scholarly journals Analyses of Influence of Frictional Heat on the Contact Stress of High-speed Micro-gears

2015 ◽  
Vol 28 (4) ◽  
pp. 244-248
Author(s):  
Cheol Kim ◽  
Hyeong-Seok Kim
Keyword(s):  
Contact Stress ◽  
High Speed ◽  
Frictional Heat

scholarly journals Operating temperatures of oil-lubricated medium-speed gears: Numerical models and experimental results

2003 ◽  
Vol 217 (2) ◽  
pp. 87-106 ◽  
Author(s):  
H Long ◽  
A A Lord ◽  
D T Gethin ◽  
B J Roylance
Keyword(s):  
Heat Transfer ◽  
Heat Flux ◽  
Surface Temperature ◽  
Rotational Speed ◽  
High Speed ◽  
Applied Load ◽  
Frictional Heat ◽  
Transfer Coefficients ◽  
Gear Teeth ◽  
Heat Transfer Coefficients

This paper investigates the effects of gear geometry, rotational speed and applied load, as well as lubrication conditions on surface temperature of high-speed gear teeth. The analytical approach and procedure for estimating frictional heat flux and heat transfer coefficients of gear teeth in high-speed operational conditions was developed and accounts for the effect of oil mist as a cooling medium. Numerical simulations of tooth temperature based on finite element analysis were established to investigate temperature distributions and variations over a range of applied load and rotational speed, which compared well with experimental measurements. A sensitivity analysis of surface temperature to gear configuration, frictional heat flux, heat transfer coefficients, and oil and ambient temperatures was conducted and the major parameters influencing surface temperature were evaluated.

The Study of Thermal Raising and Transmission Torque of High Speed Ball-Screw Lubricated by Different Greases

2015 ◽  
Vol 642 ◽  
pp. 212-216
Author(s):  
Yi Haung ◽  
Chin Chung Wei
Keyword(s):  
Contact Area ◽  
Axial Load ◽  
High Speed ◽  
Performance Test ◽  
Vertical Motion ◽  
High Viscosity ◽  
Ball Screw ◽  
Frictional Heat ◽  
Motion Platform ◽  
Base Oil

Ball screw is a high-precision and high performance linear drive of mechanical elements. The frictional heat of internal components what is very significant impact for platform transmission in high speed and the high axial load and causes the thermal expansion of element. In this research , the influence of different greases on ball screw is investigated in thermal rising of nut and driving torque in high speed and high axial load. A vertical motion platform was used for driving performance test. Thermal rising of nut of ball screw and the variance of transmission torque whose lubricated by high viscosity base oil grease is significant larger than the lower one. High viscosity grease is not easy to carry out the friction heat generated at ball and raceway contact area due to the bad flowing properties. It also has more serious wear occurred at contact area and high friction force, whose causes the large variance of transmission torque.

A Study on the Deformation due to High Speed Processing of Aircraft Wing Structure

2021 ◽  
Vol 880 ◽  
pp. 63-68
Author(s):  
Jihye An ◽  
Hyunji Kim ◽  
Dohyeon Kim ◽  
Sangkyoo Nam ◽  
Yunyoong Yoo ◽  
...  
Keyword(s):  
Residual Stress ◽  
High Speed ◽  
Tensile Force ◽  
Tensile Load ◽  
Working Hours ◽  
Frictional Heat ◽  
Aviation Industry ◽  
High Speed Machining ◽  
Skilled Workers ◽  
Processing Site

Residual stresses generated during high-speed machining of spoiler beams used in aircraft cause product deformation and dimensional mismatch, which increases the defect rate and leads to material waste. To overcome this problem, the processing site uses manual modification techniques that stretch part of the workpiece according to the experience of skilled workers. However, due to the nature of the aviation parts industry, there are no established methods for modification of product shapes and parts. Studying the modification process would allow for increased productivity, such as shorter working hours, throughout the aviation industry. In this study, a method of predicting residual stress due to frictional heat generated during high-speed machining and applying a tensile force to a model deformed by residual stress was used to modify the product. Our analysis showed that a degree of deformation similar to the measured value was produced, and that the product was modified by applying a tensile load.

Dynamic contact stress and frictional heat analysis of femoral head-on-acetabular cup interface based on calculation and simulation methods

2021 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Xingxing Fang ◽  
Dahan Li ◽  
Yucheng Xin ◽  
Songquan Wang ◽  
Yongbo Guo ◽  
...  
Keyword(s):  
Finite Element ◽  
Femoral Head ◽  
Contact Stress ◽  
Contact Area ◽  
Gait Cycle ◽  
Dynamic Change ◽  
Dynamic Contact ◽  
Frictional Heat ◽  
Acetabular Cup ◽  
Content Type

Purpose The purpose of this paper is to systematically study the dynamic contact stress, frictional heat and temperature field of femoral head-on-acetabular cup contact pairs in a gait cycle. Design/methodology/approach In this paper, four common femoral head-on-acetabular cup contact pairs are used as the research objects, mathematical calculations and finite element simulations are adopted. The contact model of hip joint head and acetabular cup was established by finite element simulation to analyze the stress and temperature distribution of the contact interface. Findings The results show that the contact stress of the head-on-cup interface is inversely proportional to the contact area; high contact stress directly leads to greater frictional heat. However, hip joints with metal-on-polyethylene or ceramic-on-polyethylene paired interfaces have lower frictional heat and show a significant temperature rise in one gait cycle, which may be related to the material properties of the acetabular cup. Originality/value Previous studies about calculating the interface frictional heat always ignore the dynamic change process in the contact load and the contact area. This study considered the dynamic changes of the contact stress and area of the femoral head-on-acetabular cup interface, and four common contact pairs were systematically analyzed.

Oil Brush Seals in Turbomachinery: Flow Analyses and Closed-Form Solutions

2020 ◽  
Vol 142 (10) ◽  
Author(s):  
Ertuğrul Tolga Duran
Keyword(s):  
Closed Form ◽  
High Speed ◽  
Closed Form Solution ◽  
Frictional Heat ◽  
Rotor Speed ◽  
Test Rig ◽  
Lifting Force ◽  
Operation Conditions ◽  
Rotor Surface ◽  
Brush Seals

Abstract Brush seals are one of the most important dynamic seals used in oil and oil mist applications in industrial turbines and aviation. Flexible bristle structure is the main structural superiority of brush seals, which enables precise clearance control and high performance in compensating rotor transients. The viscous medium between the high-speed rotor surface and brush seal bristles generates a hydrodynamic lifting force that determines seal clearance and leakage rate in oil sealing applications. Shear heating at moderate and high rotor surface speeds results in an increase in temperature and stabilization of lifting force, which is known as high-speed lift stabilization. Strong temperature–viscosity dependency of lube oils possesses the need for a detailed analysis and understanding of the effect of shear heat on hydrodynamic lift of brush seals in oil applications. To provide a better understanding about the critical balance of hydrodynamic lift force with rotor speed, temperature, and pressure, this work presents an analytical study to investigate pressure profile and shear heat temperature rise in liquid sealing medium within the hydrodynamic lift clearance. A closed-form solution to pressure and temperature distribution in axial and radial directions has been obtained by solving continuity, Navier–Stokes, and thermal energy equations for brush seals. The thermal and pressure functions are evaluated for linear and nonlinear pressure drop approaches, and the results are compared with each other. Deviation in nonlinear and linear pressure, resulting temperature level differences, and effect of rotor speed are detailed within the content of this study. The provided closed-form functions for pressure and temperature profiles are useful for designers since these can be utilized for turbine operation conditions. Dynamic test rig design for high-speed leakage performance measurement of turbomachinery seals is detailed, where the test rig can also be adopted for stiffness, frictional heat, power loss, torque loss, and bucket tip stability testing in oil and air environment. The test setup can also be used for testing dynamic seals other than brush seals.

scholarly journals A HIGH SPEED VACUUM CENTRIFUGE SUITABLE FOR THE STUDY OF FILTERABLE VIRUSES

1936 ◽  
Vol 64 (4) ◽  
pp. 503-528 ◽  
Author(s):  
Johannes H. Bauer ◽  
Edward G. Pickels
Keyword(s):  
Centrifugal Force ◽  
Yellow Fever ◽  
High Speed ◽  
Yellow Fever Virus ◽  
High Vacuum ◽  
Fever Virus ◽  
Compressed Air ◽  
Frictional Heat ◽  
High Speeds ◽  
Very High

1. A high speed centrifuge is described in which the speed is limited only by the strength of the material of which the rotor is made. It carries sixteen tubes, each of which conveniently accommodates 7 cc. of fluid. 2. The centrifuge operates in a very high vacuum and therefore requires only a small amount of driving energy. The arrangement has been found to eliminate the possibility of producing injurious frictional heat. 3. The rotating parts are supported by anair-bearing and are driven by compressed air. 4. The centrifuge has been successfully operated at a speed of 30,000 revolutions per minute, representing a maximum centrifugal force in the fluid of 95,000 times gravity. 5 Celluloid tubes used for centrifugation of fluid at high speeds are described. 6. Experiments are described in which good sedimentation of the yellow fever virus was obtained.

Performances of HSK Spindle/Toolholder Interface for HSM

2006 ◽  
Vol 532-533 ◽  
pp. 269-272
Author(s):  
Song Zhang ◽  
Xing Ai ◽  
Jian Feng Li ◽  
Xiu Li Fu
Keyword(s):  
Finite Element Method ◽  
Finite Element ◽  
Stress Distribution ◽  
Contact Stress ◽  
High Speed ◽  
Rapid Development ◽  
High Speed Machining ◽  
The Finite Element Method ◽  
Axial Movement ◽  
Contact Stress Distribution

With the rapid development of high-speed machining technology, more and more machining centers have been equipped with the HSK toolholders. In this paper, the performances of the HSK spindle/toolholder interface, such as the axial movement, the radial deflection and the contact stress distribution, were simulated by means of the finite element method and compared with the traditional BT interface. From the simulated results, it was pointed out that the performances of the HSK interface were obviously superior to that of the BT interface, and the HSK interface was much more suitable for high-speed machining.

Research on Commercial Vehicle Clutch Release Bearing Fatigue Life Prediction Model

2013 ◽  
Vol 423-426 ◽  
pp. 1853-1857
Author(s):  
Guo Liang Chen ◽  
Xiao Yang Chen
Keyword(s):  
Fatigue Crack ◽  
Fatigue Life ◽  
Prediction Model ◽  
Contact Stress ◽  
Life Prediction ◽  
High Speed ◽  
Commercial Vehicle ◽  
Smelting Process ◽  
Fatigue Life Analysis ◽  
Life Prediction Model

Commercial vehicle clutch release bearings working at high speed, strong vibration,high temperature, damp and easy pollution conditions. Fatigue life analysis is based on the release bearing rings or rolling body began to appear fatigue spalling, in which this kind of phenomenon is under cyclic stress. The contact stress distribution is not uniform, the contact stress is mainly concentrated near the surface; influenced by the geometry and physical properties and lubrication of the surface significantly. Contact between the two types of fatigue crack extension methods: fatigue crack surface under expansion and surface fatigue crack propagation. The surface crack growth mainly originated from two kinds of cases: crack caused by surface pre crack and contact between the two surface asperity each other. New life prediction model for the release bearing based on L-P theory and Tallian model ,in which influence factors of fatigue life is introduced on the smelting process, surface defect, surface roughness, residual stress, elastohydrodynamic lubrication oil film,environmental cleanliness, temperature, the effect of varying load characteristics and other factors of fatigue life. The results show that: the clutch release bearing life prediction model of new and more close to the real conditions of automobile clutch, provide the theory basis for the development of a new generation high-speed heavy-duty clutch release bearing of the commercial vehicle.

DYNAMIC ANALYSIS OF A ROTARY HOLLOW SHAFT WITH HOT-FIT PART USING CONTACT ELEMENTS WITH FRICTION

2011 ◽  
Vol 35 (3) ◽  
pp. 461-474 ◽  
Author(s):  
Shin-Yong Chen ◽  
Chieh Kung ◽  
Jung-Chun Hsu
Keyword(s):  
Natural Frequency ◽  
Contact Stress ◽  
High Speed ◽  
Modal Testing ◽  
Key Factors ◽  
Normal Contact Stress ◽  
Normal Contact ◽  
Hollow Shaft ◽  
Testing Experiment ◽  
Local Stiffness

One of the key factors in designing a motor built-in high speed spindle is to assemble the motor rotor and shaft by means of hot-fit. Presented in this paper is a study of the influence of a hot-fit rotor on the local stiffness of the hollow shaft. Dynamic analyses of the rotor-hollow shaft assembly using contact elements are conducted. The normal contact stress state between the rotor and the hollow shaft is obtained through the use of contact elements with friction effects included. The normal contact stress, considered as the pr-stress between the rotor and the hollow shaft, is then adopted for subsequent modal analyses. In this study, the modal analysis results are verified by a modal testing experiment. The percent errors of the first natural frequency and the second natural frequency are down to about 0.58% and 0.79%, respectively.

scholarly journals Dynamic Analysis of the High-Speed and Long-Runout Landslide Movement Process Based on the Discrete Element Method: A Case Study of the Shuicheng Landslide in Guizhou, China

2021 ◽  
Vol 2021 ◽  
pp. 1-16
Author(s):  
Guoqing Xia ◽  
Chun Liu ◽  
Chong Xu ◽  
Tiancheng Le
Keyword(s):  
Internal Friction ◽  
High Speed ◽  
Average Velocity ◽  
Source Area ◽  
Discrete Element ◽  
Frictional Heat ◽  
Long Runout ◽  
Movement Process ◽  
The Impact ◽  
Landslide Movement

On July 23, 2019, a high-speed and long-runout landslide occurred in Jichang Town, Shuicheng County, Guizhou Province, China, causing 42 deaths and 9 missing. This paper used the discrete element software MatDEM to construct a three-dimensional discrete element model based on digital elevation data and then simulated and analyzed the movement and accumulation process of the landslide. The maximum average velocity of the source area elements reached 14 m/s when passed through the scraping area; meanwhile, the velocity of the scraping area elements increased rapidly. At 90 s, the maximum displacement of the source area elements reached 1358.5 m. The heat generated during the movement of the landslide was mainly the frictional heat, and the frictional heat increased sharply when the source area elements passed through the scraping area. The change of frictional heat has a certain positive correlation with the velocity of the scraping area elements. Finally, the volume of the scraping area elements was 2.4 times greater than the source area elements in the deposits. The scraping effect increases the volume of the sliding body and expands the impact area of the landslide disaster. Additionally, by setting different compressive and tensile strengths as well as internal friction coefficients to analyze the influences of their value changes on the landslide movement process, the results show that the smaller the strengths and internal friction coefficient of the model, the greater the depth and area of the scraping area, which will result in a thicker accumulation; meanwhile, the average displacement, average velocity, and heat will also increase.

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