Sökning: "Short cracks"

Visar resultat 16 - 20 av 54 avhandlingar innehållade orden Short cracks.

  1. 16. On dynamic crack growth in discontinuous materials

    Författare :Johan Persson; Per Gradin; Per Isaksson; Sverker Edvardsson; Pär Jonsén; Mittuniversitetet; []
    Nyckelord :;

    Sammanfattning : In this thesis work numerical procedures are developed for modeling dynamic fracture of discontinuous materials, primarily materials composed of a load-bearing network. The models are based on the Newtonian equations of motion, and does not require neither stiffness matrices nor remeshing as cracks form and grow. LÄS MER

  3. 17. 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

  4. 18. Contact fatigue and crack propagation studies of sintered PM steel

    Författare :Anders Holmberg; Åsa Kassman Rudolphi; Urban Wiklund; Johan Ahlström; Uppsala universitet; []
    Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; Tribology; PM steel; Fatigue; Crack Initiation; Crack Propagation; Material Analysis; Teknisk fysik med inriktning mot tribomaterial; Engineering Science with specialization in Tribo Materials;

    Sammanfattning : Gears made of PM steel are of interest for the automotive industry because from the press/sinter route, complex geometries can be produced to near net shape with only a few processing steps while keeping the material and energy usage at a minimum. However, the PM steels of today have significant performance limitations caused by the inherent porosity which impairs the mechanical properties by acting as stress raisers in the material. LÄS MER

  5. 19. Damage mechanics analysis of inelastic behaviour of fiber composites

    Författare :Peter Lundmark; Luleå tekniska universitet; []
    Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; Polymera konstruktionsmaterial; Polymeric Composite Materials;

    Sammanfattning : Composite laminates under service loading undergo complex combinations of thermal and mechanical loading, leading to microdamage accumulation in the plies. The first mode of damage is usually intralaminar cracking with the crack plane transverse to the laminate middle-plane, spanning the whole width of the specimen. LÄS MER

  7. 20. 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