Measuring of Core Split Line Defect on Pillar Type Vented Brake Disc and Investigation of Crack Occurrence Potential on the Disc Caused by Its Geometric Deviation

Abstract

In this study, a measuring method was defined to convert the level of defects on the pillar type ventedbrake disc to numeric data where the defects were formed due to missing material in the structure of thedisc. Subsequently, the geometric defects which are existing in the core on the droplets were examinedwith the defined method in only pillar type vented brake disc. Finally, some thermal performance tests(brake disc thermal fatigue test on bench in accordance with Society of Automotive Engineers BrakeRotor Thermal Cracking Procedure for Vehicles (SAE J2928) [1] and brake disc crack test on vehicle;special test procedure of an original equipment manufacturer, which is performed for inspectingstructural strength) and thermal fatigue test with thermal shock (test procedure formed by authors) wereperformed with defected brake discs to evaluate the risk of defected brake disc usage on the vehicle interms of safety. The main open point is to determine whether the defect can transform to crack byinfluencing with notch effect during the worst usage conditions. In the conducted tests; it wasinvestigated that the worst core split line defects which are specified by the defined measuring flow maycause a crack formation by proceeding notch effect under the worst usage condition. In order to simulatethe worst usage condition; test laboratories, equipment and test track were used in this period forperforming brake disc thermal fatigue test, crack test with thermal shock and crack test on vehicle.