Automatic discrete failure study of cage free ball bearings based on variable diameter contact

Yanling Zhao,Jingwei Zhang,Enwen Zhou 대한기계학회 2021 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.35 No.11

A motion model of adjacent rollers and a contact model between rollers and raceways were established to improve the Archard wear model, and the automatic discrete failure conditions of bearing without cage were studied by combining finite element and experiment. The results show that adjacent rollers produce discrete spacing when passing through the reducer raceway, and the automatic discrete failure depends on the wear depth of the reducer raceway. The wear depth is related to the wear times. The wear depth increases linearly with the increase of wear times to a certain extent. The discrete spacing generated by the reducer raceway is not enough to disperse the adjacent rollers. The experimental results show that the wear depth of reducer raceway increases with the increase of bearing operation time, and the error decreases with the increase of wear time. The theoretical calculation value is slightly larger than the experimental value, and the average error is within an acceptable range, which verifies the correctness of the automatic discrete failure model and the automatic discrete numerical simulation.

Discrete theory of rolling elements for a cageless ball bearing

Yanling Zhao,Qiyu Wang,Mingzhu Wang,Chengyi Pan,Yudong Bao 대한기계학회 2022 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.36 No.4

For the case of magnetic levitation loss, the rotor of an active magnetic bearing is forced by gravity to drop onto stator laminations, and cageless touchdown bearings with high rigidity and load-bearing capacity ensure back-up support. However, the contact collision of rolling elements in a cageless bearing will lead to deterioration of bearing performance and instability of the rotor system. For this purpose, a method based on noncontact between adjacent rolling elements in cageless bearings is proposed in this paper. First, combined with space geometry, the contact process and the change in radius of rotation when a rolling element passes through a discrete groove are analysed, and a clearance between the adjacent rolling elements is generated by changing the rotation speed. Based on this, a design principle for setting a discrete groove on an outer ring raceway is proposed, and the equation for the circumferential discrete clearance for the rolling element based on bearing kinematics is given. Combined with the characteristics of discrete groove structures, a differential equation for the discrete dynamics of rolling elements with variable stiffness coefficients is proposed. We then determine the influence of the discrete groove structure on the discrete motion of the rolling element and bearing dynamic characteristics. Third, the dynamics simulation is combined with a vibration characteristics experiment and discrete motion experiment for a rolling element in a cageless bearing. Our research results show that a discrete groove design for the raceway can be used to realize stable discrete motion of the rolling element, and that such a discrete groove structure will not adversely affect the vibration characteristics of the bearing. The feasibility of the discrete design of cageless bearings with rolling element is verified, and theoretical guidance for the development and application of cageless bearings is provided.

Waste-to-energy: biobutanol production from cellulosic residue of sweet potato by Clostridia acetobutylicum

Yanling Jin,Liang Zhang,Zhuolin Yi,Yang Fang,Hai Zhao 대한환경공학회 2022 Environmental Engineering Research Vol.27 No.5

Biobutanol has been emerging as a renewable replacement to overcome fossil fuel limit due to its attractive qualities. The waste resources utilization is an economically feasible and eco-friendly way to produce biobutanol. In this work, the potential of butanol fermentation with sweet potato residue (SPR) obtained from ethanol fermentation was evaluated. To assist sugar release for butanol production by Clostridia acetobutylicum, a pretreatment approach with dilute sulfuric acid was established via response surface methodology. The maximum butanol concentration of 3.77 g/L was obtained at the optimal conditions of pretreatment at 1% (v/v) dilute sulfuric acid, and 115℃ for 30 min. Detoxifying the hydrolysate with XAD-4 resin significantly enhanced butanol fermentation performance, while adding nutritional supplements had no significant influence. The stability of the fermentation process was verified by the 2 L-scale of fermentation, resulting in 7.96 g/L of butanol, 13.42 g/L h of Acetone-Butanol-Ethanol (ABE), and 0.34 g/g of ABE yield, respectively. This study demonstrates a bio-refinery strategy of conversion from waste biomass to energy, confirms the feasibility of utilizing the cost saving SPR as feedstock to produce butanol through fermentation, and provides a novel approach for minimization of environmental pollution.

Effect of High-Energy Electro-Pulses on the Compression Deformation Behavior of Ti-6Al-4V Alloy

Zhiyong Zhao,Hongliang Hou,Ning Zhang,Yanling Zhang,Yaoqi Wang,Guofeng Wang 대한금속·재료학회 2016 METALS AND MATERIALS International Vol.22 No.4

Compression tests of Ti–6Al–4V alloy were conducted using an electron universal testing machine with discharge voltages that range from 50 V to 70 V and strain rate of 0.01 s −1 . Isothermal compression at equivalent temperatures was also performed on a universal testing machine with furnace, with the same strain rate. Results show that the deformability of Ti–6Al–4V alloy can be significantly improved by high-energy electro-pulses, and the deformation resistance and yield stress were also decreased. Moreover, the effect of high-energy electropulses on compression mechanical properties of Ti–6Al–4V alloy increased with increasing discharge voltage. However, elongation and deformation resistance of compressions with high-energy electro-pulses were higher than isothermal compressions at equivalent temperatures. This result proved that the deformability improvement of Ti–6Al–4V alloy by high-energy electro-pulses results from the joint effects of temperature and electro-plasticity. Fracture modes in different experimental conditions were analyzed by observing the fracture morphologies of specimens by using a scanning electron microscope. Under high-energy electro-pulses, the micro morphology of compression fracture changes from elongated oval to equiaxed dimples, and the fracture modes transfer from intergranular to transgranular fracture.

《Castle peak》Celadon tea set design

Zhou Yanling,Zhao Xin 한국디자인학회 2023 한국디자인학회 국제초대전도록 Vol.2023 No.10

Correlations of Fecal Bacterial Communities with Age and Living Region for the Elderly Living in Bama, Guangxi, China

Liang Zhao,Xuewei Qiao,Jun Zhu,Xiaoying Zhang,Jingli Jiang,Yanling Hao,Fazheng Ren 한국미생물학회 2011 The journal of microbiology Vol.49 No.2

Bama County (Guangxi, China) is famous for its longevous population. In this study, intestinal microflora of 17 healthy elderly subjects of different ages and from different regions (rural and urban) in Bama,were analyzed by denaturing gradient gel electrophoresis (DGGE). Significant effects of age and living region on the whole intestinal bacterial communities were observed by redundancy analysis (RDA). A total of 11 bacterial strains that were correlated with age and living region were identified using a t-value biplot combined with band sequencing. Four bacterial strains were correlated with both age and living region of the elderly in Bama. Two Bacteroides strains and one Ruminococcaceae strain were abundant in the rural, younger elderly; conversely, one Desulfovibrio strain was high in the urban, older elderly. Another Bacteroidetes strain was only correlated with the participant’s age, and its abundance increased with the age of the elderly. The richness of one Clostridium sordellii strain, which was only correlated with the elderly living region, was high in the urban elderly. The study also found five other novel bacterial strains that were correlated with the age or living region of the elderly in Bama. These results expand our understanding of age- and region-effects on the intestinal microflora of the elderly and raise the possibility of developing probiotics originating from centenarians.

Design of FBG Demodulation System Based on Arrayed Waveguide Grating

Mingze Wu,Yanling Xiong,Naikui Ren,Junsheng Han,Lei Zhao 보안공학연구지원센터 2016 International Journal of Smart Home Vol.10 No.7

Array waveguide grating(AWG) is a kind of role scattered light passive device base on the plane wave circuit technology. A broadband laser beam can be divided into multi-beam laser light by wavelength. In this paper, the characteristics of AWG are used and based on previous studies. Using an array waveguide grating fiber Bragg grating (FBG) demodulation method, and the mathematical model of FBG is set up in theory. With the simulation analysis, the linear relationship between the AWG dual channel optical power ratio and the FBG central wavelength is obtained. The linear relationship was verified by experiments.

Study on Thermal Load Capacity of Transmission Line Based on IEEE Standard

Fan Song,Yanling Wang,Lei Zhao,Kun Qin,Likai Liang,Zhijun Yin,Weihua Tao 한국정보처리학회 2019 Journal of information processing systems Vol.15 No.3

With the sustained and rapid development of new energy sources, the demand for electric energy is increasingday by day. However, China’s energy distribution is not balanced, and the construction of transmission lines isin a serious lag behind the improvement of generating capacity. So there is an urgent need to increase theutilization of transmission capacity. The transmission capacity is mainly limited by the maximum allowableoperating temperature of conductor. At present, the evaluation of transmission capacity mostly adopts the staticthermal rating (STR) method under severe environment. Dynamic thermal rating (DTR) technique canimprove the utilization of transmission capacity to a certain extent. In this paper, the meteorological parametersaffecting the conductor temperature are analyzed with the IEEE standard thermal equivalent equation ofoverhead transmission lines, and the real load capacity of 220 kV transmission line is calculated with 7-yearactual meteorological data in Weihai. Finally, the thermal load capacity of DTR relative to STR under givenconfidence is analyzed. By identifying the key parameters that affect the thermal rating and analyzing therelevant environmental parameters that affect the conductor temperature, this paper provides a theoretical basisfor the wind power grid integration and grid intelligence. The results show that the thermal load potential oftransmission lines can be effectively excavated by DTR, which provides a theoretical basis for improving theabsorptive capacity of power grid.

Study on design and simulation of a novel isolator cylindrical roller bearing

Chengyi Pan,Chuan Wang,Yanling Zhao,Guanqun Cao 대한기계학회 2022 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.36 No.8

The sliding friction of the cylindrical roller bearing makes the internal resistance of the bearing large. Thus, this paper proposes to replace the cage with rolling isolators being placed between the cylindrical rollers, making the rub of all the elements be rolling friction. Therefore, the driving torque of the bearing is greatly reduced. First, the structure and working principle of this kind of bearing are described, the geometric parameter relationship of the roller and the isolator is analyzed, the feasible range of the parameters of the isolator is deduced based on the NFL203V type cageless bearing is proposed. Then, the ADAMS software is used for motion simulation of this novel cylindrical roller bearing. The best design plan is obtained through a comparison of the different schemes. Finally, experiments of bearing temperature are conducted, which shows the working temperature of the isolator cylindrical roller bearing is lower than that of the traditional roller bearings.

Microstructure and tribological properties of Stellite 12 coating by laser cladding on 304 stainless steel surface

Rui Wang,Changyao Ouyang,Yanling Li,Chunjiang Zhao,Qiaofeng Bai 대한기계학회 2023 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.37 No.8

In the present study, the Stellite 12 coating was prepared on 304 stainless steel using laser cladding technology. The phase composition, microstructure, and friction behavior of the cladding layer under the four loads were analyzed. The results showed severe lattice distortion in the coating. As the temperature gradient and solidification rate were diverse in each region, the upper, middle, and lower sections of the coating layer exhibited various microstructure morphologies. The intergranular part of the cladding layer was mainly the eutectic structure, and the inner crystal was mainly Co solid solution. Spalling and adhesive phenomena appeared at the bottom of the specimen when the action was under a load of 90 N and 150 N. The average wear of the cladding layer improved with the increase in load, the shear stress and temperature in the contact zone were enhanced distinctly, and the specimen became more prone to plastic deformation and wear intensification.