scholarly journals The Influence of Hydrothermal Aging on the Dynamic Friction Model of Rubber Seals

Polymers ◽  
2020 ◽  
Vol 12 (1) ◽  
pp. 102
Author(s):  
Jian Wu ◽  
Hang Luo ◽  
Haohao Li ◽  
Benlong Su ◽  
Youshan Wang ◽  
...  
Keyword(s):  
Friction Coefficient ◽  
Coulomb Friction ◽  
Dynamic Performance ◽  
Static Friction ◽  
Friction Model ◽  
Dynamic Friction ◽  
Hydrothermal Aging ◽  
Static Friction Coefficient ◽  
Sealing Ring ◽  
Friction Performance

Cylinder has become an indispensable and important pneumatic actuator in the development of green production technology. The sealing performance of the cylinder directly affects its safety and reliability. Under the service environment of the cylinder, hydrothermal aging of the rubber sealing ring directly affects the dynamic friction performance of the cylinder. So, the dynamic friction model of the cylinder has been developed based on the LuGre friction model, which considers the influence of hydrothermal aging. Here, the influences of the static friction coefficient and Coulomb friction coefficient on the friction model are analyzed. Then, the aging characteristic equation of rubber is embedded in the model for revealing the influence of aging on the friction coefficient of the model. Results show that the aging temperature, aging time, and compressive stress affects the friction coefficient; the variation of the static friction coefficient is larger than that of the Coulomb friction coefficient. The improved cylinder friction model can describe the influence of the aging process on the cylinder friction characteristics, which is of great significance in the design of the cylinder’s dynamic performance.

Experimental investigation and prediction method of fretting wear in rack-plane spline couplings

2020 ◽  
pp. 135065012093983
Author(s):  
Xiangzhen Xue ◽  
Jipeng Jia ◽  
Qixin Huo ◽  
Junhong Jia
Keyword(s):  
Friction Coefficient ◽  
Wear Mechanism ◽  
Static Friction ◽  
Experimental Results ◽  
Fretting Wear ◽  
Accurate Estimation ◽  
Dynamic Friction ◽  
Static Friction Coefficient ◽  
Dynamic Friction Coefficient ◽  
Involute Spline

To investigate the fretting wear of involute spline couplings in aerospace, rack-plane spline couplings rather than the conventional involute spline couplings in aerospace were used to conduct tribological experiments, and it was assumed that the rack-plane spline couplings exhibit consistent contact stress with the real involute spline couplings in aerospace. The relationships among the static friction coefficient, dynamic friction coefficient, and fretting friction coefficient were established via tribological experiments, as well as the fretting-wear mechanism of the rack-plane spline couplings was examined. A fretting-wear estimation model based on the fretting-wear mechanism was developed. By applying the modified Archard equation and Arbitrary Lagrangian–Eulerian adaptive, mesh smoothing algorithm of Abacus was used. According to our experimental results, the fretting wear of the rack-plane spline couplings consisted primarily of abrasive wear, oxidative wear, and adhesive wear. For both, lubrication and non-lubrication settings, the fretting friction coefficient of 18CrNi4A steel (0.27) fluctuated between 0.12 (dynamic friction coefficient) and 0.35 (static friction coefficient). The fretting-wear results estimated via numerical prediction were consistent with the experimental results. When sm (vibration amplitude) was 20, 35, and 50 µm, the most difference in the fretting wear between the experimental results and numerical estimation was 0.001, 0.0007, and 0.001 mm, respectively. Therefore, the proposed model provides a method for accurate estimation of the fretting-wear. Additionally, the model contributes to the precise design of involute spline couplings in aerospace.

The Simulation Research of Dual Clutch Transmission's Starting Process Based on Dynamic Friction Coefficient

2013 ◽  
Vol 401-403 ◽  
pp. 320-325
Author(s):  
Ming Ming Qiu ◽  
Han Zhao ◽  
Fa Ming Sha
Keyword(s):  
Friction Coefficient ◽  
Vibration Analysis ◽  
Working Condition ◽  
Static Friction ◽  
Dynamic Friction ◽  
Simulation Research ◽  
Static Friction Coefficient ◽  
Dynamic Friction Coefficient ◽  
Friction Plate ◽  
Starting Process

Introduce the dynamic friction coefficient of clutch friction plate. Establish Mathematical model of starting process, carried out vibration analysis for frictional sliding process systematically, validated the analysis using Matlab/simulink software. Meanwhile, compared with the starting process by static friction coefficient. The results show that using dynamic friction coefficient to analyse starting process conforms to the actual working condition.

Static Friction Model for Rough Surfaces With Asymmetric Distribution of Asperity Heights

2004 ◽  
Vol 126 (3) ◽  
pp. 626-629 ◽  
Author(s):  
Ning Yu, ◽  
Shaun R. Pergande, and ◽  
Andreas A. Polycarpou
Keyword(s):  
Friction Coefficient ◽  
Normal Load ◽  
Static Friction ◽  
Friction Model ◽  
Published Data ◽  
Asymmetric Distribution ◽  
Adhesion Forces ◽  
Normal Contact ◽  
Static Friction Coefficient ◽  
Gaussian Case

The CEB static friction model is extended to include asymmetric distributions of asperity heights, using the normalized one-parameter Weibull distribution. The normal contact, tangential (friction), and adhesion forces are calculated for different skewness values, and are used to obtain the static friction coefficient. It is predicted that surfaces with negative skewness experience higher static friction coefficient compared to the Gaussian case, under the same external normal load, which agrees with published data. This effect is magnified for lower external loads, as is commonly encountered in microtribological applications.

Properties Analysis of Disk Spring with Effects of Asymmetric Variable Friction

2021 ◽  
Author(s):  
Renzhen Chen ◽  
Xiaopeng Li ◽  
Jinchi Xu ◽  
Zemin Yang ◽  
Hexu Yang
Keyword(s):  
Friction Coefficient ◽  
Vibration Isolation ◽  
Normal Load ◽  
Static Friction ◽  
Primary Objective ◽  
Friction Model ◽  
Computational Accuracy ◽  
Static Friction Coefficient ◽  
Disk Spring ◽  
Variable Friction

The primary objective of this fundamental research is to investigate the mechanical properties of the disk spring when the friction at the contact edges is asymmetric and varies with the load. The contact mechanics study shows that the static friction and static friction coefficient on fractal surfaces change depending on the normal load. In this paper, a fractal contact model based on the W-M function is used to explore the connection between the static friction and the normal load. Subsequently, taking into account the asymmetry of the contact surface at the edge, the variable static friction coefficient is brought into the existing model to obtain an improved static model of the disk spring. Different fractal dimensions, frictional states and free heights are considered under quasi-static loading condition, the relative errors between this paper and the method using Coulomb friction are also calculated, and experimental validation was performed. The static stiffness and force hysteresis of the disk spring for different forms of asymmetric variable friction are discussed. It is shown that using the variable friction model can improve the computational accuracy of the disk spring model under small loads and help to improve the design and control accuracy of preload and vibration isolation equipment using the disk spring as a component.

A Static Friction Model for Elastic-Plastic Contacting Rough Surfaces

2004 ◽  
Vol 126 (1) ◽  
pp. 34-40 ◽  
Author(s):  
Lior Kogut ◽  
Izhak Etsion
Keyword(s):  
Friction Coefficient ◽  
Rough Surfaces ◽  
Static Friction ◽  
Friction Model ◽  
Plasticity Index ◽  
High Plasticity ◽  
Elastic Plastic ◽  
Static Friction Coefficient ◽  
Contact Adhesion ◽  
Limiting Case

A model that predicts the static friction for elastic-plastic contact of rough surfaces is presented. The model incorporates the results of accurate finite element analyses for the elastic-plastic contact, adhesion and sliding inception of a single asperity in a statistical representation of surface roughness. The model shows strong effect of the external force and nominal contact area on the static friction coefficient in contrast to the classical laws of friction. It also shows that the main dimensionless parameters affecting the static friction coefficient are the plasticity index and adhesion parameter. The effect of adhesion on the static friction is discussed and found to be negligible at plasticity index values larger than 2. It is shown that the classical laws of friction are a limiting case of the present more general solution and are adequate only for high plasticity index and negligible adhesion. Some potential limitations of the present model are also discussed pointing to possible improvements. A comparison of the present results with those obtained from an approximate CEB friction model shows substantial differences, with the latter severely underestimating the static friction coefficient.

scholarly journals Bolted Joint Preload Distribution from Torque Tightening

2021 ◽  
Vol 71 (2) ◽  
pp. 329-342
Author(s):  
Welch Michael
Keyword(s):  
Friction Coefficient ◽  
Static Friction ◽  
Bolted Joints ◽  
Dynamic Friction ◽  
Bolted Joint ◽  
Classical Analysis ◽  
Joint Design ◽  
Static Friction Coefficient ◽  
Bolt Preload ◽  
Torque Wrench

Abstract The purpose of this paper is to develop an understanding of how bolt preloads are distributed within a joint as each bolt is tightened in turn by the use of a calibrated torque wrench. It discusses how the order that the joints nuts/bolts are tightened can affect the final bolt preload. It also investigates the effect on incrementally increasing the bolt preload through a series of applications of the controlled torque tightening sequence. Classical analysis methods are used to develop a method of analysis that can be applied to most preloaded bolted joints. It is assumed that the static friction coefficient is approximately 15% less than the dynamic friction. It is found that the bolt preload distribution across the joint can range from slightly above the target preload to significantly less than the target preload. The bolts with a preload greater than the target preload are found to be those tightened towards the end of the tightening sequence, usually located close to the outer edges of the joint’s bolt array. The bolts with a preload less than the target preload are those tightened early in the tightening sequence, located centrally within the joints bolt array. The methods presented can be used to optimise bolted joint design and assembly procedures. Optimising the design of preloaded bolted joints leads to more efficient use of the joints.

Static Friction Research of LIGA-Microstructure: Comparison between Theory and Experiments

2011 ◽  
Vol 301-303 ◽  
pp. 1109-1114
Author(s):  
Qian Qian Wang ◽  
Geng Chen Shi ◽  
Xin Xiong
Keyword(s):  
Surface Roughness ◽  
Friction Coefficient ◽  
Static Friction ◽  
Micro Electro Mechanical System ◽  
Friction Model ◽  
Roughness Effects ◽  
Static Friction Coefficient ◽  
Liga Technology ◽  
Optical Profilometer ◽  
Mems Device

Micro electro mechanical system (MEMS) has been increasingly used in military application. For the reliability and specialty of military requirements, the material of the MEMS device is supposed to be metal and the device is moveable. Lithographic, Galvanoforming, Abformung (LIGA) technology capable of producing high aspect ratio structures in metals like nickel is one of the important fabrication technologies in military MEMS. There are many moveable MEMS device like micro-gear and micro-slider producing by LIGA technology. But the moveable devices cannot behave well because of the friction effect. In this paper, an improved elastic-plastic model including roughness effects and an experimental procedure that predict the static friction prosperity of LIGA-processed nickel is proposed. Firstly, we use the 3D optical profilometer to research the surface roughness of LIGA-processed nickel, the surface heights distribution was found to be nearly Gaussian distribution. Secondly, the static friction model, the Kogut-Etsion (KE) model is adopted to obtain the static friction coefficient. Finally, a special designed static friction coefficient measurement apparatus is used to conduct the friction experiments. The results indicate that the surface roughness affects the friction and the smoother surface leads to a higher friction coefficient. Also good agreement was found between simulations and experimental results.

Application of Elastic-Plastic Static Friction Model to Rough Surface With Asymmetric Asperity Distribution

2008 ◽  
Author(s):  
Chul-Hee Lee ◽  
Andreas A. Polycarpou
Keyword(s):  
Surface Roughness ◽  
Friction Coefficient ◽  
Static Friction ◽  
Friction Model ◽  
Experimental Measurements ◽  
Height Distribution ◽  
Elastic Plastic ◽  
Static Friction Coefficient ◽  
Non Gaussian ◽  
Asperity Distribution

The asymmetric height distribution in surface roughness is usually indispensable in engineering surfaces prepared by specific manufacturing process. Moreover, the running-in process develops severe asymmetric roughness distribution in the surface interfaces. In this paper, the effect of asymmetric asperity distribution on static friction coefficient is investigated theoretically and by comparing it with experimental results. In order to generate a probability density function of non-Gaussian surface roughness, the Pearson system of frequency curves was used. Subsequently, the Kogut and Etsion (KE) model of elastic-plastic static friction was modified to calculate the contacting interfacial forces. For the experiments, actual roller and housing surfaces from a CV (Constant Velocity) joint were prepared to measure the static friction coefficient as it clearly shows the asymmetry of roughness distribution due to the manufacturing and also running-in process. The experimental measurements were subsequently compared with the modified KE static friction model with Gaussian as well as Pearson distributions of asperity heights. It was found that the model with Pearson distribution captures the experimental measurements well in terms of the surface conditions.

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