Presentation of a new method to measure the friction coefficient using an electromagnetic digital device

2010 ◽  
Vol 224 (9) ◽  
pp. 1019-1026 ◽  
Author(s):  
L Petit ◽  
M Bigerelle ◽  
A Jourani ◽  
E Dore ◽  
C Prelle ◽  
...  
Keyword(s):  
Friction Coefficient ◽  
New Method ◽  
Digital Device

scholarly journals A new method to calculate the friction coefficient of ball screws based on the thermal equilibrium

2019 ◽  
Vol 11 (1) ◽  
pp. 168781401882073
Author(s):  
Lu-Chao Zhang ◽  
Li Zu
Keyword(s):  
Friction Coefficient ◽  
Temperature Rise ◽  
Thermal Equilibrium ◽  
Heat Dissipation ◽  
Mechanical Efficiency ◽  
New Method ◽  
Measuring System ◽  
Ball Screw ◽  
Heat Absorption ◽  
Screw Mechanism

Based on the theory of thermal transmission, this article provides a new method to acquire the friction coefficient in ball screw mechanism. While the screw is in thermal equilibrium, the heat absorption is equal to the heat dissipation. The heat absorption is able to be achieved by calculating the heat energy due to the friction at the contact area and the heat dissipation can be calculated by the law of thermodynamics. When the temperature rise is determined, the heat dissipation can be obtained and the friction coefficient in ball screw mechanism can be calculated further. In order to confirm the validity of this method, a measuring system is constructed to obtain the temperature rise of ball screws. The experimental results show that the temperature rise has the same tendency with the theoretical values depending on this model. Therefore, it can be exploited to predict the temperature rise of ball screws in the rated life cycle when the ball screw is under the condition of thermal equilibrium. Furthermore, this model can be used to evaluate the mechanical efficiency, which is an important parameter for the performance of the ball screw.

Slipping Dynamics of Slender-Beam Payloads During Lay-Down Operations

2018 ◽  
Vol 140 (8) ◽  
Author(s):  
Shenghai Wang ◽  
Aldo Ferri ◽  
William Singhose
Keyword(s):  
Friction Coefficient ◽  
Flat Surface ◽  
New Method ◽  
Line Contact ◽  
Horizontal Position ◽  
Vertical Orientation ◽  
Dynamic Analyses ◽  
Theoretical Predictions

When laying down a long slender beam from a near-vertical orientation, to a horizontal position on a flat surface, the payload may slip and move suddenly in unintended and unpredictable ways. This occurs during crane operations when the movements of the overhead trolley and lowering of the hoist cable are not properly coordinated. The payload's unintended sliding can potentially cause damage and injure people. This paper presents static and dynamic analyses of slender-beam payload lay-down operations that establish a structured method to predict the safe conditions for lay-down operations. Also, a new method to measure the friction coefficient of surface-to-line contact is proposed. Lay-down experiments are carried out to verify the theoretical predictions.

A Research on the Measurement of Friction Coefficient of Plastic Forming by Floating Die Extrusion

2011 ◽  
Vol 328-330 ◽  
pp. 530-537
Author(s):  
Xuan Rong Xin ◽  
Cheng Song He ◽  
Long Long Shan
Keyword(s):  
Friction Coefficient ◽  
Extrusion Process ◽  
New Method ◽  
Experimental Device ◽  
Plastic Forming ◽  
Die Extrusion ◽  
Extrusion Technology

A new measurement of friction coefficient which is more applicable to overload extrusion technology is proposed in this paper. It determines the friction coefficient of overload plastic forming by firstly determining the load mutation of friction by a floating die experimental device. It is proved in this experiment that the friction coefficient in extrusion process can be precisely determined and the effectiveness of lubricating can be evaluated objectively by this new method which is easier to understand and master than the theory that determines the friction coefficient by ring upsetting.

Lattice-Boltzmann Simulation of Polymer-Solvent Systems

1998 ◽  
Vol 09 (08) ◽  
pp. 1429-1438 ◽  
Author(s):  
Patrick Ahlrichs ◽  
Burkhard Dünweg
Keyword(s):  
Friction Coefficient ◽  
Lattice Boltzmann ◽  
Fluid Velocity ◽  
New Method ◽  
Velocity Autocorrelation Function ◽  
Lattice Boltzmann Simulation ◽  
Solvent Systems ◽  
The Difference ◽  
Definition Of ◽  
Polymer Solvent

We investigate a new method for simulating polymer-solvent systems which combines a lattice-Boltzmann approach for the fluid with a continuum molecular dynamics (MD) model for the polymer chain. The two parts are coupled by a friction force which is proportional to the difference of the monomer velocity and the fluid velocity at the monomer's position. The strength of the coupling can be tuned by a friction coefficient. Using this approach we examine the dynamics of one monomer immersed in the fluid, and by adding fluctuations to the fluid and the monomer, also the velocity autocorrelation function of one monomer. This results in the definition of an effective friction coefficient for the dynamics of the monomer. Furthermore we analyze the mapping of the model to an MD simulation, allowing us to compare results obtained using the new method with MD.

A New Method of Screw Strength Calculation

1971 ◽  
Vol 93 (4) ◽  
pp. 1233-1238
Author(s):  
J. B. Popper
Keyword(s):  
Friction Coefficient ◽  
Tensile Load ◽  
Strength Calculation ◽  
New Method ◽  
Shear Stresses ◽  
Safety Factors ◽  
Tightening Torque ◽  
Realistic Picture ◽  
The Way

By considering several factors usually neglected, a more realistic picture of screw strength is obtained. These are: thread geometry, combined tensile and shear stresses, and uncertainty in the exact value of the friction coefficient. This uncertainty increases the tightening torque necessary to obtain a required tensile load, and reduces the effective screw strength considerably. Taking all these factors into account, the calculated screw strength is much smaller, but more realistic, so that smaller safety factors can be employed, yet more reliable designs obtained. The equations derived point the way towards two methods for increasing screw strength. These are: use of preload-indicating washers; and turning the screw back by a certain amount after the initial tightening. The first method alone can double the usable screw strength.

scholarly journals Biotribology of Synovial Cartilage: A New Method for Visualization of Lubricating Film and Simultaneous Measurement of the Friction Coefficient

Materials ◽  
2020 ◽  
Vol 13 (9) ◽  
pp. 2075
Author(s):  
Pavel Čípek ◽  
Martin Vrbka ◽  
David Rebenda ◽  
David Nečas ◽  
Ivan Křupka
Keyword(s):  
Friction Coefficient ◽  
Simultaneous Measurement ◽  
Film Formation ◽  
New Method ◽  
Cartilage Tissue ◽  
Evaluation Procedure ◽  
Synovial Joint ◽  
Friction Forces ◽  
Lubrication Film ◽  
Lubricating Film

A healthy natural synovial joint is very important for painless active movement of the natural musculoskeletal system. The right functioning of natural synovial joints ensures well lubricated contact surfaces with a very low friction coefficient and wear of cartilage tissue. The present paper deals with a new method for visualization of lubricating film with simultaneous measurements of the friction coefficient. This can contribute to better understanding of lubricating film formation in a natural synovial joint. A newly developed device, a reciprocating tribometer, is used to allow for simultaneous measurement of friction forces with contact visualization by fluorescence microscopy. The software allowing for snaps processing and subsequent evaluation of fluorescence records is developed. The evaluation software and the follow-up evaluation procedure are also described. The experiments with cartilage samples and model synovial fluid are carried out, and the new software is applied to provide their evaluation. The primary results explaining a connection between lubrication and friction are presented. The results show a more significant impact of albumin proteins on the lubrication process, whereas its clusters create a more stable lubrication layer. A decreasing trend of protein cluster count, which corresponds to a decrease in the thickness of the lubrication film, is found in all experiments. The results highlight a deeper connection between the cartilage friction and the lubrication film formation, which allows for better understanding of the cartilage lubrication mechanism.

Application of Energy Principle to Dry Sliding Friction

2005 ◽  
Author(s):  
Zhongming Xu ◽  
Ping Huang
Keyword(s):  
Friction Coefficient ◽  
Friction Force ◽  
Sliding Friction ◽  
Critical Value ◽  
New Method ◽  
Dry Sliding ◽  
Operational Parameters ◽  
Energy Principle ◽  
Dry Sliding Friction ◽  
Elastic Surfaces

A new method named as energy principle method is used to calculate and research the friction force and friction coefficient of two flat elastic surfaces. The studies reveal the relationships between friction coefficient and parameters of a tribo-system such as microstructure of interface, performance of material, operational parameters and geometry parameters. When the height of an asperity increases in the model, the friction coefficient increases rapidly to a critical value, and then hardly increases after that.

Selective Sampling and Orientation of Non-Homogeneous Tissues

1968 ◽  
Vol 26 ◽  
pp. 98-99
Author(s):  
C. C. Clawson ◽  
L. W. Anderson ◽  
R. A. Good
Keyword(s):  
Electron Microscopy ◽  
Electron Microscope ◽  
Light Microscopy ◽  
Random Sampling ◽  
New Method ◽  
Microscope Examination ◽  
Small Areas ◽  
Selective Sampling ◽  
Large Numbers ◽  
Specific Orientation

Investigations which require electron microscope examination of a few specific areas of non-homogeneous tissues make random sampling of small blocks an inefficient and unrewarding procedure. Therefore, several investigators have devised methods which allow obtaining sample blocks for electron microscopy from region of tissue previously identified by light microscopy of present here techniques which make possible: 1) sampling tissue for electron microscopy from selected areas previously identified by light microscopy of relatively large pieces of tissue; 2) dehydration and embedding large numbers of individually identified blocks while keeping each one separate; 3) a new method of maintaining specific orientation of blocks during embedding; 4) special light microscopic staining or fluorescent procedures and electron microscopy on immediately adjacent small areas of tissue.

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