Journal articles: 'Pressure-based friction'

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Ozaki, Shingo, Takeru Matsuura, and Satoru Maegawa. "Rate-, state-, and pressure-dependent friction model based on the elastoplastic theory." Friction 8, no. 4 (January 4, 2020): 768–83. http://dx.doi.org/10.1007/s40544-019-0321-3.

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AbstractAdhesion is one of essences with respect to rubber friction because the magnitude of the friction force is closely related to the magnitude of adhesion on a real contact area. However, the real contact area during sliding depends on the state and history of the contact surface. Therefore, the friction force occasionally exhibits rate-, state-, and pressure dependency. In this study, to rationally describe friction and simulate boundary value problems, a rate-, state-, and pressure-dependent friction model based on the elastoplastic theory was formulated. First, the evolution law for the friction coefficient was prescribed. Next, a nonlinear sliding surface (frictional criterion) was adopted, and several other evolution laws for internal state variables were prescribed. Subsequently, the typical response characteristics of the proposed friction model were demonstrated, and its validity was verified by comparing the obtained results with those of experiments conducted considering the contact surface between a rough rubber hemisphere and smooth acrylic plate.

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Cramer, David D., and Junjing Zhang. "Pressure-Based Diagnostics for Evaluating Treatment Confinement." SPE Production & Operations 36, no. 03 (January 18, 2021): 530–52. http://dx.doi.org/10.2118/205003-pa.

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Summary In multiple-stage hydraulic fracturing treatments performed in horizontal wells, treatment confinement is the state in which fracturing fluid and proppant flow out of the wellbore only through the specific perforations targeted for the fracturing stage. The terms treatment confinement and treatment isolation are synonymous. Isolation from previously treated intervals is a necessary condition for efficient treatment along the lateral. Failure to confine fracturing stages can be a result of failure of the fracture plug to maintain a seal or the development of casing breaches (holes) in the proximity of the fracture plug. Both conditions can be strongly impacted by proppant induced erosion. This paper is a sequel to a previous publication in which casing erosion and breaches were investigated in fracture treated horizontal wells in the Montney Formation (White et al. 2020). Integrated diagnostic methods based on data from treating pressure analysis, fiber-optic measurements, and downhole imaging were applied to investigate the root cause of failure. It was determined that treatment pressure analysis was effective in diagnosing casing and associated fracture plug integrity-loss events. This was achieved by (1) identifying treating pressure trends and anomalies during the main part of the treatment that signify confinement loss, (2) calculating near-wellbore friction at the end of treatments to compare to the friction expected for a confined treatment, and (3) analyzing step-down tests conducted during the pad stage and overflush stage at the end of the treatment to determine the near-wellbore frictional components of perforation friction and near-wellbore tortuosity. This information enables comparison of previous with current treatments for determining the effects of job design and fracture plug modifications on treatment confinement. The objective of this paper is to validate that useful conclusions on the degree of treatment confinement can be made using only stand-alone pressure-based analysis. This is achieved by comparing the analysis results with fiber-optic and post-treatment wellbore imaging measurements. Also highlighted is the use of downhole gauges for accurately calculating pipe friction, which is necessary for accurately calculating bottomhole treating pressure at the active treatment interval.

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Ates, Hakan, Mehmet Turker, and Adem Kurt. "Effect of friction pressure on the properties of friction welded MA956 iron-based superalloy." Materials & Design 28, no. 3 (January 2007): 948–53. http://dx.doi.org/10.1016/j.matdes.2005.09.015.

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Hattori, Yasuhisa, and Yusuke Kato. "Dynamic Friction Behavior of Paper-Based Wet Friction Material Subjected to Contact Pressure Fluctuation." Tribology Online 7, no. 3 (2012): 184–89. http://dx.doi.org/10.2474/trol.7.184.

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Fu, Rong, Fei Gao, and Bao Yun Song. "Study on Friction Properties of Cu-Fe-Based Powder Metallurgy Materials under Dry and Wet Friction Conditions." Advanced Materials Research 150-151 (October 2010): 1806–9. http://dx.doi.org/10.4028/www.scientific.net/amr.150-151.1806.

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Copper-iron-based friction materials were prepared by powder metallurgy process. The effects of friction velocity and friction pressure on friction and wear behavior of the material under dry and wet friction conditions were investigated with a constant-speed friction machine. The results show that, at low speed friction, the dry friction coefficient is higher than wet friction coefficient and the friction coefficient increases with increasing friction pressure. The reason is that the water film plays an important role in cleaning and lubricating. At high speed friction, there is not much difference between dry and wet friction coefficients and the friction coefficient is not sensitive to friction pressure changes. This is due to the metal matrix high-temperature softening, caused by high speed friction, which controls the friction properties.

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Zhang, Yao, and Wan Ling Zhang. "Research Pressure Loss Based on Gas Liquid Two Phrase Flow Experiment System." Applied Mechanics and Materials 404 (September 2013): 302–6. http://dx.doi.org/10.4028/www.scientific.net/amm.404.302.

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This paper discussed the pressure drop about the friction pressure drop and gravity pressure drop in the pipe. Represent the model of pressure drop. Calculate the pressure drop in the experiment system. Flow pattern and pressure drop has the directly relationship. And the friction pressure drop is the main factor of influences internal fluid mechanism. Pressure drop is basic of research the water rate and dynamics fluid.

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Man, Jiaxiang, Jiyun Zhao, Liangchen Song, and Haifeng Yang. "Study the Influence of Surface Morphology and Lubrication Pressure on Tribological Behavior of 316L–PTFE Friction Interface in High-Water-Based Fluid." Coatings 10, no. 4 (April 19, 2020): 405. http://dx.doi.org/10.3390/coatings10040405.

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Because of the low viscosity of high-water-based fluids, the intense wear and leakage of key friction pairs represent a bottleneck to the wide application of the high-water-based hydraulic motor in engineering machinery. In this work, based on the common characteristics of plane friction pairs, the friction experiments of a 316L stainless steel (316L)–polytetrafluoroethylene (PTFE) friction pair under various working condition were carried out by a self-designed friction experimental system with fluid lubrication. The influence of lubrication pressure and surface morphology on the 316L–PTFE friction pair was investigated both experimentally and theoretically. The experimental and numerical results indicated that increasing lubrication pressure reduced the surface wear of PTFE sample, but the leakage of 316L–PTFE friction pair also increased. It could not form an effective fluid lubrication film in the 316L–PTFE friction pair under low lubrication pressure, which caused the severe wear in friction pair interface. The smooth 316L surface could be conducive to the formation of high-water-based fluid lubrication film in 316L–PTFE friction interface. The pressure distribution of high-water-based fluid lubrication film in 316L–PTFE friction pair was also obtained in fluent. The PTFE surface was easily worn when the lubrication film in the friction pair was too thin or uneven. The friction and wear were obviously improved when the normal load was balanced by the bearing capacity of the high-water-based fluid lubrication film.

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Day, A. J. "An Analysis of Speed, Temperature, and Performance Characteristics of Automotive Drum Brakes." Journal of Tribology 110, no. 2 (April 1, 1988): 298–303. http://dx.doi.org/10.1115/1.3261604.

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Finite element analysis techniques have been used to simulate braking friction in a large, heavy duty twin leading shoe brake. Temperature, lining wear and pressure distributions, and thermal distortions of the brake drum which are generated during high pressure brake applications from two different road speeds have been predicted and compared with experimental data. Two different types of brake lining, a conventional asbestos-based resin-bonded composite friction material and a heavy duty resin-bonded semi-metallic type of friction material have been studied in this way, and it is shown that observed in-stop and speed-related brake performance are strongly dependent upon the rate of frictional energy transformation at the lining/drum interface, which defines the development of interface transient temperatures. By relating the measured friction characteristic of the friction material to predicted lining friction surface temperatures good correlation between predicted and actual brake performance is demonstrated.

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Zhang, Zhigang, Ling Zou, Hang Liu, Yonglong Chen, and Benzhu Zhang. "Effects of operating and material parameters on the thermal characteristics of a wet clutch." Advances in Mechanical Engineering 13, no. 7 (July 2021): 168781402110341. http://dx.doi.org/10.1177/16878140211034101.

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Based on the frictional mechanism of a wet clutch, frictional models of wet clutch engagement were established using the modified Reynolds equation and the elastic contact model between frictional pairs. Then, the heat flux models for the viscous shear and asperity friction were built, and the two-dimensional transient thermal models for the separator plate, friction disk, and ATF heat convection model were deduced based on the heat transfer theory and conservation law of energy. Finally, the Runge–Kutta numerical method was used to solve the frictional and thermal models. The average temperature of the separator plate, friction disk, and ATF were calculated. The effects of operating and material parameters, such as applied pressure, initial angular velocity, friction lining permeability, surface combined roughness RMS, equivalent elastic modulus, and ATF flow, on the thermal characteristics of friction pairs and ATF during engagement, were studied. The simulation results show that the temperature characteristics of the separator plate, friction disk, and ATF depend mainly on the viscous shear and asperity friction heat flux, and that the operating and material parameters of the wet clutch also have significant impacts on the overall variation trend of the thermal characteristics of the separator plate, friction disk, and ATF.

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Serafińska, Aleksandra, Wolfgang Graf, and Michael Kaliske. "Artificial Neural Networks Based Friction Law for Elastomeric Materials Applied in Finite Element Sliding Contact Simulations." Complexity 2018 (November 19, 2018): 1–15. http://dx.doi.org/10.1155/2018/4396758.

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A realistic characterization of the frictional behaviour of materials and mechanical systems is of prime importance for the assessment of their contact interaction properties, especially in the context of undesired temperature rise or intensive wear leading to service life reduction. A characteristic tribological property of elastomeric materials is the dependency of the friction coefficient on the local contact pressure, sliding velocity, and temperature in the contact interface. Thus, the friction coefficient is not constant in the entire contact area but varies according to the magnitudes of the aforementioned three influencing factors. In this contribution, a friction law based on artificial neural networks (ANN) is presented, which is able to capture the nonlinear dependencies of the friction coefficient on the contact pressure, sliding velocity, and temperature. Due to an extraordinary adaptivity of the ANN structure, these nonlinear relations stemming from experimental data can be modelled properly within the introduced friction law, in contrast to other friction formulations, which are limited by the fitting quality of their parameters. The ANN based friction law is implemented into a contact formulation of the finite element method (FEM). Especially, the linearization of contact contributions to the weak form of momentum balance equation, required for the FEM, is developed taking into account the differentiability of the ANN. The applicability of the developed friction law within the finite element analysis of tires as well as within sliding simulations of rubber elements is presented in this paper.

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Cheng, Hai Qian, Qing Hua Cheng, and Kai Yin Zhang. "Analysis on Pre-Stressed Friction Loss in Bending Channel under Contact Pressure Non-Uniform Distribution Hypothesis." Advanced Materials Research 255-260 (May 2011): 49–53. http://dx.doi.org/10.4028/www.scientific.net/amr.255-260.49.

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The pre-stressed friction loss formula in bending channel recommended by Bridge Rules was based on the uniform distribution hypothesis of contact pressure. From some conflicts in application of the formula, the non-uniform distribution law of the contact pressure was revealed. On the basis of elastic contact analysis, two types of non-uniform distribution hypothesis were proposed, including cosine and second-degree parabola distribution. Then the contact positive pressure expressions were derived respectively and the frictional resistance was calculated to compare with the calculated value under the uniform distribution. The results indicate that the friction resistance under any non-uniform distribution of positive pressure is less than under the uniform distribution. So the uniform distribution assumption of contact pressure does not cause Bridge Specifications formula underestimate friction loss. It is necessary to do further research on the applicability of Coulomb’s law under the contact conditions in the curved channel.

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Li, Zhao, Ziran Li, and Yang Wang. "An Integrated Approach for Friction and Wear Simulation of Tire Tread Rubber. Part I: Friction Test, Characterization, and Modeling." Tire Science and Technology 48, no. 2 (June 27, 2019): 123–45. http://dx.doi.org/10.2346/tire.19.170174.

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ABSTRACT: To simulate tire tread friction and wear, a variety of factors have to be taken into account. Among them, the local nonlinear constitutive equation for friction and wear in the contact interface and the related solving strategies, including the wear increment optimization and worn mesh update, are very critical to the predicting methodology. This two-part contribution addresses an integrated approach for friction and wear simulation of tire tread rubber. In Part I, a modified friction test scheme of rubber wheels with the Laboratory Abrasion and Skid Tester (LAT 100) is proposed, along with numerical verification, which greatly improved the distribution uniformities of the contact pressure and sliding velocity. In order to investigate the friction characteristics of tire tread rubber, various contact conditions were conducted, and then a unified friction model was put forward to describe the nonlinear relationship of rubber friction with contact pressure and sliding velocity. Based on the established frictional contact model, the locked traction and cornering rolling were simulated, and the calculated friction forces and lateral forces agree with the experimental results on the whole.

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Chassagne, Fanette, Emilie Benoist, Pierre Badel, Reynald Convert, Laurence Schacher, and Jérôme Molimard. "Characterization of Fabric-to-Fabric Friction: Application to Medical Compression Bandages." Autex Research Journal 20, no. 2 (May 13, 2020): 220–27. http://dx.doi.org/10.2478/aut-2019-0050.

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AbstractFabric-to-fabric friction is involved in the action mechanism of medical compression devices such as compression bandages or lumbar belts. To better understand the action of such devices, it is essential to characterize, in their use conditions (mainly pressure and stretch), the frictional properties of the fabrics they are composed of. A characterization method of fabric-to-fabric friction was developed. This method was based on the customization of the fourth instrument of the Kawabata Evaluation System, initially designed for fabric roughness and friction characterization. A friction contactor was developed so that the stretch of the fabric and the applied load can vary to replicate the use conditions. This methodology was implemented to measure the friction coefficient of several medical compression bandages. In the ranges of pressure and bandage stretch investigated in the study, bandage-to-bandage friction coefficient showed very little variation. This simple and reliable method, which was tested for commercially available medical compression bandages, could be used for other medical compression fabrics.

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Hu, Juqi, Subhash Rakheja, and Youmin Zhang. "Tire–road friction coefficient estimation based on designed braking pressure pulse." Proceedings of the Institution of Mechanical Engineers, Part D: Journal of Automobile Engineering 235, no. 7 (January 5, 2021): 1876–91. http://dx.doi.org/10.1177/0954407020983580.

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Knowledge of tire–road friction coefficient (TRFC) is valuable for autonomous vehicle control and design of active safety systems. This paper investigates TRFC estimation on the basis of longitudinal vehicle dynamics. A two-stage TRFC estimation scheme is proposed that limits the disturbances to the vehicle motion. A sequence of braking pressure pulses is designed in the first stage to identify desired minimal pulse pressure for reliable estimation of TRFC with minimal interference with the vehicle motion. This stage also provides a qualitative estimate of TRFC. In the second stage, tire normal force and slip ratio are directly calculated from the measured signals, a modified force observer based on the wheel rotational dynamics is developed for estimating the tire braking force. A constrained unscented Kalman filter (CUKF) algorithm is subsequently proposed to identify the TRFC for achieving rapid convergence and enhanced estimation accuracy. The effectiveness of the proposed methodology is evaluated through CarSim™-MATLAB/Simulink™ co-simulations considering vehicle motions on high-, medium-, and low-friction roads at different speeds. The results suggest that the proposed two-stage methodology can yield an accurate estimation of the road friction with a relatively lower effect on the vehicle speed.

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Yang, Guang Biao, and Tie Shan Zhang. "Study on Design Method of Clutch Pressure Plate Based on Thermal Deformation." Advanced Materials Research 978 (June 2014): 114–17. http://dx.doi.org/10.4028/www.scientific.net/amr.978.114.

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With the method of finite element, the sliding friction process of pressure plate and friction disc during clutch engagement was simulated to get temperature field and thermal deformation of the pressure plate. The law of temperature distribution on the pressure plate, which achieve from the simulation is same with the one measured by thermocouple. On this basis, analyzed the influence of pressure plate’s thermal deformation to torque transmission ability of clutch and put forward the structure design method of clutch pressure plate.

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He, Jun, Huang Ping, and Qian Qian Yang. "Study on Photoelastic Method for Measuring Elastohydrodynamic Lubrication Pressure in Line Contact." Applied Mechanics and Materials 281 (January 2013): 329–34. http://dx.doi.org/10.4028/www.scientific.net/amm.281.329.

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In the present paper, a new method for measuring elastohydrodynamic lubrication (EHL) pressure in line contact is proposed, which is based on the photoelastic technique. The pressure distribution of EHL film and the inner stresses in the friction pairs are fundamental issues to carry out EHL research. The film thickness, pressure and temperature have been successfully obtained with solving the basic equations such as Reynolds equation and energy equation simultaneously or separately, with numerical model of EHL problem. The film thickness can be also measured with the optical interference technique. However, the pressure measurement is still a problem which has not been well solved yet, so as the inner stresses inside the friction pairs. With the experimental mechanics, the photoelastic technique is a possible method to be used for measuring the pressure distribution of EHL film and inner friction pair in the line contact. Therefore, A flat plastic disk and a steel roller compose the frictional pairs of the photoelastic pressure measuring rig with combining the monochromatic LED light source, polarizer CCD camera and stereomicroscope to form the whole pressure measuring system of the line contact EHL. The experimental results with the rig display the typical features of EHL pressure. This shows that the method is feasible to be used for measuring the pressure of EHL film and the inner stresses of the friction pairs in the line contact.

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Han, Wei, Lu Xiong, and Zhuoping Yu. "A novel pressure control strategy of an electro-hydraulic brake system via fusion of control signals." Proceedings of the Institution of Mechanical Engineers, Part D: Journal of Automobile Engineering 233, no. 13 (January 22, 2019): 3342–57. http://dx.doi.org/10.1177/0954407018821016.

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With the development of electro-hydraulic brake system in the automotive application, pressure control is at the top of a brake system engineer’s agenda. This work focuses on the development of a pressure-loop controller for a motor-type electro-hydraulic brake system, which is composed of an electro-mechanical actuator and a hydraulic link. The pressure control issue of motor-type electro-hydraulic brake system is influenced intensely by the nonlinearities (i.e. friction) and uncertainties (e.g. temperature variation, brake pad wear, and so on) of the system and by the very demanding performance specifications (i.e. supporting cooperative work with hydraulic control unit of anti-lock brake system). The pressure control of motor-type electro-hydraulic brake system is investigated, and a novel pressure–based control strategy via fusion of control signals is proposed to improve the pressure tracking performance. The control strategy comprises online model–based friction compensation, online dither–based friction compensation, and feedback control. Four original contributions make this work distinctive from the existing relevant literature. Selecting the Coulomb+viscous friction model can maximize to reduce difficulty of parameter identification and Stribeck effects detection based on maintaining the pressure tracking accuracy. Thanks to the model-based friction compensation torque, the signal magnitude of dither-based friction compensation torque can be decreased so that the vehicle comfort can be improved. The compensation parameters of both the model-based and dither-based friction compensation can be online modified according to the operating point of system. The robustness of the fusion controller is enhanced by employing the sliding mode control algorithm with conditional integrator. The performance of the proposed control strategy is evaluated by hardware-in-the-loop-simulation and vehicle experiment in typical braking situations. The experimental results with fusion control show improved pressure tracking performance in comparison with that without fusion control.

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Ma, Xinling, Hongtao Wang, and Wei Yang. "Tribological Behavior of Aligned Single-Walled Carbon Nanotubes." Journal of Engineering Materials and Technology 126, no. 3 (June 29, 2004): 258–64. http://dx.doi.org/10.1115/1.1752924.

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An abnormal friction law refers to the case where the friction force does not increase monotonically with the normal pressure. We investigate the possibility of abnormal tribological behavior for two surfaces coated with aligned single-walled carbon nanotubes (SWCNTs). Detailed molecular dynamics simulations for aligned SWCNTs predict modulated variation between the kinetic friction force and the applied pressure. The interacting SWCNTs float with respect to each other at about the equilibrium separation of van der Waals interaction, and the wavy contact profile breaks the symmetry of the contacting cross-section. Cases treated by molecular dynamics simulation include two aligned (10,10) SWCNTs with periodic end conditions, and a stack of three aligned (10,10) SWCNTs with free end boundary conditions. A continuum theory based on the wall deflection under finite deformation, in combination with an adhesion criterion similar to the JKR theory, on the other hand, predicts a declining law between the frictional force and the pressure. The correlation of the data obtained through the atomistic and the continuum approaches relies on a deeper understanding on the friction process among SWCNTs.

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Liu, Tianshu, Takashi Misaka, Keisuke Asai, Shigeru Obayashi, and Jie-Zhi Wu. "Feasibility of skin-friction diagnostics based on surface pressure gradient field." Measurement Science and Technology 27, no. 12 (October 28, 2016): 125304. http://dx.doi.org/10.1088/0957-0233/27/12/125304.

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Manring, Noah D. "Friction Forces Within the Cylinder Bores of Swash-Plate Type Axial-Piston Pumps and Motors." Journal of Dynamic Systems, Measurement, and Control 121, no. 3 (September 1, 1999): 531–37. http://dx.doi.org/10.1115/1.2802507.

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In this research, the friction within the cylinder bore of a swash-plate type axial-piston machine is examined. Unlike previous research, this work develops a mathematical model for the friction based upon lubricating conditions which are described by the well-known Stribeck curve. Furthermore, a test device is built for measuring the frictional characteristics during low pressure and low speed operation and these results are compared with the mathematical model. For high pressure and high speed considerations, a numerical investigation based upon the model is conducted and it is shown that the friction associated with a pumping piston is greater than the friction associated with a motoring piston. It is also shown that increased piston speeds usually reduce the friction within the cylinder bore; however, a “cross-over” condition may exist where the increased speed will actually increase the friction as a result of increased fluid shear. Furthermore, it is shown that speed changes have a more significant impact on motoring pistons as opposed to pumping pistons due to a difference in the location of hydrodynamic lubrication within the cylinder bore. It is noted that this difference exits due to the bore geometry and the direction of piston travel.

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Zhang, Su Mei, Pei Hong Guo, Jia Nan Zhu, and Xiao Ping Wen. "Molecular Dynamics Simulation of Water-Based Nano-Lubrication." Advanced Materials Research 773 (September 2013): 585–88. http://dx.doi.org/10.4028/www.scientific.net/amr.773.585.

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Molecular dynamics simulations of water-based nanolubrication in Couette flow are carried out. The water molecules are simulated by the TIP3P model. Three different shear rates are 20 m/s and 40 m/s and 60 m/s, and the vertical pressure acted on the metal wall are 10GPa, 20 GPa, 30 GPa and 40 GPa respectively. The simulated results show that the greater pressure, the smaller the stable value of friction spacing, while the reduction rate of the stable value becomes small. Meanwhile, as pressure increases, the stabilization time is longer. However, under the same pressure, shear rate of influence on the friction spacing is not obvious. The friction spacing increases with the number of particles, showing that the presence of nanoparticles can enhance the bearing capacity.

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Wei, Long, Peng Gao Zhang, and Gui Fang Fang. "Simulation Calculation of Friction Factor of the End Face for Mechanical Seals Based on Fractal Theory." Applied Mechanics and Materials 687-691 (November 2014): 142–47. http://dx.doi.org/10.4028/www.scientific.net/amm.687-691.142.

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In order to study the effects of operating parameters and surface topography on friction factors between the end faces for mechanical seals, a friction factor fractal model between end faces for contact mechanical seals was established based on the contact fractal model and the average film thickness fractal model, adopting fractal parameters to represent surface topography, separating friction into viscous shear friction of liquid film and contact friction of asperities, and representing the effect of actual rough surface on viscous shear stress of liquid film by introducing the contact factor. The influencing factors of friction factor for B104a-70 mechanical seal were analyzed by simulating. Results showed that the friction factor between the surfaces increases with the increases of spring pressure when the end faces are coarser, while the friction factor decreases slightly with the increases of spring pressure when the end faces are smoother. The friction factor between the faces decreases with the increases of the sealed fluid pressure, which increases approximate linearly with the increases of rotating speed, and it increases with the increases of fractal dimension of end faces and the decreases of the characteristic scale factor.

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Loukidis, D., and R. Salgado. "Active pressure on gravity walls supporting purely frictional soils." Canadian Geotechnical Journal 49, no. 1 (January 2012): 78–97. http://dx.doi.org/10.1139/t11-087.

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The active earth pressure used in the design of gravity walls is calculated based on the internal friction angle of the retained soil or backfill. However, the friction angle of a soil changes during the deformation process. For drained loading, the mobilized friction angle varies between the peak and critical-state friction angles, depending on the level of shear strain in the retained soil. Consequently, there is not a single value of friction angle for the retained soil mass, and the active earth pressure coefficient changes as the wall moves away from the backfill and plastic shear strains in the backfill increase. In this paper, the finite element method is used to study the evolution of the active earth pressure behind a gravity retaining wall, as well as the shear patterns developing in the backfill and foundation soil. The analyses relied on use of a two-surface plasticity constitutive model for sands, which is based on critical-state soil mechanics.

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Mukherjee, H., and J. P. Brill. "Pressure Drop Correlations for Inclined Two-Phase Flow." Journal of Energy Resources Technology 107, no. 4 (December 1, 1985): 549–54. http://dx.doi.org/10.1115/1.3231233.

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Pressure drop behavior in two-phase inclined flow was studied. For bubble and slug flow, a no-slip friction factor calculated from the Moody diagram was found adequate for friction head loss calculations. In downhill stratified flow, the friction pressure gradient is calculated based on a momentum balance equation for either phase assuming a smooth gas-liquid interface. For this calculation, a prior knowledge of the liquid holdup is needed. For annular-mist flow, a friction factor correlation is presented that is a function of holdup ratio and no-slip Moody friction factor. Results agree well with the experimental data and correlations were further verified with Prudhoe Bay and North Sea data.

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Yu, Liang, Biao Ma, Man Chen, He Yan Li, and Jikai Liu. "Experimental study on the friction stability of paper-based clutches concerning groove patterns." Industrial Lubrication and Tribology 72, no. 4 (July 29, 2019): 541–48. http://dx.doi.org/10.1108/ilt-03-2019-0098.

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Purpose This paper aims to study and compare the friction stability of wet paper-based clutches with regard to the radial grooves (RG) and waffle grooves (WG). Design/methodology/approach This paper presents an experimental study of a wet clutch concerning the effect of groove patterns on the friction torque and surface temperature. The friction stabilities of RG and WG are investigated with the applied pressure, rotating speed and automatic transmission fluid (ATF) temperature taken into consideration. Findings The friction torque and surface temperature of WG are larger than those of RG under the same operating condition. The friction torque difference between RG and WG grows with the increase of applied pressure and narrows with the increase of ATF temperature. Additionally, their temperature difference expands via increasing the rotating speed and ATF temperature or reducing the applied pressure; in this way, not only the variable coefficient difference between RG and WG can be narrowed, but also the friction stability of the clutch can be improved dramatically. Originality/value This paper explains the thermodynamic differences between RG and WG; moreover, it is verified experimentally that WG has a better friction stability than RG.

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Han, Han. "Influence of Material Anisotropy and Friction on Ring Deformation." Journal of Tribology 124, no. 3 (May 31, 2002): 637–44. http://dx.doi.org/10.1115/1.1473144.

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The influence of material anisotropy and friction on ring deformation has been examined in relation to the distribution of normal pressure and frictional shear stress, deformed ring shapes, and estimated errors in the coefficient of friction. Based on the flow rule associated with von Mises’ and Hill’s yield criteria, the analyses have been carried out with the finite element method (FEM) for three cases, namely, (1) an anisotropic ring oriented 90 deg to the axis of rotational symmetrical anisotropy under uniform coefficient of friction; (2) an isotropic ring under frictional anisotropy condition; and (3) an anisotropic ring oriented 0 deg to the axis of rotational symmetrical anisotropy under uniform coefficient of friction. In the first two cases, the results show that the influence of anisotropy on ring deformation is quite similar to that obtained by changing the frictional condition. Therefore, in the third case, if the anisotropic behavior is mistakenly attributed to friction, the possible estimated error for the coefficient of friction can be as high as 80 percent for a pronounced anisotropic material. Deformed ring shapes have been verified in experiments using the extruded annealed aluminum alloy AA6082 (Al-Si1Mg0.9Mn0.1).

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Zhao, Tian Yang, Dan Jiang, Song Yu, Jie Wang, and Ping Yang. "Analysis of High Pressure Transients in Water Hydraulic Pipeline Using Matlab/Simulink." Key Engineering Materials 621 (August 2014): 311–16. http://dx.doi.org/10.4028/www.scientific.net/kem.621.311.

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Based on the continuity equation and the motion equation of fluid dynamics, a mathematical model of high pressure transients in water hydraulic pipeline is presented. In the model, the friction item is consist of steady friction item and dynamic friction item, using the Darcy-Weisbach equation to solve steady viscous friction item and using four exponential terms instead of weighting function to solve dynamic friction item. By finite difference method accompanied with Matlab/Simulink, an example of high pressure turbulent flow in water hydraulic pipeline is configured so as to simulate the dynamic characteristics of pressure transients. The comparison between the observed result and the simulation result shows the mathematical model of high pressure transients in water hydraulic pipeline with turbulent flow is reasonable.

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Hora, Pavel, Maysam Gorji, and Bekim Berisha. "Modeling of Friction Phenomena in Extrusion Processes by Using a New Torsion-Friction Test." Key Engineering Materials 491 (September 2011): 129–35. http://dx.doi.org/10.4028/www.scientific.net/kem.491.129.

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During the extrusion processes very complex adhesion and friction effects between the die surface and the extruded material occur. If they can not be controlled, the process can not be controlled either. In the framework of this study, a recently developed experiment for the investigation of the frictional phenomena under extrusion conditions will be presented. Based on the so called Torsion-Tribo-Test, low and high pressure load cases are considered. The experimental layout, the evaluation method as well as some measurements will be presented.

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Yang, Wei, Hongtao Wang, and Y. Huang. "Abnormal Tribological Behavior of Multiwalled Nanotube Rafts Part I: Aligned Rafts." Journal of Engineering Materials and Technology 127, no. 4 (November 15, 2004): 383–92. http://dx.doi.org/10.1115/1.1867980.

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When two material surfaces are brought into contact, the classical Amonton’s law predicts a monotonically increasing relation between the frictional force and the normal pressure. An abnormal friction law refers to the case where the friction force declines as the normal pressure increases. We investigate the possibility of abnormal tribological behavior for two surfaces coated with aligned multiwalled nanotube rafts. Part I of the investigation is devoted to the case when two contacting nanotube rafts are aligned to each other, while part II is aimed at more general case of arbitrarily oriented nanotube rafts. The analysis in part I is based on the JKR theory of adhesion and linear elasticity for aligned multiwalled carbon nanotube raft configuration. It gives rise of several interesting predictions. First, two surfaces covered by aligned nanotubes can adhere when bringing into a pressureless contact. Second, the aligned multiwalled nanotube rafts exhibit a detachment work that declines with the contacting pressure. Third, in contrast to the Amonton’s law, the frictional force would decline as the normal pressure increases.

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Yang, D. Y., and J. S. Ryoo. "An Investigation into the Relationship between Torque and Load in Ring Rolling." Journal of Engineering for Industry 109, no. 3 (August 1, 1987): 190–96. http://dx.doi.org/10.1115/1.3187117.

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In the ring-rolling process most of the required forming energy is transferred from the roll into the deforming region by the aid of friction between the roll surface and the ring. In this paper a concept of “equivalent” coefficient of friction (μeq) is proposed, which is the ratio of frictional force of the driven roll to pressing load of the pressure roll. Considering the ring geometry and the related kinematics, the relationship between equivalent coefficient of friction and process parameters is derived. The upper-bound torque is also found based on the geometrical simplifications, and the roll of μeq for the upper-bound solution is investigated. The effects of various process parameters on equivalent coefficient of friction in ring rolling are then discussed.

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Laghrouche, Salah, Fayez Shakil Ahmed, and Adeel Mehmood. "Pressure and Friction Observer-Based Backstepping Control for a VGT Pneumatic Actuator." IEEE Transactions on Control Systems Technology 22, no. 2 (March 2014): 456–67. http://dx.doi.org/10.1109/tcst.2013.2258466.

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Lei, Gaoyang, Guiyun Xu, Xiaoguang Zhang, and Baolai Tian. "Study on dynamic characteristics and compensation of wire rope tension based on oil pressure sensor." Advances in Mechanical Engineering 11, no. 3 (March 2019): 168781401983602. http://dx.doi.org/10.1177/1687814019836024.

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The oil pressure sensors are installed on the hydraulic connection device to monitor the tension of wire ropes. The change of acceleration during the operation process of hoist causes the tension change of each wire rope. It leads to impact on the cylinder of hydraulic connection device, enlarges the pressure loss, and makes the non-linear friction become more complex which affects the monitoring accuracy. In this article, the mathematical model of hydraulic connection device is established. To analyze the dynamic characteristics of the hydraulic connection system, the model of single hydraulic cylinder and hydraulic connection device is established and simulated by AMESim software. Then, the friction and pressure compensation in the working process of hydraulic connecting device are obtained by LuGre friction model and corresponding formulas of pressure loss. Finally, the monitoring system is designed and real-time compensation test is carried out. The results show that the compensation improves the accuracy of the real-time measurement system of wire rope tension.

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Wiercigroch, M., V. W. T. Sin, and Z. F. K. Liew. "Non-reversible dry friction oscillator: Design and measurements." Proceedings of the Institution of Mechanical Engineers, Part C: Journal of Mechanical Engineering Science 213, no. 5 (May 1, 1999): 527–34. http://dx.doi.org/10.1243/0954406991522752.

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A Coulomb oscillator with a variable normal force has been designed and manufactured to carry out a wide range of experimental dynamic analysis, especially the study of the non-reversibility of dry friction characteristics. The design choice was based on the criteria of accuracy of the mathematical model and flexibility in terms of parameter changes such as the natural frequency of the system, coefficient of friction and normal force. The system consists of a block mass attached to two coil springs and a dry frictional damper in which the friction force is varied by a pneumatic actuator. This allows a constant pressure between sliding surfaces to be maintained. The experimental set-up, the calibration procedure for the clamping device and typical results are presented. Experimental non-reversible dry friction characteristics are discussed.

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Nauman, Malik Muhammad, Muhammad Sameer, Murtuza Mehdi, Asif Iqbal, and Zulfikre Esa. "Heat Transfer and Pressure Drop in Wavy-Walled Tubes: A Parameter-BASED CFD Study." Fluids 5, no. 4 (November 9, 2020): 202. http://dx.doi.org/10.3390/fluids5040202.

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Co-relations of friction factor and Nusselt number for plain tubes have been widely developed, but less analysis has been done for tubes with wavy surfaces. This paper uses the Computational Fluid Dynamics (CFD) tool for the analysis of heat transfer and pressure drop in wavy-walled tubes, which can be utilized as a heating element for fluids. An investigation was done for the effect of Reynolds number (Re) and wavy-walled tube geometry on friction factor and Nusselt number of laminar and turbulent flow inside wavy-walled tubes. The numerical results and experimental comparison indicate that heat transfer and pressure drop for water are significantly affected by wavy-walled tube parameters and flow Reynolds number. These wavy-walled tubes are capable of increasing the heat transfer to or from a fluid by an order of magnitude but at an expense of higher pumping power. This ratio was found to remain at the minimum at a wave factor of 0.83 for 34 < Re < 3500 and maximum at a wave factor of 0.15 for 200 < Re < 17,000. New correlations of friction factor and Nusselt number based on wavy-walled tube parameters are proposed in this paper, which can serve as design equations for predicting the friction factor and heat transfer in wavy-walled tubes under a laminar and turbulent regime with less than 10% error. The quantitative simulation results match the experimental results with less than 15% error. The qualitative comparison with the experiments indicates that the simulations are well capable of accurately predicting the circulation zones within the bulgy part of the tubes.

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Yang, Yong Jie, Xian Xian Lin, and Dong Hua Lv. "Design of Monitoring and Controlling Software of Footwear Sole Friction Based on QT." Advanced Materials Research 424-425 (January 2012): 1347–51. http://dx.doi.org/10.4028/www.scientific.net/amr.424-425.1347.

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Slip resistance of footwear sole affects the comfort and safety of shoes directly, and slip resistance is mainly expressed by the coefficient of friction. Within a certain range, the greater the coefficient of friction, the better the slip resistance. In order to determine the safety performance of shoes, the system will obtain the coefficient of friction by measuring the tension and pressure put on shoes, so it’s very important to do the measurement precisely. Based on QT development environment and Monitoring-controlling System of footwear sole friction, the software will execute real-time receiving, processing, controlling, displaying, drawing and saving collected data of tension and pressure via serial communication and finally on the basis of the system test to verify the correctness of the software and measurement accuracy

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Wassink, Dirk B., Viesturs G. Lenss, Joel A. Levitt, and Kenneth C. Ludema. "Physically Based Modeling of Reciprocating Lip Seal Friction." Journal of Tribology 123, no. 2 (February 29, 2000): 404–12. http://dx.doi.org/10.1115/1.1310370.

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Lip seal friction under constant speed sliding is modeled as the sum of three physically based components: (1) viscous shear loss in the lubricant; (2) hysteresis losses due to roughness-imposed deformation of the seal material, and (3) hysteresis losses due to deformation caused by varying intermolecular forces at the sliding interface. Increasingly thick hydrodynamic films progressively reduce contributions of the roughness and intermolecular components. Peaks in friction expected from these two components are smaller, occurring at lower sliding speed, than in “dry” rubber friction. Model simulations capture friction trends with temperature, hydraulic pressure, seal material, lubricant viscosity and shaft roughness.

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Alexandrov, S. "Comparison of Double-Shearing and Coaxial Models for Pressure-Dependent Plastic Flow at Frictional Boundaries." Journal of Applied Mechanics 70, no. 2 (March 1, 2003): 212–19. http://dx.doi.org/10.1115/1.1532319.

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The qualitative difference in solution behavior in the vicinity of maximum friction surfaces is demonstrated for two distinct models of pressure-dependent plasticity (the double-shearing and coaxial models) using closed-form solutions for planar flow through an infinite wedge-shaped channel and plane-strain compression of an infinite block between parallel plates. Singular velocity fields (some components of the strain rate tensor approach infinity at the friction surface) occur in the solutions based on the double-shearing model. This is similar to behavior in the vicinity of maximum friction surfaces in classical plasticity of pressure-independent materials. A singular velocity field is also obtained in the solution based on the coaxial model for the problem of channel flow; but, in contrast to the double-shearing model and classical plasticity, sticking must occur at this friction surface. For the problem of compression of a material obeying the coaxial model, no solution based on conventional assumptions exists with the maximum friction law. This is quite different from both the corresponding solution based on the double-shearing model and the channel flow solution based on the coaxial model.

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Hara, Yutaka, Naoki Horita, Shigeo Yoshida, Hiromichi Akimoto, and Takahiro Sumi. "Numerical Analysis of Effects of Arms with Different Cross-Sections on Straight-Bladed Vertical Axis Wind Turbine." Energies 12, no. 11 (June 1, 2019): 2106. http://dx.doi.org/10.3390/en12112106.

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Most vertical axis wind turbines (VAWTs) need arms connecting the blades with the rotational axis. The arms increase the power loss of VAWTs; however, the distribution between the pressure and friction influences and their degrees of influence have not yet been investigated in detail in past research. We applied computational fluid dynamics (CFD) targeting a small-sized straight-bladed VAWT to elucidate the effects of arms on turbine performance. In the analysis, three kinds of arms with different cross-sections (NACA 0018 airfoil, 18% rectangular, circular) with the same height were added to an armless rotor. The tangential forces and resistance torques caused by the added arms were recalculated by dividing the pressure and friction influences based on the surface pressure and friction distributions obtained by the CFD on an arm or a blade. The pressure-based tangential force of an arm, regardless of the cross-section, had a tendency to increase near the connection part between the arm and a blade. Though the value was small, the friction on the rectangular arm generated a driving force, whereas the friction on the other arms generated resistance forces. The pressure-based tangential force of a blade increased for a wide region around the connection part. The friction-based tangential force of a blade dropped around the connection part of every arm-equipped rotor. The arm resistance torque added to a VAWT by the existence of arms was larger than the added blade resistance torque in the cases of rectangular and circular arm rotors. Conversely, in the case of the airfoil arm rotor, the resistance torque added to blades became larger than that of arms.

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Lee, Keng-Lin, Riccardo Artoni, Fu-Ling Yang, and Patrick Richard. "Analytical nonlocal model for shear localization in wall-bounded dense granular flow." EPJ Web of Conferences 249 (2021): 03022. http://dx.doi.org/10.1051/epjconf/202124903022.

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This work employs a Landau-Ginzburg-type nonlocal rheology model to account for shear localization in a wall-bounded dense granular flow. The configuration is a 3D shear cell in which the bottom bumpy wall moves at a constant speed, while a load pressure is applied at the top bumpy wall, with flat but frictional lateral walls. At a fixed pressure, shear zones transit from the top to the bottom when increasing lateral wall friction coefficient. With a quasi-2D model simplification, asymptotic solutions for fluidization order parameters near the top and bottom boundaries are sought separately. Both solutions are the Airy function in terms of a depth coordinate scaled by a characteristic length which measures the width of the corresponding shear zone. The theoretical predictions for the shear zone widths against lateral wall friction coefficient and load pressure agree well with data extracted from particle-based simulation for the flow.

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Muraki, M., K. Tagawa, H. Ide, and T. Nakamura. "Frictional Behaviour of Lubricants during Deep Drawing and Ironing Processes for Zinc-Coated Steel Sheets." Proceedings of the Institution of Mechanical Engineers, Part J: Journal of Engineering Tribology 210, no. 3 (September 1996): 189–97. http://dx.doi.org/10.1243/pime_proc_1996_210_498_02.

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Frictional behaviour of lubricants during the deep drawing and the ironing processes was studied for two types of zinc-coated steel sheets at low speeds. Deep drawability of galvannealed steel sheet (GA) was significantly improved by an increase in viscosity as well as by addition of the friction modifiers, which was due to reduction in frictional forces in the flange zone and around the die radius. In contrast to the results in the drawing test, the frictional characteristics in the ironing test were little affected by the viscosity because the ironing process was primarily performed in the boundary lubrication regime. As to workpiece materials, a double-layer steel (GAE) coated with an electrogalvanized iron-rich alloy layer on the surface of GA was superior to GA in terms of deep drawability due to the lower contact ratio based on high hardness of the top coating layer and probably due to a low coefficient of friction in the boundary contact area. When compared with the effects of the friction modifiers, active sulphur EP (extreme pressure) additive showed the most significant effect on formability and the lowest friction in the ironing process. On the other hand calcium sulphonate raised formability in the deep drawing, but was ineffective for reducing friction in the ironing process.

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Zhang, Jing, Ke Shi Zhang, Yan Ke Shi, and Hui Juan Hu. "Analysis on Force of Pressure Head during ECAP Based on Simulation." Advanced Materials Research 181-182 (January 2011): 299–304. http://dx.doi.org/10.4028/www.scientific.net/amr.181-182.299.

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The main effect factors about force of pressure head (FPH) are investigated by numerical simulation for the process of equal-channel angular pressing (ECAP). The influence of extrusion mould design parameters which including corner angler ( ) and corner radius (R), friction condition between mould’s inner wall and multi specimen in the mould, different last location of pressure head and extrusion specimen etc on force of pressure head, are analyzed and discussed by numerical simulation.

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42

Topczewska, Katarzyna. "Thermal Stresses Due to Frictional Heating with Time-Dependent Specific Power of Friction." Acta Mechanica et Automatica 11, no. 4 (December 1, 2017): 280–84. http://dx.doi.org/10.1515/ama-2017-0043.

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AbstractIn this paper influence of temporal profile of the specific friction power (i.e. the product of the coefficient of friction, sliding velocity and contact pressure) on thermal stresses in a friction element during braking was investigated. Spatio-temporal distributions of thermal stresses were analytically determined for a subsurface layer of the friction element, based on the model of thermal bending of a thick plate with unfixed edges (Timoshenko and Goodier, 1970). To conduct calculations, the fields of dimensionless temperature were used. These fields were received in the article (Topczewska, 2017) as solutions to a one-dimensional boundary-value problem of heat conduction for a semi-space heated on its outer surface by fictional heat flux with three, different time profiles of the friction power.

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Kong, Xiang Zhen, and Fa Ye Zang. "Pressure Pulsation System in Electro-Hydraulic Control Valve of Engineering Mechanical." Advanced Materials Research 418-420 (December 2011): 1800–1803. http://dx.doi.org/10.4028/www.scientific.net/amr.418-420.1800.

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In order to overcome steady-state error and low-velocity scrawl problems caused by friction in electro-hydraulic control system of engineering mechanical, method for overcoming nonlinear friction force of pressure pulsation system is adopted in this study. A new pressure pulsation system is proposed, mathematical model of the pressure pulsation system is established, based on the MATLAB fuzzy control strategy and simulation. The results show good dynamic performance of the system.

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Krykhtin, Yu, and V. Karlov. "TO THE COMPARISON OF TWO METHODS OF MANUFACTURING NEW DRY FRICTION PRODUCTS." IZVESTIA VOLGOGRAD STATE TECHNICAL UNIVERSITY, no. 3(238) (April 21, 2020): 34–37. http://dx.doi.org/10.35211/1990-5297-2020-3-238-34-37.

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The technological indicators of manufacturing methods and the physicotechnical and tribotechnical properties of new dry friction friction products made of friction powder materials based on Fe , two different methods, are used: separate pressing and sintering under pressure and dynamic hot pressing. Approximate dependencies of effect of porosity of friction materials on their tribotechnical properties are obtained.

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45

Wang, Wei. "Analysis on the Side Leakage Amount of the Friction between Piston and Cylinder Block in Axial Piston Pump." Applied Mechanics and Materials 635-637 (September 2014): 341–45. http://dx.doi.org/10.4028/www.scientific.net/amm.635-637.341.

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The spherical distribution pairs of the plunger and the cylinder friction, has an important influence on the performance of spherical port plate axial piston pump. Based on the analysis of fluid viscosity change with pressure and temperature, considering friction differential pressure flow and shear flow, establishes the mathematics model of the friction pair of leakage. The simulation analysis using MATLAB software, the leakage flow rate is not proportional to pressure, but with the increase of pressure leakage flow was increased, and with the increase of pressure viscosity coefficient and temperature coefficient of viscosity, the leakage flow rate correction coefficient increases obviously, so in the choice of the hydraulic oil cylinder hole, should choose a relatively moving average leakage rate had no effect the piston ring slot.

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Setiawan, Irwan, Nurrohman ., and Hablinur Al Kindi. "ANALISA PRESSURE DROP DENGAN PENAMBAHAN ZAT ADITIF CAIRAN COOLANT PADA PIPA SILINDER MENGGUNAKAN METODE EMPIRIS DAN METODE EKSPERIMEN." AME (Aplikasi Mekanika dan Energi): Jurnal Ilmiah Teknik Mesin 4, no. 1 (January 1, 2018): 1. http://dx.doi.org/10.32832/ame.v4i1.985.

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The flow of fluid through the pipe creates fluid friction with pipe walls causing pressure drop and fluid flow velocity affecting the use of energy to drain it. Pressure drop can be affected by several factors such as friction or friction factor, pipe length, pipe diameter and fluid velocity. In this research, it will analyze pressure drop on piping system based on friction, fluid flow characteristics, and fluid velocity. The analysis was done by using two methods, namely experimental method and empirical calculation method. The stages of this study consist of problem analysis, literature study, calibration, data retrieval, empirical data processing and experiments, validation, analysis of results and conclusions. Based on the results of empirical and experimental research, the lowest pressure drop in the experiment and empirical was the 12 LPM discharge copper pipe and the water coolant ratio is 0: 100. This means that the best material pipes used were copper pipes rather than steel and galvanized pipes. The results of the tests and experiments have been tested for validation. The validation value of empirical and experimental data measurement is 91%.

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Zhang, Man, Liangping Xia, Suihu Dang, Lifang Shi, Axiu Cao, and Chunlei Du. "Self-powered flexible pressure sensors based on nanopatterned polymer films." Sensor Review 40, no. 6 (October 19, 2020): 629–35. http://dx.doi.org/10.1108/sr-01-2020-0010.

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Purpose The pressure sensors can convert external pressure or mechanical deformation into electrical power and signal, which cannot only detect pressure or strain changes but also harvest energy as a self-powered sensor. This study aims to develop a self-powered flexible pressure sensor based on regular nanopatterned polymer films. Design/methodology/approach In this paper, the self-powered flexible pressure sensor is mainly composed of two nanopatterned polymer films and one conductive electrode layer between them, which is a sandwich structure. The regular nanostructures increase the film roughness and contact area to enhance the friction effect. To enhance the performance of the pressure sensor, different nanostructures on soft polymer sensitive layers are fabricated using UV nanoimprint lithography to generate more triboelectric charges. Findings Finally, the self-powered flexible pressure sensor is prepared, which consists of sub-200 nm resolution regular nanostructures on the surface of the elastic layer and an indium tin oxide electrode thin film. By converting the friction mechanical energy into electrical power, a maximum power of 423.8 mW/m2 and the sensitivity of 0.8 V/kPa at a frequency of 5 Hz are obtained, which proves the excellent sensing performance of the sensor. Originality/value The acquired electrical power and pressure signal by the sensor would be processed in the signal process circuit, which is capable of immediately and sustainably driving the highly integrated self-powered sensor system. Results of the experiments show that this new pressure sensor is a potential method for personal pressure monitoring, featured as being wearable, cost-effective, non-invasive and user-friendly.

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Qiu, Bingjing, Jiyun Zhao, and Jiaxiang Man. "Comparative study of materials for friction pairs in a new high water-based hydraulic motor with low speed and high pressure." Industrial Lubrication and Tribology 71, no. 1 (January 14, 2019): 164–72. http://dx.doi.org/10.1108/ilt-01-2018-0006.

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Purpose Aiming at improving the mechanical efficiency, the applicability and the working life of high water-based hydraulic motor (HWBHM) under working conditions at low speed and high pressure, the friction performance of different matching materials for piston slipper – crankshaft pair with high water-based hydraulic fluid (HWBHF) under working conditions at low speed and high pressure – were studied. Design/methodology/approach The friction experiments for different materials (316L, 316L with surface coating OVINO – tetrahedral amorphous carbon [TAC; 316L-TAC] – 316L with surface coating OVINO-graphite intercalated compound [GIC; 316L-GIC] and polyetheretherketone [PEEK] reinforced with 30 per cent carbon fiber [PEEK-30CF]) under HWBHF lubrication were implemented on a pin-disk friction abrasion machine to determine the variations of coefficient of friction (CoF) and wear rate for each matching materials. In addition, the roughness and the morphology of worn surface of different matching materials were quantitatively characterized. Findings The study revealed that material combinations have different friction performances. Test results showed that the abrasion of matching type stainless steel (SS) and SS is rather serious, and the method of surface coating could improve the friction performance of SS when friction with other materials. For matching type of SS with surface treatment (SS-ST) and SS-ST, 316L-GIC and 316L-GIC have relatively stable CoF, and the wear rate was smaller than other matching materials, while 316L-TAC and 316L-TAC has the smaller CoF than that of 316L-GIC. Matching materials 316L-GIC with PEEK-30CF of matching type SS-ST and PEEK-30CF has more stable COF and better wear resistance than those of other matching materials. Originality/value This research has laid a foundation for the improvement of service life and working efficiency of friction pair in HWBHM under working conditions at low speed and high pressure.

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Ramezani, Sepehr, and Keivan Baghestan. "Observer-based nonlinear precise control of pneumatic servo systems." Proceedings of the Institution of Mechanical Engineers, Part E: Journal of Process Mechanical Engineering 233, no. 2 (February 12, 2018): 165–76. http://dx.doi.org/10.1177/0954408918756906.

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Pneumatic systems are used in a wide range of industrial robotic and automation systems due to their interesting properties. However, air compressibility, friction, and the other nonlinear characteristics of a servo pneumatic system are difficulties, which contribute to use modern controllers. Conventional linear controllers face steady-state error and uncertainty. Nonlinear modeling with model-based control is a good choice to deal with this problem. In this paper, behavior equation of flow and pressure, friction, and other nonlinear factors are studied. Afterward to reach precise position tracking and low steady error, sliding mode control is proposed. In this way, measurement of pressures and other states of system is required. To reduce the cost of using pressure sensor, observation of pressure with nonlinear high gain observer is suggested. It was seen that the new proposed approach solved the observability problem of servo pneumatic systems. Pressure signal of each sides of cylinder are observed simultaneously by measurement of piston position. Finally, stability of designed controller is studied in the presence of observed states. Experimental results validate the advantage of using designed controller-observer instead of conventional proportional–integral–derivative controller with different input signals in the presence of high friction actuator.

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Wu, Ke, Ming Yue Ma, and Dong Xue Hao. "Study on Grouting Pressure of Splitting Grouting Based on Cylindrical Expansion Considering Large Strain." Advanced Materials Research 378-379 (October 2011): 288–91. http://dx.doi.org/10.4028/www.scientific.net/amr.378-379.288.

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Anti-seepage reinforcement technology of splitting grouting to improve the stability of dam, has been an effective reinforcement method in the field of dam reinforcement. Based on the extended SMP criterion and stress-dilatancy relation considering large strain, the governing equations of axisymmetric problem in the plane strain condition and the partial differential equations for the boundary-value problem of cavity expansion in frictional cohesive soils were established. Then, the early phase of splitting grouting is regarded as the plane strain question of cylindrical expansion infinite soil. Under initial grouting pressure, the soil body was supposed as ideal elastic mass. However, the soil body was supposed to generate plastic damage considering large strain with the increase of grouting pressure and submit the extended spatial mobilization plane theory. Solutions of radial and hoop stresses and strains around the grouting cavity were obtained by recursive computations. Furthermore, the influence of damage softening parameter, cohesion and friction angle was examined by a parametric study.

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Journal articles on the topic 'Pressure-based friction'

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