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Jakub Kõo

Selle kollektsiooni püsiv URIhttp://hdl.handle.net/10492/7087

Sirvi

Sirvi Jakub Kõo Märksõna "curvature method" järgi

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  • Pisipilt
    Kirje
    Measurement of residual stresses in the cold-rolled Fe-Ni-Mn/Invar thermo-bimetallic plate
    (Trans Tech Publications Ltd, 2026) Lille, Harri; Kõo, Jakub; Valgur, Jaak; Ryabchikov, Alexander; Reitsnik, Renno; Veinthal, Renno
    The paper presents a method for measuring residual stresses in normal thermo-bimetal Fe-Ni-Mn/Invar strips with a thickness of 0.76 mm. For this purpose, a setup was designed which permits to remove layers from a strip substrate by electrochemical etching. Residual stresses in the directions that are longitudinal and transversal to rolling are determined by the curvature method based on the layer growing/removing techniques. As a reference, residual stresses were also determined by hole-drilling technique. Tensile and compressive residual stresses arose both in active and in passive layers and were considerably higher when determined by the hole-drilling technique.
  • Pisipilt
    Kirje
    Relaxation of residual stresses in brush-plated gold and silver coatings on copper and on brass substrates
    (Trans Tech Publications Ltd, 2026) Lille, Harri; Kõo, Jakub; Ryabchikov, Alexander; Reitsnik, Renno; Sergejev, Fjodor; Dong, Minjie
    The investigated brush-plated gold and silver coatings are used for refining the surface properties of electric apparatuses. Tensile residual stresses generated in the plated coatings were determined by the curvature method and by instrumented indentation testing of a thin-walled open ring substrate, as described in our earlier papers. These stresses relax over time and their dependence on relaxation time was approximated by a linear-fractional function. The Young´s modulus and nanohardness of the coatings were determined. The surface morphology and structure in cross section of the coated substrates were presented.