The dimensionless boundary problem that describes the axisymmetric temperature field in the friction pair of the multidisc brake under nonstationary friction with account for the thermal characteristics of the materials, as well as the design and performance parameters of the discs, has been developed. Using the multidisc brake of the wheel tractor as an example, the application of the boundary problem to the numerical study of regularities of the formation of temperature field in the rubbing discs has been shown. It has been found that the error of calculating the temperature in the friction pair for the braking period does not exceed 10% of the point estimate of the mathematical expectation of its experimental value; during the whole period of friction, the calculated values of the temperature have been within the confidence interval for the mathematical expectation of the measured temperature. Under the conditions of the friction of the discs that simulate service brakings of the wheel tractor, for the frictional pairs of the multidisc brake, it has been found that the maximum temperature of the friction contact of the discs nonlinearly depends on the time and this dependence has the maximum. At the stage of decreasing temperature of the friction contact of the discs, the position of the temperature maximum in the friction pair shifts from the friction surface to the bulk of the steel disc. At the stage of elevating temperature of the friction surface, the fraction of the power of frictional heat generation that enters the steel disc is an inverse nonlinear function of the time; at the stage of decreasing temperature of the friction contact of the discs, it is equal to zero. Multifactorial functional dependences of the maximum temperature of the tribocontact of the friction pairs of the multidisc brake with the linings made of various frictional materials on values of the main performance parameters have been obtained. The temperature increment of the friction contact of discs is directly proportional to the maximum power of friction; it is a direct nonlinear function of the duration of friction and an inverse nonlinear function of the coefficients of heat exchange of the discs with the environment. It has been found that the replacement of the material of the lining of the composite disc from the frictional material based on cellulose fibers to the composite frictional material with the polymer binder leads to a decrease in the maximum temperature increment in the tribocontact of the friction pairs by 1.041.14 times; when the frictional material based on cellulose fibers is replaced by the metal-ceramic frictional material, the maximum temperature increment decreases by 1.531.94 times.
Studying thermal state of friction pairs of multidisc brake
Journal of Friction and Wear ; 34 , 6 ; 421-428
2013
8 Seiten, 4 Bilder, 2 Tabellen, 17 Quellen
Article (Journal)
English
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