Xiaoyu Chen, Yonggang Leng, Fei Sun, Xukun Su, Shuailing Sun and Junjie Xu
The existing Nonlinear Dynamic Vibration Absorbers (NLDVAs) have the disadvantages of complex structure, high cost, high installation space requirements and difficulty in…
Abstract
Purpose
The existing Nonlinear Dynamic Vibration Absorbers (NLDVAs) have the disadvantages of complex structure, high cost, high installation space requirements and difficulty in miniaturization. And most of the NLDVAs have not been applied to reality. To address the above issues, a novel Triple-magnet Magnetic Dynamic Vibration Absorber (TMDVA) with tunable stiffness, only composed of triple cylindrical permanent magnets and an acrylic tube, is designed, modeled and tested in this paper.
Design/methodology/approach
(1) A novel TMDVA is designed. (2) Theoretical and experimental methods. (3) Equivalent dynamics model.
Findings
It is found that adjusting the magnet distance can effectively optimize the vibration reduction effect of the TMDVA under different resonance conditions. When the resonance frequency of the cantilever changes, the magnet distance of the TMDVA with a high vibration reduction effect shows an approximately linear relationship with the resonance frequency of the cantilever which is convenient for the design optimization of the TMDVA.
Originality/value
Both the simulation and experimental results prove that the TMDVA can effectively reduce the vibration of the cantilever even if the resonance frequency of the cantilever changes, which shows the strong robustness of the TMDVA. Given all that, the TMDVA has potential application value in the passive vibration reduction of engineering structures.
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Keywords
Yuyang Zhang, Yonggang Leng, Hao Zhang, Xukun Su, Shuailing Sun, Xiaoyu Chen and Junjie Xu
An appropriate equivalent model is the key to the effective analysis of the system and structure in which permanent magnet takes part. At present, there are several equivalent…
Abstract
Purpose
An appropriate equivalent model is the key to the effective analysis of the system and structure in which permanent magnet takes part. At present, there are several equivalent models for calculating the interacting magnetic force between permanent magnets including magnetizing current, magnetic charge and magnetic dipole–dipole model. How to choose the most appropriate and efficient model still needs further discussion.
Design/methodology/approach
This paper chooses cuboid, cylindrical and spherical permanent magnets as calculating objects to investigate the detailed calculation procedures based on three equivalent models, magnetizing current, magnetic charge and magnetic dipole–dipole model. By comparing the accuracies of those models with experiment measurement, the applicability of three equivalent models for describing permanent magnets with different shapes is analyzed.
Findings
Similar calculation accuracies of the equivalent magnetizing current model and magnetic charge model are verified by comparison between simulation and experiment results. However, the magnetic dipole–dipole model can only accurately calculate for spherical magnet instead of other nonellipsoid magnets, because dipole model cannot describe the specific characteristics of magnet's shape, only sphere can be treated as the topological form of a dipole, namely a filled dot.
Originality/value
This work provides reference basis for choosing a proper model to calculate magnetic force in the design of electromechanical structures with permanent magnets. The applicability of different equivalent models describing permanent magnets with different shapes is discussed and the equivalence between the models is also analyzed.
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Dunying Deng, Yunfan Liao, Meichao Lin, Xiaxuan Xiong and Yonggang Tong
The purpose of this paper is to develop advanced materials with outstanding mechanical properties and high-temperature oxidation performance for their potential application in…
Abstract
Purpose
The purpose of this paper is to develop advanced materials with outstanding mechanical properties and high-temperature oxidation performance for their potential application in high-temperature structural components.
Design/methodology/approach
The alloy ingots with high-purity Co, Cr, Ni, Al and Y metals (= 99.9 Wt.%) were prepared in a vacuum arc melting furnace under an argon atmosphere.
Findings
This study investigated the impact of the Y content on the microstructure and oxidation behavior of CoCrNiAl medium entropy alloys at 1,200°C. All alloys exhibit a combination of ß and γ phases, with CoCrNiAlY 0.11revealing the presence of obvious sub-micron γ phase precipitates within the ß phase. The oxidation behavior of CoCrNiAlYx (x = 0.05, 0.08, 0.11) at 1,200°C demonstrates the formation of a dense oxide scale on the alloy surface. The surface with aluminum oxide accompanied by yttrium oxide exhibits improved adhesion between the matrix and oxide scale. The CoCrNiAlY0.11 alloy, with a decreased oxidation rate of 7.8 × 10–6 mg2 cm−4s−1, displays the best oxidation resistance among these alloys with varying Y content.
Originality/value
The study examines the optimal content of Y in the CoCrNiAl medium alloy and its superior oxidation behavior at 1,200°C.