Friction occurs in all mechanical systems,e.g. bearings, transmissions, hydraulic and pneumatic cylinders, valves, brakes and wheels. Friction appears at the physical interface between two surfaces in contact. Lubricants such as grease or oil are often used but the there may also be a dry contact between the surfaces. Friction is strongly influenced by contaminations. There is a wide range of p...

In this paper, a SDOF system with nonlinear viscous friction under harmonic excitation is studied. A nonlinear viscous friction model is built as an exponential expansion of the relative slip velocity. According to the adaptive control theory, an adaptive controller for the friction compensation of the SDOF system with nonlinear viscous friction is put forward by using the model-based parameter...

frictional shear stress is usually determined by utilizing the coefficient of friction or the constant friction factor models. the present study deals with finite element analysis of double cup extrusion process to determine the relationship between constant friction factor (m) and coefficient of friction (µ), since the metal flow in this process is very sensitive to frictional conditions. ther...

The mechanism for emergence of helical electron bunch(HEB) from an ultrarelativistic circularly polarized laser pulse propagating in near-critical density(NCD) plasma is investigated. Self-consistent three-dimensional(3D) Particle-in-Cell(PIC) simulations are performed to model all aspects of the laser plasma interaction including laser pulse evolution, electron and ion motions. At a laser inte...

Transient high altitude optical emissions referred to as “sprites” are believed to occur as a result of the transfer of large amounts of charge (∼100-300 C) from cloud altitudes of 5-10 km to the ground. Using a general subionospheric ELF propagation model, we quantitatively interpret magnetic field waveforms of ELF radio atmospherics originating in mid-western U.S. lightning discharges and obs...

This paper presents a comparative study among friction behavior of several double-acting pneumatic actuators available to industrial use. A brief review covering the manner that pneumatic actuator manufacturers and current literature approach friction force and its usual models also is presented. After depicting friction test methodology and test apparatus, the comparison work is carried out th...

Distinctly quantum friction effects of three types are surveyed: internal friction, measurement-induced friction, and quantum-fluctuation-induced friction. We demonstrate that external driving will lead to quantum internal friction, and critique the measurement-based interpretation of friction. We conclude that in general systems will experience internal and external quantum friction over and b...

The friction is detrimental to the normal work of the servo system, but the friction mechanism is very complicated. In this paper, Tustin friction model is used as the friction parameter identification, reflecting the phenomenon of friction in the system, and laying the foundation for the friction compensation. Tustin model is a nonlinear friction one, and the friction properties can be reflect...

Friction and wear become significant at small scale lengths, particularly in MEMS/NEMS. Nanopatterns are regarded as a potential approach to solve these problems. In this paper, we investigated the friction behavior of nanopatterned silicon surfaces with a periodical rectangular groove array in dry and wear-less single-asperity contact at the nanoscale using molecular dynamics simulations. The ...

The present work aims at reducing the friction of rubber soles sliding on ceramic floorings. Fitting bored cylindrical protrusions with different diameters on rubber soles was proposed. Experiments were carried out to evaluate the performance of the proposed protrusions in increasing friction coefficient at dry and contaminated floorings. It was found that, at dry sliding, friction coefficient ...