A thermodynamic model describing the phase transition of first order between structure states of lubricant material in the boundary friction regime is proposed. It is shown that lubricant melts with temperature increase or at shear of rubbing surfaces if the elastic strain (stress) exceeds the critical value. The phase diagram with domains of dry and sliding friction is constructed. The depende...

It has been shown recently that steady frictional sliding along an interface between dissimilar elastic solids with Coulomb friction acting at the interface is ill-posed for a wide range of material parameters and friction coefficients. The ill-posedness is manifest in the unstable growth of interfacial disturbances of all wavelengths, with growth rate inversely proportional to the wavelength. ...

In addition to the bulk properties of a workpiece material, characteristics of the tribofilms formed as a result of workpiece material mass transfer to the friction surface play a significant role in friction control. This is especially true in cutting of hardened materials, where it is very difficult to use liquid based lubricants. To better understand wear performance and the formation of ben...

in all engineering applications where solid surfaces slide on each other, friction plays an important role. it becomes even more important, particularly in metal forming processes where the two sliding materials are metallic. among forming processes, forging is an important process, because of improving material structure, mechanical properties and reducing production time. an inverse analysis ...

In this paper, the gear material 20CrMnTi was selected as the research object. Friction and wear behavior was performed on the M2000 friction and abrasion tester. The friction and wear mechanisms of 20CrMnTi steel were discussed under coupling of rolling and sliding. The results show that damage of steel-steel couples under coupling of rolling and sliding is caused by the interaction of mechani...

Angled polyurethane fiber arrays are modified by adding soft spherical and spatula shaped tips via dipping. These fibers are characterized for adhesion and friction and compared with unmodified fibers and flat material samples. Sphere and spatula tip fiber samples demonstrate increased adhesion, with 10 and 23 times the maximum adhesion of the unmodified fiber sample, respectively. The sphere a...

Retropatellar complications after total knee arthroplasty (TKA) such as anterior knee pain and subluxations might be related to altered patellofemoral biomechanics, in particular to trochlear design and femorotibial joint positioning. A method was developed to test femorotibial and patellofemoral joint modifications separately with 3D-rapid prototyped components for in vitro tests, but material...

Friction plays an important role in the behavior of flowing granular media. The effective friction coefficient is a description of shear strength in both slow and rapid flows of these materials. In this paper, we study the steady state effective friction coefficient μ in a granular material in two steps. First, we develop a new relationship between the steady state effective friction coefficien...

We present an active approach for discriminating different materials by impulsively contacting (hitting) them, and sensing and interpreting the resulting sounds. In theory, the angle of internal friction is diagnostic of material, but invariant over object shape. In our experiments, we observe that the angle of internal friction is not invariant over the frequency of the sound spectrum for whic...

Ring rolling is one of the most significant methods for producing rings with highly precise dimensions and superior qualities such as high strength uniformity, all accomplished without wasting any materials. In this article, we have achieved analytical formulas for calculating the pressure and shear friction over the contact arcs between the rollers and ring in the ring rolling process for the ...