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Today, the most brake systems used on vehicles are the disc brakes. During the braking process, the large amount of frictional heat is generated on the contact surfaces of disc brakes. In order to ensure the safety of the drivers and the traffic participants, the optimal performance of brake system of the vehicles under the different working conditions should be ensured. Therefore, it can be considered that the brake system an essential element in the vehicle. Practical experiences showed that the most important factor that affects performance of the brake system is the excessive heat that generated during the braking process. Therefore, it's necessary to pay high attention on the air cooling of the brake system. This is one of the reasons why the ventilated discs are used, besides that their usage provides the reduction of the inertial masses which meaning less cost. In order to provide a good cooling, it's necessary to find the optimal vanes shape to increase the degree of air cooling as much as possible. The aim of this research paper is to analyse the air flow through four different ventilated brake discs; each one has the shape of vane. Comparisons were made between the results of the selected models of the ventilated brake discs. The results presented the air flow currents through the disc, as well as the turbulences that occurred during the air flow around vanes. [ABSTRACT FROM AUTHOR]

The paper gives a numerical procedure for determining the reliability, based on known theoretical models for distribution of the working stress and the corresponding mechanical properties of materials. The procedure is based on one of the transformed forms of the general equations for the analytical determination of reliability. Along with a presentation of the method, a detailed explanation is given of the algorithm that the created computer program is based on. The verification procedure is performed as an example for a combination of normal distributions of the working and the critical stresses. At the end of the paper is presented a discussion on impact of each of the factors that influence the accuracy of solutions of the considered method. [ABSTRACT FROM AUTHOR]

In the introductory part, the history development is presented, and it points out the importance of using the Fault Tree Analysis - FTA method for analysis of the reliability and safety of technical systems. By analyzing a number of references related to the FTA method, the FTA methodology is established, and explanation of some steps by this method is given in this paper. As an example of the practical application of methods, the failure of the solar concentrators is analyzed. For the failure analysis of the considered device, it is necessary to know the structure, functioning, working conditions and all factors that have a greater or less influence on its reliability. Along with an explanation of certain parts of the fault tree, the estimation of the significance of certain events is done, and it is considered to be able to eliminate causes of failure or to minimize the consequences of failure. [ABSTRACT FROM AUTHOR]