Sökning: "growth irregularities"

Visar resultat 1 - 5 av 12 avhandlingar innehållade orden growth irregularities.

1. 1. Rail Corrugation Growth on Curves

   Författare :Peter Torstensson; Chalmers tekniska högskola; []
   Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; short-pitch rail corrugation; rotating flexible wheelset model; small radius curves; prediction of long-term roughness growth; plastic deformation; non-Hertzian and non-steady wheel‒rail contact; wear; rutting corrugation;

   Sammanfattning : The development of periodic irregularities with distinct wavelengths (corrugation) on the low rail of small radius curves is studied through mathematical modelling, numerical simulations, field measurements and laboratory investigations. One year of monitoring of roughness on the low rail of a 120 m radius curve on the metro of Stockholm Public Transport (SL) showed severe growth of rail corrugation with wavelengths of about 5 cm and 8 cm. LÄS MER

3. 2. On Peritectic Reactions and Transformations and Hot Forming of Cast Structures

   Författare :Hani Nassar; Hasse Fredriksson; Rian Dippenaar; KTH; []
   Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; peritectic reactions; massive transformations; thermal analysis; Fe-base alloys; steels; growth irregularities; hot forming; compression testing; flow stress; grain size.; Metallurgical manufacturing engineering; Metallurgisk produktionsteknik; Metallurgical process engineering; Metallurgisk processteknik;

   Sammanfattning : This thesis deals with peritectic reactions and transformations that occur during the solidification of many alloys. Peritectics are believed to be a major cause of crack-formation in many steels, thus, good knowledge of the mechanisms by which these phenomena occur is essential for preventing such defects. LÄS MER

4. 3. Dynamic Train/Track Interaction: Simulation of Railhead Corrugation Growth under a Moving Bogie Using Mathematical Models Combined with Full-Scale Measurements

   Författare :Annika Igeland; Chalmers tekniska högskola; []
   Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; railhead corrugation growth; railway and track irregularities; railway dynamics and measurements; train track interaction; complex-valued modal analysis;

   Sammanfattning : Heavier trains and higher speeds have increased the need for high-quality tracks and vehicles in order to fulfill safety and environmental requests. The phenomena involved in dynamic train/track interaction lead to noise radiation, induce ground-borne vibrations and degrade the track structure and the railcar wheels. LÄS MER

5. 4. Growth of fatigue cracks subjected to non-proportional Mode I and II

   Författare :Peter Dahlin; Mårten Olsson; Veronique École; KTH; []
   Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; Fatigue crack growth; Mode II overloading; Crack closure; Sequential mixed mode loading; Other engineering mechanics; Övrig teknisk mekanik;

   Sammanfattning : This thesis deals with some aspects of crack growth in the presence of cyclic loading, i.e. fatigue. The cyclic load cases studied here are primary of non-proportional mixed mode type. LÄS MER

7. 5. Strain-assisted corrosion cracking and growth rate inhibitors

   Författare :Andrey P Jivkov; Mekanik; []
   Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; vacuum technology; vibration and acoustic engineering; Maskinteknik; hydraulik; vakuumteknik; vibrationer; akustik; materialteknik; Mechanical engineering; Material technology; Materiallära; Stress intensity factor; Inhomogeneous materials; Crack evolution; Stress corrosion cracking; Moving boundary; hydraulics;

   Sammanfattning : A model for evolution of cracks as a result of strain-assisted corrosion is presented. The considered cracks possess a realistic geometry, where the tip region is an integral part of the crack surface instead of being a singular point. This geometry is either implicitly defined or is a consequence of crack nucleation from surface irregularities. LÄS MER