|
|
Comparison of strains determined by finite element method and by optical measurement system
Zajíček, Vít ; Hlavoň, Pavel (referee) ; Vlk, Miloš (advisor)
This thesis focuses on the comparison of numerical simulation and optical measurement of deformation of the turbinehousing made by Honeywell company. The numerical calculation performed by finite element method to simulate transient thermal load on the measured entity. Numerical result of the strain state of the body caused by temperature gradients. To verify the simulation is used an experimental digital correlation method VIC-3D. The thesis also mentioned the theoretical foundations of digital correlation methods and thermal analysis.
|
|
|
Stress analysis of the total hip joint endoprosthesis head under ISO 7206-5 loading
Varga, Jozef ; Hlavoň, Pavel (referee) ; Fuis, Vladimír (advisor)
The aim of this work is to analyse axisymetric tasks by norm ISO 7206-5, which is used to determination of static strength of ceramic heads. In the numeric analysis there will be considered form variances from nominal conicalness and circularity of stem sections i.e. possible variances caused by production. Furthermore form changes of recess inside of the head measured on real samples will be considered. All these variances from nominal values are necessary to analyse in more details, because they can participate in destruction of ceramic heads. The stem system, ceramic head and load cone (DHK) will be simulated as a 2D axisymetric task and 3D quarter symetrical task. That is why is necessary to undertake also comparing analysis of 2D and 3D tasks and compare results or eventually evaluate the error. This problem is solved using of Finite element System ANSYS 11.0.
|
|
|
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.
|
|
|
Dynamic Behavior of Laval Rotor
Nováková, Naděžda ; Hlavoň, Pavel (referee) ; Malenovský, Eduard (advisor)
The aim of this bachebor’s thesis is to specify self-frequency of model rotor system and verify that the system may be considered as Laval rotor. The natural frequency is obtained by calculating from the known relations for the circular rotor vibration. Verify that the model rotor system can be Laval rotor, is performed by using experimental measurements, which is determined in shaft deflection trajectory during gradually increasing speed. The measured values are then processed in program MATLAB. The results are compared with theory of Laval rotor
|
|
|
Assesment of residual stress with drilling hole method using FEM
Civín, Adam ; Vlk, Miloš (referee) ; Hlavoň, Pavel (advisor)
Residual state of stress in structural materials affect positively or negatively behaviour of component parts. The goal of this scope is not to deal with possible process of creating residual stresses neither about elimination of residual stress, but is focused how to determine magnitude of residual stress by hole-drilling method. We need to know magnitude and direction (angular orientation) of principal stresses to determine how residual state of stress affects behaviour of specimen. The most widely used modern technique for measuring residual stresses is hole-drilling strain-gage method. Hole-drilling method is in scope of this paper and is restricted only for measuring uniform residual stresses of steel specimens with finite dimensions. Structural, linear, elastic and isotropic material model is used with material properties =0,3 and E=2,1[10]^5 MPa. For correct application of this method we need to determine calibration coefficients “a“ and “b“ first. These coefficients are used to determine magnitude and direction of residual stresses in specific depth and diameter of drilled hole for materials with finite dimensions. Geometry and shape of model is simply represented by block with planar faces. Note that numerical determination of calibration coefficients is useful only for one type of strain gauge rosette RY 61 S. Main goals of this thesis are motivation and request to clearly report effectiveness, accuracy and applicability of calibration coefficients in relation to thickness of specimen, dimensions of drilled hole, condition of “through” or “blind” hole and number of drilled increments. High quality and accuracy of created numerical model is necessary too. Numerical simulation of residual stresses by MKP needs to be done to obtain requested results. All results are presented by 3D, 2D graphs and tables and compared with analytical results or results from other authors. Although is this publication focused on numerical modeling using FEM, hole-drilling method has many significant restrictions. The most substantial of them is influence of eccentricity of drilled hole, creation of stress concentration near drilled area and subsequent plastification, influence of geometrical inaccuracy of hole, etc. All these aspects have significant influence of determining calibration coefficients and can not be included into numerical simulation. These problems are closely discussed in background research. All obtained results should be helpful for practical use of calculated calibration coefficients to determine uniform residual stresses of specimens with various thickness and drilled hole. All these results are also applicable only for one type of strain gauge rosette, which is RY 61 S.
|
|
|
Comparison of strains determined by finite element method and by optical measurement system
Zajíček, Vít ; Hlavoň, Pavel (referee) ; Vlk, Miloš (advisor)
This thesis focuses on the comparison of numerical simulation and optical measurement of deformation of the turbinehousing made by Honeywell company. The numerical calculation performed by finite element method to simulate transient thermal load on the measured entity. Numerical result of the strain state of the body caused by temperature gradients. To verify the simulation is used an experimental digital correlation method VIC-3D. The thesis also mentioned the theoretical foundations of digital correlation methods and thermal analysis.
|
|
|
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.
|
|
|
Assesment of residual stress with drilling hole method using FEM
Civín, Adam ; Vlk, Miloš (referee) ; Hlavoň, Pavel (advisor)
Residual state of stress in structural materials affect positively or negatively behaviour of component parts. The goal of this scope is not to deal with possible process of creating residual stresses neither about elimination of residual stress, but is focused how to determine magnitude of residual stress by hole-drilling method. We need to know magnitude and direction (angular orientation) of principal stresses to determine how residual state of stress affects behaviour of specimen. The most widely used modern technique for measuring residual stresses is hole-drilling strain-gage method. Hole-drilling method is in scope of this paper and is restricted only for measuring uniform residual stresses of steel specimens with finite dimensions. Structural, linear, elastic and isotropic material model is used with material properties =0,3 and E=2,1[10]^5 MPa. For correct application of this method we need to determine calibration coefficients “a“ and “b“ first. These coefficients are used to determine magnitude and direction of residual stresses in specific depth and diameter of drilled hole for materials with finite dimensions. Geometry and shape of model is simply represented by block with planar faces. Note that numerical determination of calibration coefficients is useful only for one type of strain gauge rosette RY 61 S. Main goals of this thesis are motivation and request to clearly report effectiveness, accuracy and applicability of calibration coefficients in relation to thickness of specimen, dimensions of drilled hole, condition of “through” or “blind” hole and number of drilled increments. High quality and accuracy of created numerical model is necessary too. Numerical simulation of residual stresses by MKP needs to be done to obtain requested results. All results are presented by 3D, 2D graphs and tables and compared with analytical results or results from other authors. Although is this publication focused on numerical modeling using FEM, hole-drilling method has many significant restrictions. The most substantial of them is influence of eccentricity of drilled hole, creation of stress concentration near drilled area and subsequent plastification, influence of geometrical inaccuracy of hole, etc. All these aspects have significant influence of determining calibration coefficients and can not be included into numerical simulation. These problems are closely discussed in background research. All obtained results should be helpful for practical use of calculated calibration coefficients to determine uniform residual stresses of specimens with various thickness and drilled hole. All these results are also applicable only for one type of strain gauge rosette, which is RY 61 S.
|
|
|
Stress analysis of the total hip joint endoprosthesis head under ISO 7206-5 loading
Varga, Jozef ; Hlavoň, Pavel (referee) ; Fuis, Vladimír (advisor)
The aim of this work is to analyse axisymetric tasks by norm ISO 7206-5, which is used to determination of static strength of ceramic heads. In the numeric analysis there will be considered form variances from nominal conicalness and circularity of stem sections i.e. possible variances caused by production. Furthermore form changes of recess inside of the head measured on real samples will be considered. All these variances from nominal values are necessary to analyse in more details, because they can participate in destruction of ceramic heads. The stem system, ceramic head and load cone (DHK) will be simulated as a 2D axisymetric task and 3D quarter symetrical task. That is why is necessary to undertake also comparing analysis of 2D and 3D tasks and compare results or eventually evaluate the error. This problem is solved using of Finite element System ANSYS 11.0.
|
|
|
Dynamic Behavior of Laval Rotor
Nováková, Naděžda ; Hlavoň, Pavel (referee) ; Malenovský, Eduard (advisor)
The aim of this bachebor’s thesis is to specify self-frequency of model rotor system and verify that the system may be considered as Laval rotor. The natural frequency is obtained by calculating from the known relations for the circular rotor vibration. Verify that the model rotor system can be Laval rotor, is performed by using experimental measurements, which is determined in shaft deflection trajectory during gradually increasing speed. The measured values are then processed in program MATLAB. The results are compared with theory of Laval rotor
|
guest ::
