scholarly journals Non-Hertzian Elastohydrodynamic Contact Stress Calculation of High-Speed Ball Screws

2021 ◽  
Vol 11 (24) ◽  
pp. 12081
Author(s):  
Tiewei Sun ◽  
Min Wang ◽  
Xiangsheng Gao ◽  
Yingjie Zhao
Keyword(s):  
Contact Stress ◽  
Calculation Method ◽  
High Speed ◽  
Contact Region ◽  
Friction Torque ◽  
Wear Depth ◽  
Asperity Contact ◽  
Stress Calculation ◽  
Elastohydrodynamic Contact ◽  
The Asymmetry

In order to eliminate the calculation error of the Hertzian elastohydrodynamic contact stress due to the asymmetry of the contact region of the helix raceway, a non-Hertzian elastohydrodynamic contact stress calculation method based on the minimum excess principle was proposed. Firstly, the normal contact stresses of the screw raceway and the nut raceway were calculated by the Hertzian contact theory and the minimum excess principle, respectively. Subsequently, the Hertzian solution and the non-Hertzian solution of the elastohydrodynamic contact stress could be determined by the Reynolds equation under different helix angles and screw speeds. Finally, the friction torque test of the double-nut ball screws was designed and implemented on a self-designed bed for validation of the proposed method. The comparison showed that the experimental friction torque was the good agreement with the simulated friction torque, which verified the effectiveness and correctness of the non-Hertzian elastohydrodynamic contact stress calculation method. Under the large helix angle, the calculation accuracy of asperity contact stress for the non-Hertzian solution was more accurate than that of the Hertzian solution at the contact region of ball screws. Therefore, the non-Hertzian elastohydrodynamic contact stress considering the asymmetry of the raceway contact region could more accurately analyze the wear depth of the high-speed ball screws.

Dynamic Analysis of Spiral-Groove Rotary Seal Ring for Wet Clutches

2014 ◽  
Vol 136 (3) ◽  
Author(s):  
Yi M. Zhao ◽  
Ji B. Hu ◽  
Chao Wei
Keyword(s):  
High Speed ◽  
Friction Torque ◽  
Step Response ◽  
Asperity Contact ◽  
Seal Ring ◽  
Spiral Groove ◽  
Rotary Seal ◽  
Lubrication Performance ◽  
Bearing Force ◽  
Time Marching

A tribo-dynamic model of a spiral-groove rotary seal ring is developed through coupling lubrication and dynamic equations. Effects of centrifugation, hydrodynamics, cavitation, and asperity contact are considered. To represent real rough surfaces, asperity contact is described by a statistics-based model. A global time marching scheme is developed to obtain the motion of seal ring and key parameters such as bearing force, friction torque, and leakage rate. Dynamic behaviors and seal characteristics of spiral-groove rotary seal ring under real and step change oil filling conditions are analyzed. The result shows that the rotary seal ring operates steadily under real conditions and has fast and stable step response. It is also indicated that the seal ring can achieve full film lubrication under high speed conditions through the oil filling and dispersing stage. The steady lubrication performance is experimentally validated.

A Study of High-Speed Angular Contact Ball Bearing Thermo-Mechanical Coupling Characteristics

2013 ◽  
Vol 397-400 ◽  
pp. 131-134
Author(s):  
Chun Li Lei ◽  
Zhi Yuan Rui ◽  
Bao Cheng Zhou ◽  
Jing Fang Fang
Keyword(s):  
Contact Stress ◽  
High Speed ◽  
Thermal Deformation ◽  
Ball Bearing ◽  
Contact Region ◽  
Element Model ◽  
Machining Accuracy ◽  
Angular Contact Ball Bearing ◽  
Mechanical Coupling ◽  
Coupling Characteristics

Heat generation and deformation of bearing are key factors that influence the rigidity and machining accuracy of the high-speed precision spindle system. Based on heat transfer and thermodynamics, the finite element model of angular contact ball bearing is established for thermal deformation. The contact stress and thermal deformation are analyzed and obtained at a speed of . The results show that the maximum contact stress and thermal deflection appeared at contact region, which is in accordance with actual status. The results provide the reference and the theory basis for research into thermal deformation of bearing.

Optimization of crankpin bearing lubrication under dynamic loading considering effect of micro asperity contact

2020 ◽  
Vol 72 (10) ◽  
pp. 1173-1179
Author(s):  
Vanliem Nguyen ◽  
Zhenpeng Wu ◽  
Vanquynh Le
Keyword(s):  
Peer Review ◽  
High Speed ◽  
Contact Region ◽  
Simulation Method ◽  
Radial Clearance ◽  
Asperity Contact ◽  
Content Type ◽  
Research Results ◽  
Crank Mechanism ◽  
Tribology Performance

Purpose To improve the lubrication and tribology performance (LTP) of the crankpin bearing, this paper aims to propose the optimization of the crankpin bearing parameters considering effect of the high-speed dynamic load and micro asperity contact. Design/methodology/approach A numerical simulation method combined by the slider-crank-mechanism dynamic and lubrication models is applied to solve the dynamic and lubrication equations of crankpin bearing. These equations are then computed via an algorithm program written in Matlab software. The contact force (Wac) in the asperity contact region, friction force (Ff) and friction coefficient (μ) of crankpin bearing are chosen as objective functions. The original parameters and experimental data of the engine are used for the simulation to enhance the reliability of the research results. The parameters are then optimized to obtain the minimum values of Wac, Ff and μ. Findings The research results show that the LTP is significantly improved with optimized parameters. Particularly, the maximum values of Wac and Ff are greatly decreased by 27 and 32%, respectively. Originality/value Reducing the width, radius and surface roughness and increasing the radial clearance of crankpin bearing can improve better the LTP. Peer review The peer review history for this article is available at: https://publons.com/publon/10.1108/ILT-02-2020-0072/

Design of Electrolytic Strengthening Machine for Cutting Edge of Cutter

2016 ◽  
Vol 693 ◽  
pp. 1585-1590
Author(s):  
Yi Zhuo Guo ◽  
Xian Guo Yan ◽  
Shu Juan Li ◽  
Hong Guo
Keyword(s):  
Service Life ◽  
Calculation Method ◽  
High Speed ◽  
High Speed Steel ◽  
Cutting Edge ◽  
The Cost ◽  
Electric Quantity

Many studies have proved the service life of cutter can be prolonged by electrolytic strengthening. Based on the theory of electrolytic strengthening technology, this paper introduced and developed prototype equipment for strengthening cutting edge of rotary cutter and put forward a calculation method of total electric quantity consumption during the electrolysis suitable for microcontroller. The M8 high-speed steel tap is taken as a strengthening example. After finished the strengthening process that it clearly see the results of the surface of tap was obviously polished by observing the micrograph. This equipment improves the reliability of electrolytic strengthening and the cost is relatively cheap.

High-Resolution Measurements at Nucleate Boiling of Pure FC-84 and FC-3284 and Its Binary Mixtures

2009 ◽  
Vol 131 (12) ◽  
Author(s):  
Enno Wagner ◽  
Peter Stephan
Keyword(s):  
Binary Mixtures ◽  
High Speed ◽  
Contact Region ◽  
Infrared Camera ◽  
Nucleate Boiling ◽  
Heated Wall ◽  
Rear Side ◽  
Phase Contact ◽  
Pure Fluids ◽  
Three Phase

In a special boiling cell, vapor bubbles are generated at single nucleation sites on top of a 20μm thick stainless steel heating foil. An infrared camera captures the rear side of the heating foil for analyzing the temperature distribution. The bubble shape is recorded through side windows with a high-speed camera. Global measurements were conducted, with the pure fluids FC-84 and FC-3284 and with its binary mixtures of 0.25, 0.5, and 0.75mole fraction. The heat transfer coefficient (HTC) in a binary mixture is less than the HTC in either of the single component fluid alone. Applying the correlation of Schlünder showed good agreement with the measurements (1982, “Über den Wärmeübergang bei der Blasenverdampfung von Gemischen,” Verfahrenstechnik, 16(9), pp. 692–698). Furthermore, local measurements were arranged with high lateral and temporal resolution for single bubble events. The wall heat flux was computed and analyzed, especially at the three-phase-contact line between liquid, vapor, and heated wall. The bubble volume and the vapor production rate were also investigated. For pure fluids, up to 50–60% of the latent heat flows through the three-phase-contact region. For mixtures, this ratio is clearly reduced and is about 35%.

Grease soap particles passing through an elastohydrodynamic contact under side slip conditions

2000 ◽  
Vol 214 (4) ◽  
pp. 317-325 ◽  
Author(s):  
P Eriksson ◽  
V Wikström ◽  
R Larsson
Keyword(s):  
Film Thickness ◽  
High Speed ◽  
Previous Investigation ◽  
Video Camera ◽  
Slip Conditions ◽  
High Speed Video ◽  
Elastohydrodynamic Contact ◽  
High Speed Video Camera ◽  
Pure Rolling ◽  
Minimum Film Thickness

In a previous investigation, grease thickener fibres were tracked as they passed through an elastohydrodynamic (EHD) contact in pure rolling using interferometry in a standard ball-and-disc apparatus. In order to capture single thickener fibres, a high-speed video camera was used. Here, the experiments have been repeated introducing different amounts of side slip for different rolling speeds and a faster video camera capable of capturing 4500 frames/s. The contact was lubricated with a continuous supply of grease. Two greases, based on the same synthetic poly(α-olefin) but thickened with Li-12-OH and lithium complex soap respectively, were studied. It was observed that the thickener fibres were stretched both before entering the contact and as they passed through it. Fibres seem to avoid the minimum film thickness regions and, if they enter, the film is restored immediately after passage.

Numerical calculation of crack width in prestressed concrete beams with bond-slip effect

2019 ◽  
Vol 15 (2) ◽  
pp. 523-536
Author(s):  
Jinliang Liu ◽  
Yanmin Jia ◽  
Guanhua Zhang ◽  
Jiawei Wang
Keyword(s):  
Numerical Calculation ◽  
Numerical Model ◽  
Prestressed Concrete ◽  
Calculation Method ◽  
Crack Width ◽  
Calculation Model ◽  
Content Type ◽  
Bond Slip ◽  
Stress Calculation ◽  
Bonding Performance

Purpose The calculation of the crack width is necessary for the design of prestressed concrete (PC) members. The purpose of this paper is to develop a numerical model based on the bond-slip theory to calculate the crack width in PC beams. Design/methodology/approach Stress calculation method for common reinforcement after beam crack has occurred depends on the difference in the bonding performance between prestressed reinforcement and common reinforcement. A numerical calculation model for determining the crack width in PC beams is developed based on the bond-slip theory, and verified using experimental data. The calculation values obtained by the proposed numerical model and code formulas are compared, and the applicability of the numerical model is evaluated. Findings The theoretical analysis and experimental results verified that the crack width of PC members calculated based on the bond-slip theory in this study is reasonable. Furthermore, the stress calculation method for the common reinforcement is verified. Compared with the model calculation results obtained in this study, the results obtained from code formulas are more conservative. Originality/value The numerical calculation model for crack width proposed in this study can be used by engineers as a reference for calculating the crack width in PC beams to ensure the durability of the PC member.

Calculation method of dynamic loads spectrum and effects on fatigue damage of a full-scale carbody for high-speed trains

2019 ◽  
Vol 58 (7) ◽  
pp. 1037-1056 ◽  
Author(s):  
Yaohui Lu ◽  
Wei Bi ◽  
Xing Zhang ◽  
Jing Zeng ◽  
Tianli Chen ◽  
...  
Keyword(s):  
Fatigue Damage ◽  
Calculation Method ◽  
High Speed ◽  
Full Scale ◽  
Dynamic Loads ◽  
High Speed Trains

scholarly journals Influence of the Lubrication Oil Temperature on the Disengaging Dynamic Characteristics of a Cu-Based Wet Multi-Disc Clutch

2021 ◽  
Vol 11 (23) ◽  
pp. 11299
Author(s):  
Liangjie Zheng ◽  
Biao Ma ◽  
Man Chen ◽  
Liang Yu ◽  
Qian Wang
Keyword(s):  
Dynamic Characteristics ◽  
Hydrodynamic Lubrication ◽  
Friction Pair ◽  
Automatic Transmission ◽  
Friction Torque ◽  
Asperity Contact ◽  
Uniformity Coefficient ◽  
Lubrication Oil ◽  
The Impact ◽  
First Time

Clutch disengaging dynamic characteristics, including the disengaging duration and the variations of friction pair gaps and friction torque, are crucial to the shifting control of an automatic transmission. In the present paper, the influence of lubrication oil (ATF) temperature on disengaging dynamic characteristics is investigated through a comprehensive numerical model for the clutch disengaging process, which considers the hydrodynamic lubrication, the asperity contact, the heat transfer, the spline resistance, and the impact between the piston and clutch hub. Moreover, the non-uniformity coefficient (NUC) is proposed to characterize the disengaging uniformity of friction pairs. As the ATF temperature increases from 60 °C to 140 °C, the clutch disengaging duration shortens remarkably (shortened by 55.1%); besides, the NUC sees a decreasing trend before a slight increase. When the ATF temperature is 80 °C, the distribution of friction pair gaps is most uniform. During the disengaging process, the increase of ATF temperature not only accelerates the change of the lubrication status between friction pairs but also contributes to the decrease of contact torque and hydrodynamic torque. This research demonstrates for the first time, evidence for clutch disengaging dynamic characteristics with the consideration of ATF temperature.

Sign in / Sign up

Export Citation Format

Share Document