A mathematical model which describes an explicit time-dependent quasistatic frictional contact problem between a deformable body and a foundation is introduced and studied, in which the contact is bilateral, the friction is modeled with Tresca’s friction law with the friction bound depending on the total slip, and the behavior of the material is described with a viscoelastic constitutive law wi...

We present experimental data for the static or breakloose friction for lubricated elastomer contacts, as a function of the time of stationary contact. Due to fluid squeeze-out from the asperity contact regions, the breakloose friction force increases continuously with the time of stationary contact. We consider three different cases: (a) PDMS rubber balls against flat smooth glass surfaces, (b)...

The objective of this PhD thesis was the study of friction in carbon nanotubes by analytical methods and molecular dynamics simulations. The goal of this research was to characterize the properties of friction in nanotubes and from a more general point of view the understanding of the microscopic origin of friction. Indeed, the relative simplicity of the system allows us to interpret more easil...

one of the great challenges in the processing of materials using equal channel angular pressing (ecap) is the high forming forces required to produce large shear deformation in the material. researchers show that the friction forces between the die and the sample constitute a great part of the total forming forces. recently, ultrasonic vibrations are successfully implemented into the ecap proce...

This paper characterizes polygons that are small-time locally controllableby stable pushing as a function of the polygon shape, the location of the center of friction, and the friction coefficient at the pushing contact. Such polygons can be pushed to follow any path arbitrarily closely, a useful property for planar manipulation. Because the pushes are stable, pushing plans can be executed with...

An investigation was carried out to understand the effects of solidification time of the cylindrical specimen on hardness, wear rate and the coefficient of friction of Aluminium alloy (LM4). The commercially available LM4 Aluminium alloy was melted in a crucible furnace under argon atmosphere. The molten metal was poured into sand moulds having dissimilar size holes. The cast rods were tested f...

A model reference adaptive controller (MRAC) for compensating friction and payload uncertainties in a servopneumatic actuation system is presented in this paper. A friction model combining viscous and Coulomb friction is formulated within the framework of an adaptive controller. Due to the asymmetric nature of Coulomb friction in pneumatic piston actuators, a bi-directional Coulomb friction mod...

Background. China is the largest producer of rape oilseed in the world; however, the mechanization level of rape harvest is relatively low, because rape materials easily adhere to the cleaning screens of combine harvesters, resulting in significant cleaning losses. Previous studies have shown that bionic nonsmooth surface cleaning screens restrain the adhesion of rape materials, but the underly...

An earthquake source mechanism is described from the standpoint that the dynamic characteristics of friction play a more important role in the dislocation motion than the boundary condition does. By considering an earthquake dislocation as a slip motion in a mechanical system involving friction, which depends upon velocity during slip, a displacement time function G(t)=1-exp(-t/τ)(1+t/τ) which ...

A wet-plate clutch (Fig. 1) is a mechanical device that transmits torque from its input axis to its output axis by means of friction. The input axis of the clutch is connected to a drum, which is a hollow cylinder with grooves on the inside. A first set of friction plates (clutch plates) with external toothing that can slide in those grooves are pressed against a second set of friction plates (...