A Study on the Contact Pressure and Thermo-Elastic Behavior of a Brake Disc-Pad by Infrared Images and Finite Element Analysis

Abstract

Featured Application: Design and performance evaluation of disc/pad; drum/shoe; friction clutches, etc.Abstract: To understand the tribological characteristics of a frictional brake system, it is very important to measure the contact pressure between the brake disc and pads. But until now there have been no direct methods by which to measure the contact pressure. In this study, an attempt to indirectly estimate the contact pressure is proposed. Infrared thermal images and finite element analysis were used as tools. For the thermo-elastic finite element analysis, uniform, linear, quadratic, and quartic heat flux profiles in the radial direction were applied on the disc surface. Thermal and stress fields were obtained under various conditions in the disc fixing holes and on the contact faces of the two half discs. From the numerical results, it was found that the effect of the boundary conditions on the magnitude of thermal stress was about 10%. Numerical temperature data in the radial direction could be curve-fitted to functions with the same order as the heat flux profiles. The coefficients of correlation of the curve-fittings were more than 0.91. It could be concluded that using temperature profiles obtained with an infrared camera, contact pressure distributions on the disc surface could be inferred.2 of 12 discs, the mounting seat and bolts were not included. More realistic 3-dimensional transient heat problems have been conducted using finite element analysis. One of the main merits of finite element analysis is that it can easily reflect non-linear physical or/and mechanical properties in simulation. investigate the influence of temperature dependent properties such as friction coefficient, thermal conduction coefficient, and specific heat on the temperatures and wear of brake discs. Their numerical results showed that fluctuating properties had an effect on the temperature fields and wear in the disc.Computer enhancement has allowed researchers to deal with coupled thermo-mechanical problems. Belhocine and Bouchetara [8] first obtained heat convection coefficients on every surface of the disc by air flow analysis, then performed a thermo-mechanical coupled analysis for full and ventilated brake discs. The maximum temperature on the ventilated disc surface was higher by 60 • C at 100 km/h. Hwang and Wu [9] applied a multi-body technique and a thermo-mechanical coupled model. According to their results, there were fluctuations in temperatures and stresses in the disc. Jian and Shui [10] also performed a thermo-mechanical coupled simulation for a disc/pad unit and compared their numerical and experimental results. They showed that the two results were in good agreement, and temperatures on the disc surface fluctuated during braking. Yan et al.[11] simulated turbulent flow on a ventilated disc with cross-drilled holes using finite element analysis. The cross-drilled holes provided 15-17% higher cooling capacity. Yan et al. [12] showed that X-type cooling vanes were more efficient than conventional radial vanes...

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