A Simplified Model of the Base-Excited Coulomb Friction Oscillator With Contact Compliance and Inertia

Volume 1 ◽  
2004 ◽  
Author(s):  
Jin-Wei Liang
Keyword(s):  
Approximate Model ◽  
Contact Dynamics ◽  
Contact Model ◽  
Order System ◽  
Stick Slip ◽  
Sliding Motion ◽  
Contact Compliance ◽  
Friction Oscillator ◽  
Rigid Contact ◽  
Two Degree Of Freedom

This work investigates a base-excited Coulomb oscillator with contact compliance and inertia. The full-order system is a two degree-of-freedom (DOF) problem. The study first shows that two existing approximate models, including the rigid-contact model (RCM) and the compliant-contact model (CCM) cannot closely capture the dynamical characteristics of the global pure-sliding responses of the full-order system (FOS). To complement for this, this study proposes a new approximate model denoted as the reduced-order system (ROS), which is especially suitable for studying the contact dynamics subjected to the global pure-sliding motion. Numerical results show that the ROS not only has the merit of simplicity can also reliably depict the global pure-sliding features of the FOS. Furthermore, relevant stick-slip phenomena associated with the ROS (the transformed problem) are revealed and illustrated in time-domain and phase-space trajectories.

Braking Impact of Normal Dither Signals

2005 ◽  
Author(s):  
Jeff Badertscher ◽  
Kenneth A. Cunefare
Keyword(s):  
Contact Stiffness ◽  
Frequency Control ◽  
Primary Resonance ◽  
Theoretical Models ◽  
Friction Reduction ◽  
Hertzian Contact ◽  
Brake Squeal ◽  
Stick Slip ◽  
Friction Oscillator ◽  
Braking Torque

Dither control is a method of introducing high frequency control efforts into a system to suppress a lower frequency disturbance. One application of dither control is the suppression of automotive brake squeal. Brake squeal is a problem that has plagued the automotive industry for years. Placing a piezoceramic stack actuator in the piston of a floating caliper brake creates an experimental normal dither system. Many theoretical models indicate a reduction in the braking torque due to the normal dither signal. Using a Hertzian contact stiffness model the loss in friction is due to lowering the average normal force. There are also theories that the dither signal eliminates the ‘stick-slip’ oscillation causing an effective decrease in the friction force. Yet another theory indicates that the effective contact area is reduced, lowering the mean coefficient of friction. A particular approach considering a single degree of freedom friction oscillator predicts a maximum friction reduction of 10%, occurring at the primary resonance of the system. This paper will concentrate on validating this claim by experimentally determining braking torque reduction for a variety of dither control signals. Several dither control frequencies were chosen at system resonances, while others were chosen at frequencies most likely to provide control of the system. These frequencies were chosen based on previous squeal suppression research. The results indicate that dither control frequencies at system resonances have a greater impact on the braking system’s performance. In general, dither control reduces braking torque by no more than 2%.

scholarly journals Simulated Nanoscale Peeling Process of Monolayer Graphene Sheet: Effect of Edge Structure and Lifting Position

2010 ◽  
Vol 2010 ◽  
pp. 1-12 ◽  
Author(s):  
Naruo Sasaki ◽  
Hideaki Okamoto ◽  
Shingen Masuda ◽  
Kouji Miura ◽  
Noriaki Itamura
Keyword(s):  
Graphene Sheet ◽  
Atomic Scale ◽  
Monolayer Graphene ◽  
Lattice Period ◽  
Force Curve ◽  
Stick Slip ◽  
Edge Structure ◽  
Sliding Motion ◽  
Peeling Process ◽  
Surface Contact

The nanoscale peeling of the graphene sheet on the graphite surface is numerically studied by molecular mechanics simulation. For center-lifting case, the successive partial peelings of the graphene around the lifting center appear as discrete jumps in the force curve, which induce the arched deformation of the graphene sheet. For edge-lifting case, marked atomic-scale friction of the graphene sheet during the nanoscale peeling process is found. During the surface contact, the graphene sheet takes the atomic-scale sliding motion. The period of the peeling force curve during the surface contact decreases to the lattice period of the graphite. During the line contact, the graphene sheet also takes the stick-slip sliding motion. These findings indicate the possibility of not only the direct observation of the atomic-scale friction of the graphene sheet at the tip/surface interface but also the identification of the lattice orientation and the edge structure of the graphene sheet.

scholarly journals Stability of PDF Controller With Stick-Slip Friction Device

1997 ◽  
Vol 119 (3) ◽  
pp. 486-490 ◽  
Author(s):  
Jia-Yush Yen ◽  
Chih-Jung Huang ◽  
Shu-Shung Lu
Keyword(s):  
Control Algorithm ◽  
Controller Design ◽  
System Model ◽  
Pole Placement ◽  
Order System ◽  
Stick Slip ◽  
Precision Control ◽  
Experimental Works ◽  
The Stability ◽  
Control Accuracy

This paper presents the precision control of drive devices with significant stick-slip friction. The controller design follows the Pseudo-Derivative Feedback (PDF) control algorithm. Using the second order system model, the PDF controller offers arbitrary pole placement. In this paper, the stability proof for the controller with stick-slip friction is presented. On the basis of this proof, the stability criteria are derived. The paper also includes both the computer simulation and the experimental works to confirm the theoretical result. The experiments conducted on a Traction Type Drive Device (TTDD) shows that control accuracy of as high as ±1 arc – second is achieved.

Existence of Stick-Slip Periodic Solutions in a Dry Friction Oscillator

2011 ◽  
Vol 28 (3) ◽  
pp. 030502 ◽  
Author(s):  
Qun-Hong Li ◽  
Yu-Ming Chen ◽  
Zhi-Ying Qin
Keyword(s):  
Periodic Solutions ◽  
Dry Friction ◽  
Stick Slip ◽  
Friction Oscillator

Flexible Wheel/Rail Contact Model for Railway Vehicle Dynamics Without Pre-Calculation

2007 ◽  
Author(s):  
Mohammad Durali ◽  
S. Hassan Salehi ◽  
Mohammad Mehdi Jalili
Keyword(s):  
Vehicle Dynamics ◽  
Contact Forces ◽  
Contact Model ◽  
Railway Vehicle ◽  
Dynamic Problems ◽  
Vehicle Dynamic ◽  
Rail Vehicle ◽  
Rigid Contact ◽  
Contact Situation ◽  
Contact Mechanism

An advanced method using progressive concept of geometrical correspondence is applied to create a new wheel/rail contact model based on virtual penetration theory. The geometry and contact mechanism are solved simultaneously because of the independency in a defined correspondence. The model takes the penetrated profiles of wheel and rail and also associated creeps as inputs, and produces driving contact forces as output. The advantage of this model is that it doesn’t require pretabulation of rigid contact situation. The method allows calculating flexible, non-elliptical, multiple contact patches during integration of the model. Consequently the rails with substructures can vibrate separately from the vehicle in a flexible wheel/rail contact model. The simulation results indicate that this method can be used in various rail vehicle dynamic problems.

scholarly journals Stick/slip phenomena in dynamics: Choice of contact model. Numerical predictions & experiments

2008 ◽  
Vol 43 (10) ◽  
pp. 1211-1224 ◽  
Author(s):  
E. Chatelet ◽  
G. Michon ◽  
L. Manin ◽  
G. Jacquet
Keyword(s):  
Contact Model ◽  
Stick Slip ◽  
Numerical Predictions
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