Contact area and pressure

The shape of the contact area between the tyre and the pavement surface varies depending on the applied load and the internal tyre pressure. Lister and Nunn (1968) found that, by keeping the internal tyre pressure PJj constant and equal to the pressure recommended by the manufacturer, the shape of the contact area is almost cyclic when the applied load (P) is approximately 1/3 of the maximum allowable (P ) by the manufacturer. 

Similarly, by keeping the load constant to 1/3 of the maximum allowable and decreasing the tyre pressure below the typical value recommended by the manufacturer, the shape changes to approximately elliptical. 

Because of the great variability in load and tyre pressure, even for a given type of tyre, and for simplicity reasons, the representative contact area is assumed to be circular. 

the radius of the contact area is determined from the following equation  

The load distribution in this cyclic area is affected by the actual tyre load (P)/maximum permissible load (P ) ratio. When this ratio is lower than 1, the load distribution is parabolic, and when it is equal to 1, the distribution is uniform. 

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Kimizuka M., Kurosawa H., and Fukubayashi T. 1980. Load-bearing pattern of the ankle joint. Contact area and pressure distribution. Arch. Orthop. Trauma Surg. 96 45-49. 

Pereira D.S., Koval K.J., Resnick R.B., et al. 1996. Tibiotalar contact area and pressure distribution the effect of mortise widening and syndesmosis fixation. Foot Ankle 17 269. 

Morimoto Y, Ferretti M, Ekdahl M et al (2009) Tibiofemoral joint contact area and pressure after single- and double-bundle anterior cruciate ligament reconstruction. Arthroscopy 25 62-69... 

H. Yoshida, A. Faust, J. Wilckens, M. Kitagawa, J. Fetto, Edmund Y. -S. Chao, Three-dimensional dynamic hip contact area and pressure distribution during daily activities. Journal of Biomechanics, 2005, 39, 1996-2004. 

In a draw-out MCC all current-carrying components should be periodically checked for their silver-plating, proper contact area, spring pressure and tightness of joints (this procedure can follow the manufacturer s maintenance schedule) or at least during the six-monthly or yearly maintenance check ups of the busbars and the busbar joints as noted above. The contacts or their springs may be replaced when the contacts are worn out or... 

These considerations of contact efficiency and pressure drop in relation to bubbles in fluidization points to an area of endeavor where bubbles are absent. 

It is shown in Eq. (2.69) that the maximum pressure p0 occurs at the center of the contact area and is given by... 

Qualitatively, since the contact area increases linearly with applied pressure, the effective pressure is constant for a given pad. Soft, compliant pads have a larger contact area and lower effective pressure whereas hard, stiff pads have a smaller contact area and higher effective pressure. Thus soft pads push abrasive particles against the wafer over a larger area but with less force than hard pads do. 

Fig. 13.15), so as to resemble the surface of a latex particle. The two rubber cylinders, A and B, were mounted vertically, one above the other. The upper cylinder was held fixed during the experiment whereas the position of the lower cylinder could be moved up and down by a micrometer drive unit (D). Moving the cylinder A up towards B, after polymer had been adsorbed onto the poly(methyl methacrylate) surfaces, distorted the soft, elastic surfaces in the centi region, resulting in flat discs in the zone of interaction. The distance of separation between the surfaces was measured by multiple beam interferometry. The applied pressure caused an equilibrium contact area to be formed, the magnitude of which could also be determined interferometrically. The relationship between contact area and the equilibrium pressure was established by direct calibration. In this fashion, the equilibrium pressure could be measured for a given distance of separation. 

Miyanaga Y., Fukubayashi T., and Kurosawa H. 1984. Contact study of the hip joint load deformation pattern, contact area, and contact pressure. Arch. Orth. Trauma Surg. 103 13-17. 

If the interface reaction is the rate-controlling mechanism, in which the solid phase is dissolved into the liquid phase through reaction, the rate of mass transport is proportional to the contact area and the increased activity of the solid phase at the contact region due to the capillary pressure, which is given by... 

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