Dynamic analysis of offshore wind turbines

Jianping Zhang,Mingqiang Wang,Zhen Gong,Fengfeng Shi 한국풍공학회 2020 Wind and Structures, An International Journal (WAS Vol.31 No.4

For large-scale 5MW offshore wind turbines, the discrete equation of fluid domain and the motion equation of structural domain with geometric nonlinearity were built, the three-dimensional modeling of the blade considering fluid-structure interaction (FSI) was achieved by using Unigraphics (UG) and Geometry modules, and the numerical simulation and the analysis of the vibration characteristics for wind turbine structure under rotating effect were carried out based on ANSYS software. The results indicate that the rotating effect has an apparent effect on displacement and Von Mises stress, and the response and the distribution of displacement and Von Mises stress for the blade in direction of wingspan increase nonlinearly with the equal increase of rotational speeds. Compared with the single blade model, the blade vibration period of the whole machine model is much longer. The structural coupling effect reduces the response peak value of the blade displacement and Von Mises stress, and the increase of rotational speed enhances this coupling effect. The maximum displacement difference between two models decreases first and then increases along wingspan direction, the trend is more visible with the equal increase of rotational speed, and the boundary point with zero displacement difference moves towards the blade root. Furthermore, the Von Mises stress difference increases gradually with the increase of rotational speed and decreases nonlinearly from the blade middle to both sides. The results can provide technical reference for the safe operation and optimal design of offshore wind turbines.

Influence of structure coupling effect on damping coefficient of offshore wind turbine blades

Jianping Zhang,Zhen Gong,Haolin Li,Mingqiang Wang,Zhiwei Zhang,Fengfeng Shi 한국풍공학회 2019 Wind and Structures, An International Journal (WAS Vol.29 No.6

The aim of this study was to explore the influence of structure coupling effect on structural damping of blade based on the blade vibration characteristic. For this purpose, the scaled blade model of NREL 5 MW offshore wind turbine was processed and employed in the wind tunnel test to validate the reliability of theoretical and numerical models. The attenuation curves of maximum displacement and the varying curves of equivalent damping coefficient of the blade under the rated condition were respectively compared and analyzed by constructing single blade model and whole machine model. The attenuation law of blade dynamic response was obtained and the structure coupling effect was proved to exert a significant influence on the equivalent damping coefficient. The results indicate that the attenuation trend of the maximum displacement response curve of the single blade varies more obviously with the increase of elastic modulus as compared to that under the structure coupling effect. In contrast to the single blade model, the varying curve of equivalent damping coefficient with the period is relatively steep for the whole machine model. The findings are of great significance to guide the structure design and material selection for wind turbine blades.

THE DIFFERENTIAL EFFECTS OF FACE GAIN VERSUS FACE LOSS ON LUXURY BRAND CONSUMPTION

Jianping Liang,Rajeev Batra,Zhuomin Shi 글로벌지식마케팅경영학회 2019 Global Fashion Management Conference Vol.2019 No.07

On the massive metal accumulation on the eastern margin of the North China Craton and the prospecting evaluation – a case study of Jiaojia gold concentration belt

Rui Shi,Jianping Chen 한국지질과학협의회 2015 Geosciences Journal Vol.19 No.4

North China Craton, with characteristics of the multistage tectonic evolution, has experienced a long geological history of more than 3.8 billion years, which records almost all the major geological events from the early crust development stage to the Mesozoic and has formed rich mineral resources and unique dominant minerals. Jiaodong terrane, on the eastern margin of the North China Craton, has become the basement after experiencing the evolution of Precambrian formation. Controlled by the tectonic regime in the Mesozoic, this terrane witnessed the strong crust-mantle interaction, and became the largest gold producer in China after forming the massive metal accumulation and an outbreak of large-scale metallogenic events. Previous scholars have conducted extensive researches on the metallogenic theory of Jiaodong Gold Concentrating Area and applied it to prospecting and exploration; with the increasing difficulty in prospecting and the deployment of deep prospecting, finding out the new prospecting methods has become the study focus. Based on the analysis of the regional tectonic evolution and the research on the metallogenic theory of the massive metal concentration, this paper has summed up some favorable geological conditions for ore-formation and ore-controlling, and with Jiaojia gold concentration belt as a case study and combined with the geophysical and geochemical data in this area, this paper has deduced the deep mineralization space with the three-dimensional geological modeling technique, which has achieved the integration of metallogenic theory and prospecting methods. The result indicates that forecast areas deep resources in the Jiaojia gold concentration belt is 842.88 t. More importantly, it delineated 7 undeveloped predicted targets for deep prospecting which provided a scientific basis for prospecting exploration.

A Multimodal Fusion Algorithm Based on FRR and FAR Using SVM

Yong Li,Meimei Shi,En Zhu,Jianping Yin,Jianmin Zhao 보안공학연구지원센터 2013 International Journal of Security and Its Applicat Vol.7 No.3

A Study on Multivariable Optimization in Precision Manufacturing Using MOPSONNS

Zhaopeng He,Tielin Shi,Jianping Xuan,Su Jiang,Yinfeng Wang 한국정밀공학회 2020 International Journal of Precision Engineering and Vol.21 No.11

7075 aluminum alloy has been widely applied in the field of aerospace and marine sheet metal because of its protruding mechanical and corrosion resistance. In this paper, the problem of selecting optimal process parameters to optimize multiple processing variables had been studied in precision manufacturing. Multi-objective particle swarm optimized neural networks system was put forward to determine the optimal cutting conditions with multi-objective particle swarm algorithm and multiple neural networks as prediction models of machining variables. Precision parts manufacturing of 7075 aluminum alloy would go through two operations of material removal and surface forming. Firstly, optimal cutting conditions were determined to minimize tool wear while maximizing metal removal rate in material removal stage. Secondly, it was significant and meaningful to select optimal cutting conditions corresponding to the best surface quality and minimum root mean square of tool vibration in surface forming stage. Orthogonal experiments had been carried out to observe the relationship between machining-related variables and cutting parameters in detail. Multiple neural networks were trained to establish predictive models of cutting process from orthogonal experimental and statistical data. Maximum deviation theory sorted the Pareto solutions searched by optimization process of neural networks driven by multi-objective particle swarm algorithm. The top ranking Pareto solutions had been determined as the optimal cutting parameters combination for material removal and surface forming stages, respectively. Finally, the proposed optimization system can also be used to optimize the processing of other difficult-to-machine materials.

An Improved and Efficient Analytical Model for Magnetic Field Calculation in Linear Permanent Magnet Machines

Baocheng Guo,Rong Guo,Hengzai Hu,Jianping Shi,Chunmei Feng 한국자기학회 2022 Journal of Magnetics Vol.27 No.1

A simple and improved analytical model (AM) for linear permanent magnet synchronous machine (LPMSM) based on the correction factor is presented in this paper. A slotless linear permanent magnet machine (PLPM) with AM developed in Cartesian coordinate is selected to investigate. Consequently, the fitting equations of curvature factors for the permanent magnet and armature are obtained. The subdomains for LPMSM are simplified from 6 down to 3 domains based on curvature equations. The magnetic flux density and force show that the proposed approach agrees with the finite element (FE) model. Moreover, the reduced calculation domains and harmonic orders make AM proposed in the paper much faster. The main contribution of the work is to present a simple strategy for coordinate transformation and calculation strategy for LPMSM, which provides guideline for designers to investigate the machines developed in Cartesian coordinate.