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Influence of production stresses on the safety of cylindric pressure vessels
Krakovský, Andrej ; Profant, Tomáš (referee) ; Burša, Jiří (advisor)
The bachelor thesis deals with influence of production stresses on the safety of cylindrical pressure vessels. Pressure vessels are made by sheet rolling. In this process the yield strength is exceeded, which leads to creating residual stresses. These stresses can influence final safety of vessels, if any heat treating isn’t done. In this thesis residual stresses are analytically calculated for cylindrical pressure vessel of wagon tank and for theoretical thick-walled vessel. After that safety with and without residual stresses are compared. The last part of this thesis describes method of removing these stresses.
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Influence of the residual stresses on the contact failure of ceramic laminates
German, Roman ; Majer, Zdeněk (referee) ; Ševeček, Oldřich (advisor)
The presence of the compressive or tensile thermal residual stresses in layers of a ceramic laminate induced due to different volume change of each layer´s material during the cooling from the sintering temperature can considerably affect resistivity of ceramics against contact damage. Within this work 2D parametric FEM models were created, in order to study the effect of the surface layer thickness, residual stress values and indenting body dimension on the initiation and propagation of the cone crack in the surface layer of the laminate. For the analysis of the critical conditions for the crack initiation, the coupled stress-energy criterion was used and for the determination of the direction of crack propagation we used the maximum tangential stress criterion. The results show that compressive thermal stresses in the surface layer increase the critical force for the crack initiation, shorten the crack distance from the contact area and shorten the occurred crack itself. Moreover, the compressive stresses enlarge the angle of the crack declination during the propagation process which cause an earlier crack arrest. The tensile thermal stresses have exactly the opposite effect. Results of simulations were compared to experimental results but due to lack of available measurements, the verification is partially limited.
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Influence of the residual stresses on the contact failure of ceramic laminates
German, Roman ; Majer, Zdeněk (referee) ; Ševeček, Oldřich (advisor)
The presence of the compressive or tensile thermal residual stresses in layers of a ceramic laminate induced due to different volume change of each layer´s material during the cooling from the sintering temperature can considerably affect resistivity of ceramics against contact damage. Within this work 2D parametric FEM models were created, in order to study the effect of the surface layer thickness, residual stress values and indenting body dimension on the initiation and propagation of the cone crack in the surface layer of the laminate. For the analysis of the critical conditions for the crack initiation, the coupled stress-energy criterion was used and for the determination of the direction of crack propagation we used the maximum tangential stress criterion. The results show that compressive thermal stresses in the surface layer increase the critical force for the crack initiation, shorten the crack distance from the contact area and shorten the occurred crack itself. Moreover, the compressive stresses enlarge the angle of the crack declination during the propagation process which cause an earlier crack arrest. The tensile thermal stresses have exactly the opposite effect. Results of simulations were compared to experimental results but due to lack of available measurements, the verification is partially limited.
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Influence of production stresses on the safety of cylindric pressure vessels
Krakovský, Andrej ; Profant, Tomáš (referee) ; Burša, Jiří (advisor)
The bachelor thesis deals with influence of production stresses on the safety of cylindrical pressure vessels. Pressure vessels are made by sheet rolling. In this process the yield strength is exceeded, which leads to creating residual stresses. These stresses can influence final safety of vessels, if any heat treating isn’t done. In this thesis residual stresses are analytically calculated for cylindrical pressure vessel of wagon tank and for theoretical thick-walled vessel. After that safety with and without residual stresses are compared. The last part of this thesis describes method of removing these stresses.
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