Sökning: "surface irregularities"

Visar resultat 1 - 5 av 24 avhandlingar innehållade orden surface irregularities.

  1. 1. Mechanical track deterioration due to lateral geometry irregularities

    Författare :Kalle Karttunen; Chalmers tekniska högskola; []
    Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; rolling contact fatigue; track maintenance; track irregularities; wear; multibody dynamics simulations; Railway track geometry;

    Sammanfattning : This thesis deals with how a degraded track geometry influences further degradation of the geometry and the formation of rolling contact fatigue (RCF) and wear of rails. The overall objective is optimisation of railway maintenance. For this, further understanding and quantification of the deterioration of track components are needed. LÄS MER

  3. 2. Surface defects in rails - Potential influence of operational parameters on squat initiation

    Författare :Robin Andersson; Chalmers tekniska högskola; []
    Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; NATURVETENSKAP; NATURAL SCIENCES; TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; RCF; squats; dynamic vehicle–track interaction; rail corrugation; Rail surface irregularities;

    Sammanfattning : Despite significant efforts throughout the last decades, the mechanisms behind the formation of squats — a form of rolling contact fatigue (RCF) damage in rails — are not fully understood. Proposed causes of initiation involve, but are not limited to, small initial rail surface irregularities which yield high contact stresses, rail corrugation and varying friction conditions. LÄS MER

  4. 3. Models of Surface Roughness with Applications in Paper Industry

    Författare :Jan-Olof Johansson; Matematisk statistik; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Statistik; actuarial mathematics; operations research; programming; Matematik; Statistics; Mathematics; estimation.; Surface roughness; parametric models; operationsanalys; programmering; aktuariematematik; Wood; pulp and paper technology; Pappers- och massateknik;

    Sammanfattning : This thesis comprises general parametric models for surface roughness. The models can be used in several technical and natural applications but are here only applied to the micro-structure of paper. In that application, earlier models are generalized and new models introduced. LÄS MER

  5. 4. Surface Engineering in Sheet Metal Forming

    Författare :Per Carlsson; Mikael Olsson; Niklas Axén; Uppsala universitet; []
    Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; Materials science; Friction; wear; metal coated steel sheet; dry lubricants; galling; PVD coatings; Materialvetenskap; Materials science; Teknisk materialvetenskap; materialvetenskap; Materials Science;

    Sammanfattning : In recent years, surface engineering techniques have been developed in order to improve the tribological performance in many industrial applications. In sheet metal forming processes, the usage of liquid lubricants can be decreased by using self lubricated tribo surfaces which will result in more environmentally friendly workshops. LÄS MER

  7. 5. Squat defects and rolling contact fatigue clusters - Numerical investigations of rail and wheel deterioration mechanisms

    Författare :Robin Andersson; Chalmers tekniska högskola; []
    Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; NATURVETENSKAP; NATURAL SCIENCES; TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; rail surface irregularities; rolling contact fatigue clusters; dynamic vehicle–track interaction; rolling contact fatigue; studs; squats; fracture mechanics;

    Sammanfattning : Squat defects, a type of localised rolling contact fatigue damage appearing on rail surfaces with rail break as an ultimate consequence, have concerned infrastructure managers for the last couple of decades. In recent years similar types of defects—so-called studs—that are visually resembling squats, have started to appear. LÄS MER