Abstract:When designing or developing friction materials, it is crucial to predict how the modification of the formulation will affect their properties. Fibres are introduced in the composition of the phenolic-based brake friction materials to improve their mechanical strength. Apart from reinforcing the composite, fibres can also affect its tribological and thermophysical properties. In this study two composite friction materials are compared. The difference between the materials was the type of reinforcing fibre used… Show more
“…The above compositions of the mixtures have already been used in the stand tests for the 1xBg braking system. The papers [18,22] contain extended information on their material, and tribological and mechanical characteristics. The bench test on a full-scale inertia dynamometer was carried out at the Railway Institute in Warsaw (Fig.…”
Section: Experimental Studies Of Temperature Distribution In a Railwa...mentioning
confidence: 99%
“…The tread wear was observed only in the rolling contact area (wheel-rail) after repeated braking, in which the tread volume temperature reached 300°C. On the other hand, the articles [21,22] present the experimental results on a reduced and full-scale inertia dynamometer, in which organic composite friction materials (used in block systems) have been compared, that allowed to examine the influence of selected components on the properties of the composite. The test results show a significant influence of the properties of the mixture on the temperature distribution, friction coefficient and wear of the friction pair elements.…”
The article describes two numerical FEM models of frictional heating to estimate the temperature distribution in the 2xBgu friction brake of a rail vehicle during repetitive braking. The numerical tests were compared with the temperature measurements carried out on a full-scale inertia dynamometer for two different friction materials of brake blocks working in the 2xBgu system. The paper demonstrates, by comparison with experimental data, that the proposed numerical models can be used as a tool supporting engineering works to determine the temperature of friction elements of a railway block brake, also for long-lasting braking processes.
“…The above compositions of the mixtures have already been used in the stand tests for the 1xBg braking system. The papers [18,22] contain extended information on their material, and tribological and mechanical characteristics. The bench test on a full-scale inertia dynamometer was carried out at the Railway Institute in Warsaw (Fig.…”
Section: Experimental Studies Of Temperature Distribution In a Railwa...mentioning
confidence: 99%
“…The tread wear was observed only in the rolling contact area (wheel-rail) after repeated braking, in which the tread volume temperature reached 300°C. On the other hand, the articles [21,22] present the experimental results on a reduced and full-scale inertia dynamometer, in which organic composite friction materials (used in block systems) have been compared, that allowed to examine the influence of selected components on the properties of the composite. The test results show a significant influence of the properties of the mixture on the temperature distribution, friction coefficient and wear of the friction pair elements.…”
The article describes two numerical FEM models of frictional heating to estimate the temperature distribution in the 2xBgu friction brake of a rail vehicle during repetitive braking. The numerical tests were compared with the temperature measurements carried out on a full-scale inertia dynamometer for two different friction materials of brake blocks working in the 2xBgu system. The paper demonstrates, by comparison with experimental data, that the proposed numerical models can be used as a tool supporting engineering works to determine the temperature of friction elements of a railway block brake, also for long-lasting braking processes.
“…The above friction materials have already been used in the bench tests for the 1xBg braking system 20 . The papers 9 , 20 contain extended information on their material, and tribological and mechanical characteristics. Figure 1 Photographs of the organic composite brake blocks after testing: ( a ) made of Material A; ( b ) made of Material B.…”
Section: Experimental Studies Of Temperature Distribution In a Railwa...mentioning
confidence: 99%
“…That change of the friction material type, and thus also the tribological characteristics of the friction interface, created a field for further research 5 – 7 . The experimental results on a reduced and full-scale inertia dynamometer, for organic composite brake blocks were compared in the articles 8 , 9 . The studies focused on examining the influence of the selected components on the properties of the composite.…”
The article presents finite element models of the 2xBgu type tread brake for the simulation of extended repeated frictional heating carried out on a full-scale inertia dynamometer. The numerical calculations were conducted for the brake blocks made of two organic composite materials newly developed specifically for this study. The transient temperature changes obtained from the 2D axisymmetric and 3D finite element analyses and experimental data agreed well during continuous process of about 1200 s. Simulation of such a long period of braking sequence required introducing simplifications in the boundary conditions in the contact area, convection cooling, arrangement of the model (2D axisymmetric, 3D). The focus was laid on representation of variation of the coefficient of friction and the temperature dependence of the properties of the friction materials during braking. The carried out research indicates limitations in the finite element analysis and directions of necessary improvements in modelling as well as measurements with the use of embedded thermocouples.
“…The substitution of traditional cast iron shoes with composite ones aims at a considerable reduction of the noise levels produced during braking operations. One of the greatest benefits of composite shoes is that their composition can be changed by the manufacturer to obtain different mechanical, frictional, and thermal properties [11,12]. Composite brake blocks are classified into LL and K types, depending on their friction level.…”
In recent years, the interest in monitoring the operating conditions of freight wagons has grown significantly to improve the safety of railway vehicles. The railway research group of the Politecnico di Torino has been working for years on the development of solutions to effectively monitor the operating conditions of passenger and freight rail vehicles. As part of the national Cluster ITS Italy 2020 project funded by Italian ministry of education, university and research (MIUR), the Politecnico di Torino has collected a considerable amount of data thanks to the wired and wireless prototypes developed. The data obtained are used in this paper for the validation and calibration of a finite element (FE) model that simulates the temperature variation of a cast iron brake block due to braking operations of an intermodal freight wagon. The developed model can be a useful tool to predict the temperature at the wheel–shoe interface as a function of the current operating conditions since a direct measurement is not easy to perform.
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