We study the dependence of friction on surface roughness, sliding velocity, and temperature. Expanding on the classic treatment of Greenwood and Williamson, we show that the fractal nature of a surface has little influence on the real area of contact and the static friction coefficient. A simple scaling argument shows that the static friction exhibits a weak anomaly mu ~ A(0)(-chi/4), where A0 ...

Analytical and numerical modeling of the nonlinear interaction of shear wave with a frictional interface is presented. The system studied is composed of two homogeneous and isotropic elastic solids, brought into frictional contact by remote normal compression. A shear wave, either time harmonic or a narrow band pulse, is incident normal to the interface and propagates through the contact. Two f...

physical properties are often required for designing post harvest handling and processing equipment for agricultural products. persimmon (khormandy cultivar) is rich in vitamin a, calcium, potassium, tannic acid and antioxidant phenolic compounds. in this study changes in the physical properties of persimmon fruit during storage were studied. properties such as fruit dimensions, mass, geometric...

– A first-principle continuum-mechanics expression for the rolling friction coefficient is obtained for the rolling motion of a viscoelastic sphere on a hard plane. It relates the friction coefficient to the viscous and elastic constants of the sphere material. The relation obtained refers to the case when the deformation of the sphere ξ is small, the velocity of the sphere V is much less than ...

Amorphous packings of frictionless, spherical particles are isostatic at jamming onset, with the number of constraints (contacts) equal to the number of degrees of freedom. Their structural and mechanical properties are controlled by the interparticle contact network. In contrast, amorphous packings of frictional particles are typically hyperstatic at jamming onset. We perform extensive numeric...

To study how macroscopic friction phenomena originate from microscopic junction laws, we introduce a general statistical framework describing the collective behavior of a large number of individual microjunctions forming a macroscopic frictional interface. Each microjunction can switch in time between two states: a pinned state characterized by a displacement-dependent force and a slipping stat...

Some physical properties of pumpkin (Cucurbita pepo L.) and watermelon (Citrullus lanatus L.) seeds were determined at a moisture content of 9.87% and 2.87% (dry basis), respectively. The mean values of length, width, thickness and geometric mean diameter were 19.92, 11.30, 3.22, 9.71 mm for pumpkin seeds, and 13.28, 8.00, 2.64, 6.52 mm for watermelon seeds, respectively. The mean 1000 seed mas...

A sphere moving down the surface of a static sphere and a simple phase diagram. Abstract A small sphere placed on the top of a big static fric-tionless sphere, slips until it leaves the surface at an angle θ l = cos −1 2/3. On the other extreme, if the surface of the big sphere has coefficient of static friction , µ s → ∞, the small sphere starts rolling and continues to do so until it leaves t...

When one rigid object (the pusher) pushes another (the slider) across a horizontal support plane, Coulomb’s law admits some surprising phenomena. First, it is possible to move the slider by moving the pusher away from the slider: pulling. Second, it is possible to obtain slip between the two objects even with an infinite coefficient of friction. Thus the common conception that infinite friction...