Pure rolling

The impingement of one body on another is characterized by the short duration of the contact. However, even a single such contact can result in detectable removal of material, as described by Bowden and Tabor [10] for a hard metal hammer striking orthogonally a single time against a softer nail. The wear process in such case involves adhesive transfer of metal during contact. 

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Gravity die cast ZA alloy test plates and 99.99% pure rolled zinc samples were exposed at a waste water treatment plant in Detroit, Michigan, USA. The results after one year are summarised in Table 4.38 . 

A conventional optical test rig is shown in Fig. 2 [13]. A superfinished steel ball is loaded against the flat surface of a float-glass disk. Both surfaces can be independently driven. Nominally a pure rolling is used as shown in Fig. 2 that the disk is driven by a shaft and the ball is driven by the disk. 

The time dependent phenomenon also can be seen in Fig. 31. The static him of decane added with 3 % palimitic acid (Curve A in Fig. 31) starts at 5 nm and then subsides by about 2.5 nm for nearly 15 minutes, and it returns to 5 nm and keeps constant for more than two hours. But when the system starts pure rolling at a speed of 3.12 mm/s as shown in Fig. 31 (Curve B), the him keeps the increasing tendency... 

In the experiments of pure rolling cases, Guangteng [51], Ehret [52], Felix [53] reported that the surface feature of a defect deformed prior to entering the high-pressure region... 

In Felix s experiments conducted on the surfaces prepared with arrayed defects and in lubricated contact [54], the dependence of deformation on the slide-to-roll ratio was also observed, but in a more complex mode, as presented in Fig. 24. In pure rolling, the defects deform and entrap lubricant underneath during their passage through the inlet zone. For the same reason as discussed above in single defect case, the... 

Cheng [13] reported that for nearly pure rolling (U = U2) there was no significant thermal effect on either the pressure level or the film thickness, but for cases involving moderate or high slip the temperature... 

Pure rolling Wheel on rail Cam on rolling follower Ring on ring (same diameters)... 

It is clearly seen from equation (21) that when slide-roll ratio equatls zero, the pressure gradiant will always be zero through out the whole contact zone. This means that the lubrication equation is not suitable for pure rolling condition. Perhaps the case is caused by neglecting the higher order terms of perturbation e u2+--- 6bc,. But... 

There has been considerable progress in the development of theoretical solutions to the elastohydrodynamic lubrication point contact problem in recent years, yet such solutions have been restricted to pure rolling or rolling together with some sliding in the direction of lubricant entrainment. In the present paper we examine the role of spinning motion upon the lubrication of a notional point contact formed between two ellipsoids lubricated by either isovlscous or plezovlscous fluids. 

Nonholonomic constraints occur in mechanics for example when pure rolling of two surfaces is modeled, see [RS88]. In practice pure rolling is an idealization, if creepage effects can be neglected. 

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