Mechanical and Dynamic Maps of Disc Brakes under Different Operating Conditions

Abstract

The operating conditions during the braking process in an automobile affect the tribological contact between the pad and disc brake, thus, influencing the times and distances of braking and, in a more significant way, the safety of the braking process. This mathematical work aimed to provide a general visualization of the disc brake’s mechanical, dynamic, and thermal behavior under different operating conditions through 2D maps of the power dissipated, braking time, and braking distance of a disc brake with a ventilation blade N- 38 type. However, the dissipated energy on the disc brake in terms of temperature was analyzed considering Newton’s cooling law and mathematical calculations through classical theories of the dynamic and mechanical behavior of the disc brakes. For this purpose, the Response Surface Methodology (RSM) and Distance Weighted Least Squares (DWLS) fitting model considered different operating conditions of the disc brake. The results demonstrate that the disc brakes can be used effectively in severe operational requirements with a speed of 100 km/h and an ambient temperature of 27 °C, without affecting the occupant’s safety or the braking system and the pad. For the different conditions evaluated, the instantaneous temperature reaches values of 182.48 and 82.94 °C, where the high value was found for a total deceleration to 100 km/h to 0, which represent a total braking distance of around 44.20 to 114.96 m depending on the inclination angle (θ). Furthermore, the energy dissipation in the disc brakes depends strongly on the disc, blades and pad geometry, the type of material, parameters, and the vehicle operating conditions, as can be verified with mathematical calculation to validate the contribution of the effectiveness of the braking process during its real operation.

Dynamic and Stationary Testing of Vehicle Braking Systems

“…From the results achieved, it can be concluded that vehicles 1 and 4 had insufficient braking values during the stationary test due to lower braking forces measured on the cylinder brake test bench. According to García-León et al (2021) and Gurumoorthy et al (2021), insufficient values of braking forces can be caused by malfunctions of the vehicle´s brake system, such as excessive wear of brake discs and brake linings, insufficient pressure in the brake system, which is caused by air leak on the master brake cylinder. In another case, the insufficient values of braking forces can also be caused by the pollution of vehicle´s tires or the cylinders of the brake seat and, last but not least, by insufficient pressure in the tires, as stated by Senabre et al (2012b) They indicate that by changing the tire pressure, it is possible to obtain incorrect braking force results on the brake cylinder test bench, which implies that tire pressure is a determining factor in assessing the condition of the vehicle´s braking system.…”