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Dynamics of Railway Track

100%

Bajer C. , Bogacz R.

Machine Dynamics Problems

2004

tom Vol. 28, No. 1

7-16

The classic and reinforced railway track is composed of two infinite rails separated from sleepers by visco-elastic pads. There are numerous assumptions leading to different simplifications in railway track modelling. The rails are modelled as infinite Timoshenko beams, sleepers by lumped masses or elastic bodies and ballast as a visco-elastic foundation. Nowadays the interest of engineers is focused on the Y-shaped sleepers. The fundamental qualitative difference between the track with classic or Y sleepers is related to local longitudinal symmetric or antymetric features of railway track. The sleeper spacing influences the periodicity of elastic foundation coefficient, mass density (rotational inertia) and shear effective rigidity. The track with classical concrete sleepers is influenced much more by rotational inertia and shear deflections than the track with Y sleepers. The increase of elastic wave velocity in track with Y sleepers and more uniform load distribution will be proved by the analysis and simulations. The analytical and numerical analysis allows us to evaluate the track properties in a range of moderate and high speed train. However, the correct approach is not simple, since the structure of the track interacts with wheels, wheelsets, boogies and vehicles, depending on the complexity of the analysis.

Vibrations due to the passage of a railway vehicle on straight and curved tracks

100%

Konowrocki R. , Bajer C.

2008

tom Vol. 23

199--204

The paper presents the results of vibration measurements on line of railway during passages of a train at a constant speed. The measurements have been performed on a railway track at straight and curve sections as well as and inside the train on the floor. The experimental results exhibited higher amplitudes of vibrations on the curve of the track than on its straight segments. The lateral slip in rail/wheel contact zone is considered as a possible reason of such a phenomenon.

Dynamics of Y-type Track

100%

Bajer C. , Bogacz R.

tom Vol. 21

93--96

General numerical description of a mass moving along a structure

100%

Dyniewicz B. , Bajer C.

tom Vol. 25

135--140

The paper deals with vibrations of structures under a moving inertial load. The space-time finite element, approach has been used for a general description of the moving mass particle. Problems occur when we perform computer simulations. In the case of wave problem numerical description of the moving inertial loads requires great mathematical care. Otherwise we get a wrong solution. There is no commercial computing packages that would enable us direct simulation of moving loads, both gravitational and inertial.

Moving inertial load and numerical modelling

100%

Bajer C. , Dyniewicz B.

2008

tom Vol. 23

65--70

The paper presents the numerical approach to the moving mass prob¬lem. We consider the string and beam discrete element carrying a mass particle. In the literature efficient computational methods can not be found. The same disadvantage can be observed in commercial codes for dynamic simulations. Classical finite element solution fails. The space-time finite element approach is the only method which now results in convergent solutions and can be successfully applied in practice. Characteristic matrices and resulting solution scheme are briefly described. Examples prove the efficiency of the approach.