Following 1 second the boundary condition of angular displacement is activated (shown in Fig. 4) in the model and as a result the wheel starts rotating. As the rail can move freely in Z direction – and no other boundary condition influence the Z direction moving as a consequence of friction- assuming rolling the rail displacement is equal to the circumferential displacement of the wheel. In order to check the above the absolute displacements of the contacting elements were studied and the obtained result is shown in Fig.8.
Fig. 8 Absolute displacement of the contacting elements
It can be seen that the circumferential displacement is equal to the Z directional displacement of the rail. The contact status in time 1st and 6th seconds were studied in order to make sure weather the sticking zone is maintained during the rotational displacement and the results are summarized in Tab. 3. The figures in Tab. 3 show the contact status on the rail surface.
It can be seen from the results obtained that due to the acting friction between the wheel and the rail pure rolling can be observed.
The contact range traveling was also examined and the result is shown in Fig. 9. It can be seen in the figure that the stress value remained about constant compared to the results shown in Fig. 5. However the curve shapes showed some distortion in the direction opposite to the travel direction.
1st second 6th second Tab. 3. Change of contacting status affected by the angular rotation
Fig. 9. Traveling of contact region due to the rotational displacement
Conclusion
From the results obtained can be seen that the developed finite element model is suitable for restricted examination of the wheel-rail connection of a starting railway carriage. The results obtained show well those trends, phenomena taking place between the wheel and rail affected by friction. Later on the results may be made more accurate by refining the mesh however it increases the calculation time in a great extent. Introducing further boundary conditions the model can be made suitable for more detailed examination of contact connection in case of partial slipping.
Acknowledgement:
The work reported in the paper has been developed in the framework of the project „Talent care and cultivation in the scientific workshops of BME" project. This project is supported by the grant TÁMOP - 4.2.2.B-10/1--2010-0009REFERENCES
Books:[1] Muttnyánszky Á.: Szilárdságtan. Budapest: Műszaki Könyvkiadó 1981. Journals:[2]
Kazinczy L. Dr.: A kerék-sín között fellépő Hertz-féle érintkezési feszültség vizsgálata közúti vasúti felépítmények esetében, Műszaki Szemle 9-10, 12-16. 2000.
Rail Wheel rim
Proceedings of the PhD Workshop –
organized George Oláh PhD School
in the framework of TÁMOP-4.2.2/B-10/1-2010-0009 May 17, 2012
The George Oláh PhD School is named after Nobel laurate George Oláh a former student and fellow of the present Faculty of Chemical Engineering and Biotechnology. The School is entitled to provide PhD degrees (25-30 degrees annually) in the disciplines Chemical Science, Chemical Engineering, Bioengineering and Environmental Engineering. While the publication requirements are among the highest within Hungary compared to the PhD schools at related scientific disciplines, the success rate for the students is above 60%, showing the quality of the students and also their tutors. The multidisciplinary character of the School helps in developing cooperations internally, but also at the international level, resulting in several joint degrees with other universities (France, Netherlands). In accordance with the international trends the importance of computer modeling is increasing not only in chemical engineering but also in chemistry and in biology related sciences, and the six projects launched within the framework of TAMOP -4.2.2/B-10/1-2010-0009. are well integrated parts of the PhD School’s activity.
2. Description of the projects launched within the framework of TAMOP -4.2.2/B-10/1-2010-0009
1./ Methodological Development of highly efficient computing
For the description of the molecular systems, solid phases and chemical (including biochemical) reactions highly accurate ab initio and density functional methods need further improvement. Not only the development of new algorythms is aimed, but the computational implementation of the results and testing is of importance. Among ab initio methods the development of multireference description of the wavefunction is of increasing importance (Mihály Kállay). The use of this computer-intensive methodology highly requires supercomputing capacities. It is unavoidable for the accurate description of certain systems – such as biradicaloid molecules, homolytical chemical reactions or photochemical processes. At the field of density functional theory the development of meta-GGA functionals (Gábor Csonka in cooperation with John Perdew) should be mentioned. A practically important investigation is the testing the usefulness of applying GPU-s for the calculations.
2./ Modeling of enzyme reactions and other biological systems. The proper description of the thermodynamics and kinetics of the enzyme reactions is of key importance for the understanding of biochemical processes. To gain this knowledge is not merely of scientific interest, but with a detailed knowledge of the mechanism the enzymatic reactivity can be modified. By speeding up (or slowing down) enzymatic reactions biochemical cycles can be fine-tuned, resulting in possible medical applications. Bioinformatics can also be highly useful, by investigating the similarities of the proteins of related species. The following enzyme systems are in the focus of our interest: The cytochrome P450 family of enzymes, are investigated by Julianna Oláh, and the ammonia-liases by László Poppe. The detailed investigation of the dUTP-ases is an important project in the group of Beáta Vértessy, while
- and -glucanazes are targeted by Ákos Sveiczer. The transketolase enzymatic reaction is investigated by László Nyulászi. In many cases the work facilitates cooperation between the above research groups, which are themselves specified either in the experimental or the computational approaches.
efficiency, or development of environmentally benign procedures) of the reactions, by selecting the most proper conditions (temperature, pressure, solvent etc.). Computational studies coupled by experimental investigations provide very important results in this aspect.
Both in the fields of organic, inorganic and organometallic chemistry computed results (reaction energy, activation barrier, simulated spectral data of products and intermediates) being in good agreement with experimental result should be used as to verify the results.
Organometallic, supramolecular, cycloaddition and organocatalytic and photochemical reactions are planned to investigate in this part of the project.
4./ Modelling new and unusually bound compounds and interactions for chemical and materials science applications. Computational modelling allows the estimation of the stability of unusual componds under unusual circumstances. Among these structures metal halides are of great importance. These systems can be found as monomers or oligomers only at high temperatures, however, are important under these circumstances eg. in the lighting industry. Hipervalent and hypovalent compounds of main group elements (among others phosphorus and silicon compounds, but also divalent carbon compounds) are also specific targets, such compounds can be used as catalysts, as they are able to change their oxidation state. Investigation of supramolecular systems including their optical properties as well as the photophysical properties of organic and organometallic polimers and oligomers with possible applications as OFET and OLED are also of high current interest.
5./ Molecular dinamincs simulations of surfaces, interfaces and condensed crystalline structures. Apart from the investigation of isolated molecules in the gaseous phase or solution investigation of condensed phase systems and their interfaces is of current interest.
Many of these calculations uses molecular dynamics, utilising mainly molecular mechanical force field, but also quantum mechanical calculations at some ab initio (density functional) levels, using often periodic boundary conditions. These simulations can be used for crystalline systems, and nano sized materials can also be treated. At this end heterogenous catalysts can also be investigated, but modeling the shape and size of the system it is also possible to predict changes in the physical properties.
6./ Modelling Chemical Unit Operations and Processes. In chemical unit operations process flowsheeting is of increasing importance. Process flowsheeting is the use of computer aids to perform steady-state heat and mass balancing, sizing and costing calculations for a chemical process. This methodology can be used in many processes, among others in pervaporation, or in combination of different processes.
Proceedings of the presentations of the workshop held at 17. 05. 2012