TY - BOOK

T1 - Crossings – Deformation, Damage and Optimization

AU - Wiedorn, Julian

N1 - no embargo

PY - 2020

Y1 - 2020

N2 - In this thesis an explicit finite element model for the impact of a wheel on a nose of a railway crossing is introduced. The crucial parameters that describe the dynamic response (contact forces and pressures) of the impact of the wheel on the crossing nose are used to develop a simplified model. This includes (a) geometrical parameters described by the geometry of the crossing and wheel, such as impact angles (movement of the wheel due to the wing rail and crossing nose) and rail radii but also (b) dynamical parameters, such as the velocity of the wheel. First the influence of those parameters is evaluated performing a parametric study. The simplified model and its results provide a fast way to calculate the dynamic forces and stresses for geometry evaluation and optimization. Including plastic material behavior the deformation of three crossing nose materials (manganese steel, chromium-bainitic steel and tool steel) is predicted. By applying a damage parameter the deformed crossings are then compared and the influence of different axle loads, velocities and wheel types is evaluated. Furthermore, the positive effect of changing the geometry of higher strength steel crossings is discussed. To investigate the severe deformation of manganese steel crossings, explosion-depth hardened manganese crossings are modelled using measured geometries and hardness measurements of crossings in track. Additionally, the observed ability of manganese steel crossings to withstand unfavorable load situations is calculated.

AB - In this thesis an explicit finite element model for the impact of a wheel on a nose of a railway crossing is introduced. The crucial parameters that describe the dynamic response (contact forces and pressures) of the impact of the wheel on the crossing nose are used to develop a simplified model. This includes (a) geometrical parameters described by the geometry of the crossing and wheel, such as impact angles (movement of the wheel due to the wing rail and crossing nose) and rail radii but also (b) dynamical parameters, such as the velocity of the wheel. First the influence of those parameters is evaluated performing a parametric study. The simplified model and its results provide a fast way to calculate the dynamic forces and stresses for geometry evaluation and optimization. Including plastic material behavior the deformation of three crossing nose materials (manganese steel, chromium-bainitic steel and tool steel) is predicted. By applying a damage parameter the deformed crossings are then compared and the influence of different axle loads, velocities and wheel types is evaluated. Furthermore, the positive effect of changing the geometry of higher strength steel crossings is discussed. To investigate the severe deformation of manganese steel crossings, explosion-depth hardened manganese crossings are modelled using measured geometries and hardness measurements of crossings in track. Additionally, the observed ability of manganese steel crossings to withstand unfavorable load situations is calculated.

KW - crossing nose

KW - railway

KW - crossing

KW - contact mechanics

KW - damage

KW - deformation

KW - optimization

KW - numeric methods

KW - finite elements

KW - finite element method

KW - cyclic load

KW - plasticity

KW - plastic deformation

KW - cyclic deformation

KW - herzstück

KW - eisenbahn

KW - weiche

KW - kontaktmechanik

KW - schädigung

KW - verformung

KW - optimierung

KW - numerik

KW - numerische methoden

KW - finite elemente

KW - finite elemente methode

KW - zyklische belastung

KW - plastizität

KW - plastische verformung

KW - zyklische verformung

M3 - Doctoral Thesis

ER -