Transient Tire Slip Losses Using the Brush Theory
Tire slip losses have been shown to have a significant impact on vehicle performance in terms of energy efficiency, thus requiring accurate studies. In this paper, the transient dissipation mechanisms connected to the presence of micro-sliding phenomena occurring at the tire–road interface are investigated analytically. The influence of a two-dimensional velocity field inside the contact patch is also considered in light of the new brush theory recently developed by the authors. Theoretical results align with findings already known from literature but suggest that the camber and turn spins contribute differently to the slip losses and should be regarded as separate entities when the camber angle is sufficiently large. The present work shows that an additional amount of power which relates to the initial sliding conditions is generated or lost during the unsteady-state maneuvers. A simple example is presented to illustrate the discrepancy between the microscopic and macroscopic approaches during a transient maneuver.ABSTRACT
Tire reference frame with angular velocities.
Transient distribution of the shear stresses, micro-sliding velocity and power density losses inside the contact patch for three different values of the nondimensional traveled distance
= 1/4, 1/2, and 1, respectively. The power is only dissipated in the sliding zone, and the transient extinguishes as soon as the traveled distance equals the position of the steady-state breakaway point.
Trend of the power slip losses against the nondimensional traveled distance
= s/(2a). The two terms Pσ and (1/2)
contribute differently to the total dissipation Ps. In particular, −Pσ produces an effective energy loss as the tire keeps rolling, while (1/2) introduces extra energy which is used to reach the current deformed configuration.
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