In the optimization of wear resistance of automotive brake pads, the braking temperature as a result of contact surface of the disc and the pads of a friction brake during its operation has significant impact on brake performance. An interaction between a brake disc and brake pads of automobile brake is characterized by a number of dry contact phenomena; these phenomena are influenced by brake operation conditions (applied pressure, speed and brake interface temperature) and material characteristics of friction couple at a given time. The temperature measurement techniques, which are always available under laboratory test conditions at different radial distance enable obtaining relatively accurate values of temperature at the friction surface using thermo couples. However, measuring the sliding surface temperature at different radial distance during the entire lifetime of the brake pads is very necessary due to the demanding operating conditions of the brakes. Therefore, an appropriate mathematical model was developed in order to enable estimate of the sliding surface temperature between the brake disc and brake pads throughout the entire duration of brake application. This is achieve by infinite element method using the results of the of temperature measurement at different radial and axial distance within the brake pad and its processing, by means of an originally developed mathematical model which aided the analysis of results and validation of the mathematical model. The finite element analysis is simplified by utilizing the inherent symmetry of disc brake and applying symmetric boundary conditions. The finite element analysis results presented herein illustrate that the brake pads temperature varies at different radial distance. While making comparison of temperature at different radial distance of the pad and disc ,the maximum and minimum values and the difference between them were: pad highest surface temperature was 8800C and the lowest surface temperature value was 700°C, the difference of temperature was 130°C. Considering the wearing rate in radial and axial distance when the rate of wear rises most in radial direction, the temperature occurring on the surface and the temperature difference between two surfaces also rises. At a time of 1.5 to 2.5 sec maximum heat was generated and the temperature of pad and disc rises. Above 2.5 however, convection heat lost set in, this is as a result of nature trying to obey Newton?s law of cooling which reduced the temperature in the interval 2.5 to 4 sec. Disc surface temperature in the radial interval 75-85 mm, where the disc is exposed to air flow is relatively low. But in the interval 85-105 mm, where the disc is in contact with friction linings, the temperature increased because in the case of uniform pressure distribution, heat generation grows in the radial distance. It was finally observed that if the thickness of the pad is reduced due to excessive wear, influence of heat into the pad and caliper assembly increases and the risk of brake fluid vaporization will increase leading to brake temperature rise. Therefore, it was recommended that the material with low thermal conductivity for the pad and caliper components be used and to build a test rig for real braking system to study the heat dissipation experimentally so that the analysis result obtained from finite element method can be validated.
Modeling, Automobile, Brake Pad, Braking Temperature, Wear
Ogbeide S. O., Ph.D , ANWULE LIBERTY "MODELLING OF AUTOMOBILE BRAKE PAD WEAR" Iconic Research And Engineering Journals Volume 3 Issue 4 2019 Page 227-239
Ogbeide S. O., Ph.D , ANWULE LIBERTY "MODELLING OF AUTOMOBILE BRAKE PAD WEAR" Iconic Research And Engineering Journals, 3(4)