To analyze the pipeline response under permanent ground deformation,the evolution of resistance acting on the pipe during the vertical downward offset is an essential ingredient.However,the efficient simulation of pip...To analyze the pipeline response under permanent ground deformation,the evolution of resistance acting on the pipe during the vertical downward offset is an essential ingredient.However,the efficient simulation of pipe penetration into soil is challenging for the conventional finite element(FE)method due to the large deformation of the surrounding soils.In this study,the B-spline material point method(MPM)is employed to investigate the pipe-soil interaction during the downward movement of rigid pipes buried in medium and dense sand.To describe the density-and stress-dependent behaviors of sand,the J2-deformation type model with state-dependent dilatancy is adopted.The effectiveness of the model is demonstrated by element tests and biaxial compression tests.Afterwards,the pipe penetration process is simulated,and the numerical outcomes are compared with the physical model tests.The effects of pipe size and burial depth are investigated with an emphasis on the mobilization of the soil resistance and the failure mechanisms.The simulation results indicate that the bearing capacity formulas given in the guidelines can provide essentially reasonable estimates for the ultimate force acting on buried pipes,and the recommended value of yield displacement may be underestimated to a certain extent.展开更多
Nowadays,an increasing number of ships and marine structures are manufactured and inevitably operated in rough sea.As a result,some phenomena related to the violent fluid-elastic structure interactions(e.g.,hydrodynam...Nowadays,an increasing number of ships and marine structures are manufactured and inevitably operated in rough sea.As a result,some phenomena related to the violent fluid-elastic structure interactions(e.g.,hydrodynamic slamming on marine vessels,tsunami impact on onshore structures,and sloshing in liquid containers)have aroused huge challenges to ocean engineering fields.In this paper,the moving particle semi-implicit(MPS)method and finite element method(FEM)coupled method is proposed for use in numerical investigations of the interaction between a regular wave and a horizontal suspended structure.The fluid domain calculated by the MPS method is dispersed into fluid particles,and the structure domain solved by the FEM method is dispersed into beam elements.The generation of the 2D regular wave is firstly conducted,and convergence verification is performed to determine appropriate particle spacing for the simulation.Next,the regular wave interacting with a rigid structure is initially performed and verified through the comparison with the laboratory experiments.By verification,the MPS-FEM coupled method can be applied to fluid-structure interaction(FSI)problems with waves.On this basis,taking the flexibility of structure into consideration,the elastic dynamic response of the structure subjected to the wave slamming is investigated,including the evolutions of the free surface,the variation of the wave impact pressures,the velocity distribution,and the structural deformation response.By comparison with the rigid case,the effects of the structural flexibility on wave-elastic structure interaction can be obtained.展开更多
How to register and submit contributions： Authors are invited to submit their contributions on any of the conference topics. Submissions and conference registration can only be performed via the conference website：...How to register and submit contributions： Authors are invited to submit their contributions on any of the conference topics. Submissions and conference registration can only be performed via the conference website： http：//www.mpm2017.eu展开更多
In this article, the mathematical model of the coupling of the three-dimensional fluid flow and the large deformation of membrane structure is established. The fluid-structure coupling interaction is simulated using t...In this article, the mathematical model of the coupling of the three-dimensional fluid flow and the large deformation of membrane structure is established. The fluid-structure coupling interaction is simulated using the computational codes developed by the authors. By analyzing the interactions of membrane and flow field, the aeroelasticity of the airship is detailed. All the results are adopted in the focused study of the stratosphere airship in trimmed state.展开更多
Flutter is a self-sustained vibration which could create serious damage to compressor blades.Improving the efficiency and accuracy of Fluid-Structure Interaction(FSI)method is crucial to flutter analysis.An efficient ...Flutter is a self-sustained vibration which could create serious damage to compressor blades.Improving the efficiency and accuracy of Fluid-Structure Interaction(FSI)method is crucial to flutter analysis.An efficient FSI method which combines a fast mesh deformation technology and Double-Passage Shape Correction(DPSC)method is proposed to predict blades flutter under traveling wave modes.Firstly,regarding the fluid domain as a pseudo elastic solid,the flow mesh deformation and blade vibration response can be quickly obtained by solving the governing equations of the holistic system composed of blade and pseudo elastic solid.Then,by storing and updating the Fourier coefficients on the circumferential boundary,the phase-lagged boundary condition is introduced into the computational domain.Finally,the aerodynamic stability for the blades of an axial compressor under various Inter-Blade Phase Angle(IBPA)is analyzed.The results show that the proposed method can effectively predict the characteristics of aerodynamic damping,aerodynamic force and blade displacement.And a conceptual model is proposed to describe the motion behavior of the shock wave.Compared with the multi-passage method,the proposed method obtains almost the same unstable IBPA interval and the blade displacement error is less than 3.4%.But the calculation time is significantly shortened especially in small IBPA cases.展开更多
Due to the flexibility of the envelope of large stratosphere airships, the aerodynamic solution of such airship is closely related to its shape and the external aerodynamic forces which lead to the structural deformat...Due to the flexibility of the envelope of large stratosphere airships, the aerodynamic solution of such airship is closely related to its shape and the external aerodynamic forces which lead to the structural deformation. It is essentially one of the Fluid-Structure Interaction （FSI） problems. This article aims at the numerical investigation of nonlinear airship aeroelasticity in consideration of aerodynamics and structure coupling, using an iteration method. The three-dimensional flow around the airship was numerically studied by means of the SIMPLE method based on the finite volume method. Nonlinear finite element analysis was employed for geometrically nonlinear deformation of the airship shape. Comparison of aerodynamic parameters and the pressure distribution between rigid and aeroelastic models was conducted when an airship is in a trimmed flight state in specified flight conditions. The effect ofaeroelasticity on the airship aerodynamics was detailed.展开更多
基金supported by the National Natural Science Foundation of China(Grant Nos.42225702,42077235 and 41722209).
文摘To analyze the pipeline response under permanent ground deformation,the evolution of resistance acting on the pipe during the vertical downward offset is an essential ingredient.However,the efficient simulation of pipe penetration into soil is challenging for the conventional finite element(FE)method due to the large deformation of the surrounding soils.In this study,the B-spline material point method(MPM)is employed to investigate the pipe-soil interaction during the downward movement of rigid pipes buried in medium and dense sand.To describe the density-and stress-dependent behaviors of sand,the J2-deformation type model with state-dependent dilatancy is adopted.The effectiveness of the model is demonstrated by element tests and biaxial compression tests.Afterwards,the pipe penetration process is simulated,and the numerical outcomes are compared with the physical model tests.The effects of pipe size and burial depth are investigated with an emphasis on the mobilization of the soil resistance and the failure mechanisms.The simulation results indicate that the bearing capacity formulas given in the guidelines can provide essentially reasonable estimates for the ultimate force acting on buried pipes,and the recommended value of yield displacement may be underestimated to a certain extent.
基金supported by the National Natural Science Foundation of China(51879159,51490675,11432009,and 51579145)Chang Jiang Scholars Program(T2014099)+3 种基金Shanghai Excellent Academic Leaders Program(17XD1402300)Program for Professor of Special Appointment(Eastern Scholar)at Shanghai Institutions of Higher Learning(2013022)Innovative Special Project of Numerical Tank of Ministry of Industry and Information Technology of China(2016-23/09)Lloyd’s Register Foundation for doctoral student
文摘Nowadays,an increasing number of ships and marine structures are manufactured and inevitably operated in rough sea.As a result,some phenomena related to the violent fluid-elastic structure interactions(e.g.,hydrodynamic slamming on marine vessels,tsunami impact on onshore structures,and sloshing in liquid containers)have aroused huge challenges to ocean engineering fields.In this paper,the moving particle semi-implicit(MPS)method and finite element method(FEM)coupled method is proposed for use in numerical investigations of the interaction between a regular wave and a horizontal suspended structure.The fluid domain calculated by the MPS method is dispersed into fluid particles,and the structure domain solved by the FEM method is dispersed into beam elements.The generation of the 2D regular wave is firstly conducted,and convergence verification is performed to determine appropriate particle spacing for the simulation.Next,the regular wave interacting with a rigid structure is initially performed and verified through the comparison with the laboratory experiments.By verification,the MPS-FEM coupled method can be applied to fluid-structure interaction(FSI)problems with waves.On this basis,taking the flexibility of structure into consideration,the elastic dynamic response of the structure subjected to the wave slamming is investigated,including the evolutions of the free surface,the variation of the wave impact pressures,the velocity distribution,and the structural deformation response.By comparison with the rigid case,the effects of the structural flexibility on wave-elastic structure interaction can be obtained.
文摘How to register and submit contributions： Authors are invited to submit their contributions on any of the conference topics. Submissions and conference registration can only be performed via the conference website： http：//www.mpm2017.eu
文摘In this article, the mathematical model of the coupling of the three-dimensional fluid flow and the large deformation of membrane structure is established. The fluid-structure coupling interaction is simulated using the computational codes developed by the authors. By analyzing the interactions of membrane and flow field, the aeroelasticity of the airship is detailed. All the results are adopted in the focused study of the stratosphere airship in trimmed state.
基金The authors would like to acknowledge the support of the National Natural Science Foundation of China(No.51675406)the Basic Research Project Group,China(No.514010106-205).
文摘Flutter is a self-sustained vibration which could create serious damage to compressor blades.Improving the efficiency and accuracy of Fluid-Structure Interaction(FSI)method is crucial to flutter analysis.An efficient FSI method which combines a fast mesh deformation technology and Double-Passage Shape Correction(DPSC)method is proposed to predict blades flutter under traveling wave modes.Firstly,regarding the fluid domain as a pseudo elastic solid,the flow mesh deformation and blade vibration response can be quickly obtained by solving the governing equations of the holistic system composed of blade and pseudo elastic solid.Then,by storing and updating the Fourier coefficients on the circumferential boundary,the phase-lagged boundary condition is introduced into the computational domain.Finally,the aerodynamic stability for the blades of an axial compressor under various Inter-Blade Phase Angle(IBPA)is analyzed.The results show that the proposed method can effectively predict the characteristics of aerodynamic damping,aerodynamic force and blade displacement.And a conceptual model is proposed to describe the motion behavior of the shock wave.Compared with the multi-passage method,the proposed method obtains almost the same unstable IBPA interval and the blade displacement error is less than 3.4%.But the calculation time is significantly shortened especially in small IBPA cases.
文摘Due to the flexibility of the envelope of large stratosphere airships, the aerodynamic solution of such airship is closely related to its shape and the external aerodynamic forces which lead to the structural deformation. It is essentially one of the Fluid-Structure Interaction （FSI） problems. This article aims at the numerical investigation of nonlinear airship aeroelasticity in consideration of aerodynamics and structure coupling, using an iteration method. The three-dimensional flow around the airship was numerically studied by means of the SIMPLE method based on the finite volume method. Nonlinear finite element analysis was employed for geometrically nonlinear deformation of the airship shape. Comparison of aerodynamic parameters and the pressure distribution between rigid and aeroelastic models was conducted when an airship is in a trimmed flight state in specified flight conditions. The effect ofaeroelasticity on the airship aerodynamics was detailed.
