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Visar resultat 1 - 5 av 52 avhandlingar som matchar ovanstående sökkriterier.

1. 1. Continuous Welded Railway Rails: Residual Stress Analyses, Fatigue Assessments and Experiments

   Författare :Anders Skyttebol; Chalmers tekniska högskola; []
   Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; microstructure; laser cladding; plasticity; rolling contact; computational welding mechanics; materials testing; flash butt welding; fatigue; railway rails; fatigue crack propagation; finite element method;

   Sammanfattning : Railway rails are today often continuously welded. This type of joint generally requires less maintenance than is needed for the bolted joints. It has also reduced wheel damage and made the ride more comfortable. However, these joints are subject to damage. LÄS MER

3. 2. Rolling Contact Fatigue of Railway Rails with Emphasis on Crack Initiation

   Författare :Jonas Ringsberg; Chalmers tekniska högskola; []
   Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; variable amplitude; crack closure; rolling contact fatigue; crack propagation; railway rails; damage accumulation; critical plane approach; crack initiation; plasticity; multiaxial fatigue;

   Sammanfattning : Increased traffic density and the heavier axle loads of modern trains have led to severe problems with rolling contact fatigue (RCF) which cause initiation of surface cracks in railheads. In this thesis, a specific type of surface crack, the head check, is studied numerically with emphasis on fatigue crack initiation. LÄS MER

4. 3. Degradation of railway rails from a materials point of view

   Författare :Martin Schilke; Chalmers tekniska högskola; []
   Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; Anisotropy; White etching layer; Rail grade; Rolling contact fatigue; Three dimensions; Plastically deformed layer; Railway Rail; Crack;

   Sammanfattning : From time to time railway rails need to be replaced. In that case and when new track is built, a decision has to be made about which rail grade that is going to be installed. The intention of this work was to compare different rail steels concerning their suitability from a mechanical durability perspective. LÄS MER

5. 4. Optimisation of Railway Switches and Crossings

   Författare :Björn Pålsson; Chalmers tekniska högskola; []
   Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; wheel and rail wear; railway turnout; optimisation; switch crossing; dynamic vehicle-turnout interaction;

   Sammanfattning : Methods for simulation-based optimisation of the design of railway turnouts (switches & crossings, S&C) are developed and demonstrated. Building on knowledge of dynamic wheel–rail interaction in turnouts, it is investigated how rail profile degradation can be reduced by the optimisation of geometry and component stiffness of the track superstructure. LÄS MER

7. 5. EMC in railway systems : measurements, modeling and analysis

   Författare :Stefan Niska; Luleå tekniska universitet; []
   Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; Drift och underhållsteknik; Operation and Maintenance;

   Sammanfattning : The subject of this study and resulting thesis was to investigate the electromagnetic compatibility (EMC) problems in the multi-electrical signaling circuitry along a railway track. These signaling systems have been expanding over time from buried multi-wired electrical copper cables to optical fiber cables, sometimes located parallel to the contact line in the catenaries. LÄS MER