Hertzian Contact Pressure Analysis of Frictional Coupling Elements of Multidisk Stepless Transmission With Initial Line Contact

2009 ◽  
Author(s):  
S. A. Lukowski ◽  
L. A. Medeksza ◽  
D. N. Kunz ◽  
Jeff Hoerning
Keyword(s):  
Contact Area ◽  
Quantitative Estimation ◽  
Active Surface ◽  
Hertzian Contact ◽  
Graphical Form ◽  
Geometrical Features ◽  
Maximum Contact ◽  
Contact Pressures ◽  
Initial Line ◽  
Pressure Analysis

This paper presents an analysis of the contact pressures and the contact area of mating disks in a frictional transmission. Hertz’s formulations are adopted to determine the maximum contact pressures as well as the size of the contact area resulting from elastic deformation due to the clamping force. Hertz’s formulations are expressed in terms of geometrical features of the active surface of mating disks. The obtained relationships can be readily applied for quantitative estimation of the contact pressures and the contact area parameters for different ranges of transmission ratio. Samples of numerical results are presented in graphical form.

Geometry of Contact and Hertzian Stress Analysis of Frictional Coupling Elements of Multidisk Stepless Transmission With Initial Point Contact

1991 ◽  
Vol 113 (4) ◽  
pp. 416-421
Author(s):  
S. A. Lukowski ◽  
L. A. Medeksza ◽  
P. W. Claar
Keyword(s):  
Contact Area ◽  
Quantitative Estimation ◽  
Point Contact ◽  
Initial Point ◽  
Active Surface ◽  
Contact Stresses ◽  
Graphical Form ◽  
Clamping Force ◽  
Geometrical Features ◽  
Maximum Contact

This paper presents an analysis of the contact stresses and the contract area of mating disks in frictional transmission. Hertz’s formulations are adopted to determine the maximum contact stresses as well as the size of the contact area resulting from elastic deformation due to clamping force. Hertz’s formulations are expressed in terms of geometrical features of the active surface of mating disks. The obtained relationships can be readily applied for quantitative estimation of the contact stresses and the contact area parameters for different range of transmission ratio. Samples of numerical results are presented in graphical form.

Repair of Lateral Meniscus Posterior Horn Detachment Lesions

2012 ◽  
Vol 40 (11) ◽  
pp. 2604-2609 ◽  
Author(s):  
Carl K. Schillhammer ◽  
Frederick W. Werner ◽  
Matthew G. Scuderi ◽  
John P. Cannizzaro
Keyword(s):  
Acl Reconstruction ◽  
Contact Pressure ◽  
Contact Area ◽  
Lateral Meniscus ◽  
Posterior Horn ◽  
Normal Contact ◽  
Intact State ◽  
Peak Contact Pressure ◽  
Maximum Contact ◽  
Contact Pressures

Background: Posterior horn detachment (PHD) lesions of the lateral meniscus are commonly associated with acute anterior cruciate ligament (ACL) tears. Multiple surgeons have advocated for repair of this lesion at the time of ACL reconstruction. However, the biomechanical consequences of this lesion and its subsequent repair have not been evaluated. Hypothesis: The PHD lesion of the lateral meniscus will lead to increased tibiofemoral contact pressures, and repair of this lesion to bone via a tibial tunnel can restore normal contact pressures during simulated gait. Study Design: Controlled laboratory study. Methods: Lateral compartment contact pressures were measured via a sensor on the tibial plateau in 8 cadaver knees with the knee intact, after sectioning the posterior horn of the lateral meniscus to simulate PHD, and after repairing the injury. The repair was performed using an ACL tunnel guide to drill a tunnel from the anteromedial tibia to the posterior horn attachment site. Dynamic pressure data were continuously collected using a conductive ink pressure sensing system while each knee was moved through a physiological gait flexion cycle. Results: Posterior horn detachment caused a significant increase in tibiofemoral peak contact pressure from 2.8 MPa to 4.2 MPa ( P = .03). After repair of the lesion to bone was performed through a transtibial tunnel, the peak contact pressure was 2.9 MPa. Posterior horn detachment also significantly decreased the maximum contact area over which tibiofemoral pressure is distributed from 451 mm2 in the intact state to 304 mm2 in the detached state. Repair of the PHD lesion increased the maximum contact area to 386 mm2, however, this area was also significantly less than in the intact state ( P = .05). Conclusion: Posterior horn detachment of the lateral meniscus causes increased peak tibiofemoral contact pressure. The peak pressure can be reduced to a normal level with repair of the lesion to bone via a transtibial tunnel. Clinical Relevance: Posterior horn detachment of the lateral meniscus is a lesion often associated with an acute ACL tear. Debate exists concerning the importance of repairing PHD lesions at the time of ACL reconstruction. The data provided in this study may influence surgeons’ management of the lesion.

scholarly journals Improved design criterion for frictionally engaged contacts in overrunning clutches

2021 ◽  
Author(s):  
Nadine Nagler ◽  
Armin Lohrengel
Keyword(s):  
Design Process ◽  
Contact Area ◽  
Axial Load ◽  
State Of The Art ◽  
Tangential Force ◽  
Design Criterion ◽  
Hertzian Contact ◽  
Loss Of Function ◽  
Axial Loads ◽  
Improved Design

AbstractOverrunning clutches, also known as freewheel clutches, are frictionally engaged, directional clutches; they transmit torque depending on the Freewheel clutch rings’ rotation directions. The torque causes a tangential force in the Hertzian contact area. The hitherto “state-of-the-art design criterion” bases on this load situation. In practice, axial loads additionally act on the frictionally engaged Hertzian contact area. This additional axial load can cause the loss of the friction connection and so the freewheel clutch slips. This publication presents an improved design criterion for frictionally engaged contacts in freewheel clutches. It allows to consider tangential as well as axial loads during the design process. Additionally, it offers the possibility to estimate the probability of frictional engagement loss and gross slip based on the freewheel clutch’s application scenario. This publication points out how to use the improved design criterion to design freewheel clutches that are more robust against a loss of function.

Experimental and Theoretical Study of the Contact Mechanics of Five Total Knee Joint Replacements

1995 ◽  
Vol 209 (4) ◽  
pp. 225-231 ◽  
Author(s):  
T Stewart ◽  
Z M Jin ◽  
D Shaw ◽  
D D Auger ◽  
M Stone ◽  
...  
Keyword(s):  
Plastic Deformation ◽  
Knee Joint ◽  
Contact Pressure ◽  
Contact Stress ◽  
Linear Elasticity ◽  
Contact Area ◽  
Elasticity Analysis ◽  
Joint Replacements ◽  
Total Knee ◽  
Maximum Contact

The tibio-femoral contact area in five current popular total knee joint replacements has been measured using pressure-sensitive film under a normal load of 2.5 kN and at several angles of flexion The corresponding maximum contact pressure has been estimated from the measured contact areas and found to exceed the point at which plastic deformation is expected in the ultra-high molecular weight polyethylene (UHMWPE) component particularly at flexion angles near 90°. The measured contact area and the estimated maximum contact stress have been found to be similar in magnitude for all of the five knee joint replacements tested. A significant difference, however, has been found in maximum contact pressure predicted from linear elasticity analysis for the different knee joints. This indicates that varying amounts of plastic deformation occurred in the polyethylene component in the different knee designs. It is important to know the extent of damage as knees with large amounts of plastic deformation are more likely to suffer low cycle fatigue failure. It is therefore concluded that the measurement of contact areas alone can be misleading in the design of and deformation in total knee joint replacements. It is important to modify geometries to reduce the maximum contact stress as predicted from the linear elasticity analysis, to below the linear elastic limit of the plastic component.

Analysis and Comparison of Seal Ability of Premium Tubing Connections under Axial Alternating Load

2013 ◽  
Vol 423-426 ◽  
pp. 2035-2039
Author(s):  
Long Cang Huang ◽  
Yin Ping Cao ◽  
Yang Yu ◽  
Yi Hua Dou
Keyword(s):  
Contact Pressure ◽  
Oil And Gas ◽  
Element Analysis ◽  
Gas Well ◽  
Cycle Number ◽  
Compression Load ◽  
Well Production ◽  
Maximum Contact ◽  
Contact Pressures ◽  
Better Than

In the process of oil and gas well production, tubing connection stand the axial alternating load during open well, shut well and fluid flow. In order to know premium connection seal ability under the loading, two types of P110 88.9mmx6.45mm premium tubing connections which called A connection and B connection are performed with finite element analysis, in which contact pressures and their the regularities distribution on sealing surface are analyzed. The results show that with the increasing of cycle number, the maximum contact pressures on sealing surface of both A connection and B connection are decreased. The decreasing of the maximum contact pressures on B connection is greater than those on A connection. With the increasing of cycle number of axial alternating compression load, the maximum contact pressure on sealing surface of A connection is decreased, and the maximum contact pressure on sealing surface of B connection remains constant. Compared the result, it shows that the seal ability of A connection is better than B connection under axial alternating tension load, while the seal ability of B connection is better than type A connection under axial alternating compression load.

Analysis of Premium Connection of Connecting and Sealing Ability Loaded by Axial Tensile Loads

2012 ◽  
Vol 268-270 ◽  
pp. 737-740
Author(s):  
Yang Yu ◽  
Yi Hua Dou ◽  
Fu Xiang Zhang ◽  
Xiang Tong Yang
Keyword(s):  
Finite Element ◽  
Contact Pressure ◽  
Tensile Load ◽  
Element Model ◽  
Sealing Ability ◽  
Axial Tensile ◽  
High Level ◽  
Maximum Contact ◽  
Contact Pressures ◽  
The Finite Element Model

It is necessary to know the connecting and sealing ability of premium connection for appropriate choices of different working conditions. By finite element method, the finite element model of premium connection is established and the stresses of seal section, shoulder zone and thread surface of tubing by axial tensile loads are analyzed. The results show that shoulder zone is subject to most axial stresses at made-up state, which will make distribution of stresses on thread reasonable. With the increase of axial tensile loads, stresses of thread on both ends increase and on seal section and shoulder zone slightly change. The maximum stress on some thread exceed the yield limit of material when axial tensile loads exceed 400KN. Limited axial tensile loads sharply influence the contact pressures on shoulder zone while slightly on seal section. Although the maximum contact pressure on shoulder zone drop to 0 when the axial tensile load is 600KN, the maximum contact pressure on seal section will keep on a high level.

Experimental and numerical study on cavitation under elastohydrodynamic lubrication point contact

2021 ◽  
pp. 135065012110527
Author(s):  
Mingfei Ma ◽  
Wen Wang ◽  
Wenxun Jiang
Keyword(s):  
Contact Area ◽  
Numerical Study ◽  
Ambient Pressure ◽  
Point Contact ◽  
Elastohydrodynamic Lubrication ◽  
Hertzian Contact ◽  
Pressure Area ◽  
Cavitation Pressure ◽  
Experimental Researches ◽  
State 1

As a common phenomenon in elastohydrodynamic lubrication, cavitation has an effect on the completeness of the oil film in the contact area. Many studies have therefore been conducted on cavitation. Experimental researches on cavitation usually rely on optical interference observation, which offers a limited resolution and observation range. In this paper, an infrared thermal camera is used to observe the cavity bubbles on a ball-on-disc setup under sliding/rolling conditions. The results show that the cavity length increases with an increases of the entrainment speed and the viscosity of the lubricants. These observations are explained by a numerical model based on Elrod's algorithm. Effects of entrainment speed and lubricant viscosity on the breakup of cavitation bubbles and the cavitation states are investigated. Both the simulation and experimental results show that a negative pressure area is present behind the Hertzian contact area. The ambient pressure plays a role in maintaining cavitation state 1. The cavitation pressure is close to the vacuum pressure when the entrainment speed is low and to the ambient pressure instead when the entrainment speed is high.

Approximate Analytical Model for Hertzian Elliptical Wheel/Rail or Wheel/Crossing Contact Problems

2008 ◽  
Vol 130 (4) ◽  
Author(s):  
F. D. Fischer ◽  
M. Wiest
Keyword(s):  
Contact Pressure ◽  
Contact Problems ◽  
Hertzian Contact ◽  
Contact Theory ◽  
Technical Accuracy ◽  
Elliptical Contact ◽  
Current Approximation ◽  
Analytical Expressions ◽  
Maximum Contact ◽  
Hertzian Contact Theory

The Hertzian contact theory is approximated according to a concept by Tanaka (2001, “A New Calculation Method of Hertz Elliptical Contact Pressure,” ASME J. Tribol., 123, pp. 887–889) yielding simple analytical expressions for the elliptical semi-axes, the maximum contact pressure, the mutual approach and the contact spring constant. Several configurations are compared using the exact Hertz theory and the current approximation. The results agree within technical accuracy.

scholarly journals Contact pressures and the impact of farm equipment on Latosol with the presence and absence of sugarcane straw

2016 ◽  
Vol 40 (3) ◽  
pp. 265-278 ◽  
Author(s):  
Reginaldo Barboza da Silva ◽  
Piero Iori ◽  
Zigomar Menezes de Souza ◽  
Danilo de Moraes Gomes Pereira ◽  
Oswaldo Julio Vischi Filho ◽  
...  
Keyword(s):  
Contact Pressure ◽  
Contact Area ◽  
Structural Changes ◽  
Front Axle ◽  
Real Contact Area ◽  
Digital Measurement ◽  
Farm Equipment ◽  
Presence And Absence ◽  
The Impact ◽  
Contact Pressures

ABSTRACT High contact pressures applied to soil result in a greater degree of compaction, in addition to promoting other negative effects. The objective of this study was to quantify contact areas by using different methodologies, and pressures of farm equipment employed in production activity and evaluate structural changes caused in a Red Latosol with the presence and absence of straw cover. The design was completely randomized in a factorial scheme of type 4 (tire on front axle, tire on rear axle, tire on a sugarcane wagon and metallic track of sugar cane Harvester) x 2 (presence and absence of straw). The contact area (CA) of the run was obtained by three procedures: analytical measure of the area of an ellipse (CA1); digital measurement of area of an ellipse (CA2); and measurement of real contact area (RCA), with digital resources. The contact pressure was calculated from the ratio of mass of each machine's axle and the contact area of the run. The contact area obtained according to the procedure of the ellipse (CA1 and CA2) is overrated when compared to actual area obtained digitally (RCA). The straw reduces the contact pressure in the soil, due to the deep tire treads and consequently, increased contact area. Areas where the traffic of the machines occurred with soil covered with the presence of straw showed reduced soil resistance to penetration, cone index and pre-consolidation pressure, confirming that the increased contact area produced by straw reduced the pressure applied and the compression power dissipated in the soil.

Bearing Pressures and Cracks: Bearing Pressures Through a Slightly Waved Surface or Through a Nearly Flat Part of a Cylinder, and Related Problems of Cracks

1939 ◽  
Vol 6 (2) ◽  
pp. A49-A53 ◽  
Author(s):  
H. M. Westergaard
Keyword(s):  
Horizontal Plane ◽  
Wave Length ◽  
Circular Cylinders ◽  
Fourth Power ◽  
Classical Study ◽  
Partial Contact ◽  
Initial Separation ◽  
Noncircular Cylinder ◽  
Contact Pressures ◽  
Initial Line

Abstract The task is undertaken of determining the bearing pressures, and the stresses and deformations created by them, in some cases that differ from those considered by Hertz in his classical study of contact. Thus two solids are examined which, before loading, are in contact along a row of evenly spaced lines in a horizontal plane, as indicated in Fig. 1(a). Between these lines the surfaces have a separation defined by a nearly flat cosine wave. A uniform pressure on top of the upper solid creates contact over an area consisting of a row of strips, reduces the separation of the solids between the strips, as suggested in Fig. 1(b), and creates contact pressures distributed as indicated in Fig. 1(c), with vertical rises in the diagram of pressure at the edges of the strips. At a greater load the width of the strip becomes equal to the wave length, and the contact is complete. At still greater loads the stresses increase as if the two solids were one. The procedure by which this problem is solved is demonstrated first by showing its easy application to some well-known cases, especially Hertz’s problem of circular cylinders in contact. Further applications are to a noncircular cylinder resting on a solid with a flat top, with an initial separation of the surfaces varying as the fourth power of the distance from the initial line of contact; to partial contact of two surfaces which are initially plane, except that one of them has a ridge or several parallel ridges; and to some related problems in which two parts of the same body are partially separated by the forming of one or more cracks.

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