scholarly journals Correlation between the anisotropy of an AA2021-T351 aluminium rolled thick plate and the occurrence of the stick-slip phenomenon

2021 ◽  
Vol 13 (1) ◽  
pp. 193-201
Author(s):  
Nicolae-Alexandru STOICA ◽  
Alina-Maria STOICA ◽  
Andrei TUDOR ◽  
Victor MANOLIU ◽  
Mihail BOTAN ◽  
...  
Keyword(s):  
Contact Pressure ◽  
Thick Plate ◽  
Dynamic Instability ◽  
Rolling Direction ◽  
Contact Interface ◽  
Stick Slip ◽  
Sliding Speed ◽  
Sliding Surfaces ◽  
Ultra High Molecular Weight ◽  
Slip Phenomenon

The stick-slip phenomenon is a dynamic instability that appears at the contact interface of two sliding surfaces. Its occurrence is influenced by the relative sliding speed, the contact pressure, and the system rigidity, but also by the state of contact between the two sliding surfaces. The present paper aims to study the influence of the anisotropy of an aluminium AA2021-T351 plate on the stick-slip phenomenon. For this, using the CETR UMT II tribometer, linear sliding tests have been performed on the aluminium alloy thick plate surface using a cylindrical pin made of ultra-high-molecular-weight polyethylene (UHMWPE) along three directions: a longitudinal one, corresponding to the rolling direction of the sample (0°), a transverse one, perpendicular to the rolling direction (90°), and a median direction (45°). Varying the sliding speed, the contact pressure, and the system rigidity, it was possible to observe the influence of the material anisotropy on the specific parameters of the stick-slip phenomenon.

Tribological Properties and Microstructure Evolution of Ultra-High Molecular Weight Polyethylene

1999 ◽  
Vol 121 (2) ◽  
pp. 394-402 ◽  
Author(s):  
C. Klapperich ◽  
K. Komvopoulos ◽  
L. Pruitt
Keyword(s):  
Electron Microscopy ◽  
Molecular Weight ◽  
Wear Rate ◽  
High Molecular Weight ◽  
Contact Pressure ◽  
Wear Debris ◽  
Third Body ◽  
Sliding Speed ◽  
Delamination Wear ◽  
Ultra High Molecular Weight

The friction and wear properties of unmodified ultra-high molecular weight polyethylene (UHMWPE) were investigated experimentally. Dinks of semicrystalline UHMWPE were slid against polished CoCrWNi pins in bovine serum at ranges of contact pressure and sliding speed typical of those encountered in total joint replacements. The coefficient of friction was monitored continuously during testing, and the wear rate was determined from surface profilometry measurements of worn disk surfaces accounting for strain relaxation. Scanning electron microscopy (SEM) results demonstrated that surface deterioration comprises adhesion, third-body abrasion by polyethylene wear debris, and delamination wear. The contribution of these mechanisms to the overall wear rate and the formation of wear debris depends predominantly on the contact pressure and secondarily on the sliding speed. Transmission electron microscopy (TEM) yielded new insight into the evolution of the microstructure morphology of UHMWPE during sliding. Cross sections parallel to the wear tracks obtained from various depths were analyzed with the TEM to develop a spatial mapping of the subsurface microstructure as a function of contact pressure. Alignment of crystalline regions (lamellae) in the polyethylene microstructure parallel to the sliding surface was found to occur during sliding even at relatively low contact pressures. SEM observations suggested that the highly oriented microstructure is the precursor to delamination wear, leading to the formation of wear particles larger than those produced by adhesion and third-body abrasion at the contact interface.

Paper 16: Friction in Wet Clutches

1967 ◽  
Vol 182 (14) ◽  
pp. 132-138 ◽  
Author(s):  
E. M. Evans ◽  
J. Whittle
Keyword(s):  
Coefficient Of Friction ◽  
Power Transmission ◽  
Sliding Speed ◽  
Friction Materials ◽  
Friction Characteristics ◽  
Sliding Surfaces ◽  
Base Oils ◽  
Wet Friction ◽  
Friction Clutch ◽  
The Coefficient Of Friction

This paper is intended to demonstrate that designers of wet clutches for power transmission can obtain the optimum friction characteristics for specific applications by considering the interaction between friction materials and lubricants. A friction clutch plate rig is described and the friction results obtained are presented. It is shown that a wide variation of coefficients of friction and frictional characteristics in wet friction clutches can be obtained by changing the oils and friction materials. In particular the coefficient of friction is dependent upon (1) the oil, (2) the materials of the sliding surfaces, (3) sliding speed, and (4) temperature. It is also shown that the coefficient of friction is affected by ( a) refining treatment given to the oil, ( b) different base oils, and ( c) additives.

Preliminary Study on Stick-Slip in Drillstring With Analytical Model Expressed With Neutral Delay Differential Equation

2014 ◽  
Author(s):  
Tomoya Inoue ◽  
Tokihiro Katsui ◽  
Chang-Kyu Rheem ◽  
Zengo Yoshida ◽  
Miki Y. Matsuo
Keyword(s):  
Differential Equation ◽  
Analytical Model ◽  
Delay Differential Equation ◽  
Drill Bit ◽  
Neutral Delay ◽  
Stick Slip ◽  
Scientific Drilling ◽  
Neutral Delay Differential Equation ◽  
Delay Differential ◽  
Slip Phenomenon

Stick-slip is a major problem in offshore drilling because it may cause damage to the drill bit as well as crushing or grinding the sediment layer, which is crucial problem in scientific drilling because the purpose of the scientific drilling is to recover core samples from the layers. To mitigate stick-slip, first of all it is necessary to establish a model of the torsional motion of the drill bit and express the stick-slip phenomenon. Toward this end, the present study proposes a model of torsional waves propagating in a drillstring. An analytical model is developed and used to derive a neutral delay differential equation (NDDE), a special type of equation that requires time history, and an analytical model of stick-slip is derived for friction models between the drill bit and the layer as well as the rotation speed applied to the uppermost part of the drill string. In this study, the stick-slip model is numerically analyzed for several conditions and a time series of the bit motions is obtained. Based on the analytical results, the appearance of stick-slip and its severity are discussed. A small-scale model experiment was conducted in a water tank to observe the stick-slip phenomenon, and the result is discussed with numerical analysis. In addition, utilizing surface drilling data acquired from the actual drilling operations of the scientific drillship Chikyu, occurrence of stick-slip phenomenon is discussed.

Effect of laser-textured micro dimples on inhibition of stick-slip phenomenon of sliding guideway

2022 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Yonghong Fu ◽  
Jie Yang ◽  
Hao Wang ◽  
Yuyang He
Keyword(s):  
Hydrodynamic Lubrication ◽  
Textured Surface ◽  
Stick Slip ◽  
Content Type ◽  
Speed Range ◽  
Lubrication Condition ◽  
Micro Dimples ◽  
Pin On Disk ◽  
Micro Dimple ◽  
Slip Phenomenon

Purpose This study aims to investigate the efficacy of micro dimple in inhibiting stick-slip phenomenon on the sliding guideway. Design/methodology/approach In this study, micro-dimples were fabricated by laser on surfaces of steel disk and guideway. The disks and guideways were respectively performed pin-on-disk tribological tests and working condition experiments to study differences in lubrication condition and friction stability between textured and untextured surfaces. Findings Micro-dimples help reduce critical sliding speed that allows contact surfaces to enter in hydrodynamic lubrication regime. This increases hydrodynamic lubrication range and narrows speed range where stick-slip phenomenon can occur, enhancing sliding guideway’s adaptability for broader working conditions. Furthermore, friction stability on the textured surface improved, lowering the occurrence possibility of stick-slip phenomenon. Finally, difference between static and kinetic frictions on the textured surface is lower relative to the untextured surface, which decreases the critical velocity when the stick-slip phenomenon occurs. Originality/value The results indicate that laser-textured micro-dimples are significantly conducive to inhibit stick-slip phenomenon, thus providing smoother movement for the guideway and eventually increasing precision of the machine.

scholarly journals FRICTION ANALYSIS IN CASE OF THE CARRIAGE- FEED SHAFT CINEMATIC COUPLING AT CNC LATHE

2020 ◽  
Vol 7 (5) ◽  
pp. 30-37
Author(s):  
Daniel Popescu
Keyword(s):  
Mathematical Model ◽  
Rational Design ◽  
Normal Force ◽  
Stick Slip ◽  
Disturbing Force ◽  
Dimensional Precision ◽  
Cnc Lathe ◽  
Elastic Systems ◽  
Friction Analysis ◽  
Slip Phenomenon

The paper presents a mathematical model for analysis of friction between the tool bearing saddle and conductor at CNC lathe. The analysis of longitudinal advance movement laws is performed taking into account the appearance and development of disturbing harmonic forces created by auto-vibrations determined by the interaction between the partial elastic systems of tool and workpiece. The friction force is emphasized as product of two components depending on the sliding speed and on the normal disturbing force. By establishing the dynamic response of the system, when the normal force depends linearly on speed, acceleration and mobile ensemble position, the premises are created for stability analysis of the friction movement, obtaining the limit speeds under which the stick-slip phenomenon occurs. Thus, it is provided for a rational design of CNC lathe elastic structure, in order to improve the surface quality and the dimensional precision.

scholarly journals Development of Artificial Skin Using Keratin Film for Evaluation of Puncture Performance of Microneedle

2020 ◽  
Vol 32 (2) ◽  
pp. 351-361
Author(s):  
Ryo Nishino ◽  
Seiji Aoyagi ◽  
Masato Suzuki ◽  
Atsushi Ueda ◽  
Yuki Okumura ◽  
...  
Keyword(s):  
Stratum Corneum ◽  
Human Skin ◽  
Human Hair ◽  
Subcutaneous Tissue ◽  
Artificial Skin ◽  
Resistance Force ◽  
Stick Slip ◽  
Silicon Rubber ◽  
Animal Skin ◽  
Slip Phenomenon

Humans do not feel pain when bitten by mosquitos; therefore, we have attempted to develop a microneedle that mimics the puncturing mechanism of mosquitos. We have quantitatively evaluated the puncturing performance of the developed microneedle by puncturing an artificial skin made from polydimethylsiloxane (PDMS), a kind of silicon rubber. Unlike the mono-layered PDMS, however, animal skin including human skin is structured to have a hard stratum corneum, epidermis and dermis over soft subcutaneous tissue. In this paper, we propose an artificial skin having a two-layered hard/soft structure, constructed from PDMS with a human-hair-derived keratin film adhered onto the top surface. We evaluated the hardness of the keratin film (Young’s modulus) and found that it could qualitatively simulate the hard layers of the skin including the stratum corneum. The artificial skin we developed reproduced the following phenomena: the decrease in resistance force of animal skin at the point when the needle penetrates the surface followed by variation in resistance due to the stick-slip phenomenon as the needle penetrates more deeply.

Simulacija i odstranjivanje stick-slip efekta servosistema sprovodnog aparata hidraulične turbine

2021 ◽  
Vol 23 (1) ◽  
pp. 37-41
Author(s):  
Darko Babunski ◽  
◽  
Emil Zaev ◽  
Atanasko Tuneski ◽  
Laze Trajkovski ◽  
...  
Keyword(s):  
Hydraulic Cylinder ◽  
Friction Model ◽  
Slip Effect ◽  
Hydraulic Systems ◽  
Hydraulic Actuator ◽  
Stick Slip ◽  
Hydro Turbine ◽  
Servo Mechanism ◽  
The Mathematical Model ◽  
Slip Phenomenon

Friction is a repeatable and undesirable problem in hydraulic systems where always has to be a tendency for its removal. In this paper, the friction model is presented through which the most accurate results are achieved and the way of friction compensation, approached trough technique presented with the mathematical model of a hydraulic cylinder of a hydro turbine wicket gate controlled by a servomechanism. Mathematical modelling of a servo mechanism and hydraulic actuator, and also the simulation of hydraulic cylinder as a part of a hydro turbine wicket gate hydraulic system where the stick-slip phenomenon is present between the system components that are in contact is presented. Applied results in this paper and the theory behind them precisely demonstrate under what circumstances the stick-slip phenomenon appears in such a system. The stick-slip effect is simulated using Simulink and Hopsan software and the analysis of the results are given in this paper. Removal of the stick-slip effect is presented with the design of a cascade control implemented to control the behaviour of the system and remove the appearance of a jerking motion.

scholarly journals Tribological functionalization of titanium alloys by Micro-Arc Oxidation for marine applications

2020 ◽  
Vol 321 ◽  
pp. 09001
Author(s):  
Aude MATHIS ◽  
Thierry MILLOT ◽  
Vincent BRANGER ◽  
Remy MULLER ◽  
Jean-Yves GUENEHEUX
Keyword(s):  
Friction Coefficient ◽  
Titanium Alloys ◽  
Pure Titanium ◽  
Dynamic Contact ◽  
Electrochemical Process ◽  
Commercially Pure Titanium ◽  
Tribological Behaviour ◽  
Stick Slip ◽  
Micro Arc Oxidation ◽  
Slip Phenomenon

Micro-arc Oxidation (MAO) process is a plasma assisted electrochemical process, which allows formation of ceramic-like dry oxides on top of light alloys surfaces. The good corrosion resistance as well as the low density of titanium alloys are recognized and so required for conception of structural parts in marine environment. However, their tribological behaviour reveals an important tendency to stick-slip phenomenon, which makes use of these alloys for dynamic contact mechanisms difficult. Through the MAO project from IRT M2P, formation of a MAO coating composed of aluminium titanate has been investigated to improve tribological behaviour of a commercially pure titanium (Grade 2) and an α+β alloy (TA6V, Grade 5). Pin-on-disc testing has been carried out to evaluate friction coefficient and the presence or not of stick-slip phenomenon in various contact configurations (involving non-treated titanium surfaces, MAO treated surfaces, with steel or titanium balls …) in dry or artificial seawater media. Those test campaigns are completed by evaluation of fatigue behaviour, and tribological testing on a demonstrator. Finally, this study highlights influence of MAO coating on diminishing (to removed) stick-slip phenomenon, accompanied by a reduction of friction coefficient, whatever the kind of contact (single treated surface or both ones) and the medium.

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