Sökning: "squats"

Visar resultat 1 - 5 av 8 avhandlingar innehållade ordet squats.

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

    Författare :Robin Andersson; Chalmers University of Technology; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; 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

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

    Författare :Robin Andersson; Chalmers University of Technology; []
    Nyckelord :NATURVETENSKAP; TEKNIK OCH TEKNOLOGIER; NATURAL SCIENCES; 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

  3. 3. Damage and thermally induced defects in railway materials

    Författare :Casey Jessop; Chalmers University of Technology; []
    Nyckelord :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

  4. 4. Altered movement patterns and deviating muscular activity in individuals with anterior cruciate ligament injury

    Författare :Anna Trulsson; Fysioterapi; []
    Nyckelord :MEDICIN OCH HÄLSOVETENSKAP; MEDICAL AND HEALTH SCIENCES; MEDICIN OCH HÄLSOVETENSKAP; MEDICAL AND HEALTH SCIENCES; Movement pattern; Physiotherapy; Motor control; Sensorimotor control; Neuromuscular control; Anterior cruciate ligament; Muscular activity; Motor skills; Single leg squat; Electromyography EMG ; Postural orientation; Assessment; Task performance; Reproducibility of findings; Performance test; Hop test; knee; dynamic joint stability;

    Sammanfattning : The purpose of this thesis was to increase the understanding of altered movement patterns in individuals with anterior cruciate ligament (ACL) injury in order to improve ACL rehabilitation, and to develop an observational instrument termed Test for Substitution Patterns (TSP) for standardized, quantifiable scoring of altered movement patterns in legs and trunk. In all, 142 participants, 93 with ACL-rupture (37 women) and 49 uninjured participants were investigated. LÄS MER

  5. 5. Elastic-Plastic Fracture Mechanics and RCF in Rails

    Författare :Johan Tillberg; Chalmers University of Technology; []
    Nyckelord :RCF; elastic-plastic fracture mechanics; Material-forces; Multiple crack interaction;

    Sammanfattning : This thesis concerns issues regarding the modeling and numerical simulation of singularcracks and their propagation in the context of Rolling Contact Fatigue (RCF) in rails.Typically, such cracks are associated with squats and head-checks in the rail head. LÄS MER