Design and Modeling for 2D Plate Type MR Damper

A two-dimensional magnetorheological damper is developed for the engineering two-dimensional damping need. The velocity and pressure distribution model of the two-dimensional plate-type damper, and the damping force calculation model are established based on the Navier-Stokes equation. Several structural and physical parameters, including the working gap δ, the length a, and the width a of the middle slide plate, are analyzed theoretically. The damping performance of the two-dimensional plate-type magnetorheological damper was evaluated using a two-dimensional vibration test-bed, with the effect of the excitation current analyzed. The experimental results suggest a significant influence of Coulomb damping force on the damping force of magnetorheological damper when using appropriate magnetorheological fluid. As the excitation current increases, the damping force of magnetorheological damper becomes larger while the system amplitude decreases gradually in both directions, a maximum reduction of 2.5956 times. It's confirmed that the design of the two-dimensional plate-type magnetorheological damper is reasonable

Enhance the viscosity properties of ball-shaped Carbonyl iron based magnetorheological fluid by adding glass particles

In this study, the effect of nonmagnetizable glass particles to the viscosity properties of the ball-shaped Carbonyl iron based magnetorheological fluid containing a mixture of magnetizable and nonmagnetizable particles were investigated. Two different MR fluids with different mass fraction of Carbonyl iron and glass particles were tested in the experiments. Experiment results show that the viscosity is greatly improved when the glass particles are added in the magnetorheological fluid. When the added glass particles mass fraction up to 10%, the viscosity is at the highest value under the application of the currents, nearly 7 times larger than MRF-60 without glass particles. MRF-60, MRF-65 two different magnetorheological fluids exhibits similar phenomena. The proper amount of glass particles can enhance the viscosity of the magnetorheological fluid

Fault Diagnosis for the Hydraulic System by Using Autoregressive Trispectrum and its Slices

This paper addresses the development of a condition monitoring procedure for mechanical parts which involves time series higher-order spectra analysis. Several approaches based on autoregressive (AR) bispectrum, trispectrum and its slices are investigated as data mining techniques in the fault diagnosis of hydraulic control valves. The characteristics of vibration signals obtained from the control valves have been extracted by means of analyzing the 2-dimensional and diagonal slices of bispectrum and trispectrum, with the main goal of detecting a possible working condition including the normal and fault conditions. The experimental analysis shows that there are distinct bump values in the center of the two-dimensional slices of trispectrum space in the fault conditions, on the contrast, the bump values disappear in normal condition. Comparisons have been done between trispectrum and bispectrum. Results show the slices of the trispectrum reveal the corresponding bispectrum and its slices for diagnosing the faults of the hydraulic control valves. The experimental and theoretical results have indicated that trispectrum is a more suitable tool for diagnosing the faults of the hydraulic control valves

Evolution of material removal in the magnetorheological polishing of Ti6Al4V by laser power bed fusion

This study aimed to obtain super smooth surface medical implant laser power bed fusion Ti6Al4V samples. A self-modified magnetorheological polishing device and polishing fluid were used to polish the laser power bed fusion additive shaped Ti6Al4V samples to study the effect of the main factors such as abrasive grain size, polishing pressure, and polishing time on the surface roughness and material-removal efficiency of the samples. With continuously decreased Al2O3 abrasive-particle size, the surface roughness initially increased and then decreased, and the material-removal rate decreased. The polishing result of 5 µm Al2O3 was better, no new scratch damage was found after 3 µm Al2O3 polishing; With increased polishing pressure from 5 N to 25 N, the deeper the abrasive particles were pressed, the greater the cutting effect and the more obvious the scratches. Surface roughness initially decreased and then increased, and the material-removal rate increased from 1.19 nm/min to 8.68 nm/min. With continuously extended polishing time, the grinding and polishing effect continued to accumulate, and the surface quality significantly improved, decreasing from 366.33 nm to 19.77 nm. These results showed that magnetorheological polishing technology was very effective in removing LPBF forming defects; the surface roughness was reduced by 96.27% and the additive defects can be completely removed

Polishing Performance and Removal Mechanism of Core-Shell Structured Diamond/SiO2 Abrasives on Sapphire Wafer

Corrosive and toxic solutions are normally employed to polish sapphire wafers, which easily cause environmental pollution. Applying green polishing techniques to obtain an ultrasmooth sapphire surface that is scratch-free and has low damage at high polishing efficiency is a great challenge. In this paper, novel diamond/SiO2 composite abrasives were successfully synthesized by a simplified sol-gel strategy. The prepared composite abrasives were used in the semi-fixed polishing technology of sapphire wafers, where the polishing slurry contains only deionized water and no other chemicals during the whole polishing process, effectively avoiding environmental pollution. The experimental results showed that diamond/SiO2 composite abrasives exhibited excellent polishing performance, along with a 27.2% decrease in surface roughness, and the material removal rate was increased by more than 8.8% compared with pure diamond. Furthermore, through characterizations of polished sapphire surfaces and wear debris, the chemical action mechanism of composite abrasives was investigated, which confirmed the solid-state reaction between the SiO2 shell and the sapphire surface. Finally, applying the elastic-plastic contact model revealed that the reduction of indentation depth and the synergistic effect of chemical corrosion and mechanical removal are the keys to improving polishing performance

Efficient algorithm for directed text detection based on rotation decoupled bounding box

A more effective directed text detection algorithm is proposed for the problem of low accuracy in detecting text with multiple sources, dense distribution, large aspect ratio and arbitrary alignment direction in the industrial intelligence process. The algorithm is based on the YOLOv5 model architecture, inspired by the idea of DenseNet dense connection, a parallel cross-scale feature fusion method is proposed to overcome the problem of blurring the underlying feature semantic information and deep location information caused by the sequential stacking approach and to improve the multiscale feature information extraction capability. Furthermore, a rotational decoupling border detection module, which decouples the rotational bounding box into horizontal bounding box during positive sample matching, is provided, overcoming the angular instability in the process of matching the rotational bounding box with the horizontal anchor to obtain higher-quality regression samples and improve the precision of directed text detection. The MSRA-TD500 and ICDAR2015 datasets are used to evaluate the method, and results show that the algorithm measured precision and F1-score of 89.2% and 88.1% on the MSRA-TD500 dataset, respectively, and accuracy and F1-score of 90.6% and 89.3% on the ICDAR2015 dataset, respectively. The proposed algorithm has better competitive ability than the SOTA text detection algorithm

sj-docx-1-pie-10.1177_09544089221124226 - Supplemental material for Synthesis of Al₂O₃/SiO₂ core–shell composite abrasives toward ultrasmooth and high-efficiency polishing for sapphire wafers

Supplemental material, sj-docx-1-pie-10.1177_09544089221124226 for Synthesis of Al2O3/SiO2 core–shell composite abrasives toward ultrasmooth and high-efficiency polishing for sapphire wafers by Yongchao Xu, Guangen Zhao, Qianting Wang and Youji Zhan, Bingsan Chen in Proceedings of the Institution of Mechanical Engineers, Part E: Journal of Process Mechanical Engineering</p