Study of the effects of relative humidity and velocity on the friction characteristics of pneumatic cylinders

2020 ◽  
Vol 34 (22n24) ◽  
pp. 2040139
Author(s):  
Thuy-Duong Nguyen ◽  
Van-Hung Pham
Keyword(s):  
Relative Humidity ◽  
Sliding Friction ◽  
Static Friction ◽  
Pneumatic Cylinder ◽  
Dynamic Friction ◽  
Friction Forces ◽  
Measuring Device ◽  
Friction Characteristics ◽  
Rod Seals ◽  
Pneumatic Cylinders

The movement of a piston rod in a pneumatic cylinder is directly affected by the air humidity in the atmosphere, especially in the case of piston rods without any means of protection or grease on their surfaces. In a pneumatic cylinder system, the friction between the piston rod and the rod seal is sliding friction, and it has a significant value that varies with the variation in the moisture on the piston rod’s surface. In this paper, an investigation of the friction characteristics of piston rods and rod seals in a pneumatic cylinder was carried out with different humidity and velocity values to understand the effect of lubricants on the moving parts of pneumatic systems in humid environments, where the friction characteristics of the displacements corresponding to the static and dynamic friction forces were displayed on a measuring device. The research results showed that the static friction forces tended to decrease by [Formula: see text] and that the dynamic friction forces tended to decrease by [Formula: see text] when the relative humidity increased from 51% to 99% at different velocities between 5 and 100 mm/s.

scholarly journals The THE EFFECT OF HUMID TROPICAL CLIMATE ON FRICTION CHARACTERISTIC OF PNEUMATIC CYLINDERS

2021 ◽  
pp. 1-6
Author(s):  
Thuy Nguyen ◽  
Van Hung Pham
Keyword(s):  
Relative Humidity ◽  
Friction Force ◽  
Static Friction ◽  
Tropical Climate ◽  
Pneumatic Cylinder ◽  
Friction Characteristic ◽  
Humid Tropical Climate ◽  
Geographical Regions ◽  
Climatic Environment ◽  
Pneumatic Cylinders

The pneumatic cylinder is influenced by many various factors at work, including the climate environment. The climatic environment consists of two characteristic factors as temperature (T) and relative humidity (RH), which change according to seasons and different geographical regions. Therefore, changing the climate characteristic factors will affect the friction characteristic of pneumatic cylinders when operating at different speeds. This article presents empirical research on the simultaneous effects of temperature and relative humidity of the environment with the humid tropical climate in Vietnam on the pneumatic cylinder's friction properties. According to experimental planning, the studies were conducted on industrial pneumatic cylinders with two input factors: the temperature of 150C, 320C and 490C and relative humidity of 51%, 75% and 99%, with velocities of 30, 50 and 100 mm/s. The results show that the static friction force and dynamic friction decrease when T, RH increases, and the influence of air relative humidity on friction force is more significant than temperature. The experiment also gives an empirical regression equation on the relationship of friction in the pneumatic cylinder, depending on the two factors of temperature and relative humidity of the humid tropical climate in Vietnam with velocities of 30, 50 and 100 mm/s.

Study on Friction Characteristics of Energizing Pneumatic Cylinders

2014 ◽  
Vol 904 ◽  
pp. 306-310 ◽  
Author(s):  
Yan Jia Zhan ◽  
Tao Wang ◽  
Bo Wang
Keyword(s):  
Special Kind ◽  
Friction Model ◽  
Pneumatic Cylinder ◽  
Working Pressure ◽  
Friction Characteristics ◽  
Factors Affecting ◽  
Output Force ◽  
Experimental Apparatus ◽  
Depth Study ◽  
Pneumatic Cylinders

As a special kind of pneumatic cylinder, energizing pneumatic cylinder can increase the output force without changing diameter by a series of two or more piston on a piston rod. Since the friction characteristics of pneumatic cylinders is one of the most important factors affecting the nonlinearity, a new experimental apparatus is designed to have an in-depth study, base on exhaust throttle. The friction of energizing pneumatic cylinder was tested under different working pressure and velocity to ascertain the parameters of stribeck model. The results show that friction model of the energizing pneumatic cylinder can be the superposition of the models of each piston.

Atomistics of Friction

2005 ◽  
Author(s):  
Motohisa Hirano
Keyword(s):  
Friction Force ◽  
Translational Motion ◽  
Static Friction ◽  
System Size ◽  
Dynamic Friction ◽  
Friction Forces ◽  
Internal Motions ◽  
Locking Mechanism ◽  
Roughness Model ◽  
Solid Bodies

The atomistic mechanisms are proposed for the origin of the static and the dynamic friction forces. The mechanism for the origin of the static friction force resembles the mechanical locking mechanism in a surface roughness model. The origin of the dynamic friction force is formulated as a problem of how the given translational kinetic energy dissipates into the internal relative motions of constituent atoms of bodies during sliding. From studying that the available phase space volume of the translational motion becomes negligible small for a large system size, compared with that of the internal motions, it is concluded that the energy dissipation occurs irreversibly from the translational motion to the internal motions. A phenomenon of superlubricity, where two solid bodies move relatively with no resistance, is discussed.

A Robust Controller for Positioning Control of Pneumatic Servo System: Design and Experiment Tests

2014 ◽  
Vol 668-669 ◽  
pp. 423-427
Author(s):  
Zhong Jie Zhang
Keyword(s):  
High Speed ◽  
Flow Characteristics ◽  
Servo System ◽  
Pneumatic Cylinder ◽  
Robust Controller ◽  
Friction Forces ◽  
Positioning Control ◽  
Pneumatic Servo System ◽  
Pneumatic Cylinders ◽  
Load Mass

The pneumatic cylinders are difficult to be controlled due to flow characteristics of control valves, compressibility of air, and static and dynamic friction forces. This paper describes the development of a robust controller based on H∞ control theory for positioning control of a high-speed pneumatic cylinder. To design the H∞ controller, one has selected appropriate weighting functions of pneumatic servo system.Simulation results show that the system is robust during the whole response process and can suppress the disturbance. Finally experiments have been performed with varying supply pressures and load mass. Experimental results imply that good performance and robustness of positioning in pneumatic servo system can be obtained using H∞ controller.

The Role of Relative Humidity, Surface Roughness and Liquid Build-Up on Static Friction Behavior of the Head/Disk Interface

1993 ◽  
Vol 115 (1) ◽  
pp. 28-35 ◽  
Author(s):  
Hong Tian ◽  
Takeo Matsudaira
Keyword(s):  
Surface Roughness ◽  
Relative Humidity ◽  
Static Friction ◽  
Height Distribution ◽  
Head Disk Interface ◽  
Friction Behavior ◽  
Friction Forces ◽  
Disk Interface ◽  
Percent Relative Humidity

Stiction at the head/disk interface has become one of the major concerns as smoother surfaces are required to achieve lower flying heights of magnetic heads over magnetic disks. In this paper, static friction forces on three types of disk samples with different surface roughness values were measured at various relative humidities. It was found that static friction coefficients were well correlated with total thickness of liquid (lubricant and adsorbed water) at the head/disk interface. The experimental data also agreed fairly well with the calculated values based on a proposed stiction model. It is implied in the stiction model that the bearing ratio or the shape of asperity height distribution, especially the part of high asperities, determines the stiction force. Moreover, long-term stiction was investigated on the unlubricated disk surfaces at 80 percent relative humidity and on the lubricated disks at 5 percent relative humidity to separate the effects of water build-up and lubricant build-up at the head/disk interface. It appears that long-term stiction occurs only when enough mobile lubricant is present and the thickness of liquid at the head/disk interface is close to a critical thickness value which is related to surface roughness values.

Analytical/Experimental Study of the Contribution of Individual Seals to Friction Force in Pneumatic Actuators

2016 ◽  
Vol 139 (2) ◽  
Author(s):  
Luigi Mazza ◽  
Guido Belforte
Keyword(s):  
Friction Force ◽  
Experimental Validation ◽  
Friction Forces ◽  
Pneumatic Actuators ◽  
Test Conditions ◽  
Lumped Parameter ◽  
Experimental Approaches ◽  
Friction Measurements ◽  
Rod Seals ◽  
Pneumatic Cylinders

This paper presents an analytical model and its experimental validation for assessing friction forces in reciprocating seals for single and double rod pneumatic cylinders. The contributions of individual piston and rod seals are analyzed using a combination of analytical and experimental approaches. The former entails a friction force formulation based on a lumped parameter seal model, whereas the latter involves carrying out measurements on complete actuators. Selecting appropriate test conditions made it possible to analyze separately the contributions that individual seals make to the overall friction measured on complete actuators. Analysis results were validated by means of friction measurements on the actuators seals, which were tested individually in specific devices. The experimental results were interpreted on the basis of the proposed analytical formulation and confirmed its validity.

A Statistical Analysis of Elastomeric Seal Degradation in a Pneumatic Cylinder With Variation of Temperature

2011 ◽  
Author(s):  
B. S. Kang ◽  
J. H. Shin ◽  
H. E. Kim
Keyword(s):  
Sliding Friction ◽  
Degradation Mechanism ◽  
Operating Parameter ◽  
Maintenance Cost ◽  
Pneumatic Cylinder ◽  
Analysis Method ◽  
Pyrolysis Gas ◽  
Life Tests ◽  
Stress Minimization ◽  
Pneumatic Cylinders

Pneumatic Cylinders are one of major mechanical components which are widely used in various industries such as automobile production line and semiconductor inspection device due to its low contamination and low maintenance cost. Most of existing studies on pneumatic cylinders have focused on their performance improvement such as operating sliding friction measurement, contact stress minimization, appropriate dynamic response, and etc. This research carried out life tests of pneumatic cylinders and the concerned failure mechanism was the degradation of pneumatic polyurethane seal since leakage caused by seal degradation occurs very frequently. The considered operating parameter was environmental temperature. To assess operating temperature as an acceleration parameter, the lifetime of a pneumatic cylinder was tested at high temperature and the degradation mechanism and characteristics of sealing surface were analyzed by statistical Weibull analysis method as well as by surface analysis using pyrolysis gas chromatography. Ultimately this research will help the life prediction of other pneumatic reciprocating machines.

scholarly journals Highly Selective Biomimetic Flexible Tactile Sensor for Neuroprosthetics

Research ◽  
2020 ◽  
Vol 2020 ◽  
pp. 1-11 ◽  
Author(s):  
Yue Li ◽  
Zhiguang Cao ◽  
Tie Li ◽  
Fuqin Sun ◽  
Yuanyuan Bai ◽  
...  
Keyword(s):  
Friction Force ◽  
Sliding Friction ◽  
Dielectric Material ◽  
Silver Nanowires ◽  
Static Friction ◽  
Tactile Sensor ◽  
Capacitive Sensor ◽  
Silver Nanowire ◽  
Friction Forces ◽  
Signal Encoding

Biomimetic flexible tactile sensors endow prosthetics with the ability to manipulate objects, similar to human hands. However, it is still a great challenge to selectively respond to static and sliding friction forces, which is crucial tactile information relevant to the perception of weight and slippage during grasps. Here, inspired by the structure of fingerprints and the selective response of Ruffini endings to friction forces, we developed a biomimetic flexible capacitive sensor to selectively detect static and sliding friction forces. The sensor is designed as a novel plane-parallel capacitor, in which silver nanowire–3D polydimethylsiloxane (PDMS) electrodes are placed in a spiral configuration and set perpendicular to the substrate. Silver nanowires are uniformly distributed on the surfaces of 3D polydimethylsiloxane microcolumns, and silicon rubber (Ecoflex®) acts as the dielectric material. The capacitance of the sensor remains nearly constant under different applied normal forces but increases with the static friction force and decreases when sliding occurs. Furthermore, aiming at the slippage perception of neuroprosthetics, a custom-designed signal encoding circuit was designed to transform the capacitance signal into a bionic pulsed signal modulated by the applied sliding friction force. Test results demonstrate the great potential of the novel biomimetic flexible sensors with directional and dynamic sensitivity of haptic force for smart neuroprosthetics.

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