Lateral Motion of an Axially Moving Tape on a Cylindrical Guide Surface

2007 ◽  
Vol 74 (5) ◽  
pp. 1053-1056 ◽  
Author(s):  
Bart Raeymaekers ◽  
Frank E. Talke
Keyword(s):  
Friction Coefficient ◽  
Friction Force ◽  
Bending Stiffness ◽  
Experimental Results ◽  
Lateral Motion ◽  
Lateral Bending ◽  
Lateral Tape Motion ◽  
Numerical Predictions ◽  
Axially Moving ◽  
Good Agreement

The lateral motion of a tape moving axially over a cylindrical guide surface is investigated. The effects of lateral bending stiffness and friction force are studied and the attenuation of lateral tape motion as a function of the guide radius and friction coefficient is determined. Good agreement between numerical predictions and experimental results is observed.

Experimental Study of a Variable Pressure Damper on Automotive Valve Motion

1996 ◽  
Author(s):  
Jin-Jang Liou ◽  
Grodrue Huang ◽  
Wensyang Hsu
Keyword(s):  
Experimental Study ◽  
Friction Coefficient ◽  
Friction Force ◽  
High Speed ◽  
Experimental Results ◽  
Variable Pressure ◽  
Friction Forces ◽  
Valve Spring ◽  
Valve Motion

Abstract A variable pressure damper (VPD) is used here to adjusted the friction force on the valve spring to investigate the relation between the friction force and the valve bouncing phenomenon. The friction force on the valve spring is found experimentally, and the corresponding friction coefficient is also determined. Dynamic valve displacements at different speeds with different friction forces are calibrated. Bouncing and floating of the valve are observed when the camshaft reaches high speed. From the measured valve displacement, the VPD is shown to have significant improvement in reducing valve bouncing distance and eliminating floating. However, experimental results indicate that the valve bouncing can not be eliminated completely when the camshaft speed is at 2985 rpm.

A Duct Optimization Study for a Vertical Axis Hydro-current Turbine Model

2011 ◽  
Vol 134 (2) ◽  
Author(s):  
M. Alidadi ◽  
V. Klaptocz ◽  
G. W. Rawlings ◽  
Y. Nabavi ◽  
S. Calisal
Keyword(s):  
Power Output ◽  
Numerical Optimization ◽  
Vertical Axis ◽  
Experimental Results ◽  
Maximum Power Output ◽  
Numerical Predictions ◽  
Optimization Study ◽  
Current Turbine ◽  
Turbine Model ◽  
Good Agreement

A numerical optimization study is used to design a duct for a model of vertical axis hydro-current turbine. The effects of this duct on the power output and torque fluctuations of the turbine model are then examined numerically and experimentally. Relatively good agreement was obtained between the experimental results and numerical predictions especially at higher tip speed ratios. Experimental results show an 85% increase in the maximum power output when the turbine is placed inside the duct. The numerical and experimental torque curves for the turbine also show substantial reductions in the torque fluctuations as a result of ducting.

A study on finite element analysis for simplification of curvature extrusion method

2018 ◽  
Vol 32 (19) ◽  
pp. 1840043
Author(s):  
J. O. Yu ◽  
Y. H. Kim ◽  
Nagamachi Takuo
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Friction Coefficient ◽  
Extrusion Process ◽  
Experimental Results ◽  
Element Analysis ◽  
Extrusion Method ◽  
Good Agreement

To eliminate the complexity of curvature extrusion process, a new extrusion method was proposed. In this study, a finite element analysis for curvature extrusion was studied to commercialize this extrusion method that creates curvature in a tilting method. When simulating an extrusion process, it is important to fix the appropriate friction coefficient and fillet value to avoid peel-out problems such that the finite element disappears. Therefore, the actual extrusion results and the simulated results were compared to find conditions that the element would not disappear. There was a good agreement between the simulation and experimental results when the coefficient friction was 0.4 and the fillet was 0.4 mm.

Theoretical Model of Plastic Hysteresis in Spherical Contact Under Combined Normal and Tangential Loading

2008 ◽  
Author(s):  
Yuri Kligerman ◽  
Izhak Etsion
Keyword(s):  
Theoretical Model ◽  
Stress State ◽  
Friction Force ◽  
Contact Area ◽  
Contact Condition ◽  
Experimental Results ◽  
Tangential Displacement ◽  
Elastic Plastic ◽  
Plastic Sphere ◽  
Good Agreement

The behavior of an elastic-plastic contact between a deformable sphere and a rigid flat under combined constant normal and reciprocating tangential loading is investigated in the present work. The theoretical model is based on the assumptions of full stick contact condition and two kinds of the sphere material hardening. Hysteretic change of friction force versus tangential displacement during reciprocating tangential loading is investigated along with the study of the change of the contact area and stress state in the elastic-plastic sphere. Good agreement between theoretical and experimental results is obtained.

Effect of Shear in Transverse Impact on Beams

1951 ◽  
Vol 165 (1) ◽  
pp. 176-188 ◽  
Author(s):  
D. G. Christopherson
Keyword(s):  
Elastic Wave ◽  
Shear Stiffness ◽  
Bending Stiffness ◽  
Experimental Results ◽  
Maximum Force ◽  
Transverse Impact ◽  
Wide Range ◽  
The Impact ◽  
Dominant Part ◽  
Good Agreement

In this paper the problem of transverse impact on a uniform beam is considered theoretically. Two examples which can be taken as representing a wide range of impacts which occur in practice are referred to particularly: (1) the beam struck transversely by a uniform square-ended rod travelling perpendicularly to it; (2) the same problem for the striker having a spherical end. In these examples it is shown that the ability of the beam to deflect in shear as well as in bending plays a dominant part in what takes place, and that, as far as the force between striker and beam is concerned, the length of the beam is usually without importance, as there is not time during the impact for an elastic wave to travel to the ends of the beam and return. It is shown that in regard to example (2) the theory presented is in good agreement with Arnold's experimental results obtained some years previously, and curves are given from which the maximum force between beam and striker can be obtained in terms of three parameters, representing respectively the velocity, the mass, and the radius of the striker, each dependent on the ratio of shear stiffness to bending stiffness for the beam.

Partial EHL friction coefficient model to predict power losses in cylindrical gears

2018 ◽  
Vol 233 (2) ◽  
pp. 303-316 ◽  
Author(s):  
Aitor Arana ◽  
Jon Larrañaga ◽  
Ibai Ulacia
Keyword(s):  
Friction Coefficient ◽  
Operating Conditions ◽  
Power Losses ◽  
Gear Mesh ◽  
Numerical Predictions ◽  
Reference Stress ◽  
Fluid Load ◽  
Stress Behaviour ◽  
Good Agreement ◽  
Ehl Friction

The accurate prediction of friction coefficient and power losses in the gear mesh is a key subject to several gear-related fields of study. However, there is still not a unified method for large ranges of operating conditions, different gear geometries and lubricant types. The current paper meets this demand by modelling partial EHL friction with an asperity-fluid load sharing approach where fluid traction is calculated with the Ree-Eyring equation and the reference stress behaviour is predicted from piezoviscosity coefficient. It will be shown that only an accurate description of the lubricant’s viscosity behaviour is required to compute friction in gears. Finally, mesh power losses are predicted considering thermal effects and numerical predictions are compared to experimental results showing good agreement.

scholarly journals Dependency of Rubber Friction on Normal Force or Load: Theory and Experiment

2017 ◽  
Vol 45 (1) ◽  
pp. 25-54 ◽  
Author(s):  
Gaetano Fortunato ◽  
Vincenzo Ciaravola ◽  
Alessandro Furno ◽  
Michele Scaraggi ◽  
Boris Lorenz ◽  
...  
Keyword(s):  
Friction Coefficient ◽  
Friction Force ◽  
Frictional Heating ◽  
Measured Temperature ◽  
Load Theory ◽  
Time Integral ◽  
Rubber Friction ◽  
Pressure Dependency ◽  
Road Surfaces ◽  
Good Agreement

ABSTRACT In rubber friction studies, it is often observed that the kinetic friction coefficient μ depends on the nominal contact pressure p. We discuss several possible origins of the pressure dependency of μ: (1) saturation of the contact area (and friction force) due to high nominal squeezing pressure; (2) nonlinear viscoelasticity; (3) nonrandomness in the surface topography, in particular the influence of the skewness of the surface roughness profile; (4) adhesion; and (5) frictional heating. We show that in most cases the nonlinearity in the μ(p) relation is mainly due to process (5), frictional heating, that softens the rubber, increases the area of contact, and (in most cases) reduces the viscoelastic contribution to the friction. In fact, because the temperature distribution in the rubber at time t depends on the sliding history (i.e., on the earlier time t′ < t), the friction coefficient at time t will also depend on the sliding history, that is, it is, strictly speaking, a time integral operator. The energy dissipation in the contact regions between solids in sliding contact can result in high local temperatures that may strongly affect the area of real contact and the friction force (and the wear-rate). This is the case for rubber sliding on road surfaces at speeds above 1 mm/s. Previously, we derived equations that described the frictional heating for solids with arbitrary thermal properties. Here, the theory is applied to rubber friction on road surfaces. Numerical results are presented and compared to experimental data. We observe good agreement between the calculated and measured temperature increase.

The Damage Behaviour of Composite Tube with Pin Joint Holes

2012 ◽  
Vol 622-623 ◽  
pp. 739-742
Author(s):  
Jiang Sun ◽  
Qi Xiao
Keyword(s):  
Stress State ◽  
Failure Mode ◽  
Failure Load ◽  
Filament Winding ◽  
Experimental Results ◽  
Damage Behavior ◽  
Composite Tube ◽  
Numerical Predictions ◽  
Good Agreement

The present investigation deals with the damage behavior of composite tube with pinned-joint holes made by filament winding technique. The pin-loaded holes are tailored to fail mainly with bearing mode. The main objective of the paper is to investigate the stress state and damage behavior of pin-loaded holes made by filament winding. The failure load and the failure mode are analyzed numerically and experimentally. A good agreement between experimental results and numerical predictions is obtained.

Lateral Motion of an Axially Moving String on a Cylindrical Guide Surface

1979 ◽  
Vol 46 (4) ◽  
pp. 905-912 ◽  
Author(s):  
K. Ono
Keyword(s):  
Friction Coefficient ◽  
Basic Equation ◽  
Lateral Displacement ◽  
The Other ◽  
Lateral Motion ◽  
One Dimensional ◽  
Axially Moving String ◽  
Transport Direction ◽  
Axially Moving ◽  
Limiting Case

Lateral motion of an axially moving string on a cylindrical guide surface is investigated theoretically and experimentally. By deriving and solving the basic equation of the system, it is found that the axially moving string slips laterally on the fixed guide surface similarly to one-dimensional heat flow. The transfer characteristics of the string lateral displacement from one side to the other over the guide surface depends on the string transport direction, if the circumferential and axial friction coefficients between string and guide are different from each other. The solution for a rotary guide can be obtained as the limiting case where the circumferential friction coefficient is zero and the axial friction coefficient is infinity.

Inducing Frictional Force to Enhance the Transient Response in Beams

2019 ◽  
Vol 22 (2) ◽  
pp. 88-93
Author(s):  
Hamed Khanger Mina ◽  
Waleed K. Al-Ashtrai
Keyword(s):  
Numerical Analysis ◽  
Transient Response ◽  
Frictional Force ◽  
Damping Ratio ◽  
Experimental Results ◽  
Damping Capacity ◽  
Tightening Force ◽  
Contact Areas ◽  
Good Agreement ◽  
Ansys Workbench

This paper studies the effect of contact areas on the transient response of mechanical structures. Precisely, it investigates replacing the ordinary beam of a structure by two beams of half the thickness, which are joined by bolts. The response of these beams is controlled by adjusting the tightening of the connecting bolts and hence changing the magnitude of the induced frictional force between the two beams which affect the beams damping capacity. A cantilever of two beams joined together by bolts has been investigated numerically and experimentally. The numerical analysis was performed using ANSYS-Workbench version 17.2. A good agreement between the numerical and experimental results has been obtained. In general, results showed that the two beams vibrate independently when the bolts were loosed and the structure stiffness is about 20 N/m and the damping ratio is about 0.008. With increasing the bolts tightening, the stiffness and the damping ratio of the structure were also increased till they reach their maximum values when the tightening force equals to 8330 N, where the structure now has stiffness equals to 88 N/m and the damping ratio is about 0.062. Beyond this force value, increasing the bolts tightening has no effect on stiffness of the structure while the damping ratio is decreased until it returned to 0.008 when the bolts tightening becomes immense and the beams behave as one beam of double thickness.

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