Rolling friction, theory

Similar to the lubricated sliding friction, rubber rollinq friction generally involves only the deformation component. Flom later found that the rolling friction theory can be extended to thermoplastics. Flom showed that the coefficient of rolling friction X can be expressed ... 

Figure 8.20. Comparison of peel theory with rolling friction results.

To satisfy the theory s assumption, it was postulated that the material be isotropic, frictional, cohesive, and compressible. Figure 2 depicts material in a press that undergoes shear deformation into a solid mass (18). In Figure 2, P = horizontal pressure between rolls, 6 = angular position of roll bite, a = nip angle. Id = roll diameter D,h = height above the roll centerline at which feed pressure Po is applied, Pra = horizontal pressure at 0 = 0, and S = roll gap. 

In theory, the oil forms in layers of globules, one layer adhering to each metal surface and any number of layers of globules in between. (See Figure 16.2.) In the illustrations, layer (1) adheres to the top surface, layer (9) in Figure 16.2(a) or layer (8) in Figure 16.2(b) adheres to the bottom surface, and the layers in between roll over each other when the bearing surfaces move. When these layers of oil roll over each other, the only friction present is... 

For dense flows at low shear rates the total solid phase kinetic and collisional pressure tensor closure derived from kinetic theory was extended by an semi-empirical frictional pressure tensor in order to consider the impact of the long term particle-particle interactions such as sliding or rolling contacts. The dispersed phase pressure was thus calculated from (4.151), closed with (4.158) and (4.155) ... 

Carter [5] developed the first theory of a onedimensional elastic contact rolling with friction in longitudinal creep, very slow rolling speed (Va) and smooth surfaces. This author experimentally and theoretically proves the coexistence of stick / slip zones in the contact, the distribution of which varies as a function of longitudinal creep. The coexistence of zones is obtained by superimposing the tangential... 

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