This paper evaluates the fatigue life properties of low carbon grey cast iron (EN-GJL-250), which is widely used for automotive brake discs. Although several authors have examined mechanical and fatigue properties at room temperatures, there has been a lack of such data regarding brake discs operating temperatures. The tension, compression and low cycle fatigue properties were examined at room temperature (RT) and at brake discs' working temperatures: 500 degrees C, 600 degrees C and 700 degrees C. The microstructure of the material was documented and analysed. Tensile stress-strain curves, cyclic hardening/softening curves, stress-strain hysteresis loops, and fatigue life curves were obtained for all the above-mentioned temperatures. It was concluded, that Young's modulus is comparable with both tension and compression, but yield its strength and ultimate strength are approximately twice as great in compression than in tension. All the mechanical properties remained quite stable until 500 degrees C, where at 700 degrees C all deteriorated drastically. During fatigue testing, the samples endured at 500 degrees C on average at around 50% of cycles at room temperature. Similar to other materials' properties, the cycles to failure have dropped significantly at 700 degrees C. (c) 2014 Elsevier Ltd. All rights reserved.

Nowadays one of the major topics in the brake development community is the NVH (noise, vibration and harshness) problem. Although reasonably well researched in the disc brake systems, the squeal prediction in the drum brakes is often neglected, manly due to its complexity. The newly developed methodology presented in this work gives the directions on how to develop a squeal free drum brake design using some novel approaches to closely correlate the numerical results with the experimental brake tests. The goal is to make a robust drum brake design that is stable under the different noise factors and under broad operational conditions. In order to predict if a brake system will generate the squeal noise during the operation, the finite element method was used to simulate the system. By solving the complex eigenvalues of the FEM (finite element method) matrices, the presence of unstable modes was predicted. A good correlation with the SAE J2521 noise matrix dynamometer test procedure was established.

A squealing noise of 50 dB was measured on a vehicle homologation test at around 900 Hz on the existing brake drum design, mounted on the rear axle of the mid-sized passenger automobile. Therefore, analysis of eigenfrequencies of the original drum design was performed using the impact hammer test and numerical analysis. It was established that a critical mode shape 0/2 exists at around 900 Hz, exactly where the squeal noise was recorded at the brake road noise evaluation vehicle test. The analysis was carried out with the intention to eliminate the possibility of the squealing noise by increasing the critical mode above 900 Hz. The relation between different brake drum modifications parameters and the eigenfrequencies was determined and the best solution was obtained. The first eigenfrequency of the proposed drum design was increased by 58 Hz and the difference between the in-plane and out-of plane mode shape was sufficient. We can conclude that the modified drum design will riot have squeal issues at 900 Hz as there are no eigenfrequencies of the brake drum in that range and therefore the problem of the loud brake is solved.

This paper shows the thermal and stress analysis of the worn brake disc for a Taurus class locomotive. The numerical analyses are carried out under the experimental testing program, Prüfprogramm No. 5, which is adjusted for this type of locomotives by UIC CODE 541-3. The simulations results under mentioned program show the most unfavorable case of braking. The numerical analysis is done with the finite element method (FEM), using ABAQUS software.

A certain number of railway brake discs made of gray cast iron, showed the presence of small cracks only after a few thousand kilometers. To investigate main causes of a brake disc failure, numerical analysis was done by using ABAQUS software. Numerical analysis resulted from a physical model of heat flux in dependence of braking time. Physical model was applied considering all demands and presumptions given by industry representatives.

Thermal and stress analysis of disc brakes under specific loads (driving downhill and braking to a standstill) was calculated. The FEM (Finite Element Method) was used to carry out the analysis. The analysis dealt with centrifugal load for two cases of braking, braking to a standstill on a flat surface and braking downhill, maintaining constant speed and afterwards braking to a standstill. The main boundary condition in both cases was the entered heat flux on the braking sin face of the disc and the force of the brake clamps. Two different discs were used, one brand new (unused) and one with permitted wearing. (C) 2009 Journal of Mechanical Engineering. All rights reserved.