Suiker A.S.J., Metrikine A.V. and de Borst R. |
Dynamic behavior of a layer of discrete particles - Part 1 – Analysis of body waves and eigen modes |
Journal of Sound and
Vibration 240(1), 1-18, 2001 |
Summary. The
current paper is one in a series of two, and discusses the body wave
propagation and the eigen modes for a layer of
discrete particles. This configuration is representative for a ballast layer
used in ordinary railway tracks. The discrete nature of the ballast is simulated
via an elastic 9-cell square lattice. After deriving the equations of motion
for the lattice, the long-wave approximation for the equations of motion is
compared with the equations of motion for a classic elastic continuum. This
comparison yields relations between the macroscopic continuum parameters and
the microscopic lattice parameters. Next, the dispersion curves that
characterize the eigen modes of the discrete layer
are derived. The difference between these dispersion curves and those of a continuous
layer are elucidated. Through a parametric study, the influence is shown of
the particle diameter and of the layer thickness on the dynamic response. In
an accompanying paper, the layer response to a moving, harmonically vibrating
load is analyzed, which is representative for a ballast track that is
subjected to an instantaneous train axle passage. |