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RISS 인기검색어
- 검색키워드
- 저자 : Hongchao Wu (검색결과 3 건)
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Tangential Damping Model of Bolted Joint with the Physics-Based Friction Coefficient
Yongsheng Zhao,Hongchao Wu,Congbin Yang,Zhifeng Liu,Qiang Cheng 한국정밀공학회 2021 International Journal of Precision Engineering and Vol.22 No.5
The stiff ness and damping modeling of joint surfaces are important for analyzing the dynamic characteristics of bolted joints, which has a great influence on the working precision of the machine tool. In this paper, a damping model is presented to predict the tangential damping of the joint accurately. The fractal theory is introduced to characterize the rough contact surface by using fractal dimension D and fractal roughness parameter G. For each micro-contact, the contact region can be divided into stick section and slip one. The energy dissipation of the micro-contact, which can be described as the tangential damping of bolted joint, emerges in the slip section. The physics-based friction coefficient is introduced to define the energy dissipation function based on the relationship between the deformation of micro-contact and the normal pressure. The energy dissipation factor and the proportional damping of the micro-contact can be obtained. The total tangential damping of bolted joint can be obtained by integrating the whole contact surfaces. Experimental set-up is designed to verify the proposed model. Compared with the constant friction coefficient damping model, the results show that the proposed model can more accurately describe the tangential damping of bolted joint.
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Wenjuan Lou,Huihui Wu,Zuopeng Wen,Hongchao Liang 한국풍공학회 2022 Wind and Structures, An International Journal (WAS Vol.34 No.2
The galloping of iced conductors has long been a severe threat to the safety of overhead transmission lines. Compared with normal transmission lines, the ultra-high-voltage (UHV) transmission lines are more prone to galloping, and the damage caused is more severe. To control the galloping of UHV lines, it is necessary to conduct a comprehensive analysis of galloping characteristics. In this paper, a large-span 1000-kV UHV transmission line in China is taken as a practical example where an 8-bundled conductor with D-shaped icing is adopted. Galerkin method is employed for the time history calculation. For the wind attack angle range of 0°~180°, the galloping amplitudes in vertical, horizontal, and torsional directions are calculated. Furthermore, the vibration frequencies and galloping shapes are analyzed for the most severe conditions. The results show that the wind at 0°~10° attack angles can induce large torsional displacement, and this range of attack angles is also most likely to occur in reality. The galloping with largest amplitudes in all three directions occurs at the attack angle of 170° where the incoming flow is at the non-iced side, due to the strong aerodynamic instability. In addition, with wind speed increasing, galloping modes with higher frequencies appear and make the galloping shape more complex, indicating strong nonlinear behavior. Based on the galloping amplitudes of three directions, the full range of wind attack angles are divided into five galloping regions of different severity levels. The results obtained can promote the understanding of galloping and provide a reference for the anti-galloping design of UHV transmission lines.
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Mishan Zhong,Jin Liu,Zhenghong Liu,Jundian Chen,Hongchao Yu,Haipeng Wang,Junshi Lu,Zijie Wu,Mingchen Pan,Liaoning Geological Exploration Institute Co., Ltd.,Yilong Wang 한국지질과학협의회 2023 Geosciences Journal Vol.27 No.4
The timing of the collision between the Songnen–Zhangguangcai Range Block (SNZRB) and the Jiamusi Block (JMSB) is poorly constrained; however, detrital zircons may provide crucial information on the history of this collision. This study focuses on the Yangmugang and Tumenling formations of the Yimianpo Group in the southeastern SNZRB, which were previously thought to have been deposited during the closure of the Mudanjiang Ocean. Detrital zircon U-Pb dating was carried out to constrain the age, provenance, and tectonic setting of the Yangmugang and Tumenling formations, and ultimately the timing of the final closure of the Mudanjiang Ocean. The detrital zircon grains in the two formations yield similar age spectra, with two major age peaks at 275 Ma and 280 Ma, 512 Ma and 525 Ma, respectively. Given the age of the youngest group and that of a granite intrusion, the Yangmugang and Tumenling formations were probably deposited during the middle Permian. The detrital zircon ages also suggest that the Paleozoic igneous rocks distributed across the eastern SNZRB were the major source of the zircons in the formations. Combined with evidence for synchronous arc magmatism, this shows that the Yangmugang and Tumenling formations were likely deposited at a convergent margin and that the collision between the SNZRB and JMSB occurred after the late Permian.
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