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Dynamic Response Study of Steel Catenary Riser Based on slender Rod Model

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China Ocean Engineering 2019年第1期33卷 57-64页

作者： LIU Zhen GUO Hai-yan College of Engineering Ocean University of China

A numerical model of the steel catenary riser(SCR) is built based on the slender rod model. The slender rod model,which describes the behavior of the slender riser in terms of the center line position, can solve the geometrical nonlinearity effectively. In a marine environment, the SCR is under the combined internal flow and external loads,such as wave and current. A general analysis considers only the inertial force and the drag force caused by the wave and current. However, the internal flow has an effect on the SCR; it is essential to explore the dynamic response of the SCR with the internal flow. The SCR also suffers the lift force and the fluctuating drag force because of the current. Finite element method is utilized to solve the motion equations. The effects of the internal flow, wave and current on the dynamic response of the SCR are considered. The results indicate that the increase of the internal flow density leads to the decrease of the displacement of the SCR, while the internal flow velocity has little effect on the SCR. The displacement of the SCR increases with the increase of the wave height and period. And the increasing wave period results in an increase in the vibration period of the SCR. The current velocity changes the displacements of the SCR in x-and z-directions. The vibration frequency of the SCR in y-direction increases with the increase of the current velocity.

关键词： steel catenary riser slender rod model internal flow dynamic response

Response of a slender cylindrical member under breaking wave impact

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Journal of Hydrodynamics 2019年第2期31卷 345-357页

作者： Manjula R. Sannasiraj S.A Department of Civil Engineering National Institute of TechnologyTiruchirappalliIndia Department of Ocean Engineering Indian Institute of Technology MadrasChennaiIndia

A slender cylindrical member is the fundamental component of many coastal and offshore *** is essential to understand the action of breaking waves on structural members since,when these members are subjected to wave impact load,the structural damages and failures may be *** the present study,an experimental investigation has been carried out to measure the response of the slender vertical cylinder subjected to breaking wave *** measurements were made in order to estimate the total force acting on the *** empirical relation is established between total impact force and the wave steepness parameter which dictates the intensity of the *** rise time is an important parameter dictating the impact *** acceleration and strain measurements were made to evaluate the response of the *** has been derived from structure *** deflection due to the moderate plunging differs by two order more than severe plunging *** rate is another important consideration for the impact *** higher strain rate increases the resistance of the *** the breaking wave impact on the cylinder,the strain rate varies from 102 to 10-4.

关键词： Breaking wave impact acceleration slender vertical cylinder wave steepness strain rate strain

Displacement Response Reconstruction of slender Flexible Structures Based on Cubic Spline Fitting Method

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维普期刊数据库

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China Ocean Engineering 2019年第2期33卷 226-236页

作者： HAN Qing-hua MA Ye-xuan FENG Xin-xin XU Wan-hai State Key Laboratory of Hydraulic Engineering Simulation and Safety Tianjin University School of Civil Engineering Tianjin University

How to reconstruct a dynamic displacement of slender flexible structures is the key technology to develop smart structures and structural health monitoring(SHM), which are beneficial for controlling the structural vibration and protecting the structural safety. In this paper, the displacement reconstruction method based on cubic spline fitting is put forward to reconstruct the dynamic displacement of slender flexible structures without the knowledge of modeshapes and applied loading. The obtained strains and displacements are compared with the results calculated by ABAQUS to check the method's validity. It can be found that the proposed method can accurately identify the strains and displacement of slender flexible structures undergoing linear vibrations, nonlinear vibrations, and parametric vibrations. Under the concentrated force, the strains of slender flexible structures will change suddenly along the axial direction. With locally densified measurement points, the present reconstruction method still works well for the strain concentration problem.

关键词： displacement reconstruction cubic spline fitting slender flexible structures linear vibrations parametric vibrations nonlinear vibrations

A physical model of asymmetric vortices flow structure in regular state over slender body at high angle of attack

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Science China(Technological Sciences) 2003年第6期46卷 561-573页

作者：邓学蓥王刚陈学锐王延奎刘沛清郗忠祥 Institute of Fluid Mechanics Beijing University of Aeronautics and Astronautics Beijing 100083 China Airfoil Research Center Northwest Polytechnic University Xian 710072 China

In subcritical Reyolds number flow region, the repeatable and determinate asymmetric vortices flow at regular state can be obtained by manually setting mini-perturbation on the nose of a pointed ogive-cylinder model at high angle of attack and zero side slip. Test results of this study involve surface pressure distributions, sectional-side-force distributions and flow visualizations. The analyses of these results revealed a complicated multi-vortices system at regular state inwhich asymmetric twin vortices with inception region and fully developed region, asymmetric triple vortices, four vortices region, five vortices region and Karman-vortex-street-like flow region aredeveloped along the slender body. The correlation between multi-vortices system structures and corresponding sectional-side-force distribution is given. The behaviors of multi-vortices flow struc-ture at the peculiar points of sectional-side-force distributions and characteristics of corresponding pressure distribution are analysed. Finally, a physical model of asymmetric multi-vortices flowstructure in regular state over slender body is developed.

关键词： slender body, high angle of attack, aerodynamics, asymmetric vortex flow, bistable flow.

STABILITY OF THE CROSSFLOW PATTERN AROUND A slender AND INFLUENCE OF DISTURBANCE

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Applied Mathematics and Mechanics(English Edition) 2004年第12期25卷 1354-1364页

作者：李国辉邓学蓥 Department of Flight Vehicle Design and Applied Mechanics Beijing University of Aeronautics and Astronautics Beijing 100083 P.R.China

Topological structure and stability of a slender cross flow is discussed by the stability theory of dynamic system. The inner boundary of flow field was limiting streamline and it was proved that the topological structure connected saddles by limiting streamline is stable. It is proved that the development of slender vortices leads to the change of topological structure about cross flow. And it is the change from stable and symmetrical vortices flow pattern to unstable and symmetrical vortices flow pattern, and then to stable and asymmetrical vortices flow pattern due to little disturbance which leads to the development of asymmetrical slender vortices. The influence of disturbance to flowfield structure was discussed by unfolding theory too.

关键词： slender topology structure stability bifurcation unfolding

Influence of nose-perturbation location on behavior of vortical flow around slender body at high incidence

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Science China(Technological Sciences) 2009年第7期52卷 1933-1946页

作者： XiaoRong Guan Cheng Xu YongJuan Wang YaPing Wang School of Mechanical Engineering Nanjing University of Science and Technology Nanjing 210094 China

Response of the vortical flow around a slender body of revolution at high incidence to the shift of a single nose perturbation was investigated systematically using numerical methods. A minute geometric bump was employed to act as the nose perturbation, and all computations were performed for subsonic flows at incidence of 50°. The computational results show that the vortical flow is more sensitive to the perturbation located axially closer to the nose apex of a slender body. With perturbation shifting axially downstream away from nose apex, there is a critical axial location appearing. The vortical flow is less sensitive to the perturbation located axially closer to the critical axial location; when perturbation traverses axially around the critical axial location, the vortical flow switches between opposite asymmetric patterns. The eventual influence of perturbation axial location on the vortical flow lies on both its relative locations to nose apex and the critical axial location. The vortical flow is more sensitive to the perturbation located circumferentially farther away from the fore-and-aft symmetric plane of a slender body, and just the asymmetrically-located perturbation can provoke the vortical flow to asymmetry. With perturbation shifting circumferentially in sequence, the vortical flow varies by degrees in manner of a single periodicity. A convective-type of instability existing in the flow field is responsible for the influence of nose perturbation on the vortical flow.

关键词： slender body of revolution high-incidence aerodynamics asymmetric vortical flow nose perturbation critical location

A CRITICAL PATTERN OF CROSSFLOW AROUND A slender

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Applied Mathematics and Mechanics(English Edition) 2005年第1期26卷 27-34页

作者：李国辉邓学蓥 Institute of Fluid Mechanics Beijing University of Aeronautics and AstronauticsBeijing 100083 P.R.China

Topological structure of a slender crossflow was discussed with topological analysis. It is pointed that the development of slender vortices leads to the change of topological structure about cross flow, and a critical flow pattern will appear. There is a high-order singular point in this critical flow pattern. And the index of the high-order singular is -3/2. The topological structure of this singular point is instable, so bifurcation will occur and the topological structure of flowfield will be changed by little disturbance.

关键词： slender high-order singular point bifurcation structure stability

Analysis on Critical Force of Unidirectional CFRP slender Column

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Journal of Harbin Institute of Technology(New Series) 2019年第4期26卷 25-31页

作者： Wenfeng Bian Weiyi Shao Baoming Wang Department of Civil Engineering Harbin Institute of TechnologyWeihai 264209 Shandong China Weihai Guangwei Composities Co. Ltd.Weihai 264209 Shandong China

Carbon Fiber Reinforced Polymer(CFRP) has such characteristics as light weight, high strength and corrosion resistance, so it is suitable for corrosive environment and large-span structures. This study investigated the stability of CFRP slender column, whose slenderness is greater than Euler’s critical load. The columns in this study were formed by a two-step process and the fiber direction was along the same direction of column axis. Firstly, we obtained the basic mechanical properties of the material by tensile experiment. Then, we studied the critical force of 10 CFRP columns with different lengths and widths by axial compression test. Finally, by comparing Euler’s formula with the modified Euler formula and combining with existing literature and experimental result of this paper, we proposed a modified Perry formula which could well predict the critical force of unidirectional CFRP extruded column and could be used for CFRP extruded column research and engineering design.

关键词： unidirectional CFRP slender column critical force stability factor modified Perry formula

PRESSURE DISTRIBUTION, SKIN FRICTION, AND HEAT TRANSFER FOR SHARP- AND BLUNT-NOSED slender BODIES IN HYPERSONIC AIR FLOW

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Chinese Science Bulletin 1966年第7期24卷 289-294页

作者：施定邦 Northwestern Institute of Technology

For hypersonic vehicles, the bodies must in general be blunt-nosed and slender in shape in order to accommodate aerodynamic heating. In this case, some hypersonic flow phenomena, such as nose bluntness, boundarylayer displacement, transverse-curvature, and real-gas effects are exhibited. In practical hypersonic air flow problems of slender bodies, the effects of leading-edge or nose bluntness and viscous interactions may be equally important. In 1960, the analysis of the combined effects of both the blunt nose and the boundary-layer displacement on characteristic aerodynamic quantities was first worked out by Cheng et al on

关键词： slender aerodynamic quantities SHARP blunt curvature accommodate SKIN FRICTION heating worked