the structural efficiency of elliptical deep-submerged Pressure Hull under hydrostatic Pressure. Minimize the buoyancy factor of a submarine Pressure Hull under hydrostatic Pressure was proposed as an objective function for both composite and steel models. The thickness and the orientation angle of each layer, the radii of the ellipse and the operating depth are taken as design variables. Also, the shell buckling strength and the angle-ply laminated failure strength are considered in the case of composite model. In the other hand, the shell thickness, the radii of the ellipse, the stiffeners offsets, the stiffeners dimensions, and the operating depth, are selected as design variables for steel model with shell buckling and materials yielding constraints. The analysis is performed using commercial finite element analysis software ANSYS. Additionally, a sensitivity analysis is performed to study the influence of the design variables on the structural optimum design. Results of this study provide a valuable reference for designers of underwater vehicles.

  • design optimization of lay up and composite material system to achieve minimum buoyancy factor for composite elliptical submersible Pressure Hull
    Composite Structures, 2015
    Co-Authors: Elsayed Fathallah, Hui Qi, Lili Tong, Mahmoud Helal
    Abstract:

    The design of laminated composite structures is very susceptible to changes in angle of fiber orientation and ply thickness. In the present work, different lay-up sequences for laminates including, cross-ply [0m/90n]s, [90m/0n]s and angle-ply [0m/±αn]s, [90m/±αn]s, [±α]ns, are analyzed. The lay-up sequence, orientation and ply number are optimized using three composite materials T700/epoxy composites, T300/Graphite/Epoxy and B(4)/5505 Boron/Epoxy. Minimize the buoyancy factor of the submersible Pressure Hull is considered as the objective function. The constraints based on the failure strength and the buckling strength of the Pressure Hull, incorporating both the Tsai–Wu and the maximum stress failure criteria. The finite element analysis and the optimization process are performed using ANSYS. Additionally, a sensitivity analysis is performed to study the influence of the design variables on the optimal structural strength design.

  • design optimization of composite elliptical deep submersible Pressure Hull for minimizing the buoyancy factor
    Advances in Mechanical Engineering, 2014
    Co-Authors: Elsayed Fathallah, Hui Qi, Lili Tong, Mahmoud Helal
    Abstract:

    The design of deep submersible Pressure Hull's structural is one of the core technologies of submersible development of human history. Submersible Pressure Hulls with fiber-reinforced multilayer constructions have been developed in the recent years as substitutes for classical metallic ring-stiffened Pressure Hulls; strength and stability are its top priority. This paper investigates the optimum design of a composite elliptical deep-submerged Pressure Hull under hydrostatic Pressure to minimize the buoyancy factor of the submersible Pressure Hull under constraints on the failure criteria and the buckling strength of the Hulls to reach the maximum operating depth. The thickness and the fiber orientation angles in each layer, the radii of the ellipse, and stringers dimensions were taken as design variables and determined in the design process. The optimization procedures are performed using commercial finite element analysis software ANSYS. Additionally, a sensitivity analysis is performed to study the infl...

Lili Tong - One of the best experts on this subject based on the ideXlab platform.

  • multi objective design optimization of composite submerged cylindrical Pressure Hull for minimum buoyancy factor and maximum buckling load capacity
    Defence Technology, 2020
    Co-Authors: Muhammad Imran, Lili Tong, Hafiz Muhammad Waqas, Ahsan Elahi, Muqeem Uddin
    Abstract:

    Abstract This paper presents the design optimization of composite submersible cylindrical Pressure Hull subjected to 3 MPa hydrostatic Pressure. The design optimization study is conducted for cross-ply layups [0s/90t/0u], [0s/90t/0u]s, [0s/90t]s and [90s/0t]s considering three uni-directional composites, i.e. Carbon/Epoxy, Glass/Epoxy, and Boron/Epoxy. The optimization study is performed by coupling a Multi-Objective Genetic Algorithm (MOGA) and Analytical Analysis. Minimizing the buoyancy factor and maximizing the buckling load factor are considered as the objectives of the optimization study. The objectives of the optimization are achieved under constraints on the Tsai-Wu, Tsai-Hill and Maximum stress composite failure criteria and on buckling load factor. To verify the optimization approach, optimization of one particular layup configuration is also conducted in ANSYS with the same objectives and constraints.

  • design optimization and non linear buckling analysis of spherical composite submersible Pressure Hull
    Materials, 2020
    Co-Authors: Muhammad Imran, Lili Tong, Hafiz Muhammad Waqas, Riaz Muhammad, Muqeem Uddin, Asghar Khan
    Abstract:

    This paper describes an optimization study of a spherical composite submersible Pressure Hull employing a genetic algorithm (GA) in ANSYS. A total of five lay-up arrangements were optimized for three unidirectional composites carbon/epoxy, glass/epoxy, and boron/epoxy. The minimization of the buoyancy factor ( B . F ) was selected as the design optimization objective. The Tsai-Wu and Tsai-Hill failure criteria and buckling strength factor ( λ ) were used as the material failure and instability constraints. To determine the effect of geometric non-linearity and imperfections on the optimized design, a non-linear buckling analysis was also carried out for one selected optimized design in ABAQUS. The non-linear buckling analysis was carried out using the modified RIKS procedure, in which the imperfection size changed from 1 to 10 mm. A maximum decrease of 65.937% in buoyancy factor ( B . F ) over an equivalent spherical steel Pressure Hull was computed for carbon/epoxy. Moreover, carbon/epoxy displayed larger decreases in buoyancy factor ( B . F ) in the case of 4 out of a total of 5 lay-up arrangements. The collapse depth decreased from 517.95 m to 412.596 m for a 5 mm lowest mode imperfection. Similarly, the collapse depth decreased from 522.39 m to 315.6018 for a 5 mm worst mode imperfection.

  • design optimization of composite submerged cylindrical Pressure Hull using genetic algorithm and finite element analysis
    Ocean Engineering, 2019
    Co-Authors: Muhammad Imran, Lili Tong, Hafiz Muhammad Waqas
    Abstract:

    Abstract The design of structures made of laminated composites greatly depends on the fiber orientation angle and the number of ply layers. In the present study design optimization of composite submerged Pressure Hull under 3 MPa hydrostatic Pressure, which corresponds to 300 m depth, is carried out. The number of layers and orientation angles are optimized for layups [0m/90n/0o], [10m/-10n/90o/-10p/10q], [α1m/α2n], [α1m/α2n/α3o] and [α1m/α2n/α3o/α4p/α5q] using three unidirectional composite materials, Carbon/Epoxy, Glass/Epoxy, and Boron/Epoxy. The optimization process is carried out in ANSYS Workbench using a Genetic Algorithm. Minimizing the buoyancy factor is used as the objective function of the optimization. The constraints on the optimization process are Tsai-Wu and Tsai-Hill failure criteria and buckling strength factor. Optimization study is also conducted for one selected layup configuration using ABAQUS and ISIGHT. Additionally, a sensitivity analysis is also carried out to study the effect of various design parameters on the optimum design of composite submerged Pressure Hull.

  • optimal structure design of elliptical deep submersible Pressure Hull
    Materials Science Forum, 2015
    Co-Authors: Fathallah Elsayed, Hui Qi, Lili Tong, Mahmoud Helal
    Abstract:

    Geometric configurations such as Hull shape, shell thickness, stiffener layout, and type of materials are the key factors influencing the structural performance of Pressure Hulls. The aim of this study is to maximize the structural efficiency of elliptical deep-submerged Pressure Hull under hydrostatic Pressure. Minimize the buoyancy factor of a submarine Pressure Hull under hydrostatic Pressure was proposed as an objective function for both composite and steel models. The thickness and the orientation angle of each layer, the radii of the ellipse and the operating depth are taken as design variables. Also, the shell buckling strength and the angle-ply laminated failure strength are considered in the case of composite model. In the other hand, the shell thickness, the radii of the ellipse, the stiffeners offsets, the stiffeners dimensions, and the operating depth, are selected as design variables for steel model with shell buckling and materials yielding constraints. The analysis is performed using commercial finite element analysis software ANSYS. Additionally, a sensitivity analysis is performed to study the influence of the design variables on the structural optimum design. Results of this study provide a valuable reference for designers of underwater vehicles.

  • design optimization of lay up and composite material system to achieve minimum buoyancy factor for composite elliptical submersible Pressure Hull
    Composite Structures, 2015
    Co-Authors: Elsayed Fathallah, Hui Qi, Lili Tong, Mahmoud Helal
    Abstract:

    The design of laminated composite structures is very susceptible to changes in angle of fiber orientation and ply thickness. In the present work, different lay-up sequences for laminates including, cross-ply [0m/90n]s, [90m/0n]s and angle-ply [0m/±αn]s, [90m/±αn]s, [±α]ns, are analyzed. The lay-up sequence, orientation and ply number are optimized using three composite materials T700/epoxy composites, T300/Graphite/Epoxy and B(4)/5505 Boron/Epoxy. Minimize the buoyancy factor of the submersible Pressure Hull is considered as the objective function. The constraints based on the failure strength and the buckling strength of the Pressure Hull, incorporating both the Tsai–Wu and the maximum stress failure criteria. The finite element analysis and the optimization process are performed using ANSYS. Additionally, a sensitivity analysis is performed to study the influence of the design variables on the optimal structural strength design.

Elsayed Fathallah - One of the best experts on this subject based on the ideXlab platform.

  • multi objective optimization of an intersecting elliptical Pressure Hull as a means of buckling Pressure maximizing and weight minimization
    Materials Testing-Materials and Components Technology and Application, 2019
    Co-Authors: Mahmoud Helal, Elsayed Fathallah
    Abstract:

    Abstract Pressure Hulls are one of the keys in the design of submarines. In order to improve the accuracy and efficiency of Pressure Hull structure, methods of optimizing it were studied. In the pr...

  • numerical analysis of sandwich composite deep submarine Pressure Hull considering failure criteria
    Journal of Marine Science and Engineering, 2019
    Co-Authors: Mahmoud Helal, Huinan Huang, Defu Wang, Elsayed Fathallah
    Abstract:

    The Pressure Hull is the primary element of submarine, which withstands diving Pressure and provides essential capacity for electronic systems and buoyancy. This study presents a numerical analysis and design optimization of sandwich composite deep submarine Pressure Hull using finite element modeling technique. This study aims to minimize buoyancy factor and maximize deck area and buckling strength factors. The collapse depth is taken as a base in the Pressure Hull design. The Pressure Hull has been analyzed using two composite materials, T700/Epoxy and B(4)5505/Epoxy, to form the upper and lower faces of the sandwich composite deep submarine Pressure Hull. The laminated control surface is optimized for the first ply failure index (FI) considering both Tsai–Wu and maximum stress failure criteria. The results obtained emphasize an important fact that the presence of core layer in sandwich composite Pressure Hull is not always more efficient. The use of sandwich in the design of composite deep submarine Pressure Hull at extreme depths is not a safe option. Additionally, the core thickness plays a minor role in the design of composite deep submarine Pressure Hull. The outcome of an optimization at extreme depths illustrates that the upper and lower faces become thicker and the core thickness becomes thinner. However, at shallow-to-moderate depths, it is recommended to use sandwich composite with a thick core to resist the shell buckling of composite submarine Pressure Hull.

  • Finite Element Modelling and Multi-Objective Optimization of Composite Submarine Pressure Hull Subjected to Hydrostatic Pressure
    Materials Science Forum, 2019
    Co-Authors: Elsayed Fathallah
    Abstract:

    Excellent mechanical behavior and low density of composite materials make them candidates to replace metals for many underwater applications. This paper presents a comprehensive study about the multi-objective optimization of composite Pressure Hull subjected to hydrostatic Pressure to minimize the weight of the Pressure Hull and maximize the buckling load capacity according to the design requirements. Two models were constructed, one model constructed from Carbon/Epoxy composite (USN-150), the other model is metallic Pressure Hull constructed from HY100. The analysis and the optimization process were completely performed using ANSYS Parametric Design Language (APDL). Tsai-Wu failure criterion was incorporated in the optimization process. The results obtained emphasize that, the submarine constructed from Carbon/Epoxy composite (USN-150) is better than the submarine constructed from HY100. Finally, an optimized model with an optimum pattern of fiber orientations was presented. Hopefully, the results may provide a valuable insight for the future of designing composite underwater vehicles.

  • design optimization of lay up and composite material system to achieve minimum buoyancy factor for composite elliptical submersible Pressure Hull
    Composite Structures, 2015
    Co-Authors: Elsayed Fathallah, Hui Qi, Lili Tong, Mahmoud Helal
    Abstract:

    The design of laminated composite structures is very susceptible to changes in angle of fiber orientation and ply thickness. In the present work, different lay-up sequences for laminates including, cross-ply [0m/90n]s, [90m/0n]s and angle-ply [0m/±αn]s, [90m/±αn]s, [±α]ns, are analyzed. The lay-up sequence, orientation and ply number are optimized using three composite materials T700/epoxy composites, T300/Graphite/Epoxy and B(4)/5505 Boron/Epoxy. Minimize the buoyancy factor of the submersible Pressure Hull is considered as the objective function. The constraints based on the failure strength and the buckling strength of the Pressure Hull, incorporating both the Tsai–Wu and the maximum stress failure criteria. The finite element analysis and the optimization process are performed using ANSYS. Additionally, a sensitivity analysis is performed to study the influence of the design variables on the optimal structural strength design.

  • Numerical investigation of the dynamic response of optimized composite elliptical submersible Pressure Hull subjected to non-contact underwater explosion
    Composite Structures, 2015
    Co-Authors: Elsayed Fathallah, Hui Qi, Lili Tong, Mohamed Helal
    Abstract:

    Predicting the dynamic response of a floating and submerged structure subjected to underwater explosion is greatly complicated by the explosion of a high explosive, propagation of shock wave, bubble-pulse and complex fluid-structure interaction (FSI) phenomena. A numerical simulation has been carried out to examine the behavior of optimized composite elliptical submersible Pressure Hull to non-contact underwater explosion (UNDEX) and take the effect of bubble-pulse. Various explosive weights and explosion distances were explored to determine the critical weights and safe distance. The optimization process is performed using ANSYS parametric design language (APDL). After that the finite element package ABAQUS was used to model the UNDEX and the FSI phenomena. Time histories of the wet-surface displacement, velocity and Tsai-Hill failure index are presented for different composite plies. All of these results can be a valuable reference for designing underwater vehicles to resist UNDEX.

Hui Qi - One of the best experts on this subject based on the ideXlab platform.

  • optimal structure design of elliptical deep submersible Pressure Hull
    Materials Science Forum, 2015
    Co-Authors: Fathallah Elsayed, Hui Qi, Lili Tong, Mahmoud Helal
    Abstract:

    Geometric configurations such as Hull shape, shell thickness, stiffener layout, and type of materials are the key factors influencing the structural performance of Pressure Hulls. The aim of this study is to maximize the structural efficiency of elliptical deep-submerged Pressure Hull under hydrostatic Pressure. Minimize the buoyancy factor of a submarine Pressure Hull under hydrostatic Pressure was proposed as an objective function for both composite and steel models. The thickness and the orientation angle of each layer, the radii of the ellipse and the operating depth are taken as design variables. Also, the shell buckling strength and the angle-ply laminated failure strength are considered in the case of composite model. In the other hand, the shell thickness, the radii of the ellipse, the stiffeners offsets, the stiffeners dimensions, and the operating depth, are selected as design variables for steel model with shell buckling and materials yielding constraints. The analysis is performed using commercial finite element analysis software ANSYS. Additionally, a sensitivity analysis is performed to study the influence of the design variables on the structural optimum design. Results of this study provide a valuable reference for designers of underwater vehicles.

  • design optimization of lay up and composite material system to achieve minimum buoyancy factor for composite elliptical submersible Pressure Hull
    Composite Structures, 2015
    Co-Authors: Elsayed Fathallah, Hui Qi, Lili Tong, Mahmoud Helal
    Abstract:

    The design of laminated composite structures is very susceptible to changes in angle of fiber orientation and ply thickness. In the present work, different lay-up sequences for laminates including, cross-ply [0m/90n]s, [90m/0n]s and angle-ply [0m/±αn]s, [90m/±αn]s, [±α]ns, are analyzed. The lay-up sequence, orientation and ply number are optimized using three composite materials T700/epoxy composites, T300/Graphite/Epoxy and B(4)/5505 Boron/Epoxy. Minimize the buoyancy factor of the submersible Pressure Hull is considered as the objective function. The constraints based on the failure strength and the buckling strength of the Pressure Hull, incorporating both the Tsai–Wu and the maximum stress failure criteria. The finite element analysis and the optimization process are performed using ANSYS. Additionally, a sensitivity analysis is performed to study the influence of the design variables on the optimal structural strength design.

  • Numerical investigation of the dynamic response of optimized composite elliptical submersible Pressure Hull subjected to non-contact underwater explosion
    Composite Structures, 2015
    Co-Authors: Elsayed Fathallah, Hui Qi, Lili Tong, Mohamed Helal
    Abstract:

    Predicting the dynamic response of a floating and submerged structure subjected to underwater explosion is greatly complicated by the explosion of a high explosive, propagation of shock wave, bubble-pulse and complex fluid-structure interaction (FSI) phenomena. A numerical simulation has been carried out to examine the behavior of optimized composite elliptical submersible Pressure Hull to non-contact underwater explosion (UNDEX) and take the effect of bubble-pulse. Various explosive weights and explosion distances were explored to determine the critical weights and safe distance. The optimization process is performed using ANSYS parametric design language (APDL). After that the finite element package ABAQUS was used to model the UNDEX and the FSI phenomena. Time histories of the wet-surface displacement, velocity and Tsai-Hill failure index are presented for different composite plies. All of these results can be a valuable reference for designing underwater vehicles to resist UNDEX.

  • design optimization of composite elliptical deep submersible Pressure Hull for minimizing the buoyancy factor
    Advances in Mechanical Engineering, 2014
    Co-Authors: Elsayed Fathallah, Hui Qi, Lili Tong, Mahmoud Helal
    Abstract:

    The design of deep submersible Pressure Hull's structural is one of the core technologies of submersible development of human history. Submersible Pressure Hulls with fiber-reinforced multilayer constructions have been developed in the recent years as substitutes for classical metallic ring-stiffened Pressure Hulls; strength and stability are its top priority. This paper investigates the optimum design of a composite elliptical deep-submerged Pressure Hull under hydrostatic Pressure to minimize the buoyancy factor of the submersible Pressure Hull under constraints on the failure criteria and the buckling strength of the Hulls to reach the maximum operating depth. The thickness and the fiber orientation angles in each layer, the radii of the ellipse, and stringers dimensions were taken as design variables and determined in the design process. The optimization procedures are performed using commercial finite element analysis software ANSYS. Additionally, a sensitivity analysis is performed to study the infl...

  • optimal design analysis of composite submersible Pressure Hull
    Applied Mechanics and Materials, 2014
    Co-Authors: Fathallah Elsayed, Hui Qi, Lili Tong, Mahmoud Helal
    Abstract:

    Recently, submersible Pressure Hulls with fiber-reinforced multilayer constructions have been developed as substitutes for classical metallic ring-stiffened Pressure Hulls. The strength and stability is its top priority. In this paper, the optimum design of elliptical composite deep-submerged Pressure Hull under hydrostatic Pressure is investigated based on the finite element analysis to minimize the buoyancy factor of the submersible Pressure Hull according to the design requirements. Minimize the buoyancy factor of a submarine Pressure Hull under hydrostatic Pressure is proposed as an objective function and the constraints based on the failure strength and the buckling strength of the Hulls are considered. The thickness and the fiber orientation angles in each layer, the radii of the ellipse, the stringers dimensions and the operating depth are taken as design variables. Additionally, a sensitivity analysis is performed to study the influence of the design variables up on the Tsai-Wu failure. Results of this study provide a valuable reference for designers of composite underwater vehicles.

Cho-chung Liang - One of the best experts on this subject based on the ideXlab platform.

  • the study on the dynamic response of cylindrical Pressure Hull on the different shock loading empirical formula
    Applied Mechanics and Materials, 2015
    Co-Authors: Tso-liang Teng, Cho-chung Liang, Hai Anh Nguyen, Chien Jong Shih
    Abstract:

    This paper focuses on the comparison between underwater explosion (UNDEX) shock loading empirical formulations. First, the numerical simulations for a cylindrical Pressure Hull subjected to UNDEX loading were conducted and the results are close to the failure modes shown in experiments of Kwon (1993). Second, the empirical UNDEX loading formula of Cole (1948), Keil (1961) and Shin (1994) used in cylinder subjected to underwater shock loading were compared. The simulation results by using three empirical formulas were compared and Shin’s (or Cole’s) empirical formula was shown to be better than the other empirical formulations when subjected to an UNDEX under the same conditions. The analytical results offer a valuable reference to the research of underwater explosion.

  • The Effect of Roundness on the Buckling Strength for the Submerged Pressure Hull
    Applied Mechanics and Materials, 2014
    Co-Authors: Cho-chung Liang, Tso-liang Teng, Chia Wei Chang
    Abstract:

    The Pressure Hull is the most important part of resisting Pressure structures of the structural systems. The submerged Pressure Hull is subjected to very high hydrostatic Pressure or underwater explosion load, which creates large compressive stress resultants. Due to this the Pressure Hull is susceptible to buckling. Buckling phenomena analysis is of greater importance in the design of the submerged Pressure Hulls. For the Pressure Hulls with local out-of-roundness, the operating depth will be greatly influenced and thus decreasing capability to resist Pressure loading. Thus, this work employs the ABAQUS finite element program to analyze the effect of roundness on the buckling strength for the cylinder Pressure Hull. Sex kinds of out-of-roundness rateφ, 0%, 1%, 3%, 5%, 10% and 15%, were studied in this study. The bulking depth and collapse depth for the cylinder Pressure Hull with different out-of-roundness rate were calculated. The Analysis models and results of this study contribute to efforts to design Pressure Hull structures.

  • optimum design of multiple intersecting spheres deep submerged Pressure Hull
    Ocean Engineering, 2004
    Co-Authors: Cho-chung Liang, Sheauwen Shiah, Hungwen Chen
    Abstract:

    Abstract The multiple intersecting spheres (MIS) Pressure Hull is a logical derivative of the single unstiffened sphere, which is frequently used for deep operating, small submersibles because of its attractive low buoyancy factor. This paper investigates the optimum design of an MIS deep-submerged Pressure Hull subjected to hydrostatic Pressure, using a powerful optimization procedure combined the extended interior penalty function method (EIPF) with the Davidon–Fletcher–Powell (DFP) method. In this study, the thickness of the shell, the width of the rib-ring, the inner radius of the rib-ring and the angle of intersection of the spherical shell are selected as design variables, and structural failure and human requirements are considered to minimize the buoyancy factor. Additionally, a sensitivity analysis is performed to study the influence of the design variables on the optimal structural strength design. The results reveal that the shell thickness is most important to lobar buckling strength, and that rib-ring width, rib-ring inner radius and spherical shell intersection angle are most important to rib-ring hoop strength. Optimization results may provide a valuable reference for designers.

  • study of the nonlinear responses of a submersible Pressure Hull
    International Journal of Pressure Vessels and Piping, 1998
    Co-Authors: Cho-chung Liang
    Abstract:

    Abstract A submarine Pressure Hull normally experiences hydrostatic Pressure at different operating depths and, during wartime, it bears shock loading produced by underwater explosions. In this study we examine the transient dynamic responses of a typical submarine Hull subjected to hydrostatic Pressure and shock loading, in which geometrically large deformation effects involving elastoplastic material behavior are considered. The finite element procedure based on Hibbitt and Karlsson's methodology is used to analyze the nonlinear response of the entire Pressure Hull. From the numerical results of a nonlinear static analysis under operating depth hydrostatic Pressure, we attempt to provide the maximum operating depth at which the behavior varies from elastic to plastic. In transient dynamic analysis under shock environment, this study not only presents the elastoplastic response of the structure but also the critical region of the model. Finally, the implications of these results for future submarine design and maintenance are discussed.

  • minimum weight design of submersible Pressure Hull under hydrostatic Pressure
    Computers & Structures, 1997
    Co-Authors: Cho-chung Liang, Hueirong Tsai
    Abstract:

    Abstract In this study, we proposed a minimum weight design of a submarine Pressure Hull under hydrostatic Pressure with constraints on factors such as general instability, buckling of shell between frames, plate yielding, and frame yielding. A typical submarine Pressure Hull is also adopted for a prototype model. This design problem is not only formulated as a discrete nonlinear, nondifferentiable, multimodal constrained minimization problem, but also solved by using the backtrack programming method. Results in this study indicate that the solution for the optimal model's weight reduces an average 6.65% more than the prototype model. The process in this study is favorable for the submersible Pressure Hull design process.