Effect of convective cooling on temperature and thermal stresses in disk during repeated intermittent braking

Initial Selection of Disc Brake Pads Material based on the Temperature Mode

“…The numerical solution of the system of equations of HDFW (1)-(32) was obtained using the finite element method adapted in COMSOL Multiphysics ® software [33]. To create the mesh of the brake, 8520 higher-order finite elements (quadratic Lagrange hexahedral elements) were used, including 1320 in the area occupied by the pad p  and 7200 elements in the area of the brake disc [34]. The value of the heat transfer coefficient was assumed to be equal 21 60 Wm K h   , which is fully justified for short-term braking of a motor vehicle [28].…”

“…A computer simulation of frictional heating of the disc brake components during the single vehicle braking with the mass m = 1524.3 kg from the initial velocity V 0 = 100 km h −1 (27.78 m s −1 ) to standstill was performed. The pad and the disc dimensions were R p = R d = 113.5 mm, r p = 76.5 mm, r d = 66 mm, δ d = 5.5 mm, δ p = 10 mm and θ 0 = 32.25 • [34]. The value of the heat transfer coefficient was assumed to be equal h = 60 W m −2 K −1 , which is fully justified for short-term braking of a motor vehicle [28].…”

Maximum temperature of the disc during repeated braking applications

“…After the moment of stop, acceleration to initial value V 0 takes place (t cn = 10 s). That cycle is repeated 10 times with the distinction that after the final 10th braking, acceleration and the following motion with the velocity V 0 last t c10 = 300 s. The schematic diagram of the considered process was adapted from the article by Adamowicz 4 and is shown in Figure 2.…”

“…4 Verification of the presented modelling of the frictional heating process is also the finite element analysis of temperature field of the ventilated brake disc proposed in the article by Yevtushenko et al, 12 where, it was shown that at each out of nine braking cycles, the temperature from numerical calculations using heat partition coefficient and constant operating parameters corresponded with the experimental data from the article by Ginsburg et al 13 All the outcomes from this study, shown in Figures 3-9, are denoted with solid lines, whereas curves marked in dashed lines are taken from the article by Adamowicz. 4 According to equation (1), contact pressure has a known exponential time profile for each out of 10 braking applications, whereas velocity has been found from the solution of the boundary value of the heat conduction problem and the initial value problem for the motion equation. The schematic diagram of changes in the velocity of the vehicle V is shown in Figure 2.…”

“…As can be seen, the dependence of velocity and temperature has a one-sided nature, which means that the influence of temperature on velocity is not taken into account. 3,4 In the other approach, it is assumed that the coefficient of friction changes with respect to time, and this relationship is mutual. Then, the initial value problem for the equation of motion and heat conduction problem require to be solved simultaneously.…”