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Computational analysis of leveling of square cross section rods
Šebek, František ; Návrat, Tomáš (referee) ; Petruška, Jindřich (advisor)
Current requirements in mechanical engineering require more accurate operations and more efficient technologies. The aim of this thesis is the analysis of the leveling of square rods. The main problem is the setting of the leveling machine for the specified material and geometric data so that the initially curved material, which passes through alternatively positioned offset rollers, is leveled as much as possible. The main factor in the leveling process is the plastification of the material used for the redistribution of the residual stress. Based on existing theo-retical knowledge in this field, programs are set up to simulate the passing of the rod through the leveling machine. Further, modifications leading to the improvement of the whole process are presented. Finally, there is a verification of the results which is made independently of the submitted solution and processed by the finite element method.
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Analysis of biotribological properties of artificial hip joint
Laštůvka, Jan ; Burša, Jiří (referee) ; Návrat, Tomáš (advisor)
The development of total hip arthroplasty has reached a state when quality prostheses are made, whose longevity is influenced significantly by material properties, design, component fixation and rate of wear of the articulating surfaces. It is the wear rate which is the most important factor influencing successful results for the use of total hip prostheses. The aim of this thesis is to perform a research on the various combinations of hip prostheses and its loading conditions. Also an experimental measurements of Bovine serum lubricating film thickness between the artificial femoral head and a glass disc are performed for different contact kinematic conditions.
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Strain, stress and strength analysis of the ball bearing considering the contact conditions
Prášil, Jiří ; Návrat, Tomáš (referee) ; Vrbka, Jan (advisor)
Motivation of this master‘s thesis is solution of practical problem of the newly developed slewing ring for tram Škoda, type: 15T. Next impulse for thesis creation was the possibility to extend product range of roller bearing ZKL. There is processed strain – stress analysis of bearing inner design making use the finite element method (FEM). Obtained results are compared with classic approach based on the Hertz theory. Important aim of this work is three main parameters optimal establishment: rolling element diameter, arrangement radius and number of rolling elements. Optimization job is realized by solutions of direct tasks with different parameters. With regard to necessity of detailed stress analysis and conservation of reasonable computational time it was chosen approach of combination global and local FEM model. It was used pre/postprocessor PATRAN and solver MARC for solution of strain and stress analysis. Analytic solution was accomplished in software EXCEL.
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Stress-strain analysis of lower limb prosthetic
Musilová, Kateřina ; Fuis, Vladimír (referee) ; Návrat, Tomáš (advisor)
This master thesis deals with lower-limb prosthesis. The aim of the first part of this work is stress-strain analysis of trans-tibial prosthesis, which is understand without prosthetic socket and the foam prosthetic feet. Analysis is made using finite element method in ANSYS Workbench 12.0 software. For the purpose of setting up the computational model it is necessary to make few partial models. Model of geometry of the prosthesis is made in SolidWorks 2009. Based on the outputs of stress-strain analysis and the results evaluation, the critical component is chosen and this one is evaluated according to limite state for fatigue. The algorithm of evaluation of named component in the state of high cycle fatigue is discussed in the second part of this thesis.
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Removal of residual stress in thin sheets by tension leveling
Dymáček, Martin ; Návrat, Tomáš (referee) ; Petruška, Jindřich (advisor)
Tension leveling is a process used in the steel industry in order to eliminate any shape imperfections of cold-rolled thin strips. The master thesis deals with developing a computer program that generates basic parameters of tension leveling line. The theoretical part of the thesis summarizes the types of the shape imperfections in strips, their causes and the principles of their elimination. This part also presents the mechanism of tension leveling and describes the present-day design of tension levelers. The practical part of the thesis starts with an analytical description of stress-strain behaviour of strip during tension leveling (supposing the simplified conditions). A computer program that allows devising basic parameters of tension leveling line is created on the basis of these analytical relations. The program results are successfully verified by numerical model based on the finite element method (FEM) created in the program ANSYS. Then the interdependencies of certain input and output parameters of created program are determined. These interdependencies can be used as effective design of tension leveling lines.
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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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Strain-stress analysis of spinal segment
Pánis, Vladimír ; Janíček, Přemysl (referee) ; Návrat, Tomáš (advisor)
Presented work deals with the strain-stress analysis of a spinal segment while monitoring the influence of total disk replacement Maverick on the global behaviour of the spinal segment. It also assesses the influence of this implant on the nearest upper intervertebral disk. On the basis of CT images was in the program Rhinoceros created the geometry model of spinal segment Th12-L2. The geometry model of implant was applied between vertebra L1 and L2 instead of intervertebral disk from which the whole core was removed, while in the immediate surrounding of implant the part of disk was left, which is important from the view of stability. Subsequently were in the program Ansys Workbench created finite element models for two states: - healthy (unbroken) status - status with applied implant Then the calculations for movements were realized: lateral flexion, flexion, extension, rotation. For the same movements were realized calculations of the model simulated spinal fusion of the vertebras L1-L2. Finally an influence both of methods (total disk replacement, spinal fusion) on the intervertebral disk Th12-L1 was compared.
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Strain-stress analysis of pathological hip joint
Stodola, Martin ; Florian, Zdeněk (referee) ; Návrat, Tomáš (advisor)
This work deals with stress-strain analysis pathological hip joint. In its introduction a research study from accessible literature sources is carried out. It covers contemporary state of scientific studies, anatomy of single components hip joint, their material properties, ways and magnitudes of loadings and most often FE model used. With use of all these informations, computational system ANSYS and gained CT scans, a model of geometry of pelvis and femur is created. Subsequently, the complete computational model o pathological hip point is compiled. On this model computational solution is executed stress-strain and sensitivity analysis. Subsequently, surgery operation is simulated on this model and it is executed stress-strain analysis. These analyses are compared with analysis of physiological hip joint.
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Stress-strain analysis of artery with atheroma
Maša, Marek ; Návrat, Tomáš (referee) ; Burša, Jiří (advisor)
The main goal of this diploma thesis was the stress-strain analysis of iliac artery with atheroma.This problem was solved using finite element method (FEM).For the calculation purposes three two-dimensional models were created. The geometry was gained from transversal sections through the iliac artery with ateroma. This geometry is educed from used literature review. The main calculation process was run by ANSYS 11.0 program system.
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Strain-stress analysis of the surface replacement of the hip joint
Vosynek, Petr ; Janíček, Přemysl (referee) ; Návrat, Tomáš (advisor)
Today is the surface hip repacement very often surgery becouse of new studies and improvements. For young and active people it's the best way to delay implantation of a total hip replacement. The objective of this study was to perform finite-element analyses of computational model of the partial/total surface replacement, conventional partial/total replacement and physiological hip joint. We obtained strain-stress states from these analyses. All results were compared one another and then were confronted with results of the physiological hip joint. The three-dimensional computational model consists of these components: sacral, pelvic and femoral bone, muscles, artificial socket, and surface hip replacement. We were using FEM system ANSYS. The geometrical models of bones were generated by means of computed tomography (CT) images. The FE model of bone reflects two types of the bone tissues (trabecular and cortical bone) and muscles which are important when standing on one leg. The model of the muscle corresponds to isometric contraction. The implants material and bone tissues were modelled as isotropic linear elastic material. The model was loaded by force, corresponding to load by standing on one leg.
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