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...

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...

three piece bogies are widely in use by the freight railway services throughout the world. in comparison with the other freight bogies they cost less and are easier to maintain. however, they do not exhibit favorable curving behavior. amongst the methods to improve the bogie performance is the proposal to introduce lateral clearance in the bogies’ axleboxs. in the case of the three piece bogies...

For the six-wheel CRAB rover, this paper presents the torque control with Kriging estimation to improve the terrainability by minimizing wheel slip. In previous works, we presented a torque control approach, effectively improving terrainability by minimizing the variance of the required friction coefficient based on the static model. Using a Kalman filter to estimate the velocity information, a...

There are several parameters that have significant influence in metal forming process. One of the most important of them is friction coefficient. Friction can change the pattern of metal flow and the force needed for deformation. It is necessary to determine the friction coefficient to study the effect of friction on metal forming process. This study is concerned with numerical and experimental...

in this research, an apparatus was made and utilized to determine the friction coeffi-cient of chickpea grains on steel surfaces. experiments were carried out on two black and galvanized surfaces and at four sliding velocities of 5, 20, 100 and 500 mm/min, at three moisture content of 7.5%, 15% and 21% wet basis (w.b.) and at three vertical pressure values of 14.28, 100 and 150 kpa. the followi...

Flat plate skin friction calculations over a range of Mach numbers from 0.4 to 3.5 at Reynolds numbers from 16 million to 492 million using a Navier Stokes method with advanced turbulence modeling are compared with incompressible skin friction coefficient correlations. The semi-empirical correlation theories of van Driest; Cope; Winkler and Cha; and Sommer and Short T’ are used to transform the...

polyvinyl ester green composites were synthesized with walnut shell powder (wsp) by in-situ polymerization technique. the green composites have been evaluated for mechanical properties such as tensile strength, tensile modulus and hardness. sliding wear loss, specific wear rate and coefficient of friction were investigated by using computerized pin-on–disc machine at normal applied loads of 20,...