Sökning: "rails"

Visar resultat 21 - 25 av 70 avhandlingar innehållade ordet rails.

1. 21. Damage and thermally induced defects in railway materials

   Författare :Casey Jessop; Chalmers tekniska högskola; []
   Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY;

   Sammanfattning : A major concern for the railway industry today is the problem of rolling contact fatigue (RCF) damage in wheels and rails as a result of increased traffic, accelerations, and loading conditions. The wheel/rail contact condition that occurs in railway applications is complex, and it is essential to understand the associated damage from combined mechanical and thermal loadings in order to predict component life and develop appropriate maintenance systems. LÄS MER

3. 22. Crack growth paths in rolling contact fatigue — Numerical predictions

   Författare :Mohammad Salahi Nezhad; Chalmers tekniska högskola; []
   Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; Vector crack tip displacement; Crack face friction; Crack growth direction; Crack propagation; Rolling contact fatigue;

   Sammanfattning : Rolling contact fatigue (RCF) cracks in railway wheels and rails are costly and complex to deal with. Despite the extensive research efforts that have been put into understanding the mechanisms and developing appropriate predictive models for RCF crack growth, there are still a lot of open questions. LÄS MER

4. 23. Modeling of phase transformations and cyclic plasticity in pearlitic steels

   Författare :Björn Andersson; Chalmers tekniska högskola; []
   Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; Phase transformations; TRIP; Pearlitic steel; FEM; Cyclic plasticity; Homogenization;

   Sammanfattning : The low rolling resistance in railway transportation is a key factor for its high efficiency, but it comes at the price of very high contact pressure between the rail and wheel. Due to the high stresses and the large number of load cycles during railway operation, both the rail and the wheel can be susceptible to fatigue crack initiation and propagation. LÄS MER

5. 24. Wheel–Rail Impact Loads and Track Settlement in Railway Crossings

   Författare :Xin Li; Chalmers tekniska högskola; []
   Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; vehicle--track dynamics; wheel--rail contact; track settlement; material modelling of ballast; Switches and crossings; turnout; cyclic loading; Green s functions;

   Sammanfattning : Turnouts (Switches & Crossings, S&C) are critical components of a railway track requiring regular maintenance and generating high life cycle costs. A main driver for the high maintenance costs is the need to repair and replace switch rails and crossings as these components are subjected to a severe load environment. LÄS MER

7. 25. Slab track optimisation considering dynamic train–track interaction

   Författare :Emil Aggestam; Chalmers tekniska högskola; []
   Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; Modelling; Genetic algorithm; Slab track; Transition zones; Dynamic vehicle–track interaction; Optimisation; Measurement; Ballastless track;

   Sammanfattning : Slab track is a type of railway track that is frequently used e.g. in high-speed applications as an alternative to ballasted track. Slab track is also well suited on bridges and in tunnels since no ballast is required and the cross-section of tunnels can be reduced. LÄS MER