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Visar resultat 21 - 25 av 51 avhandlingar som matchar ovanstående sökkriterier.

  1. 21. Influence of rail, wheel and track geometries on wheel and rail degradation

    Författare :Kalle Karttunen; Chalmers tekniska högskola; []
    Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; track geometry; rolling contact; rail; railway; Rolling contact fatigue; maintenance; wear; wheel;

    Sammanfattning : For more efficient railway maintenance there is a need to increase the understanding of the influence of operational conditions on wheel and rail degradation. To this end, the chosen primary investigation strategy is to employ dynamic multibody simulations, where operational conditions are altered, to estimate the influence on material deterioration. LÄS MER

  3. 22. Influence of thermal loading on mechanical properties of railway wheel steels

    Författare :Krste Cvetkovski; Chalmers tekniska högskola; []
    Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; contact creep.; rolling contact fatigue; martensite tempering; shear deformation; Railway wheel steels; heat treatment; residual stress; rapid heating; low cycle fatigue;

    Sammanfattning : Material integrity and properties of wheels are critical in railway traffic, as wheels fulfil the important function of transferring load and traction from the vehicle to the rail track. Steels with a pearlitic microstructure are commonly used for wheels due to their height strength, low cost and good wear properties. LÄS MER

  4. 23. Elastic-plastic fracture mechanics - Application to rolling contact fatigue in rails

    Författare :Johan Tillberg; Chalmers tekniska högskola; []
    Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; FEM; rolling contact fatigue; railway mechanics; Elastic-plastic fracture mechanics; material forces;

    Sammanfattning : Railway structures represent complex mechanical problems involving wave propagation, plastic deformations and material degradation. The wheel-rail contact loads subject the material to repeated cycles of complex stress states resulting in rolling contact fatigue (RCF). LÄS MER

  5. 24. 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

  7. 25. Wheels, Rails and Insulated Joints - Damage and Failure Probability at High Speed and Axle Load

    Författare :Johan Sandström; Chalmers tekniska högskola; []
    Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; rail breaks; probability; railway mechanics; contact mechanics; insulated joints; defects; fatigue;

    Sammanfattning : The thesis deals with some fatigue related problems in railway mechanics related to increased axle loads and speeds. The focus is on defects and discontinuities in the wheel--rail system that affect the risk of fatigue and fracture of railway components such as wheels, rails and insulated joints. LÄS MER