Optimization of Brake Disc Profile Based on the Thermal Performance for Electric Vehicles

Abstract

The brake disc market has reached the value of USD 20.9 billion in 2021 at a CAGR of 4.9% and it is expected to grow to USD 26.5 billion by 2026. However, the difficulties associated with the brake discs are significant rise in the temperature which results in, early wear, thermal cracks and brake fade leading to uneven braking and premature replacement. In this context many researchers have been studying the parameters like brake disc material and type of ventilation. The objective of the work was to study of the effect of ventilation types on thermal responses and optimize the brake disc profile for better thermal performances. Center of gravity and dynamic load transfer were calculated for two wheeler electric vehicle experimentally which was followed by computing the force required for braking process and heat flux on the brake disc analytically. Ventilation of type cross drilled holes (CD) was adopted in brake disc modelling, and was carried out in SOLIDWORKS 2022 and finite element model for the brake disc was created in ANSYS 17.2 with mesh size of 2 mm for lamellar graphite iron (LGI) with temperature dependent material properties. The transient thermal analysis for three braking cycles were carried out with the considerations such as: initial velocity of the vehicle of 96 km/h, ambient temperature of 22°C, conduction and convection modes of heat transfer and 5 s of deceleration and acceleration time. Transient thermal analysis was carried out by applying the heat flux on the frictional surface of the brake disc. For the solid disc without ventilation, it was found that the maximum temperature at the end of first braking cycle (0 to 5 s) was 157.72°C, at end of second braking cycle (10 to 15 s) was 256.95°C and at the end of third braking cycle (20 to 25s) was 349.73°C. As the wear rate for lamellar graphite iron grows exponentially beyond 300°C, ventilations were provided on the brake disc to reduce the temperature on the disc. For the optimized brake disc with ventilation type VT-12, it was found that maximum temperature at the end of first braking cycle (0 to 5 s) was 139.43°C, at end of second braking cycle (10 to 15 s) was 222.68°C and at the end of third braking cycle (20 to 25s) was 299°C. The overall character of these shows a quick rise in temperature at the start of the process, followed by the achievement of the maximum value and, eventually there is a drop in temperature.  In this research the future work can be carried out by implementing the noise, vibration and harness studies which would benefit the industry with better braking system.