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Influence of process parameters in forward extrusion on the die loading
Pokorná, Jana ; Návrat, Tomáš (referee) ; Petruška, Jindřich (advisor)
One of the decisive factors of effective using of forward extrusion technology is lifetime of forming tools. Die is very loaded forming tool which loading and therewith related lifetime can be significantly affected by its construction. Construction also affected quality of extruded material. Finete element method allows to simulate this process and assess force which is needed to extrusion and state of stress in die and extruded material. Numerical simulation was realized in program ANSYS 11.0. Influence of reduction, angle of reduction, lenght of extruded material, rounding transition of die parts, extruded material and friction coefficient on die loading and emergence of cracks in extruded material was set in this diploma thesis. Results can be used to die construction optimalization.
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Stress - strain analysis and creep assessment of the thick-walled tubular structures.
Zouhar, Michal ; Petruška, Jindřich (referee) ; Hlavoň, Pavel (advisor)
This thesis deals with the stress-strain analysis of thick-walled pipe parts. The dimension series (characterized by the D/d ratio) of three components are solved, then a direct tube, a torus with constant wall thickness (arcus) and a torus with variable wall thickness (bend). At first, the internal pressure amount, when a fully plastic state for these components is created, is solved. The amount of the limit pressure is determined analytically, numerically and by appropriate normative relations. The results and stress diagrams of individual solutions are mutually compared. Furthermore, these components are solved in the creep and are exposed to the maximum allowable normative internal pressure for 200,000 hours according to the standard – the operating time of components. The place of the maximum equivalent creep strain and the place of the maximum equivalent stress is examined. In these places the principal stresses are depicted depending on the D/d ratio. The results and stress diagrams of individual dimension series are mutually compared. From the available literary sources the condition of the limit state reach is chosen, according to which the evaluation of the limit state reach for individual components is carried out.
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Stress analysis of rotor packet of synchronic generator
Bureš, Jiří ; Houfek, Lubomír (referee) ; Petruška, Jindřich (advisor)
This diploma thesis deals with distribution stress and strain of sheets metal of rotor packet and in critical locations of supporting bars of synchronous generator. These variants are calculated and one another comparison of analytic calculation results, numeric calculation of 2D model and numeric calculation of 3D model in three vriants ( with bars of rectangle section, circular section, with upper radius). The calculation include influence of thermal expansion, centrifugal force, interference of the packet on the shaft and prestress in the axial direction of bolt. To creation of geometric model and numerical calculation is used program ANSYS 11.
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Application of ductile fracture models in computational simulation of manufacturing operations
Hůlka, Jiří ; Houfek, Lubomír (referee) ; Petruška, Jindřich (advisor)
This diploma thesis is an introduction to the ductile fracture under large plastic deformations and is focused to numerical simulation of this type of problems. Explicit finite element method (FEM) is discussed in theoretical introduction as the most powerful tool for numerical calculations in this area. Actual state of research and possibilities of ductile fracture simulations are presented. Applicable fracture criteria are collected in a summary sheet and the most important ones are selected and commented in detail. The problem of implementation of selected criteria into commercial FEM packages is discussed, too. Main part of the work is presented in chapters 7÷9 where two ductile fracture criteria (Equivalent Fracture Strain and Johnson-Cook) are applied to numerical simulation of material cutting. All results were obtained with ABAQUS/Explicit 6.5.1 and their verification was realized by experimental measurement.
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Optimization of an aircraft wing rib
Kopřiva, Lubomír ; Suchánek, Miroslav (referee) ; Petruška, Jindřich (advisor)
Topology optimization is a method providing new direction in designing of a technical objects. The aim of topology optimization is to find optimal distribution of material in design space. This diploma thesis is focused on optimization of aircraft wing rib num.6 of the airplane EV-55 using a software HW/Optistruct 7.0 implemented in a software package HyperWorks 7.0. The optimization of the rib was calculated under four different load cases. Resulting shapes of the rib were then tested by strenght calculations in software ANSYS 10.0. Finally, the obtained data of weights of optimized ribs were compared with the weight of the original rib.
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Computational simulation of leveling of non-circular rods
Stráník, Radim ; Návrat, Tomáš (referee) ; Petruška, Jindřich (advisor)
This bachelor’s thesis illustrates the principle of straightening rolled through long table roll straightening machines using repeated plastic deformation, based on Eulerian description of the material flow. Thesis describes the program on computational simulation process straightening rods and extends it an easy to use input module for entering non-circular cross-section rods. At the end of the discussion also introduces the optimal settings for all input parameters to achieve best results.
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Stress-strain analysis of axisymmetric body solved by analytical and numerical approaches
Mívalt, Tomáš ; Petruška, Jindřich (referee) ; Novák, Kamil (advisor)
The bachelor’s thesis deals with stress-strain analysis of axisymmetric body. As suitable axisymmetric body was chosen combustion engine piston. Thesis includes study of piston loads and possibilities of stress-strain calculations. This is followed by research in field of historical approaches of stress-strain calculations and tension evaluating and classification. In the practical part of thesis, analytical solution was solved with different computational models – fixed plate, supported plate and composite body – composed of shell and plate. After solving analytical models, numerical approach took place; FEM with different resolutions was used in ANSYS system. In conclusion of the thesis, all data and result were compared and appropriate conclusions were made.
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Strip rolling
Kornherr, Milan ; Suchánek, Miroslav (referee) ; Petruška, Jindřich (advisor)
This bachelor thesis focuses on theoretical analysis of the role of plastic deformation in the process of rolling strips. The work explains progress of stress waveform during straining and lightening. This work also focuses on computing of spring loading and bending moment due to specific curvature of strips. Report at the end of this work includes an illustrative example with executional program.
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