Research on torsional fretting wear behaviors and damage mechanisms of stranded-wire helical spring

Shilong Wang,Xiaoyong Li,Song Lei,Jie Zhou,Yong Yang 대한기계학회 2011 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.25 No.8

Wear on the local area of steel wires’ surface is attributed to torsional fretting on the working process of stranded-wire helical spring. A mathematical model to calculate normal contact force and angular displacement amplitude among the wires is established first when the spring is impacted. With the experimental parameters obtained from the model, the torsional fretting test, which stimulates torsional fretting among the wires in the working process of the spring, is realized successfully on a newly developed fretting tester. Torsional fretting behaviors are strongly dependent upon normal contact force, angular displacement amplitude, and number of cycles. There are three basic types of T-θ curves (short for torque), angular displacement curves during the process of torsional fretting, namely, parallelogram,elliptic, and linear T-θ curves. To analyze the damage mechanisms, distribution maps of oxygen in the wear scar of spring wires under different working conditions are revealed. The damage gets slight in the partial slip region, mainly with the abrasive wear and the slight oxidative wear, whereas the wear mechanisms are mainly the abrasive wear, the oxidative wear, and the delamination, accompanied with obvious plastic deformation in the mixed fretting and slip regions.

Mathematical model for determination of strand twist angle and diameter in stranded-wire helical springs

Shilong Wang,Song Lei,Jie Zhou,Hong Xiao 대한기계학회 2010 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.24 No.6

The twist angle of strands has a significant effect on the performance of stranded-wire helical springs. This paper proposes two models (a precise mathematical model and an approximate mathematical model) for calculation of the twist angle and the diameter of strands formed of an arbitrary number of wires. These two parameters can be derived from the screw pitch of strands and the diameter and number of their wires, regardless of the model used. In comparative and analytical studies, it was determined that for strands with the same number of wires, the larger the ratio of the screw pitch to the diameter of the wires is, the smaller the relative errors of the two models are. Only when the foresaid ratio is two times larger than the number of wires, the results of the approximate mathematical model can be acceptable. In other cases, the approximate mathematical model cannot be used. Finally, application software was developed for direct precise-mathematical-model calculation of the twist angle and diameter of strands formed of arbitrary wires.

The Analysis of Differences Between Residential Space Elements According to Chinese and Korean FengShui Theories

ShiLong Liu,Kyung-ran Lim 한국콘텐츠학회 2014 한국콘텐츠학회 ICCC 논문집 Vol.- No.-

Research on thermal deformation of large-scale computer numerical control gear hobbing machines

Shilong Wang,Yong Yang,Xianguang Li,Jie Zhou,Ling Kang 대한기계학회 2013 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.27 No.5

Research on thermal deformation of large-scale computer numerical control (CNC) hobbing machines is on the purpose of obtaining the law of thermal deformation of gear hobbing machines to improve machining precision. According to the structure characteristics of hobbing machines, this paper presents a novel computing model of thermal deformation based on the theory of the thermal expansion deformation of metallic materials, the extensional beam theory, non-uniform temperature distribution of the Euler-Bernoulli beam and Kirchhoff theory of plane-section assumption. Then, the coupling theory of axial and bending deformation of hobbing machines based on the deformation element and equilibrium element method is proposed. The experimental measurement system and platform for thermal deformation of gear hobbing machines is established. The temperature and displacement data of thermal deformation of a certain type gear hobbing machine is analyzed, which has demonstrated the law of thermal deformation of hobbing machines. The locus curves for overall displacement error of cutting points and teeth trace error are obtained. Comparing deformation theory and experimental data, the relative error is lower than 5%, which verifies the computing model proposed by this paper, and shows the research method has great significance for structural optimization, local temperature control, and prediction and compensation for thermal deformation error of gear hobbing machines.

A Mask Wearing Detection System Based on Deep Learning

Yang, Shilong,Xu, Huanhuan,Yang, Zi-Yuan,Wang, Changkun Korea Multimedia Society 2021 The journal of multimedia information system Vol.8 No.3

COVID-19 has dramatically changed people's daily life. Wearing masks is considered as a simple but effective way to defend the spread of the epidemic. Hence, a real-time and accurate mask wearing detection system is important. In this paper, a deep learning-based mask wearing detection system is developed to help people defend against the terrible epidemic. The system consists of three important functions, which are image detection, video detection and real-time detection. To keep a high detection rate, a deep learning-based method is adopted to detect masks. Unfortunately, according to the suddenness of the epidemic, the mask wearing dataset is scarce, so a mask wearing dataset is collected in this paper. Besides, to reduce the computational cost and runtime, a simple online and real-time tracking method is adopted to achieve video detection and monitoring. Furthermore, a function is implemented to call the camera to real-time achieve mask wearing detection. The sufficient results have shown that the developed system can perform well in the mask wearing detection task. The precision, recall, mAP and F1 can achieve 86.6%, 96.7%, 96.2% and 91.4%, respectively.

Fortress of meditation

Li Shilong 한국콘텐츠학회 2023 한국콘텐츠학회 ICCC 논문집 Vol.2023 No.12

Fortress of meditation

Li Shilong 한국콘텐츠학회 2023 ICCC International Digital Design Invitation Exhib Vol.2023 No.12

Enhanced friction model for high-speed right-angle gear dynamics

Zhiheng Feng,Shilong Wang,Teik C. Lim,Tao Peng 대한기계학회 2011 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.25 No.11

The modeling of elastohydrodynamic lubrication friction and the analysis of its dynamic effect on right-angle gears, such as hypoid and spiral bevel types are performed in the present study. Unlike the classically applied empirical constant coefficient of friction at the contacting tooth surfaces, the enhanced physics-based gear mesh friction model is both spatial and time-varying. The underlying formulation assumes mixed elastohydrodynamic lubrication (EHL) condition in which the division and load distribution between the full film and asperity contact zones are determined by the film thickness ratio and load sharing coefficient. In the proposed time-varying friction model, the calculation of friction coefficient is performed at each contact grid inside the instantaneous contact area that is being subjected to mineral oil lubrication. The effective friction coefficient and directional parameters synthesized from the net frictional and normal contact forces are then incorporated into a nonlinear time-varying right-angle gear dynamic model. Using this model, the effect of friction on the gear dynamic response due to the transmission error and mesh excitations is analyzed. Also, parametric studies are performed by varying torque, surface roughness and lubrication properties to understand the salient role of tooth sliding friction in gear dynamics. The simulation results are included. But experimental verification is needed.

An experimental investigation on heat transfer performance of pulsating heat pipe

Fumin Shang,Shilong Fan,Qingjing Yang,Jianhong Liu 대한기계학회 2020 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.34 No.1

Heat input and inclination angle are essential factors influencing heat transfer performance of a pulsating heat pipe (PHP). The heat transfer performance at different inclination angles is studied in this paper. The temperature distribution of a PHP at different inclination angles is obtained by using a thermocouple combined with an infrared thermal imager. The experimental results show that heat is distributed symmetrically under gravity assisted operation, and the average minimum thermal resistance is 0.17 K/W when the angle is 45°. When gravity inhibits circulation of the working fluid, temperature is distributed uniformly, and the thermal resistance increases up to a maximum value of 0.33 K/W. Meanwhile, during the gravity assist and suppression operation mode, the inclination angle only impacts the oscillating mode of the temperature. Particularly, when the angle is 90°, the PHP has the best mode of oscillation, with its heat resistance at 0.077 K/W.

Precision allocation optimization modeling of large-scale CNC hobbing machine based on precision reliability

Zongyan Hu,Shilong Wang,Chi Ma 대한기계학회 2023 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.37 No.2

Reducing manufacturing cost is the main goal of machine tool precision allocation under the condition of meeting precision design requirements. The previous studies generally took "ensuring machining errors completely within the allowable range of design precision" as constraint. Due to the strict constraint, the cost reduction effect is limited. This paper proposes a new method of precision allocation based on precision reliability. The probability that the machining errors are within the design precision allowable range is taken as the measurement index of precision reliability, and the optimization model constraint is relaxed to "that the machining errors are within the allowable range of design precision with predefined precision reliability", so as to obtain lower manufacturing cost under tolerable precision loss risk. The case study of a large-scale gear hobbing machine shows that this method can effectively reduce the manufacturing cost, and the precision allocation is more economical and reasonable.