Determining the Set of Active Constraints When a Rigid Body Compliantly Interacts With Multiple Frictional Contacts

2004 ◽  
Author(s):  
Shuguang Huang ◽  
Joseph M. Schimmels
Keyword(s):  
Rigid Body ◽  
Elastic Properties ◽  
Coefficient Of Friction ◽  
Coulomb Friction ◽  
Frictional Contact ◽  
Contact Point ◽  
Frictional Contacts ◽  
Active Constraints ◽  
The Coefficient Of Friction ◽  
Individual Contact

In this paper, the motion of an elastically suspended rigid body unilaterally constrained by frictional contact at multiple locations is studied. In this problem, each individual contact may or may not constrain the body’s motion. The set of actual active constraints is determined by: 1) the commanded motion of the body’s compliant support, 2) the coefficient of friction at each contact point, 3) the number and geometry of all potentially constraining surfaces, and 4) the elastic properties of the support. Here, the investigated problem is restricted to quasistatic motion and the interaction is characterized by Coulomb friction. We show that, for a passive compliant system, if the coefficient of friction at each contact is upper bounded, the set of active constraints is unique. A procedure to determine both the set of active constraints and the motion of the constrained body is provided.

The Motion of a Compliantly Suspended Rigid Body Constrained by Multipoint Frictional Contact

2005 ◽  
Vol 127 (4) ◽  
pp. 623-632
Author(s):  
Shuguang Huang ◽  
Joseph M. Schimmels
Keyword(s):  
Rigid Body ◽  
Friction Force ◽  
Coefficient Of Friction ◽  
Coulomb Friction ◽  
Frictional Contact ◽  
The Body ◽  
Elastic Behavior ◽  
Inertial Forces ◽  
Active Constraints ◽  
The Coefficient Of Friction

This paper addresses methods for determining the motion of an elastically suspended rigid body in frictional contact at multiple distinct locations. The methods developed assume that: (1) The motion of the support from which the body is suspended and the elastic behavior of the suspension are known; (2) inertial forces are negligible (motion is quasi-static); and (3) the contact is characterized by Coulomb friction. The derived coupled set of spatial rigid body equations is used to determine both the unknown direction of the friction force (at each point of contact) and the unknown motion of the rigid body. The uniqueness of the set of active constraints when considering multipoint contact is also addressed. We show that, for any passive compliant system, if the coefficient of friction at each contact is upper bounded, the set of active constraints is unique. A procedure to determine both the set of active constraints and the motion of the constrained body is provided.

The Motion of a Compliantly Suspended Rigid Body Constrained by Multi-Point Frictionless Contact

2002 ◽  
Author(s):  
Shuguang Huang ◽  
Joseph M. Schimmels
Keyword(s):  
Rigid Body ◽  
Elastic Properties ◽  
Elastic Behavior ◽  
Active Constraint ◽  
Frictionless Contact ◽  
Compliant Motion ◽  
Active Constraints ◽  
Surface Normal ◽  
Individual Contact

In this paper, the motion of an elastically suspended rigid body unilaterally constrained by contact at multiple locations is studied. In this problem, each individual contact may or may not constrain the body’s motion. Whether a contact provides an active constraint or not is determined by: 1) the commanded motion of the body’s compliant support, 2) the direction of the constraining surface normal, 3) the number and direction of other potentially constraining surfaces, and 4) the elastic properties of the support. Here, the investigated problem is restricted to quasistatic motion and frictionless contact. We show that the set of possible constraints that are active for a given set of contacts, elastic behavior, and commanded motion is unique. We also develop a procedure to determine the set of active constraints. This procedure is then used as part of a larger procedure to determine the compliant motion of the rigid body.

scholarly journals A Contact Characteristic of Roller Bearing with Palm Oil-based Grease Lubrication

2021 ◽  
Vol 89 (2) ◽  
pp. 139-149
Author(s):  
Yap Jun Heng ◽  
Nurul Farhana Mohd Yusof ◽  
Lee Ann Yen ◽  
Shazlina Abd Hamid ◽  
Nurul Nadzirah Mohd Yusof
Keyword(s):  
Finite Element ◽  
Coefficient Of Friction ◽  
Palm Oil ◽  
Frictional Contact ◽  
Roller Bearing ◽  
Rolling Contact ◽  
Von Mises Stress ◽  
The Coefficient Of Friction ◽  
Contact Characteristic ◽  
Von Mises

Grease lubricants are widely used in rolling contact applications to reduce friction between two rolling surfaces. Improper lubrication may cause high contact stress and deformation to the bearings and lead to machine failure The purpose of this study is to investigate the coefficient of friction produced by newly developed palm oil-based grease and to investigate the contact characteristics in lubricated roller bearings. In this work, the coefficient of friction of new greases was evaluated experimentally and the values were compared with the conventional mineral oil-based grease to investigate the friction performance. The friction test was performed using a four-ball tester. The finite element model was developed based on the roller bearing geometry and the simulation was carried out the evaluate the contact characteristic. The experimental result shows that the palm oil grease formulation A had the least coefficient of friction, followed by palm oil grease formulation B, mineral grease and food grade grease. This indicates that palm oil-based grease has the potential to be applied in rolling contact applications due to low friction characteristics. Finite element analysis shows that the maximum von Mises stress and total deformation for frictional contact are higher than the frictionless contact. For the frictional contact analysis with various lubricant COF, similar values were obtained with von Mises stress at 400.69 MPa and 3.4033×10-4 mm deformation. The finding shows that the small difference in grease COF did not affect the rolling contact. The finding also shows that the newly developed biodegradable grease has a similar performance in terms of rolling contact friction and contact characteristic in a condition that the bearing is operating in normal condition.

scholarly journals Tribology properties of hybrid graphene oxide materials as lubricant additives

2018 ◽  
Vol 226 ◽  
pp. 03019
Author(s):  
Anastasia A. Novikova ◽  
Victoria E. Burlakova ◽  
Valery N. Varavka ◽  
Tatyana G. Statsenko ◽  
Grigory B. Kharitonov ◽  
...  
Keyword(s):  
Graphene Oxide ◽  
Coefficient Of Friction ◽  
Hybrid Material ◽  
Copper Oxide Nanoparticles ◽  
Frictional Contacts ◽  
Pin On Disc ◽  
The Coefficient Of Friction ◽  
Isopropanol Solution ◽  
Uv Visible ◽  
Synthesized Materials

Graphene oxide was synthesized by the modified Hammers method. With managed hydrolysis in isopropanol solution obtained hybrid material “graphene oxide - copper oxide nanoparticles”. The phase composition of the hybrid material was studied by X-ray phase analysis and UV-visible spectroscopy. By ultrasonic processing dispersions of synthesized materials in glycerol were produced. The concentration of lubricating additives in the lube oil was 0.05 wt. %. The tribological properties of dispersions were investigated using a pin-on-disc friction machine. Tests showed that in the presence of graphene oxide, the friction coefficient was ~0.02, while with the addition of a hybrid material, the coefficient of friction was ~0.035. This is due to various mechanisms of lubrication. Reduction of the coefficient of friction in the presence of graphene oxide is associated with the formation of tribocarbon on the porosity of frictional contacts. While the addition of a hybrid material containing the CuO nanoparticles leads to the formation of a third body.

A quasistatic frictional contact problem for viscoelastic materials with long memory

2020 ◽  
Vol 27 (2) ◽  
pp. 249-264
Author(s):  
Abderrezak Kasri ◽  
Arezki Touzaline
Keyword(s):  
Contact Problem ◽  
Coefficient Of Friction ◽  
Frictional Contact ◽  
Time Discretization ◽  
Contact Boundary ◽  
Long Term Memory ◽  
Viscoelastic Materials ◽  
Existence Of A Solution ◽  
Frictional Contact Problem ◽  
The Coefficient Of Friction

AbstractThe aim of this paper is to study a quasistatic frictional contact problem for viscoelastic materials with long-term memory. The contact boundary conditions are governed by Tresca’s law, involving a slip dependent coefficient of friction. We focus our attention on the weak solvability of the problem within the framework of variational inequalities. The existence of a solution is obtained under a smallness assumption on a normal stress prescribed on the contact surface and on the coefficient of friction. The proof is based on a time discretization method, compactness and lower semicontinuity arguments.

STABILIZATION OF THE ADAPTIVE FRICTION OUTPUT PARAMETER CONTACT OF SOLIDS WITH INDIRECT CONTROL

2020 ◽  
Author(s):  
E.G Zadoshenko ◽  
◽  
A.I Sokolenko ◽  
V.V. Boginskaya ◽  
D.V Kayibanda
Keyword(s):  
Coefficient Of Friction ◽  
Positive Feedback ◽  
Output Signal ◽  
Frictional Contact ◽  
Output Parameter ◽  
Indirect Control ◽  
Functional Scheme ◽  
The Coefficient Of Friction ◽  
Sensor Transducer

It is shown that the introduction of structural-functional scheme of adaptive frictional contact of the second adder and comparator in the form of adaptive frictional contact with a positive feedback, allows you to feed the input of the sensor-Converter signal, the value of which, as well as the value of the output signal of the sensor-transducer is inversely proportional to the coefficient of friction. This allows you to eliminate the additional push node, equivalent to replacing it with the output signal of the sensitive elements.

EXISTENCE RESULTS FOR THE STATIC CONTACT PROBLEM WITH COULOMB FRICTION

1998 ◽  
Vol 08 (03) ◽  
pp. 445-468 ◽  
Author(s):  
C. ECK ◽  
J. JARUSEK
Keyword(s):  
Contact Problem ◽  
Coefficient Of Friction ◽  
Upper Bound ◽  
Penalty Method ◽  
Coulomb Friction ◽  
Existence Of Solutions ◽  
Existence Results ◽  
Static Contact ◽  
The Coefficient Of Friction ◽  
Smoothing Procedure

We prove the existence of solutions to the static contact problem with Coulomb friction, provided that the coefficient of friction is small enough. The proof employs the penalty method and a certain smoothing procedure for the friction functional. Using optimal trace estimates for the solutions of the Lamé equations, we calculate an upper bound for the admissible coefficient of friction which is greater than the corresponding bounds proposed by Necas, Jarusek and Haslinger (1980) and by Jarusek (1983).

scholarly journals Voltage-Induced Friction with Application to Electrovibration

Lubricants ◽  
2019 ◽  
Vol 7 (12) ◽  
pp. 102 ◽  
Author(s):  
Markus Heß ◽  
Valentin L. Popov
Keyword(s):  
Experimental Data ◽  
Coulomb Friction ◽  
Frictional Contact ◽  
Recent Literature ◽  
Adhesion Force ◽  
Unit Area ◽  
Macroscopic Model ◽  
Experimental Investigations ◽  
Contact Interface ◽  
Frictional Contacts

Due to the growing interest in robotic and haptic applications, voltage-induced friction has rapidly gained in importance in recent years. However, despite extensive experimental investigations, the underlying principles are still not sufficiently understood, which complicates reliable modeling. We present a macroscopic model for solving electroadhesive frictional contacts which exploits the close analogy to classical adhesion theories, like Johnson-Kendall-Roberts (JKR) and Maugis, valid for electrically neutral bodies. For this purpose, we recalculate the adhesion force per unit area and the relative surface energy from electrostatics. Under the assumption of Coulomb friction in the contact interface, a closed form equation for the friction force is derived. As an application, we consider the frictional contact between the fingertip and touchscreen under electrovibration in more detail. The results obtained with the new model agree well with available experimental data of the recent literature. The strengths and limitations of the model are clearly discussed.

Analysis of Rigid-Body Dynamic Models for Simulation of Systems With Frictional Contacts

2000 ◽  
Vol 68 (1) ◽  
pp. 118-128 ◽  
Author(s):  
P. Song ◽  
P. Kraus ◽  
V. Kumar ◽  
P. Dupont
Keyword(s):  
Rigid Body ◽  
Coulomb Friction ◽  
Dynamic Models ◽  
Stable Solution ◽  
Friction Model ◽  
Rigid Body Dynamics ◽  
Frictional Contacts ◽  
Friction Law ◽  
Rigid Body Dynamic ◽  
Body Dynamic

The use of Coulomb’s friction law with the principles of classical rigid-body dynamics introduces mathematical inconsistencies. Specifically, the forward dynamics problem can have no solutions or multiple solutions. In these situations, compliant contact models, while increasing the dimensionality of the state vector, can resolve these problems. The simplicity and efficiency of rigid-body models, however, provide strong motivation for their use during those portions of a simulation when the rigid-body solution is unique and stable. In this paper, we use singular perturbation analysis in conjunction with linear complementarity theory to establish conditions under which the solution predicted by the rigid-body dynamic model is stable. We employ a general model of contact compliance to derive stability criteria for planar mechanical systems. In particular, we show that for cases with one sliding contact, there is always at most one stable solution. Our approach is not directly applicable to transitions between rolling and sliding where the Coulomb friction law is discontinuous. To overcome this difficulty, we introduce a smooth nonlinear friction law, which approximates Coulomb friction. Such a friction model can also increase the efficiency of both rigid-body and compliant contact simulation. Numerical simulations for the different models and comparison with experimental results are also presented.

A Fundamental Study on Derailment of Wheel Flange Under Rolling-Sliding and Pure Sliding Conditions

2005 ◽  
Author(s):  
Md. Ziaur Rahman ◽  
Takumi Ban ◽  
Hideshi Kakishima ◽  
Takashi Yamamoto
Keyword(s):  
Surface Roughness ◽  
Coefficient Of Friction ◽  
Solid Lubricant ◽  
Contact Point ◽  
Testing Machine ◽  
Full Scale ◽  
Detailed Data ◽  
Friction Behavior ◽  
Fundamental Study ◽  
The Coefficient Of Friction

A newly developed full scale wheel-rail contact testing machine is used to obtain detailed data on flange climb behavior with covering various loads and displacements at the wheel flange and rail contact under both rolling-sliding and pure sliding conditions. The effects of different surface roughness of the wheel flange on coefficient of friction at the contact point in wheel flange climb mechanism were investigated. A correlation between different state of the interface (i.e. surface of dry, wet, rust, oily and different lubricated condition by solid lubricant) and wheel flange surface roughness with rail were drawn. The coefficient of friction was significantly influenced in pure sliding conditions than that of rolling-sliding conditions by the degree of the asperities on the wheel flange surface. Moreover, solid lubricant showed better performance to reduce coefficient of friction. However, the rust on the rail surfaces was one of the important factors to destabilize the friction behavior.

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