Center for Railway Engineering

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Browsing Center for Railway Engineering by Subject "A.A. LRT"

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    Thermal and Mechanical Analysis of A.A. LRT Brake Disc from Composite Material by FEM
    (Addis Ababa University, 2015-04) Fitsum, Getaneh; Demis, Alemu (PhD)
    The modeling of thermal and mechanical effects during braking has become increasingly important in product design in different transport means, road vehicles, airplanes, railway vehicles, and so forth. The thermal and mechanical analysis is a very important stage in the study of braking systems, especially of railway vehicles where it is necessary to brake huge masses because the thermal load of a braked railway disc prevails compared to other types of loads. In the braking phase, kinetic energy transforms into thermal energy resulting in intense heating and high temperature states of railway discs. Thus induced thermal loads determine thermo-mechanical behavior of the structure of railway discs. In cases of thermal overloads, which mainly occur as a result of long term braking on down grade railroads and braking to standstill on a flat railroad, the generation of stresses and deformations occurs whose consequences are the appearance of cracks on the discs, brake judder, thermo-elastic instability and finally brake disc failure. The importance to precisely determine the temperature distribution caused by the transfer process of the heat generated during braking due to the friction on contact surfaces of the braking system makes it a challenging research task. Therefore, analytical and numerical modeling of thermal and mechanical analysis during long term braking for maintaining a constant speed and braking to standstill afterwards on a down grade railroad and braking to a standstill on a flat track is processed in detail in this research. Even though brake disc is commonly made from cast iron, an attempt has been made to investigate the suitable composite material which is lighter than cast iron and has good young’s modulus, yield strength and density properties. Aluminum base metal matrix composite has a promising friction and wear behavior when used as a disc brake. Brake disc made from SiC/6061Al alloy composite material is used and an investigation is made on thermal and mechanical loads analysis for Addis Ababa LRT EW route brake applications. Consequently the result revealed that SiC/6061Al alloy composite material can effectively enhance the thermal and mechanical performance of the brake disc.