Analysis of Railway Track Stiffness Variation and Its Influence
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Date
2015-10
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AAU
Abstract
Railway track stiffness is a basic parameter of track design which influences the bearing capacity
and the dynamic behavior of passing vehicles. In particular, track geometry quality and the life
of track components. The stiffness definition must include inelastic and non-linear behavior of
the supper structure and substructure elements as well as the existence of the stiffness under
dynamic load. In most case track stiffness is a function of track superstructure and substructure
material properties.
In this paper the influence of track component stiffness variation by using time and frequency
domain of FEM (ABAQUS software) analyzed and discussed on the results observed. The
Modeling analysis of track stiffness variation depends on the track component (rail-pads, sleeper,
ballast and subgrade) stiffness variation and the Results for each track component stiffness
variations. Interactive forces, track component displacements, Velocities and acceleration were
presented. The analysis consider the influence of rail-pad stiffness, ballast stiffness, sleeper
spacing, train speed and subgrade material on track structures. During operation and moving of
the freight trains falling of small particles over the ballast layer causes an increase of stiffness in
the layer of ballast and gradual deterioration of ballast effect on size of ballast grade and forming
powder due to friction exists between stones rubbing together, which reduce the stiffness of
ballast.
Using the software ABAQUS found that, decrease in sleeper spacing and increases in ballast
young’s modulus, ballast depth, sub grade young’s modulus and rail moment of inertia increases
the track stiffness at all. In general, relatively high track stiffness is beneficial as it provides
sufficient track resistance to applied loads and results in decreased track deflection, which
reduces track deterioration. On the other hand, very high track stiffness leads to increased
dynamic forces in the wheel rail interfaces as well as on the sleepers and ballast which can cause
wear and fatigue of track components.
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Keywords
Vertical track stiffness, Rail bending stress, dynamic explicit, acceleration, sinusoidal load, stress, BOEF (Beam on Elastic Foundation)