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.

ANALYSIS OF ADAPTIVE FRICTIONAL CONTACT SOLID BODIES WITH INDIRECT REGULATION

2020 ◽  
Author(s):  
E.G. Zadoshenko ◽  
◽  
A.I. Sokolenko ◽  
V.V. Boginskaya ◽  
D.V. Kayibanda ◽  
...  
Keyword(s):  
Automatic Control ◽  
Frictional Contact ◽  
Control Unit ◽  
Output Parameter ◽  
Friction Contact ◽  
Indirect Control ◽  
The Coefficient Of Friction ◽  
Side Walls ◽  
Solid Bodies ◽  
Automatic Control Unit

Dependencies were found for determining the values of the parameters of the automatic control unit of the adaptive friction contact with indirect control, which allow stabilizing its output parameter. Profiling of the side walls of the sockets of the automatic control unit of the adaptive friction contact isperformed, which allows to exclude the influence of the coefficient of friction on the output parameter.

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.

FEATURES OF APPLICATION AND EFFECTIVENESS OF ADAPTIVE FRICTION CLUTCHES

2020 ◽  
Author(s):  
M. D. Gavrilenko ◽  
Keyword(s):  
Research And Development ◽  
Coefficient Of Friction ◽  
Negative Feedback ◽  
Positive Feedback ◽  
Total Weight ◽  
Safety Devices ◽  
New Principal ◽  
The Coefficient Of Friction ◽  
Structural Connections

It is shown that in existing studies of adaptive friction clutches are considered as safety devices only to prevent the action of overloads on the drive elements. The following has not been studied yet: while using adaptive frictional couplings their influence on total weight of elements of the drive, and also on its cost are not considered. Research and development of new principal and design schemes of adaptive friction clutches with combined, negative two-circuit, positive-negative and positive feedback, as well as improvement of existing clutches on the basis of single-circuit negative feedback by providing a variable value of the gain depending on the coefficient of friction and changes in intra-structural connections can significantly improve the accuracy of the couplings.

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.

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.

Thermomechanical analysis on the frictional contact behavior of a high-strength steel 22MnB5–die steel H13 tribopair at 800 °C by experiment and finite-element simulation

2021 ◽  
pp. 135065012098086
Author(s):  
Yi Zhang ◽  
Wei Wang ◽  
Kun Liu ◽  
Baohong Tong ◽  
Zhaowen Hu ◽  
...  
Keyword(s):  
Plastic Deformation ◽  
Finite Element ◽  
Coefficient Of Friction ◽  
Frictional Contact ◽  
High Strength ◽  
Element Model ◽  
Boron Steel ◽  
Die Steel ◽  
The Coefficient Of Friction ◽  
Worn Surface

High-strength boron steels are widely used in manufacturing the auto bodies and parts of light-weight vehicles, but the high rates of surface scratches and die wear have consistently occurred during hot stamping for these steels. For an in-depth understanding of the tribological characteristics at this interface, the frictional contact behavior and thermomechanical mechanisms of boron steel 22MnB5 against die steel H13 at 800 °C were studied through experiments and finite-element simulations. The coefficient of friction and worn surface topography were investigated by pin-on-disk sliding tests. A three-dimensional thermomechanical finite-element model of a friction pair was established to explore the interfacial dynamic variations. Experimental and simulation results show that severe elastic–plastic deformation occurred on the worn surface of the boron steel, whereas an increase in the load decreased the coefficient of friction within a certain range because the growth rate of shear force was slower than that of the normal force. When the finite-element model was changed from the gradual loading stage to the initial sliding stage, the tangential friction force further increased the plastic deformation on the surface of boron steel. The scratches and furrows were mainly caused by the compression and shear from asperities of the rough surface, as confirmed by the high-frictional-stress regions concentrated on the peaks and flanks of asperities. During the high-temperature and high-pressure experiments, the plasticized and softened surface materials of the boron steel adhered to the die surface readily, resulting in peeling and delamination.

A PIEZOELECTRIC CONTACT PROBLEM WITH SLIP DEPENDENT COEFFICIENT OF FRICTION

2004 ◽  
Vol 9 (3) ◽  
pp. 229-242 ◽  
Author(s):  
M. Sofonea
Keyword(s):  
Mathematical Model ◽  
Weak Solution ◽  
Contact Problem ◽  
Coefficient Of Friction ◽  
Dry Friction ◽  
Variational Formulation ◽  
Frictional Contact ◽  
Coupled System ◽  
Piezoelectric Body ◽  
The Coefficient Of Friction

We consider a mathematical model which describes the static frictional contact between a piezoelectric body and an obstacle. The constitutive relation of the material is assumed to be electroelastic and involves a nonlinear elasticity operator. The contact is modelled with a version of Coulomb's law of dry friction in which the coefficient of friction depends on the slip. We derive a variational formulation for the model which is in form of a coupled system involving as unknowns the displacement field and the electric potential. Then we provide the existence of a weak solution to the model and, under a smallness assumption, we provide its uniqueness. The proof is based on a result obtained in [14] in the study of elliptic quasi‐variational inequalities.

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.

Experimental Investigation of aluminum doping crumb rubber/epoxy composite in reciprocating motion

2015 ◽  
Vol 3 ◽  
pp. 1
Author(s):  
Goutam Chandra Karar ◽  
Nipu Modak
Keyword(s):  
Experimental Investigation ◽  
Coefficient Of Friction ◽  
Epoxy Composite ◽  
Normal Load ◽  
Crumb Rubber ◽  
The Other ◽  
Reciprocating Motion ◽  
Molding Process ◽  
Friction Tester ◽  
The Coefficient Of Friction

The experimental investigation of reciprocating motion between the aluminum doped crumb rubber /epoxy composite and the steel ball has been carried out under Reciprocating Friction Tester, TR-282 to study the wear and coefficient of frictions using different normal loads (0.4Kg, 0.7Kgand1Kg), differentfrequencies (10Hz, 25Hz and 40Hz).The wear is a function of normal load, reciprocating frequency, reciprocating duration and the composition of the material. The percentage of aluminum presents in the composite changesbut the other components remain the same.The four types of composites are fabricated by compression molding process having 0%, 10%, 20% and 30% Al. The effect of different parameters such as normal load, reciprocating frequency and percentage of aluminum has been studied. It is observed that the wear and coefficient of friction is influenced by the parameters. The tendency of wear goes on decreasing with the increase of normal load and it is minimum for a composite having 10%aluminum at a normal load of 0.7Kg and then goes on increasing at higher loads for all types of composite due to the adhesive nature of the composite. The coefficient of friction goes on decreasing with increasing normal loads due to the formation of thin film as an effect of heat generation with normal load.

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