An optimization framework is developed to maximize design pressure of composite cylindrical shell subjected to hydrostatic pressure. Genetic algorithm(GA) integrated with numerical analysis is used in the framework to...An optimization framework is developed to maximize design pressure of composite cylindrical shell subjected to hydrostatic pressure. Genetic algorithm(GA) integrated with numerical analysis is used in the framework to find optimal winding pattern of the composite cylinders. As a novelty, unlike other studies only considering buckling, in this study, material failure is taken as design constraint in the optimization problem.Sensitivity analyses are performed to study the effects of design variables on the buckling pressure, material failure pressure and design pressure. Comparative study is carried out to analyze the buoyancy factors of the cylindrical shell made of metal alloys and composites. Results reveal that as the shell thickness of the cylinder increases, the material failure pressure instead of the buckling pressure determines the design pressure. It can be concluded that reliable winding pattern designs can be achieved for composite cylinders under hydrostatic pressure when the Tsai-Wu failure criterion is considered.展开更多
Architects have been following nature in their constructions for a long time.Observations of nature reveal that it has many highly developed structures that provide scientists and engineers with a lot of useful clues ...Architects have been following nature in their constructions for a long time.Observations of nature reveal that it has many highly developed structures that provide scientists and engineers with a lot of useful clues for creating more efficient structures and building forms.Therefore,revealing systematic thinking about natural species is a crucial requirement for today’s buildings.A software analysis method was used to design four modules in the roof structure of the Iranian University of Science and Technology’s exhibition.The roof structure is based on the Voronax structure,which is a relaxed form of Voronoi,which is seen in the structures of many natural creatures.They were analyzed in terms of optimization and structural simulation using Grasshopper plugins and tools by taking into account Von Mises stress in the structural design.The results indicated that by increasing the density of Voronax cells in the areas with high Von Mises stress concentration,a more efficient structure could be achieved in terms of load-bearing and designing predefined free-form roof structures.By analyzing predefined roof structures in an optimum way,the study took a step toward optimizing these kinds of structures.展开更多
The key to reduce shell breakout in the continuous casting process is to control shell thickness in the mold. A numerical simulation on the turbulent flow and heat transfer coupled with solidification in the slab mold...The key to reduce shell breakout in the continuous casting process is to control shell thickness in the mold. A numerical simulation on the turbulent flow and heat transfer coupled with solidification in the slab mold using the volume of fluid （VOF） model and the enthalpy-porosity scheme was conducted and the emphasis was put upon the flow effect on the shell thickness profiles in longitudinal and transverse directions. The results show that the jet acts a stronger impingement on the shell of narrow face, which causes a zero-increase of shell thickness in a certain range near the impingement point. The thinnest shell on the slab cross-section locates primarily in the center of the narrow face, and secondly near the comer of the wide face. Nozzle optimization can obviously increase the shell thickness and make it more uniform.展开更多
In this paper,a parametric level-set-based topology optimization framework is proposed to concurrently optimize the structural topology at the macroscale and the effective infill properties at the micro/meso scale.The...In this paper,a parametric level-set-based topology optimization framework is proposed to concurrently optimize the structural topology at the macroscale and the effective infill properties at the micro/meso scale.The concurrent optimization is achieved by a computational framework combining a new parametric level set approach with mathematical programming.Within the proposed framework,both the structural boundary evolution and the effective infill property optimization can be driven by mathematical programming,which is more advantageous compared with the conventional partial differential equatiodriven level set approach.Moreover,the proposed approach will be more efficient in handling nonlinear problems with multiple constraints.Instead of using radial basis functions(RBF),in this paper,we propose to construct a new type of cardinal basis functions(CBF)for the level set function parameterization.The proposed CBF parameterization ensures an explicit impose of the lower and upper bounds of the design variables.This overcomes the intrinsic disadvantage of the conventional RBF-based parametric level set method,where the lower and upper bounds of the design variables oftentimes have to be set by trial and error;A variational distance regularization method is utilized in this research to regularize the level set function to be a desired distanceregularized shape.With the distance information embedded in the level set model,the wrapping boundary layer and the interior infill region can be naturally defined.The isotropic infill achieved via the mesoscale topology optimization is conformally fit into the wrapping boundary layer using the shape-preserving conformal mapping method,which leads to a hierarchical physical structure with optimized overall topology and effective infill properties.The proposed method is expected to provide a timely solution to the increasing demand for multiscale and multifunctional structure design.展开更多
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[0_(s)/90_(t)/0_(u)...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[0_(s)/90_(t)/0_(u)],[0_(s)/90_(t)/0_(u)]s,[0_(s)/90_(t)]s and[90_(s)/0_(t)]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.展开更多
基金the National Natural Science Foundation of China(Nos.11502210,51709229,51803303,51479170 and 61803306)the National Key Research and Development Project of China(No.2016YFC0301300)+1 种基金the Natural Science Basic Research Plan in Shaanxi Province(No.2018JQ5092)the Fundamental Research Funds for the Central Universities of China(No.3102019JC006)
文摘An optimization framework is developed to maximize design pressure of composite cylindrical shell subjected to hydrostatic pressure. Genetic algorithm(GA) integrated with numerical analysis is used in the framework to find optimal winding pattern of the composite cylinders. As a novelty, unlike other studies only considering buckling, in this study, material failure is taken as design constraint in the optimization problem.Sensitivity analyses are performed to study the effects of design variables on the buckling pressure, material failure pressure and design pressure. Comparative study is carried out to analyze the buoyancy factors of the cylindrical shell made of metal alloys and composites. Results reveal that as the shell thickness of the cylinder increases, the material failure pressure instead of the buckling pressure determines the design pressure. It can be concluded that reliable winding pattern designs can be achieved for composite cylinders under hydrostatic pressure when the Tsai-Wu failure criterion is considered.
文摘Architects have been following nature in their constructions for a long time.Observations of nature reveal that it has many highly developed structures that provide scientists and engineers with a lot of useful clues for creating more efficient structures and building forms.Therefore,revealing systematic thinking about natural species is a crucial requirement for today’s buildings.A software analysis method was used to design four modules in the roof structure of the Iranian University of Science and Technology’s exhibition.The roof structure is based on the Voronax structure,which is a relaxed form of Voronoi,which is seen in the structures of many natural creatures.They were analyzed in terms of optimization and structural simulation using Grasshopper plugins and tools by taking into account Von Mises stress in the structural design.The results indicated that by increasing the density of Voronax cells in the areas with high Von Mises stress concentration,a more efficient structure could be achieved in terms of load-bearing and designing predefined free-form roof structures.By analyzing predefined roof structures in an optimum way,the study took a step toward optimizing these kinds of structures.
基金supported by the National Natural Science Foundation of China (No.60672145)
文摘The key to reduce shell breakout in the continuous casting process is to control shell thickness in the mold. A numerical simulation on the turbulent flow and heat transfer coupled with solidification in the slab mold using the volume of fluid （VOF） model and the enthalpy-porosity scheme was conducted and the emphasis was put upon the flow effect on the shell thickness profiles in longitudinal and transverse directions. The results show that the jet acts a stronger impingement on the shell of narrow face, which causes a zero-increase of shell thickness in a certain range near the impingement point. The thinnest shell on the slab cross-section locates primarily in the center of the narrow face, and secondly near the comer of the wide face. Nozzle optimization can obviously increase the shell thickness and make it more uniform.
基金the National Science Foundation of the United States(Grant Nos.CMMI1462270 and CMMI1762287)Ford University Research Program(URP),and the start-up fund from the State University of New York at Stony Brook.
文摘In this paper,a parametric level-set-based topology optimization framework is proposed to concurrently optimize the structural topology at the macroscale and the effective infill properties at the micro/meso scale.The concurrent optimization is achieved by a computational framework combining a new parametric level set approach with mathematical programming.Within the proposed framework,both the structural boundary evolution and the effective infill property optimization can be driven by mathematical programming,which is more advantageous compared with the conventional partial differential equatiodriven level set approach.Moreover,the proposed approach will be more efficient in handling nonlinear problems with multiple constraints.Instead of using radial basis functions(RBF),in this paper,we propose to construct a new type of cardinal basis functions(CBF)for the level set function parameterization.The proposed CBF parameterization ensures an explicit impose of the lower and upper bounds of the design variables.This overcomes the intrinsic disadvantage of the conventional RBF-based parametric level set method,where the lower and upper bounds of the design variables oftentimes have to be set by trial and error;A variational distance regularization method is utilized in this research to regularize the level set function to be a desired distanceregularized shape.With the distance information embedded in the level set model,the wrapping boundary layer and the interior infill region can be naturally defined.The isotropic infill achieved via the mesoscale topology optimization is conformally fit into the wrapping boundary layer using the shape-preserving conformal mapping method,which leads to a hierarchical physical structure with optimized overall topology and effective infill properties.The proposed method is expected to provide a timely solution to the increasing demand for multiscale and multifunctional structure design.
基金This work is supported by the National Natural Science Foundation of China research grant“Study on the characteristic motion and load of bubbles near a solid boundary in shear flows”(51679056)Natural Science Foundation of Heilongjiang Province of China(E2016024).
文摘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[0_(s)/90_(t)/0_(u)],[0_(s)/90_(t)/0_(u)]s,[0_(s)/90_(t)]s and[90_(s)/0_(t)]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.
