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Study on Deformation Law of Circular Foundation Under Combined Loading

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Journal of Ocean University of China 2014年第1期13卷 51-56页

作者： ZHANG Qiyi shi hongda Department of Ocean Engineering College of Engineering Ocean University of China Key Laboratory of Ocean Engineering of Shandong Province

The foundations of some ocean engineering structures are built to withstand not only the vertical gravity load V, but also the horizontal load H induced by sea waves and current. The horizontal load includes the concentrated force load, the moment load M, and the torque load T termed also as combined loading. It is of academic and engineering significance to study the deformation law of submarine seabed due to combined loading. On the basis of the three-dimensional elastic mechanics solution of circular foundation, numerical methods are used to analyze the deformation law of submarine soil under circular foundation with six degrees of freedom. The finite element analysis results give the elastic deformation law of soil in three dimensional spaces, modify the theoretical elasticity solution, and presents nonlinear soil deformation mechanism under the circular foundation with six degrees of freedom.

关键词： degrees of freedom circular foundation deformation law combined loading elastic mechanics solution

Disaster prevention design criteria for the estuarine cities:New Orleans and Shanghai The lesson from Hurricane Katrina

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Acta Oceanologica Sinica 2006年第4期25卷 131-142页

作者： LIU Defu shi hongda PANG Liang Disaster Prevention Research Institute Ocean University of China Qingdao 266003 China College of Engineering Ocean University of China Qingdao 266071 China

The accurate prediction of the typhoon （hurricane） induced extreme sea environments is very important for the coastal structure design in areas influenced by typhoon （hurricane）. In 2005 Hurricane Katrina brought a severe catastrophe in New Orleans by combined effects of hurricane induced extreme sea environments and upper flood of the Mississippi River. Like the New Orleans City, Shanghai is located at the estuarine area of the Changjiang River and the combined effect of typhoon induced extreme sea en- vironments, flood peak runoff from the Changjiang River coupled with the spring tide is the dominate factor for disaster prevention design criteria. The Poisson-nested logistic trivariate compound extreme value distribution （PNLTCEYD） is a new type of joint probability model which is proposed by compounding a discrete distribution （typhoon occurring frequency） into a continuous multivariate joint distribution （ typhoon induced extreme events）. The new model gives more reasonable predicted results for New Orleans and Shanghai disaster prevention design criteria.

关键词： typhoon hurricane compound extreme value distribution disaster prevention design criteria

Optimization of Wind-Marine Hybrid Power System Configuration Based on Genetic Algorithm

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Journal of Ocean University of China 2017年第4期16卷 709-715页

作者： shi hongda LI Linna ZHAO Chenyu College of Engineering Ocean University of China Qingdao 266100 P. R. China

Multi-energy power systems can use energy generated from various sources to improve power generation *** paper presents a cost-power generation model of a wind-tide-wave energy hybrid power system for use on a remote island,where the configuration is optimized using a genetic algorithm.A mixed integer programming model is used and a novel object function,including cost and power generation,is proposed to solve the boundary problem caused by existence of two *** this model,the final optimized result is found to have a good fit with local resources.

关键词： genetic algorithm cost-power generation function multi-energy system marine energy

Experimental Study on the Hydrodynamic Performance of a Heaving Buoy Assembled on a Net Cage Platform

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Journal of Ocean University of China 2019年第5期18卷 1031-1040页

作者： shi hongda DONG Xiaochen FENG Liang HAN Zhi Shandong Provincial Key Laboratory of Ocean Engineering Ocean University of ChinaQingdao 266100China Department of Ocean Engineering College of EngineeringOcean University of ChinaQingdao 266100China Qingdao Municipal Key Laboratory of Ocean Renewable Energy Ocean University of ChinaQingdao 266100China

To take advantage of the abundance of both fishery and wave energy resources in offshore sea areas,a novel floating platform with a heaving buoy-based wave energy converter(WEC)assembled with a set of net cages is presented in this *** floating WEC system provides a power supply,while the net cages are used for *** is designed to have an independent and self-operation breeding *** experimental study is carried out to investigate the hydrodynamic performance of the device in a wave tank considering the factors of net cages,draft depth,and power take-off,and results show that these variables have significant effects on wave energy *** waves with short periods cause intense interactions that allow the device to undergo large relative *** draft depth could be determined according to wave period rather than wave *** study also explores the response amplitude operator of the device and determines its resonance *** experimental results could provide reliable information for future studies on phase differences and the design of two-body WECs.

关键词： heaving buoy floating platform hydrodynamic performance experimental study

Study on Hydraulic System Efficiency of Heaving-Buoy Wave Energy Converter

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Journal of Ocean University of China 2018年第5期17卷 1044-1052页

作者： shi hongda ZHAO Chenyu LIU Zhen CAO Feifei College of Engineering Ocean University of ChinaQingdao 266100China Shandong Provincial Key Laboratory of Ocean Engineering Qingdao 266100China

The hydraulic system is the key component in the widely used wave energy converters(WEC).In this paper,we theoretically analyze and describe our investigation of the efficiency of the hydraulic system by simulation and model testing of the combined heaving-buoy *** derive a new governing equation that includes nonlinear hydraulic resistance in the power take-off(PTO).We conducted a physical model experiment based on a 100-kW prototype and applied a hydraulic system with an energy *** model test results reveal an important parameter related to efficiency with respect to nonlinear hydraulic *** also studied the relationship between the efficiency and the initial ***,based on our numerical simulation results,we discuss the effect on efficiency of the gas content of the hydraulic fluid and ways to reduce its impact.

关键词： hydraulic system PTO nonlinear hydraulic resistance efficiency gas content

Theoretical Analysis of Coral Reef Stability in South Sea

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Journal of Ocean University of China 2018年第5期17卷 1026-1032页

作者： ZHANG Qiyi shi hongda GAO Wei LI Jinfeng Department of Ocean Engineering College of EngineeringOcean University of ChinaQingdao 266100China Key Laboratory of Ocean Engineering of Shandong Province Qingdao 266100China Tianjin Dredging Company Limited China Communications Construction Company LimitedTianjin 300450China

In this paper,we utilize the variational limiting equilibrium(LE) procedure to theoretically determine the slope stability of homogeneous coral sand in the South China *** establishing a reasonable functional and calculating its extremum,we can deduce the stability factor of a coral reef identical to that obtained by upper bound *** determine the accuracy of the results obtained using the variational LE procedure,we present some classical examples of homogeneous sand slopes without a hard shell and compare our results with those obtained by the upper bound theorem of plasticity.A series of extensive calculations and comparisons reveal that the results obtained by our proposed analysis method and those obtained using classical methods are slightly different,but the variational results are *** the other hand,our method solves some stability factors for reef slopes covered with a hard shell,which indicates that the existence of a hard reef shell may significantly enhance the stability of a reef slope,and that there is strong nonlinear relationship between reef stability and the mechanical characteristics of the reef shell,such as its thickness and ***,based on the variational results presented in this paper,we present a useful chart that offers a convenient and straightforward way to determine the maximum stability factor of reef *** into account the influence of the hard reef shell,we found that,in some limit equilibrium cases,the limit stability factor and critical height of a coral slope could be improved ***,this issue deserves careful attention in engineering practice.

关键词： reef stability reef shell variational results limit equilibrium

Simulation of the Power Take-off System for a Heaving Buoy Wave Energy Converter

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Journal of Ocean University of China 2020年第3期19卷 497-504页

作者： CAO Feifei shi hongda LI Ming DONG Xiaochen LI Demin College of Engineering Ocean University of ChinaQingdao 266100China Shandong Provincial Key Laboratory of Ocean Engineering Qingdao 266100China Qingdao Municipal Key Laboratory of Ocean Renewable Energy Qingdao 266100China

The heaving buoy wave energy device is popular for wave conditions with small wave heights and short periods. This paper presents the design of a wave energy converter composed of a gyro buoy, a hydraulic power take-off, and an electricity generation system. The energy accumulators are used to improve the output power with different control strategies. The quantity relations between each component are established using theoretical methods. The simulation model describes the energy conversion and calculates the operation time, energy capacity, and output power of the device under different initial pressures, release pressures, and electric resistances. As a result, the capacity is determined by the electronic load, and the maximum output power can be obtained when the accumulators are turned on and off at the same time. This study investigates the factors influencing the electric energy production and can be used to guide the optimization of this type of device.

关键词： wave energy heaving buoy power-take-off accumulator output power

Modelling and Simulation on the Effect of Hot Forming Damage on Three-Point Bending Performance of Beam Components

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Journal of Beijing Institute of Technology 2020年第3期29卷 399-409页

作者： Weimin Zhuang Pengyue Wang Yang Liu Dongxuan Xie hongda shi State Key Laboratory of Automotive Simulation and Control Jilin UniversityChangchun 130022China FAW-Volkswagen Automotive Co. Ltd.Changchun 130011China

The effects of forming damage are analyzed,which occur during hot stamping process,on the load-carrying capacity and failure mode of hot stamped beams.A damage-coupled pre-forming constitutive model was proposed,in which the damage during hot stamping process was introduced into the service *** constitutive model was applied into the three-point bending simulation of a hot stamped beam,and then the influences of forming damage on the load-carrying capacity and cracks propagation were *** results show that the forming damage reduces the maximum load capacity of the hot stamped beam by 7.5%.It also causes the crack to occur earlier and promotes crack to propagate along the radial direction of the punch.

关键词： constitutive modelling hot-stamped beam forming damage three-point bending crack propagation

Application of 2D Numerical Model to Unsteady Performance Evaluation of Vertical-Axis Tidal Current Turbine

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Journal of Ocean University of China 2016年第6期15卷 977-986页

作者： LIU Zhen QU Hengliang shi hongda HU Gexing HYUN Beom-Soo Shandong Provincial Key Laboratory of Ocean Engineering Ocean University of China Qingdao Municipal Key Laboratory of Ocean Renewable Energy Ocean University of China College of Engineering Ocean University of China College of Ocean Science and Technology Korea Maritime and Ocean University

Abstract Tidal current energy is renewable and sustainable, which is a promising altemative energy resource for the future elec- tricity supply. The straight-bladed vertical-axis turbine is regarded as a useful tool to capture the tidal current energy especially under low-speed conditions. A 2D unsteady numerical model based on Ansys-Fluent 12.0 is established to conduct the numerical simulation, which is validated by the corresponding experimental data. For the unsteady calculations, the SST model, 2x 105 and 0.01 s are se- lected as the proper turbulence model, mesh number, and time step, respectively. Detailed contours of the velocity distributions around the rotor blade foils have been provided for a flow field analysis. The tip speed ratio （TSR） determines the azimuth angle of the appearance of the torque peak, which occurs once for a blade in a single revolution. It is also found that simply increasing the incident flow velocity could not improve the turbine performance accordingly. The peaks of the averaged power and torque coeffi- cients appear at TSRs of 2.1 and 1.8, respectively. Furthermore, several shapes of the duct augmentation are proposed to improve the turbine performance by contracting the flow path gradually from the open mouth of the duct to the rotor. The duct augmentation can significantly enhance the power and torque output. Furthermore, the elliptic shape enables the best performance of the turbine. The numerical results prove the capability of the present 2D model for the unsteady hydrodynamics and an operating performance analy- sis of the vertical tidal stream turbine.

关键词： tidal current energy vertical-axis turbine unsteady numerical model duct augmentation average power coefficient tip speed ratio