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RISS 인기검색어
- 검색키워드
- 저자 : Zewei Li (검색결과 4 건)
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Experimental studies on behaviour of bolted ball-cylinder joints under axial force
Xiaonong Guo,Zewei Huang,Zhe Xiong,Shangfei Yang,Li Peng 국제구조공학회 2016 Steel and Composite Structures, An International J Vol.21 No.1
Due to excellent advantages such as better illuminative effects, considerable material savings and ease and rapidness of construction, the bolted ball-cylinder joint which is a new type joint system has been proposed in space truss structures. In order to reveal more information and understanding on the behaviour of bolted ball-cylinder joints, full-scale experiments on eight bolted ball-cylinder joint specimens were conducted. Five joint specimens were subjected to axial compressive force, while another three joint specimens were subjected to axial tensile force. The parameters investigated herein were the outside diameter of hollow cylinders, the height of hollow cylinders, the thickness of hollow cylinders, ribbed stiffener and axial force. These joint specimens were collapsed by excessive deformation of hollow cylinders, punching damage of hollow cylinders, evulsion of bolts, and weld cracking. The strain distributions on the hollow cylinder opening were mainly controlled by bending moments. To improve the ultimate bearing capacity and axial stiffness of bolted ball-cylinder joints, two effective measures were developed: (1) the thickness of the hollow cylinder needed to be thicker; (2) the ribbed stiffener should be adopted. In addition, the axial stiffness of bolted ball-cylinder joints exhibited significant non-linear characteristics.
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Numerical studies on behaviour of bolted ball-cylinder joint under axial force
Xiaonong Guo,Zewei Huang,Zhe Xiong,Shangfei Yang,Li Peng 국제구조공학회 2016 Steel and Composite Structures, An International J Vol.20 No.6
This paper presents the results of an extensive numerical analysis program devoted to the investigation of the mechanical behaviour of bolted ball-cylinder joints. The analysis program is developed by means of finite element (FE) models implemented in the non-linear code ABAQUS. The FE models have been accurately calibrated on the basis of available experimental results. It is indicated that the FE models could be used effectively to describe the mechanical performance of bolted ball-cylinder joints, including failure modes, stress distributions and loaddisplacement curves. Therefore, the proposed FE models could be regarded as an efficient and accurate tool to investigate the mechanical behavior of bolted ball-cylinder joints. In addition, to develop a further investigation, parametric studies were performed, varying the dimensions of hollow cylinders, rectangular tubes, convex washers and ribbed stiffener. It is found that the dimensions of hollow cylinders, rectangular tubes and ribbed stiffener influenced the mechanical behaviour of bolted ball-cylinder joints significantly. On the contrary, the effects of the dimensions of convex washers were negligible.
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Aerodynamic drag reduction based on static traveling wave structure
Xingjun Hu,Zewei Wang,Jiuchao Li,Guo Yu,Jingyu Wang,Wei Lan,Jinglong Zhang,Pengzhan Ma 대한기계학회 2022 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.36 No.5
To explore the influence of the traveling wave parameters on the aerodynamic characteristics of Ahmed models, the geometric model of the traveling wave wall is used as the study object, and the influence of the traveling wave geometric parameters on aerodynamic drag is studied by numerical simulation. A cosine-type traveling wave digital model is established on the basis of Ahmed’s original model. Results show that the static traveling wave structure can play a good role in reducing drag under some driving conditions. The traveling wave’s drag reduction characteristics are affected by the layout position, depth, wavelength, and other related parameters and more affected by driving speed. Finally, a group of working conditions with good drag reduction effects is selected, and the principle of drag reduction by using static traveling wave structure is explained qualitatively and quantitatively through velocity field, shear stress, and pressure field.
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Yiqun Wang,Yongpan Liu,Cong Wang,Zewei Li,Xiao Sheng,Hyung Gyu Lee,Naehyuck Chang,Huazhong Yang IEEE 2016 IEEE transactions on computer-aided design of inte Vol.35 No.2
<P>Energy harvesting from natural environment gives range of benefits for the Internet of things. Scavenging energy from photovoltaic (PV) cells is one of the most practical solutions in terms of power density among existing energy harvesting sources. PV power systems mandate the maximum power point tracking (MPPT) to scavenge the maximum possible solar energy. In general, a switching-mode power converter, an MPPT charger, controls the charging current to the energy storage element (a battery or equivalent), and the energy storage element provides power to the load device. The mismatch between the maximum power point (MPP) current and the load current is managed by the energy storage element. However, such architecture causes significant energy loss (typically over 20%) and a significant weight/volume and a high cost due to the cascaded power converters and the energy storage element. This paper pioneers a converter-less PV power system with the MPPT that directly supplies power to the load without the power converters or the energy storage element. The proposed system uses a nonvolatile microprocessor to enable an extremely fine-grain dynamic power management in a few hundred microseconds. This makes it possible to match the load current with the MPP current. We present detailed modeling, simulation, and optimization of the proposed energy harvesting system including the radio frequency transceiver. Experiments show that the proposed setup achieves an 87.1% of overall system efficiency during a day, 30.6% higher than the conventional MPPT methods in actual measurements, and thus a significantly higher duty cycle under a weak solar irradiance.</P>
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