We study theoretically and numerically the kinetics of the coefficient of friction of an elastomer due to abrupt changes of sliding velocity. Numerical simulations reveal the same qualitative behavior which has been observed experimentally on different classes of materials: the coefficient of friction first jumps and then relaxes to a new stationary value. The elastomer is modeled as a simple K...

Original scientific paper In this paper, the orthogonal cutting force model is proposed comprising forces due to flank wear in addition to the forces for chip formation during the hard turning of round bar made of steel 60WCrV7 hardened at 55+2HRc. Cutting force model includes two tool conditions: perfectly sharp tool with VBB = 0 and tool with maximum permissible flank wear VBBmax. Based on cu...

The frictional behaviors of fullerenes C60 and C70 were studied because they were speculated to be solid lubricants. For the sublimated pure C60 films on Si(001), a high friction coefficient (0.55–0.8) was observed under different loads and pin materials. For the C70 film, the friction coefficient showed a pin dependence, which changed from 0.5 with an Al2O3 pin to about 0.9 with a 440 stainles...

Some results of the influence of y radiation on the mechanical properties of PoIymethylmethacrylate are presented. Doses of 0, 50, 100, 150 and 200 kGy were employed. The internal friction (loss tangent) and storage shear modulus were measured at temperatures between 173 K and 300 K using a damped torsion pendulum. Compressive tests were made at room temperature with strain rates between 1 . 4 ...

superplastic forming (spf) is a manufacturing process utilized in the automotive industry to produce complex geometry aluminum or magnesium alloy components which cannot be fabricated at room temperature. this paper investigates the effects of the die entry radius and the interfacial friction coefficient on the required forming time and thickness distribution of a superplastic formed part. a co...

the incremental sheet metal forming (ismf) process is a new and flexible method that is well suited for small batch production or prototyping. this paper studies the use of the finite element method in the incremental forming process of aa1050 sheets to investigate the influence of tool diameter, vertical step size, and friction coefficient on forming force, spring-back, and thickness distribut...

Internal friction of deformed oriented NaCl single crystals has been measured as a function of flow stress, strain amplitude, frequency, temperature and divalent doping. In pure NaCl af er deformation a maximum of internal friction PI is observed at low temperatures. With increasing 1+ Sr doping a second but much weaker peak P2 appears at higher temperatures. The dependencies of PI on the...

Solid particles on the floor, both dry and wet, are common but their effects on the friction on the floor were seldom discussed in the literature. In this study, friction measurements were conducted to test the effects of particle size of solid contaminants on the friction coefficient on the floor under footwear, floor, and surface conditions. The results supported the hypothesis that particle ...

In this paper, we study the interfacial friction of water at graphitic interfaces with various topologies, water between planar graphene sheets, inside and outside carbon nanotubes, with the goal to disentangle confinement and curvature effects on friction. We show that the friction coefficient exhibits a strong curvature dependence; while friction is independent of confinement for the graphene...

An outstanding challenge in protein folding is understanding the origin of "internal friction" in folding dynamics, experimentally identified from the dependence of folding rates on solvent viscosity. A possible origin suggested by simulation is the crossing of local torsion barriers. However, it was unclear why internal friction varied from protein to protein or for different folding barriers ...