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Jakub Kõo

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

Sirvi

Sirvi Jakub Kõo Märksõna "deformation" järgi

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  • Pisipilt
    Kirje
    Determination of eigenstresses in electrodeposits by deformation of a thin-walled tube cathode: [full text in Russian]
    (Eesti Põllumajanduse Akadeemia, 1963) Kõo, Jakub
    A new technique for experimental determination of initial stress was developed. According to this, a coating to be investigated will be applied on the external surface of a thin-walled tubular cathode (see Figs. 2, 3). In addition, by using of electrical-resistance strain gauges on the internal surface of the cathode, strains are measured as a function of variable coating thickness. Initial stress is determined via approximation of experimental information. As an example in Fig.4 the distributions of measured deformations and initial and eigen- stresses (residual stresses) for a galvanic steel coating of a thin-walled tubular cathode are presented.
  • Pisipilt
    Kirje
    Determination of Residual Stresses in Coatings and Coated Parts
    (Tallinn Technical University, 1994) Kõo, Jakub
    The methods of experimental residual stress analysis in coatings available at present are indirect. A distinct deformation parameter of a substrate or a coating should always be measured, from which the values of residual stresses can be calculated. At the same time, distinction should be made between layer-growing (nondestructive) and layer-removing (destructive) measurement methods. In the case of growing methods, a deformation parameter is measured by applying a coating a coating to the substrate, while in the case of layer-removing methods, by removing it from the substrate. G. Stoney was the first to use a layer-growing method for determination of residual stress in galvanic coatings. By using his method (proposed in 1909), residual stress in a coating is calculated by the curvature measured during the unilateral coating of a free straight strip substrate assuming a one-dimensional state of stress. In the course of time various layer-growing methods have been developed for determination of residual stresses in coatings. Still, layer-removing methods are also applied for determination of residual stresses in coatings. It has been established that layer-growing and layer-removing methods can be described by a single algorithm. Algorithms of this kind have been developed by the author of this thesis for a free plate with a unilateral coating, for a hollow cylinder and for a hollow sphere with an outer coating. This thesis summarizes the research conducted by the author and the coauthors in the field of experimental mechanics of residual stresses in coatings and coated parts between 1965 and 1994. The thesis contains the following sections: 1. Determination of residual stresses in coated parts: general algorithm; 2. Determination of residual stresses in bars, plates, cylinders and spheres with a thick coating; 3. Methods for determination of initial stress; 4. Thermal stresses in coated parts; 5. Some results of the experiments; Conclusions; Bibliography (Main publication on the subject of the thesis; Abstracts of main reports on the subject of the thesis; References); Appendix: Examples of application.
  • Pisipilt
    Kirje
    Determination of Residual Stresses in Coatings and Coated Parts: Extended variant with additional information
    (Estonian Agricultural University, 1993) Kõo, Jakub
    The methods of experimental residual stress analysis in coatings available at present are indirect. A distinct deformation parameter of a substrate or a coating should always be measured, from which the values of residual stresses can be calculated. At the same time, distinction should be made between layer-growing (nondestructive) and layer-removing (destructive) measurement methods. In the case of growing methods, a deformation parameter is measured by applying a coating a coating to the substrate, while in the case of layer-removing methods, by removing it from the substrate. G. Stoney was the first to use a layer-growing method for determination of residual stress in galvanic coatings. By using his method (proposed in 1909), residual stress in a coating is calculated by the curvature measured during the unilateral coating of a free straight strip substrate assuming a one-dimensional state of stress. In the course of time various layer-growing methods have been developed for determination of residual stresses in coatings. Still, layer-removing methods are also applied for determination of residual stresses in coatings. It has been established that layer-growing and layer-removing methods can be described by a single algorithm. Algorithms of this kind have been developed by the author of this thesis for a free plate with a unilateral coating, for a hollow cylinder and for a hollow sphere with an outer coating. This thesis summarizes the research conducted by the author and the coauthors in the field of experimental mechanics of residual stresses in coatings and coated parts between 1965 and 1994. The thesis contains the following sections: 1. Determination of residual stresses in coated parts: general algorithm; 2. Determination of residual stresses in bars, plates, cylinders and spheres with a thick coating; 3. Methods for determination of initial stress; 4. Thermal stresses in coated parts; 5. Some results of the experiments; Conclusions; Bibliography (Main publications on the subject of the thesis; Abstracts of main reports on the subject of the thesis; References); Appendix: Examples of application. In the form of an additional information list of titles and copies of the main publications on the subject of the thesis, as well as information about the defence of the thesis and a copy of the issued doctoral diploma are submitted.