Browsing by Author "Dyja, Henryk"

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Access status: Open Access ,
Analiza parametrów siłowych końcowej fazy wyciskania metali
(Data obrony: 2008-07-01) Rękas, Artur
Wydział Metali Nieżelaznych
In the work, results of FEM numerical calculations and experimental investigations of indirect extrusion process were presented. Influence of main process parameters with regards of metal flow on the final stage of indirect extrusion force characteristic was investigated. The aim of matching process parameters that decide on the force characteristic in the final stage was to minimize length of the billet rest after indirect extrusion. Force characteristics, state of strains and stresses, distributions of temperatures, metal flow and velocity field of metal particles in the deformation zone were analysed. Metal flow was analysed for the different elongation coefficients and the different billet lengths, by using the visioplastic method. Distributions of strains allowed to determine the range of the main deformation zone. In indirect extrusion trials the force characteristics was determined for the different process parameters.
Access status: Open Access ,
Prognozowanie stateczności plastycznego płynięcia metali i ocena przydatności projektowanych narzędzi z wykorzystaniem metody elementów skończonych
(Data obrony: 2008) Mroczkowski, Marcin
Wydział Metali Nieżelaznych
In the thesis the dangerous conditions of metal plastic flow in innovative processes were studied. The hydrostatic pressures, preventing cracking of the deformed metal in the process of the cyclic extrusion compression (CEC), and the influence of tool shape on the save of stability and cohesion of the shaped material in the process of the radial extrusion, were analysed. Model and experimental study were made. The finite element software DEFORM 2D and 3D was used in numerical calculations. The experimental tests of CEC processes were carried out on the original hydraulic press. Plastic fracture conditions of metals were experienced using the tensile tests. Numerical simulations of the tensile tests were also conducted. The critical damage values according to Cockcroft-Latham's criterion were qualified using the semi empirical method. The received values were used for modelling the processes of radial extrusion with the use of the incorrect shape of tools. On the basis the comparison of experimental results with numerical prognosis, the ideal agreement was confirmed among the real and the modelled process, despite the presence of very irregular and asymmetric flowing, which causes cracks of the plastic metal. In CEC processes, the most dangerous conditions of the plastic deformation take place behind the neck die, where metal flows in radial directions from the centre to outside. It was affirmed that the achievement of very large plastic deformations was possible by gradual raising the counter-pressure, adapted to the increase of the plastic flow stresses.
Access status: Open Access ,
Sposób otrzymywania blach platerowanych opis patentowy patentu tymczasowego nr 104704
(Urząd Patentowy PRL, 1979-12-01) Dyja, Henryk; Leskiewicz, Wacław; Wosiek, Eugeniusz; Morawiecki, Marian; Sadok, Lucjan; Łuksza, Janusz; Barton, Ryszard; Cichoń, Czesław; Łabuda, Elżbieta; Akademia Górniczo-Hutnicza im. Stanisława Staszica (Kraków)
Access status: Open Access ,
Sposób otrzymywania blach platerowanych opis patentowy patentu tymczasowego nr 115433
(Urząd Patentowy PRL, 1982-06-30) Leskiewicz, Wacław; Dyja, Henryk; Wosiek, Eugeniusz; Przybyłowicz, Karol; Sadok, Lucjan; Barton, Ryszard; Akademia Górniczo-Hutnicza im. Stanisława Staszica (Kraków)
Access status: Open Access ,
Sposób wytwarzania rur platerowanych opis patentowy nr 123869
(Urząd Patentowy PRL, 1984-10-02) Wosiek, Eugeniusz; Sadok, Lucjan; Dyja, Henryk; Barton, Ryszard; Chodziński, Henryk; Pilszak, Augustyn; Świder, Jacek; Muskalski, Zbigniew; Rożek, Feliks; Łuksza, Janusz; Akademia Górniczo-Hutnicza im. Stanisława Staszica (Kraków)
Access status: Open Access ,
Wpływ rozdrobnienia struktury na mechanizmy umocnienia stali niskowęglowych odkształcanych plastycznie
(Data obrony: 2008) Muszka, Krzysztof
Wydział Inżynierii Metali i Informatyki Przemysłowej
An effect of grain refinement on the basic strengthening mechanisms of metallic materials after plastic deformation was discussed. Grain refinement levels, where the change in the deformation mechanisms is observed, have been identified with respect to resulting changes in the strengthening mechanisms of studied materials. Differences in the description of deformation and strengthening mechanisms of ultrafine-grained (UFG) and nanocrystalline materials were defined. Also, the existing flow stress models for UFG materials were presented and their physical bases were discussed with respect to their application in the computer modeling process of mechanical behavior of UFG low carbon steels. In the experimental part the UFG structures were produced in the low carbon and microalloyed steels by the means of controlled rolling and using severe plastic deformation process (MaxStrain simulator). The detailed analysis of the effect of particular processing parameters on the obtained refinement level and final mechanical properties has been performed. Utilizing results from theoretical analysis and experimental work, the verification process of chosen existing flow stress models of UFG and nanostructured materials was performed using Abaqus Explicit. Then, basing on the experimental results the modification of the KHL model has been proposed treating separately the contribution of low- and high angle grain boundaries. Effectiveness of the modified version of the KHL model was examined using experimental results.