A Mobile Mechanism With Slant Leg on a Vibratory Floor

2001 ◽  
Author(s):  
Hideya Yamaguchi ◽  
Masahito Yashima
Keyword(s):  
Numerical Simulation ◽  
Friction Force ◽  
Coefficient Of Friction ◽  
Stick Slip ◽  
Main Mass ◽  
Rotational Spring ◽  
Exciting Frequency ◽  
The Difference ◽  
Stick Slip Motion ◽  
Slip Motion

Abstract This paper investigates the characteristics of a mobile mechanism that consists of a main mass and a slant leg with a rotational spring at the joint. The device travels on an oscillating floor due to the difference in the friction force between forward and backward directions during the stick-slip motion. Numerical simulation and experimentation show that the direction and velocity of movement are controlled by the exciting frequency. Furthermore, the effects of the angle of the slant leg and the sliding coefficient of friction on those characteristics are investigated.

Studies on Friction and Formation of Transfer Layer in HCP Metals

2008 ◽  
Author(s):  
Pradeep L. Menezes ◽  
Kishore ◽  
Satish V. Kailas
Keyword(s):  
Coefficient Of Friction ◽  
Surface Texture ◽  
Soft Materials ◽  
Hard Material ◽  
Layer Formation ◽  
Ambient Conditions ◽  
Transfer Layer ◽  
Stick Slip ◽  
Stick Slip Motion ◽  
Slip Motion

Surface texture plays an important role as it predominantly controls the frictional behavior and transfer layer formation at the contacting surfaces. In the present investigation, basic studies were conducted using inclined pin-on-plate sliding tester to understand the role of surface texture of hard material on coefficient of friction and transfer layer formation when sliding against soft materials. HCP materials such as pure Mg and pure Zn were used as pins while 080 M40 steel was used as plate in the tests. Two surface parameters of steel plates — roughness and texture — were varied in the tests. Tests were conducted in ambient conditions under both dry and lubricated conditions. The morphologies of the worn surfaces of the pins and the formation of transfer layer on the counter surfaces were observed using a scanning electron microscope. It was observed for both the pin materials that the occurrence of stick-slip motion, the transfer layer formation and the value of coefficient of friction as well as its two components, namely, adhesion and plowing, depend primarily on surface texture. The effect of surface texture on coefficient of friction was attributed to the variation of plowing component of friction for different surfaces. Both the plowing component of friction and amplitude of stick-slip motion were highest for the surface texture that promotes plane strain conditions while these were lowest for the texture that favors plane stress conditions at the interface.

Steady Sliding of Two Elastic Half-Spaces With Friction Reduction due to Interface Stick-Slip

1998 ◽  
Vol 65 (2) ◽  
pp. 470-475 ◽  
Author(s):  
G. G. Adams
Keyword(s):  
Friction Coefficient ◽  
Coefficient Of Friction ◽  
Dynamic Instability ◽  
Steady Motion ◽  
Friction Reduction ◽  
Stick Slip ◽  
Interface Friction ◽  
Stick Slip Motion ◽  
Frictional Slip ◽  
Slip Motion

The sliding of two perfectly flat elastic half-spaces with a constant interfacial coefficient of friction is investigated. Previous work has demonstrated that this configuration is dynamically unstable due to the destabilization of frictional slip waves. It was speculated that this dynamic instability could lead to stick-slip motion at the sliding interface. It is shown here that stick-slip motion at the interface can exist with a speed-independent interface coefficient of friction. Steady motion persists sufficiently far from the interface and thus gives the impression of uniform sliding. This type of stick-slip motion is due to interfacial slip waves and allows the bodies to slide with an apparent coefficient of friction which is less than the interface coefficient of friction. Furthermore it is shown that the apparent friction coefficient decreases with increasing speed even if the interface friction coefficient is speed-independent. Finally, it is shown that the presence of slip waves may make it possible for two frictional bodies to slide without a resisting shear stress and without any interface separation. No distinction is made between static and kinetic friction.

Observer-based friction force estimation for brake system under low-frequency vibration

2021 ◽  
pp. 107754632110004
Author(s):  
Lu Qian ◽  
Xingwei Zhao
Keyword(s):  
Friction Force ◽  
Low Frequency ◽  
Brake System ◽  
Estimation Methods ◽  
Force Estimation ◽  
Stick Slip ◽  
Modeling Methods ◽  
Low Frequency Vibration ◽  
Stick Slip Motion ◽  
Slip Motion

Creep groan is a low-frequency vibration, which is produced by the stick–slip motion from the pad–disc contact in the brake. Friction plays a key role in generating the stick–slip motion. However, directly measuring the friction force in an actual brake system is difficult. Therefore, force estimation methods are proposed to estimate the friction force based on unknown input observers. A proportional integral observer is applied to estimate the friction force amplitude from the torsional angle of the driven shaft. An approximate H2 observer is designed to distinguish the stick region and slip region from the acceleration of the pad. Different from modeling methods, designing observers do not introduce modeling deviation and have a relatively low requirement on parameter identification. In addition, the observer methods can extract more detailed information of friction force than modeling methods. The observed friction force can be considered an index to evaluate the severity of the brake defect. The performance and effectiveness of the proposed methods are confirmed by experiments on a brake test rig.

scholarly journals Stick–slip behavior of ice streams: modeling investigations

2009 ◽  
Vol 50 (52) ◽  
pp. 87-94 ◽  
Author(s):  
Olga V. Sergienko ◽  
Douglas R. MacAyeal ◽  
Robert A. Bindschadler
Keyword(s):  
West Antarctica ◽  
Ice Streams ◽  
Stick Slip ◽  
Ice Stream ◽  
Whillans Ice Stream ◽  
Spatial Propagation ◽  
The Difference ◽  
Stick Slip Motion ◽  
Transitional Phase ◽  
Slip Motion

AbstractA puzzling phenomenon of ice-stream flow is the stick–slip motion displayed by Whillans Ice Stream (WIS), West Antarctica. In this study we test the hypothesis that the WIS stick–slip motion has features similar to those of other known stick–slip systems, and thus might be of the same origin. To do so, we adapt a simple mechanical model widely used in seismology to study classic stick–slip behavior observed in tectonic faults, in which the difference between static and dynamic friction allows for the generation and spatial propagation of abrupt slip events. We show how spatial variability in friction properties, as well as a periodic forcing intended to mimic the effect of tides, can reproduce the observed duration and periodicity of stick–slip motion in an ice stream. An intriguing aspect of the association of WIS with mechanical stick–slip oscillators is that the onset of stick–slip cycling from a condition of permanent slip appears to be associated with the reduction in overall speed of WIS. If this association is true, then stick–slip behavior of WIS is a transitional phase of behavior associated with the ice stream's recent deceleration.

scholarly journals Effects of friction models on simulation of pneumatic cylinder

2019 ◽  
Vol 10 (2) ◽  
pp. 517-528
Author(s):  
Xuan Bo Tran ◽  
Van Lai Nguyen ◽  
Khanh Duong Tran
Keyword(s):  
Friction Force ◽  
Servo System ◽  
Pneumatic Cylinder ◽  
Lugre Model ◽  
Stick Slip ◽  
Comparison Results ◽  
Pneumatic Servo System ◽  
Friction Models ◽  
Stick Slip Motion ◽  
Slip Motion

Abstract. This study examines effects of three friction models: a steady-state friction model (SS model), the LuGre model (LG model), and the revised LuGre model (RLG model) on the motion simulation accuracy of a pneumatic cylinder. An experimental set-up of an electro-pneumatic servo system is built, and characteristics of the piston position, the pressures in the two-cylinder chambers and the friction force are measured and calculated under different control inputs to the proportional flow control valves. Mathematical model of the electro-pneumatic servo system is derived, and simulations are carried out under the same conditions as the experiments. Comparisons between measured characteristics and simulated ones show that the RLG model can give the best agreement among the three friction models while the LG model can only simulate partly the stick-slip motion of the piston at low velocities. The comparison results also show that the SS model used in this study is unable to simulate the stick-slip motion as well as creates much oscillations in the friction force characteristics at low velocities.

Sign in / Sign up

Export Citation Format

Share Document