Developing a New Vibration Analysis Calculative Method for Esfahan Subway Train and Railways Design, Manufacturing and Construction
The simulated mass and spring evaluation for subway or railways construction and installation have wide applications in rail industries. This kind of design should be optimize all related parameters to reduce the amount of vibration in cities, residential areas, historical zones and other critical locations. Finite element method used too much to analyze such applications with an excellent accuracy but developing some simple, fast and user friendly evaluation always was required in subway industry. In addition, process parameter optimization required in railways to achieve optimal railways design with maximum safety, reliability and performance. The simple but useful simulated mass and spring evaluation system developed for Esfahan subway construction. This method discussed in this paper. Esfahan subway construction has a historical zone. Historical buildings should protect from harmful vibrations. Polyurethane layer used to reduce vibrations. This layer completely covered by concrete layers in all directions. It is worthy to know that, all the operation criteria like displacement and stress could be adapted with all vibration criteria like natural frequency, operation frequency and damping. Adaptation performed by changing in polyurethane layer thickness. The results showed that if 25-millimeter thickness polyurethane layer covered completely by two concrete layers with 12 millimeter thickness, the amounts of vibrations reduce considerably. In addition, it strongly recommended increasing the polyurethane layer up to 37 millimeter in historical zone to prevent potential harmful effects. The results confirmed by other commercial methods. The calculative method successfully performed. Furthermore, it is important to reduce maintenance costs in any potential design. The process parameter like rail ways dimension, rail ways material, cabins loading, cabins quality, cabins dimension and polyurethane layer thickness properly designed to keep the subway natural frequency around 18 Hz ( less than allowable 20 Hz). Numerical design results will protect all historical buildings, palaces paintings and old bridges in future subway operation times. In addition, some interesting patent and innovation in rail industry like Suspension mass tuned vibration reducer, short sleeper vibration-attenuation fastener and airtight track vibration noise reducing fastener discussed in this paper.
Finite elements method in analysis of propagation of vibrations wave in the soil
Nowadays, many residential buildings are built in areas close to railway and tram lines. Therefore, there is a necessity to find a method that allows taking into account in the process of building design influences of the vibration caused by passing trains and trams. This article presents analysis of propagation of vibration wave excited by the movement of trams in the soil on which is planned to build multi-storey residential building. To determine the amplitude of vibration the Finite Element Method (FEM) model was used. The FEM model which was used during the analysis takes into account variable heterogeneous mechanical properties of the soil. The analysis uses the results of measurements of vibration acceleration amplitudes done by employees of the Department of Robotics and Mechatronics AGH during the works on government research project 4875/B/TO2/2010/38 and the results of drilling carried out to identify the composition of the soil at the planned place of foundation building. The developed method allows determining the wave vibration in the ground without necessity to perform complex measurements of soil vibration. The proposed method can be successfully applied in the preparation of project documentation for public buildings and reduces the costs of preliminary analysis of the influence of the traffic on the dynamic properties of the newly designed facility.
High-frequency vertical wheel-rail contact forces-Validation of a prediction model by field testing
Abstract The computer program DIFF, which is being developed at CHARMEC since the late 1980s, is used to simulate vertical vehicle–track interaction at high frequencies, from about 20 Hz to at least 2000 Hz. Measured results from two field test campaigns are used to validate the vehicle–track interaction model. The first test case involves impact loads from a wheel flat, while the other case studies the influence of a corrugated rail on dynamic vertical wheel–rail contact forces. Four vehicle models and two visco-elastic track models are compared. The track models are calibrated versus test data from laboratory and field tests. Input data on rail and wheel roughness are taken from field measurements. Good agreement between calculated and measured vertical contact forces is observed, both with respect to magnitude and frequency content, for most frequencies below 2000 Hz. The best agreement is obtained when using a vehicle model that accounts for both wheelsets in a bogie, instead of using a single wheelset model.