Friction Behavior Between Epoxy and Flexible Pipes Armor Wires

2016 ◽  
Author(s):  
Diego A. Lorio ◽  
Facundo J. Wedekamper ◽  
Fabiano Bertoni ◽  
Facundo S. Lopéz ◽  
George C. Campello ◽  
...  
Keyword(s):  
Friction Coefficient ◽  
Contact Pressure ◽  
Normal Load ◽  
Surface Profile ◽  
Repeated Measurements ◽  
Analytical Models ◽  
Friction Coefficients ◽  
Wire Sample ◽  
Flexible Pipes ◽  
The Wire

The offshore industry has presented an increasing demand over the last few decades, requiring the production in deep water fields. The end fittings (EF) are critical points within the production system. Therefore, structural and fatigue analyses are essential in the EF design, making it necessary to know the stress distribution experienced by the armor wires along the EF. Numerical and analytical models are often used in order to assess the stress state. However, characteristics like geometries, materials and interactions must be previously known in order to apply these models. The purpose of this work was to analyze the arithmetic mean surface roughness (Ra) and to determine the friction coefficient (μ) for two types of armor wires when in contact with resin used to fill the EF. The resin used in the interaction with the armor wires was an epoxy filled with metallic particles. For the experimental analysis straight carbon steel armor wires with different cross-sections, typically used in 2.5″ and 8″ flexible pipes were used. Surface profile was obtained for each wire by repeated measurements along two lines over each surface. A total of three repetitions were performed in each measure line. Longitudinal roughness was determined through these profiles. Finally, friction coefficients were obtained experimentally by means of a device that allows to simulate the wire pullout and sliding process. In this device, two epoxy pads were put in contact with the surface of the analyzed wire sample, and rigid bodies in contact with the pads were used to ensure that the normal load applied is transmitted uniformly through the contact surface. The displacement rate, contact pressure between the surface of the wire and the epoxy resin pads, and axial force were recorded. The roughness in the longitudinal direction of the wires was analyzed through descriptive statistic and compared by Student’s “t” test. The highest values were obtained on wires with larger sections. This behavior is exposed on the results obtained for the friction coefficient as a function of the contact pressure. Friction coefficient for both wires was analyzed and compared using a Mann-Whitney U test. Both friction coefficients have a positive slope, indicating a small increase as the contact pressure raise. The significance value obtained for the means comparisons was p = 0.0001 and confirms that the average friction coefficient of the two wires are really different. Because of that, we conclude that is necessary to treat the EF project for different flexible pipes differentially.

Effect of Friction Coefficient on the Stiffness Excitation of Gear

2011 ◽  
Vol 86 ◽  
pp. 713-716 ◽  
Author(s):  
Yu Mei Hu ◽  
De Shuang Xue ◽  
Yang Jun Pi
Keyword(s):  
Friction Coefficient ◽  
Simulation Model ◽  
Normal Load ◽  
Single Pair ◽  
Friction Coefficients ◽  
Gear Teeth ◽  
Load Distributions ◽  
Single Tooth ◽  
Element Technique ◽  
Double Teeth

This study addresses the effect of different friction coefficients on the stiffness excitation of gear using finite element technique. Firstly, the simulation model of single pair of gear teeth mesh is established, and the effect of friction coefficient on the composite stiffness values of the teeth meshing is studied. After that, simulation model of multiple pairs of gear teeth meshing is created and the normal load distributions under different friction coefficients in a single meshing cycle are calculated using quasi-static calculation method. Finally, the relationship between friction coefficient and stiffness excitation of gear system is obtained. The investigation results indicate that at the alternation place of single tooth meshing and double teeth meshing, the stiffness excitation of the system is greater under larger friction coefficient when double teeth meshing change into single tooth meshing, while the opposite situation occur when single tooth meshing change into double teeth meshing. The amplitude value of stiffness variation for single pair of teeth meshing under different friction coefficients is 2.12%, while the amplitude value of teeth loads variation for multiple pairs of teeth meshing under different friction coefficients is 22.87%.

Experiment and simulation of friction coefficient of polyoxymethylene

2018 ◽  
Vol 70 (2) ◽  
pp. 273-281 ◽  
Author(s):  
Xiaoshuang Xiong ◽  
Lin Hua ◽  
Xiaojin Wan ◽  
Can Yang ◽  
Chongyang Xie ◽  
...  
Keyword(s):  
Mathematical Model ◽  
Friction Coefficient ◽  
Contact Pressure ◽  
Friction Force ◽  
Normal Load ◽  
Fe Model ◽  
Sliding Velocity ◽  
Experiment Data ◽  
Simulation Data ◽  
Content Type

Purpose The purposes of this paper include studying the friction coefficient of polyoxymethylene (POM) under a broad range of normal load and sliding velocity; developing a mathematical model of friction coefficient of POM under a broad range of normal loads and sliding velocities; and applying the model to dynamic finite element (FE) analysis of mechanical devices containing POM components. Design/methodology/approach Through pin-on-disc experiment, the friction coefficient of POM in different normal loads and sliding velocities is investigated; the average contact pressure is between 5 and 15 Mpa and the sliding velocity is from 0.05 to 0.9 m/s. A friction algorithm is developed and embedded in the FE model to simulate the friction of POM in different normal loads and sliding velocities. Findings The friction coefficient of POM against steel declines with the increase of normal loads when the contact pressure is between 5 and 15 Mpa. The friction coefficient of POM against steel increases markedly when the sliding velocity is between 0.05 and 0.15 m/s, it decreases sharply between 0.15-0.45 m/s and then it stabilizes at high sliding velocity between 0.45 and 0.9 m/s. The friction coefficient of POM in different working operations has a significant effect on contact stress and shear stress. The simulation data and experiment data of POM friction force fit very well; therefore, it can be concluded that the friction algorithm and FE model are accurate. Originality/value The friction coefficient of POM under a broad range of normal loads and sliding velocities is investigated. The friction coefficient model of POM is established as a function of normal loads and sliding velocities in the dry sliding condition. A friction algorithm is developed and embedded in the FE model of the friction of POM. The mathematical model of the friction coefficient accurately agrees with the experiment data, and simulation data and experiment data of the POM friction force fit very well.

The influence of mean contact pressure on the friction coefficient of a traction fluid at high pressure

2000 ◽  
Vol 214 (2) ◽  
pp. 309-312 ◽  
Author(s):  
M F Workel ◽  
D Dowson ◽  
P Ehret ◽  
C M Taylor
Keyword(s):  
High Pressure ◽  
Friction Coefficient ◽  
Contact Pressure ◽  
High Pressures ◽  
Friction Coefficients ◽  
Ball Impact ◽  
Good Consistency ◽  
Traction Fluid ◽  
Very High

A new ball impact apparatus has been developed for measuring the friction coefficients of solidified lubricants under very high pressures. Results obtained for Santotrac 50 showed a decrease in friction coefficient with increasing mean contact pressure and showed good consistency with values reported elsewhere from several different forms of apparatus.

scholarly journals Experimental Assessment of Friction Coefficient in Deep Drawing and Its Verification by Numerical Simulation

2021 ◽  
Vol 11 (6) ◽  
pp. 2756
Author(s):  
Emil Evin ◽  
Naqib Daneshjo ◽  
Albert Mareš ◽  
Miroslav Tomáš ◽  
Katarína Petrovčiková
Keyword(s):  
Friction Coefficient ◽  
Deep Drawing ◽  
Fem Simulation ◽  
Simulation Software ◽  
Analytical Models ◽  
Friction Coefficients ◽  
Aisi 304 ◽  
Steel Sheets ◽  
Strip Drawing ◽  
Steel Aisi

The friction coefficient in the simulation of stamping processes should be defined. Modern simulation software allows its definition as constant or its dependence on pressure or temperature. It is also useful in stamping processes to define different values in different regions, as it often reflects the nature of deformation process. This article deals with the regression and analytical models commonly used to determine the friction coefficients in specified areas of the stamping process. Analytical models were verified by an experimental strip drawing test under the same contact conditions. Steel sheets for the automotive industry were used in experiments and simulations—extra deep drawing quality DC 05 and austenitic stainless steel AISI 304. Friction coefficients were also evaluated when the cup test was performed. A regression model of drawing to the blankholding force was applied to the results. Conformity of friction coefficients when measured by cup tests and strip tests was confirmed. The values of the friction coefficient reached from the experiment were applied in FEM simulation software.

Bearing Friction Torque in Threaded Fasteners With Non-Flat Underhead Contact

2018 ◽  
Author(s):  
Sayed A. Nassar ◽  
Marco Gerini Romagnoli ◽  
Joon Ha Lee
Keyword(s):  
Friction Coefficient ◽  
Contact Pressure ◽  
Friction Torque ◽  
Sliding Speed ◽  
Friction Coefficients ◽  
Threaded Fasteners ◽  
Tension Testing ◽  
Contact Surfaces ◽  
Flat Contact ◽  
Bearing Friction

This study provides experimentally validated formulation of underhead bearing friction torque component during tightening of threaded fasteners with non-flat contact with the joint. Motosh model is utilized for spherical and conical contact surfaces for various scenarios of contact pressure. For each pressure scenario, a single non-dimensional 3-D graph is generated for the corresponding values of an effective bearing friction radius. A rotating sliding speed-dependent friction coefficient model is also investigated for its impact of the results of bearing friction radius. Torque-Tension testing is used to measure the bearing friction torque and the corresponding bearing friction coefficients using Motosh model, in which the newly formulated bearing friction radius expressions are entered. Obtained bearing friction coefficient values are then compared with those published by the threaded fastener manufacturer.

Discretization Pressure-Wear Theory for Bodies in Sliding Contact

1989 ◽  
Vol 111 (1) ◽  
pp. 95-100 ◽  
Author(s):  
K. M. Marshek ◽  
H. H. Chen
Keyword(s):  
Contact Pressure ◽  
Normal Load ◽  
Contact Region ◽  
Surface Profile ◽  
Leading Edge ◽  
Sliding Contact ◽  
Contact Radius ◽  
Machine Elements ◽  
Automatic Mesh ◽  
Worn Surface

A theory is presented for studying contact pressure and wear distributions for bodies in sliding contact. This theory can be used in designing machine elements for improved wear resistance and failure prediction. A point force-displacement influence function and a profile function are employed in conjunction with a discretization method, an automatic mesh generation technique and a discretized wear equation to determine the instantaneous contact pressure distribution and the corresponding worn surface profile for a given sliding distance. The theory is implemented in a computer program and is applied to a simple unlubricated sliding contact and adhesive wear problem. The results show that a higher pressure will exist at the leading edge of the sliding block and thus there results a higher wear at the leading edge of the sliding block than the trailing edge. This study also shows the sliding contact wear of a copper sphere on a steel plane. As expected, instantaneous contact radius increases as the sliding contact continues (for the same normal load) and therefore results in a smaller pressure within the contact region.

Frictional Characteristics of Steel Materials Sliding against Mild Steel

2014 ◽  
Vol 903 ◽  
pp. 33-38
Author(s):  
Mohammad Asaduzzaman Chowdhury ◽  
Dewan Muhammad Nuruzzaman ◽  
Mohammad Lutfar Rahaman
Keyword(s):  
Stainless Steel ◽  
Friction Coefficient ◽  
Relative Humidity ◽  
Mild Steel ◽  
Normal Load ◽  
Operating Conditions ◽  
Sliding Velocity ◽  
Friction Coefficients ◽  
Friction Process ◽  
Different Types

In this study, friction coefficients of different steel materials are investigated and compared. Experiments are carried out when different types of steel discs such as stainless steel 201 (SS 201), stainless steel 301 (SS 301) and mild steel slide against mild steel pin. Experiments are conducted at normal load 5, 7.5 and 10 N, sliding velocity 0.5, 0.75 and 1 m/s and relative humidity 70%. The effects of duration of rubbing on the friction coefficient of different steel materials are investigated. Results show that during friction process, test disc takes less time to stabilize with the increased normal load or sliding velocity. It is found that friction coefficient decreases with the increase in normal load while it increases with the increase in sliding velocity for all the tested materials. As a comparison, it is found that at identical operating conditions, friction coefficients are different for different steel materials depending on normal load or sliding velocity.

Calculated Behavior and Effective Factors for Bolt Self-Loosening Under a Transverse Cyclic Load Generated by a Linearly Vibrating Washer

2005 ◽  
Author(s):  
Yasuo Fujioka ◽  
Tomotsugu Sakai
Keyword(s):  
Surface Roughness ◽  
Friction Coefficient ◽  
Contact Pressure ◽  
Common Knowledge ◽  
Axial Direction ◽  
Element Analysis ◽  
Friction Coefficients ◽  
Friction Forces ◽  
Contact Surfaces ◽  
The Individual

It is common knowledge that a bolt is apt to loosen due to slippage between the contact surfaces of joined parts. Loosening tests using real parts enable precise scrutiny of real phenomena under the influence of multiple factors such as slip distance, surface roughness, and coefficient friction. However, estimating the influence of the individual factors is very difficult because the friction forces of real contact surfaces are compiled based on variations in friction coefficients, meaning friction is not stable. Therefore, the effects of factors were investigated using Finite Element Analysis (FEA) to control friction coefficients. The procedures were as follows. Assuming a joined structure consisting of a bolt, nut, and washer, bolt axial tension was generated through constant movement of a washer in the bolt’s axial direction, following which the washer was constantly vibrated in one direction transverse to the bolt axis. This vibration generated displacements equivalent to the degree of slippage between the two clamped parts. During vibration, the rotating angles of the bolt and the contact pressure of the threads and bearing surfaces were calculated. The results were as follows. The vibrating displacements of a washer have considerable influence on the rotational loosening of a bolt. In cases where there was only minor displacement of the washer vibrations, the rotational loosening angle rapidly decreased, although the loosening did not cease completely. Therefore, the magnitude of what is called “critical slip” was not confirmed under the conditions of this study. In addition, the friction coefficient has a significant influence on the rotational loosening of a bolt. When the respective friction coefficient values of the threads and bearing surfaces are not balanced, rotational loosening cannot continue. Surface roughness readily affects contact pressure, so it tends to make the contact pressure localized. In particular, high-pressure areas were affected by several projections set on the threads. However, under those conditions the rotational loosening did not differ greatly from the results of the fine surface models subject to the same vibrating amplitude and friction coefficient. Consequently, the localized contact pressure had little evident effect on loosening. Above all, FEA reproduced the loosening of the bolt, and the reference made in this analysis is useful.

scholarly journals New Equation for Predicting Pipe Friction Coefficients Using the Statistical Based Entropy Concepts

Entropy ◽  
2021 ◽  
Vol 23 (5) ◽  
pp. 611
Author(s):  
Yeon-Woong Choe ◽  
Sang-Bo Sim ◽  
Yeon-Moon Choo
Keyword(s):  
Friction Coefficient ◽  
Accurate Determination ◽  
Mean Velocity ◽  
Friction Coefficients ◽  
Flow Discharge ◽  
Comparison Results ◽  
Flow Loss ◽  
Key Variables ◽  
New Equation

In general, this new equation is significant for designing and operating a pipeline to predict flow discharge. In order to predict the flow discharge, accurate determination of the flow loss due to pipe friction is very important. However, existing pipe friction coefficient equations have difficulties in obtaining key variables or those only applicable to pipes with specific conditions. Thus, this study develops a new equation for predicting pipe friction coefficients using statistically based entropy concepts, which are currently being used in various fields. The parameters in the proposed equation can be easily obtained and are easy to estimate. Existing formulas for calculating pipe friction coefficient requires the friction head loss and Reynolds number. Unlike existing formulas, the proposed equation only requires pipe specifications, entropy value and average velocity. The developed equation can predict the friction coefficient by using the well-known entropy, the mean velocity and the pipe specifications. The comparison results with the Nikuradse’s experimental data show that the R2 and RMSE values were 0.998 and 0.000366 in smooth pipe, and 0.979 to 0.994 or 0.000399 to 0.000436 in rough pipe, and the discrepancy ratio analysis results show that the accuracy of both results in smooth and rough pipes is very close to zero. The proposed equation will enable the easier estimation of flow rates.

scholarly journals Theoretical Studies of the Interaction between Screw Surface and Material in the Mixer

Materials ◽  
2021 ◽  
Vol 14 (4) ◽  
pp. 962
Author(s):  
Andrzej Marczuk ◽  
Vasily Sysuev ◽  
Alexey Aleshkin ◽  
Petr Savinykh ◽  
Nikolay Turubanov ◽  
...  
Keyword(s):  
Friction Coefficient ◽  
High Efficiency ◽  
Animal Feed ◽  
Structural Features ◽  
Power Demand ◽  
Friction Coefficients ◽  
Length Unit ◽  
Mixing Chamber ◽  
Size Of Particles ◽  
The Impact

Mixing is one of the most commonly used processes in food, animal feed, chemical, cosmetic, etc., industries. It is supposed to provide high-quality homogenous, nutritious mixtures. To provide appropriate mixing of materials while maintaining the process high efficiency and low energy consumption it is crucial to explore and describe the material flow caused by the movement of mixing elements and the contact between particles. The process of mixing is also affected by structural features of the machine components and the mixing chamber, speed of mixing, and properties of the mixed materials, such as the size of particles, moisture, friction coefficients. Thus, modeling of the phenomena that accompany the process of mixing using the above-listed parameters is indispensable for appropriate implementation of the process. The paper provides theoretical power calculations that take into account the material speed change, the impact of the material friction coefficient on the screw steel surface and the impact of the friction coefficient on the material, taking into account the loading height of the mixing chamber and the chamber loading value. Dependencies between the mixer power and the product degree of fineness, rotational speed of screw friction coefficients, the number of windings per length unit, and width of the screw tape have been presented on the basis of a developed model. It has been found that power increases along with an increase in the value of these parameters. Verification of the theoretical model indicated consistence of the predicted power demand with the power demand determined in tests performed on a real object for values of the assumed, effective loading, which was 65–75%.

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