Computational analysis via FEM of Tirefond screws used in the fastening system of railroads aiming to avoid a recurrent failure case.
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Date
2019
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Abstract
This work presents a computational evaluation of a Tirefond screw used in Brazilian railroads to
support the plate on the wood sleepers. This component has been studied because nowadays it is
manufactured by a common low carbon steel, and due to the increase of trains speed and the axle
load transported it has been failing with a short life time, causing significant economic losses to
the companies that control the Brazilian railways. In this context, static and dynamic analysis
were performed using the Finite Element Method (FEM) in order to better understand the recurrent failure causes. The obtained results highlighted the critical stress concentration points
where the component fatigue life is low, explaining the premature failures. Based on the generated information, it was possible to propose and to evaluate the effects of geometric and materials change on the Tirefond screw fatigue performance. The actual geometry was evaluated but
replacing the actual steel by a carbonitrited SAE 1015 and by a quenched and tempered SAE
4340. Geometric changes as the increase of the screw diameter and elimination of the continuous
diameter decrease as it moves away from the screw head were tested. The best solution that
guaranteed a fatigue life higher than 106 cycles for all critical positions along the screw structure
were the combination of the use of a SAE 4340 steel in a higher diameter screw and the use of a
carbonitrited SAE 1015 steel with a continuous 22 mm diameter.
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Keywords
Fatigue behavior, Finite Element Method
Citation
MOREIRA, T. M. M. et al. Computational analysis via FEM of Tirefond screws used in the fastening system of railroads aiming to avoid a recurrent failure case. Engineering Failure Analysis, v. 106, n. 104186, dez. 2019. DisponĂvel em: <https://www.sciencedirect.com/science/article/pii/S1350630718314651>. Acesso em: 10 mar. 2020.