Research on pressure compensation and friction characteristics of piston rod seals with different degrees of wear

2020 ◽  
Vol 142 ◽  
pp. 105999 ◽  
Author(s):  
Xiuxu Zhao ◽  
Xiangyu He ◽  
Liting Wang ◽  
Peng Chen
Keyword(s):  
Friction Characteristics ◽  
Pressure Compensation ◽  
Rod Seals

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 Design and Performance Study for Electrothermally Deep-Sea Drive Microunits Using a Paraffin Phase Change Material

Micromachines ◽  
2021 ◽  
Vol 12 (4) ◽  
pp. 415
Author(s):  
Dayong Ning ◽  
Zihao Li ◽  
Gangda Liang ◽  
Qibo Wang ◽  
Weifeng Zou ◽  
...  
Keyword(s):  
Phase Change ◽  
Phase Change Material ◽  
Deep Sea ◽  
Hydraulic System ◽  
Functional Verification ◽  
Performance Study ◽  
Micro Electro Mechanical Systems ◽  
Pressure Compensation ◽  
And Performance ◽  
Change Material

Considering the further exploration of the ocean, the requirements for deep-sea operation equipment have increased. Many problems existing in the widely used deep-sea hydraulic system have become increasingly prominent. Compared with the traditional deep-sea hydraulic system, actuators using a paraffin phase change material (PCM) have incomparable advantages, including lightweight structure, low energy consumption, high adaptability to the deep sea, and good biocompatibility. Thus, a deep-sea drive microunit (DDM) based on paraffin PCM is proposed in this paper. The device adopts a flexible shell, adapting to the high-pressure environment of the deep-sea based on the principle of pressure compensation. The device realizes the output of displacement and force through the electrothermal drive, which can be used as actuator or power source of other underwater operation equipment. The microunit successfully completes the functional verification experiments in air, shallow water, and hydrostatic pressure of 110 MPa. In accordance with experimental results, a reasonable control curve is fitted, highlighting its potential application in deep-sea micro electro mechanical systems, especially in underwater soft robot.

scholarly journals Shear Friction Characteristics and Modification Factor of Concrete Prepared Using Expanded Bottom Ash and Dredged Soil Granules

2019 ◽  
Vol 13 (1) ◽  
Author(s):  
Keun-Hyeok Yang ◽  
Kyung-Ho Lee
Keyword(s):  
Shear Crack ◽  
Bottom Ash ◽  
Lightweight Aggregate Concrete ◽  
Maximum Aggregate Size ◽  
Crack Plane ◽  
Upper Bound Theorem ◽  
Friction Characteristics ◽  
Dredged Soil ◽  
Shear Friction ◽  
Modification Factor

Abstract The objective of this study is to assess the shear friction characteristics of lightweight aggregate concrete (LWAC) prepared using artificially expanded bottom ash and dredged soil granules. A total of 37 concrete mixtures were prepared under the classification of three series. In the first and second series, the natural sand content for replacing lightweight fine aggregates and the water-to-cement ratio varied to obtain different densities and compressive strengths of concrete. The third series was designed to estimate the effect of the maximum aggregate size on the friction resistance along the shear crack plane of the monolithic interfaces. The frictional angle of the LWAC tested was formulated as a function of the ratio of the effective tensile and compressive strengths of concrete through the expansion of the integrated mathematical models proposed by Kwon et al., based on the upper-bound theorem of concrete plasticity. When predicting the shear friction strength of LWAC, the present mathematical model exhibits relatively good accuracy, yielding the mean and standard deviation of the ratios between experiments and predictions of 1.06 and 0.14, respectively, whereas the empirical equations proposed by the AASHTO provision and Mattock underestimated the results. Ultimately, an advanced modification factor for shear design of LWAC is proposed as a function of the density and compressive strength of concrete and the maximum size of aggregates.

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