Vrednovanje zaostalih naprezanja u zavaru metodom bušenja otvora

Residual stresses arise in the structures without loading during the technological processes, e.g. casting, rolling, welding, and pressing. In the paper is described the process of quantification of residual stresses by the hole-drilling method. For determination of residual stresses were used the procedures in which are supposed constant or linear distributions of stresses along the hole.Zaostala naprezanja nastaju u neopterećenim izradcima tijekom tehnoloških procesa, npr., pri odlijevanju, valjanju, zavarivanju i prešanju. U članku je opisan postupak vrednovanja zaostalih naprezanja u zavarenom spoju primjenom metode bušenja otvora. Za određivanje zaostalih naprezanja rabljen je postupak u kojemu se predmnijeva stalna ili linearna raspodjela naprezanja duž otvora

Vrednovanje zaostalih naprezanja u zavaru metodom bušenja otvora

Residual stresses arise in the structures without loading during the technological processes, e.g. casting, rolling, welding, and pressing. In the paper is described the process of quantification of residual stresses by the hole-drilling method. For determination of residual stresses were used the procedures in which are supposed constant or linear distributions of stresses along the hole.Zaostala naprezanja nastaju u neopterećenim izradcima tijekom tehnoloških procesa, npr., pri odlijevanju, valjanju, zavarivanju i prešanju. U članku je opisan postupak vrednovanja zaostalih naprezanja u zavarenom spoju primjenom metode bušenja otvora. Za određivanje zaostalih naprezanja rabljen je postupak u kojemu se predmnijeva stalna ili linearna raspodjela naprezanja duž otvora

Quantification of Residual Stresses in Hot Rolled Steel Sheets by the Hole Drilling Method

The paper deals with the problems of quantification of residual stresses in hot rolled sheets produced under various regimes. On the base of stress distribution along width and thickness of the belt is pointed out on possibilities of belt deformation from the plane as a result of action of torsional moment as an integral internal quantity in cross-section. For the non-uniformly distributed stresses along the thickness of the sheet the new method for residual stresses determination was developed. Application of the method is described in the paper

The Strain Gage Method for Determination of Input Working Life Parameters of Pipes in Compressor Stations

For determination of safety operation of compressor stations and assessment of their residual working life is necessary to know the levels of residual stresses, operational loading as well as functionality of real support elements and influence of history of previous loading. The method described in the paper was verified several times during solution of problems concerning safety operation of piping yards. The method was also verified by the numerical methods of mechanics

Application of photostress method in stress analysis of a rotating disc

The presented article demonstrates the application of PhotoStressR method in stress analysis of a rotating disc of a constant thickness, which was made of a photoelastic material PS-1A. Isoclinic fringes were observed on the rotating disc using linear polarized light at revolutions 5 000 RPM. Observations were carried out under angle parameter 0 o to 90 o with 10 o increase. A set of isostatic lines of I and II set was made from the set of obtained isoclinic lines. During gradual increase of rotations of the rotating disc up to 17 000 RPM, and with circular polarized light, we observed the distribution of colourful isochromatic fringes on the rotating disc. The field of isochromatic fringes, gained experimentally, at 15 000 RPM was compared with the field which was gained by means of a numerical analysis

Economic evaluation of investment project in the area of sheet metal processing

The article is oriented on the process modelling in selected company. The aim of the process modelling is a possibility to prevent the formation of future risks as a consequence of a wrong decision concerning a capital project. The analysis of actual state in society with the focus on the means of processing the lamination using computer numeric control technology is also a part of article. Based on the analysis mentioned above, the selection and the definition of the capital project have already been carried out. Final section evaluates the capital project using methodology of economic indicators by means of economic indicators of effectiveness and brings a decision whether to accept or refuse given investment

Verification of the material properties of the structure elements of compressor station for the needs of their redesign

This paper discusses the importance and complexity prediction of fatigue life in connection with reconstruction or rebuilding of compressor station and in connection with degradation of material and change of its static and fatigue mechanical characteristics. The subject of the research is the piping ring, which was removed above a T-module of a turbocompressor of compressor station. The paper brings partial results of testing and analysis of the macrostructure and mechanical properties of the base material and the material in the weld area of removed piping ring

The analysis of failure causes of the rotor shaft of steam turbines

The rotors of steam turbines belong to the extremely loaded parts of turbo generators due to various mechanical and thermal influences during their operation. The following paper presents the results of the analysis of failure causes of the rotor shaft of a steam turbine with the power of 6,43 MW, which occurred after approximately one year of operation. The analysis was performed on the basis of the analysis of the chemical composition and microstructure of the material, the mechanical properties of the material under static and fatigue loading, as well as operational loading of the critical location of the shaft, using numerical and analytical methods. The conclusions about the possible causes of the shaft failure were drawn on the basis of the results obtained

The failure analysis of the holder of a crusher moving knife

The paper deal s with the analysis of the causes of knife holder failure. The holder is a part of the car tyre shredding equipment. Based on the evaluation of the operating conditions of the machine, examination of the condition of the knife holder after the failure, analysis of the fractured surface, as well as the material properties of the examined structural elements, it was possible to draw conclusions as to the reasons of eventual failures