Investigation of Third Body Phenomenon in Model Braking Using Infrared Camera

Abstract

During the braking process there are several phenomena that influence whole process in many ways. One of them is existence of the intermediate layer called third body, which exists between connecting surfaces of the friction pair. The third body phenomenon is very hard to classify, describe, and what is most important, to see. Most obvious and visible sign of the third body existence is debris left after friction. Using standard camera or naked eye it is not possible to observe any particles during braking process due to their small size (dust like) and high temperature. However it was performed by the use of thermal camera, which can record particles’ heat signatures and made possible their observation during braking process. All of the tests and investigations were made using inertial type test stand designed for friction material testing in repeatable conditions. Two sets of data were obtained as the results of the study. One set from electrical measurements of the braking torque, braking force and rotational speed. Second one was recorded film using the infrared camera. When compared together, it was clearly seen that emission of the particles occurred during braking process can be linked with the braking torque behaviour. The novelty of the proposed method is to use of the infrared camera in the observations of the existence and amount of the third body phenomenon. Infrared based investigations base on the assumption that particles (and gases) are emitted from the friction area and intensity of the emission is linked with the braking torque changes. In the authors’ opinion connection between thermal observation and braking torque measurement proves influence of the third body on the braking torque in friction interaction (braking).