Andmebaasi logo

Jakub Kõo

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

Sirvi

Sirvi Jakub Kõo Autor "Ryabchikov, Alexander" järgi

Nüüd näidatakse 1 - 2 2
  • Pisipilt
    Kirje
    Consideration of Thermal Stresses in Experimental Residual Stress Analysis for Coatings
    ([Warsaw University of Technology], 2004) Kõo, Jakub; Ryabchikov, Alexander; Estonian Agricultural University
    Usually, the coefficients of thermal expansion of the coating and substrate are different and the temperature of coating process differs from room temperature (20ºC). Therefore thermal stresses are generated in coated parts. In experimental analysis of residual stresses it may turn out that caoting temperature differs from the temperature at which the deformation parameters of the substrate are measured. In Susch cases the measurement results have to be corrected taking into account the thermal stresses. In this study, the equations for correction of the residual stresses in coatings, determined from the measured longitudinal deformations of the wire, and from the tubular and strip substrates [1-3], are presented. Three examples of application are given.
  • Pisipilt
    Kirje
    On the Determination of Residual Stress in Coatings from Measured Longitudinal Deformation of a Substrate
    ([Warsaw University of Technology], 2000) Kõo, Jakub; Ryabchikov, Alexander; Estonian Agricultural University
    A method of measuring longitudinal deformation for determination of residual stresses in a long homogeneous cylinder by removal of thin cylindrical concentric layers was proposed by Heyn an Bauer [1]. In [2-6] it is shown that computation of residual stresses is possible from the longitudinal deformation of a cylindrical substrate, measured during coating deposition. The present paper presents a generalized theory of the method of measuring the longitudinal deformation of a long cylindrical substrate for determination of initial residual stresses in coatings. Unlike in [2-6], the possibility of prestressing the substrate by an elastic element (spring) is taken into account [7]. Special cases like (1) Poisson´s rations of the substrate and coating are equal, (2) Poisson´s ratios and the moduli of elasticity of the substrate and coating are equal, (3) a thin coating is applied on a rigid substrate, etc. are examined. A linear-fractional function is proposed for approximation of the dependence of initial stress on coating thickness.