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Zuocai Dai,Shanyong Chen,Xuhui Xie,Lin Zhou 한국정밀공학회 2019 International Journal of Precision Engineering and Vol.20 No.8
Surface damage has great influence on optical properties, especially the laser-induced damage threshold of optics, and it has become a difficult and basic issue to find suitable methods to efficiently remove the surface damage for improving the surface quality. In this paper, the characteristic evolution of brittle scratch and ground/lapped surface damage during inductively coupled plasma etching (ICPE) process are experimentally investigated on fused silica. Results of damage removal tests show ICPE can efficiently remove brittle scratch and eliminate the lateral and medial cracks. The PV (peak to valley) and RMS (root mean square) values of surface roughness increase with the exposure of lateral and medial cracks, and then gradually decreases with further etching. Finally, the ground and lapped fused silica surfaces with a size of 300 × 300 × 20 mm3 are efficiently processed by ICPE. The power spectral density analysis further demonstrates that the damage can be efficiently removed by ICPE. This study reveals the damage evolution during ICPE process and also provides technical guidance for optimizing the efficient damage removal process to rapidly improve surface quality, precision and fabrication efficiency of fused silica optics.
Effect of Grinding Parameters on Industrial Robot Grinding of CFRP and Defect Formation Mechanism
Fangyuan Wang,Shanyong Xuan,Zongyu Chang,Kai Jin,Yulong Gao,Hao Wang,Qiye Song 한국정밀공학회 2024 International Journal of Precision Engineering and Vol.11 No.2
The use of industrial robots for grinding CFRP is a green processing method. This method not only allows in-situ repair to reduce unnecessary waste of resources, but also produces no excessive contaminants. The effect of various process parameters, including grinding directions, the mesh size of grinding heads and rotating speed, on the grinding quality of Carbon Fiber Reinforced Polymers (CFRP) using industrial robots was investigated. The mechanism of grinding defects was also studied. According to the experimental results, the CFRP grinding process is mainly controlled by the rotating speed, number of grinding heads, and grinding direction. In particular, high-speed grinding helps to improve the surface quality of CFRP. In turn, the use of diamond grinding heads with too small or too large particles may reduce surface quality. Grinding quality changes with the grinding direction. In the grinding direction between 0° and 90°, the surface roughness increases with the angle (but drops at 60°), and The same trend is observed in the grinding direction between 90° and 150°, whereby the surface roughness increases with the angle (but drops at 120°). The surface quality of CFRP is thereby improved after grinding in the direction of 0°, 60°, 120° and 180°. Furthermore, the fiber pull-out occurs, when the feed direction and fiber orientation are aligned. Finally, the low-frequency vibration easily causes fiber pull-out defects.
Design and experimental demonstration of coaxially folded all-reflective imaging system
Yupeng Xiong,Yifan Dai,Shanyong Chen,Guipeng Tie 한국광학회 2019 Current Optics and Photonics Vol.3 No.3
With slimmer, lighter and all-reflective imaging systems in high demand for consumer and military applications, coaxially folded optical image systems are widely considered because they can extend focal length and reduce track length. Most of these systems consist of multiple surfaces, and these surfaces are machined on one element or grouping processing on two elements. In this paper, we report and first experimentally demonstrate an all-aluminum all-reflective optical system which consists of two optical elements, with two high order aspherical surfaces in each element. The coaxially folded system is designed with Seidel aberration theory and advanced optimization with Zemax. The system is made of all-aluminum material processing by single point diamond turning (SPDT). On this basis, we completed the system integration and performed an imaging experiment. The final system has the advantages of short track length and long focal length and broad application prospects in the micro-unmanned aerial vehicle field.
Filtration-induced pressure evolution in permeation grouting
Zilong Zhou,Haizhi Zang,Shanyong Wang,Xin Cai,Xueming Du 국제구조공학회 2020 Structural Engineering and Mechanics, An Int'l Jou Vol.75 No.5
Permeation grouting is of great significance for consolidating geo-materials without disturbing the original geo-structure. To dip into the filtration-induced pressure increment that dominates the grout penetration in permeation grouting, nonlinear filtration coefficients embedded in a convection-filtration model were proposed, in which the volume of cement particles in grout and the deposited particles of skeleton were considered. An experiment was designed to determine the filtration coefficients and verify the model. The filtration coefficients deduced from experimental data were used in simulation, and the modelling results matched well with the experimental ones. The pressure drop revealed in experiments and captured in modelling demonstrated that the surge of inflow pressure lagged behind the stoppage of flow channels. In addition, both the consideration of the particles loss in liquid grout and the number of filtrated particles on pore walls presented an ideal trend in filtration rate, in which the filtration rate first rose rapidly and then reached to a steady plateau. Finally, this observed pressure drop was extended to the grouting design which alters the water to cement (W/C) ratio so as to alleviate the filtration effect. This study offers a novel insight into the filtration behaviour and has a practical meaning to extend penetration distance.
A new reconfigurable liquid-metal-antenna-based sensor
Xiao-Ping Zhou,Yihui Fu,Hantao Zhu,Zihao Yu,Shanyong Wang 국제구조공학회 2022 Smart Structures and Systems, An International Jou Vol.30 No.4
In this paper, a new sensor chip with frequency reconstruction range of 2.252 GHz ~ 2.450 GHz is designed and fabricated. On this basis, a self-designed "T-shaped" shell is added to overcome the disadvantage of uneven deformation of the traditional steel shell, and the range of the sensor chip is expanded to 0 kN ~ 96 kN. The liquid metal antenna is used to carry out a step-by-step loading test, and the relationship between the antenna resonance frequency and the pressure load is analyzed. The results show that there is a good linear relationship between the pressure load and the resonant frequency. Therefore, the liquid metal antenna can be regarded as a pressure sensor. The cyclic loading and unloading experiments of the sensor are carried out, and different loading rates are used to explore the influence on the performance of the sensor. The loading and unloading characteristic curves and the influence characteristic curves of loading rate are plotted. The experimental results show that the sensor has no residual deformation during the cycle of loading and unloading. Moreover, the influence of temperature on the performance of the sensor is studied, and the temperature correction formula is derived.