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- 저자 : Wenzhan Yang (검색결과 3 건)
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Yanfei Guo,ZhouSuo Zhang,Wenzhan Yang,Jianbin Cao,Teng Gong 대한기계학회 2021 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.35 No.3
A novel method for early looseness state identification of bolted joint beams is proposed in this paper based on generalized variational mode decomposition (GVMD) and a similarity index. In the proposed method vibration signals are decomposed by GVMD, which has the property of the multiscale and fixed-frequency decomposition. To effectively extract the desired modes, the frequency band allocation is designed through flexibly defining scale parameters and prior center frequencies according to the characteristics of the signal itself and real needs. A new similarity index is formed based on the centroid frequency ratio of sensitive vibration modes to reliably identify early looseness state. The effectiveness of the proposed method is verified by impulse experiments of bolted joint transverse beam and bolted joint vertical beam. The results indicate that compared with other methods, the proposed method can effectively identify the early looseness state of the bolted joint beams, and has a good repeatability.
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Non uniform virtual material modeling on contact interface of assembly structure with bolted joints
Jianbin Cao,Zhousuo Zhang,Wenzhan Yang,Yanfei Guo 국제구조공학회 2019 Structural Engineering and Mechanics, An Int'l Jou Vol.72 No.5
Accurate modeling of contact interface in bolted joints is crucial in predicting the dynamic behavior for bolted assemblies under external load. This paper presents a contact pressure distribution based non-uniform virtual material method to describe the joint interface of assembly structure, which is connected by sparsely distributed multi-bolts. Firstly, the contact pressure distribution of bolted joints is obtained by the nonlinear static analysis in the finite element software ANSYS. The contact surface around bolt hole is divided into several sub-layers, and contact pressure in each sub-layer is thought to be evenly. Then, considering multi-asperity contact at the micro perspective, the relationship between contact pressure and interfacial virtual material parameters for each sub-layer is established by using the fractal contact theory. Finally, an experimental platform for the dynamic characteristics testing of a beam lap structure with double-bolted joint is constructed to validate the efficiency of proposed method. It is found that the theoretical results are in good agreement with experimental results by impact response in both time- and frequency-domain, and the relative errors of the first four natural frequencies are less than 1%. Furthermore, the presented model is used to examine the effect of rough contact surface on dynamic characteristics of bolted joint.
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Effects of Nickel Additive on Micro-Arc Oxidation Coating of AZ63B Magnesium Alloy
Wen Zhan,Feng Tian,Gui Ou-Yang,Bo-Yi Gui 한국정밀공학회 2018 International Journal of Precision Engineering and Vol.19 No.7
Based on environmentally friendly and green manufacturing of magnesium alloys, micro-arc oxidation coatings were prepared in optimized metasilicate solutions on AZ63B magnesium alloys surfaces. Effect of nickel additive on working voltage, surface morphology, thickness, hardness, composition and corrosion resistance of micro-arc oxidation coating of magnesium alloys was studied. The surface morphology, composition, microstructure and corrosion resistance of conversion coatings were investigated by using scanning electron microscopy (SEM), energy dispersion spectrometry (EDS), X-ray diffraction (XRD) and electrochemical tests respectively. The results show that brown coating was prepared in electrolyte with the addition of nickel acetate, which can accelerate growth of micro-arc oxide film layer and make the smaller hole on the surface. The micro-arc oxide coating mainly consists of Mg2SiO4, MgSiO3, MgAl2O4, Ni2SiO4. Potentiodynamic measurements and electrochemical impedance spectroscopy (EIS) testify that the corrosion resistant of micro-arc oxidation film adding nickel acetate electrolyte increases significantly.
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