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Dimensioning of thick-walled pipe in creep
Zouhar, Michal ; Hutař, Pavel ; Náhlík, Luboš ; Hlavoň, P.
The numerical simulations of the creep in the case of X10CrMoVNb91 steel were performed. Geometry of the objects studied well-fit usual parts of the pipe system. The discrepancies between numerical simulations and usual standard Design By Formula (DBF) used for the pipe system lifetime prediction were found. Therefore, accurate numerical simulations based on creep description of the material behaviour is necessary for the accurate estimation of the service conditions.
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Napjatostní analýza keramické hlavice totální kyčelní endorpotézy s mikro a makro tvaovými odchylkami
Fuis, Vladimír ; Hlavoň, Pavel
The paper deals with the problems of ceramic head of hip joint endoprosthesis destructions in vivo, and with assessing the impact of shape deflections of conical surfaces on the tensile stress in the head. There are assumed two material characteristics of the stem – the first is linear elastic and the second is bilinear plastic modelled austenitic steel used in the bio-implants. Concerned are shape deviations from the ideal conical surfaces of the stem and the head of the endoprosthesis. The shape deviations may be modelled at the macro-level - this concerns model shape inaccuracies such as deviation from the nominal degree of taper, at the micro-level - when the stochastic distribution of unevenness on the contact areas is respected. The problem of stress in ceramic heads was solved using the algorithm of the finite element method – system ANSYS under ISO 7206-5 loading.
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Napěťová analýza radiální náhrady vřetenní kosti v loketním kloubu
Hlavoň, Pavel ; Florian, Z.
The paper is focused on computational modeling of elbow articulation with radial head replacement. The main part of the project is aimed towards the creation of computational model of suitable partial endoprothesis of proximal part of the radial bone tissue which would keep the function of the elbow articulation while replacing the distance created by resection. The geometrical and computational model of particular radial head replacement and elbow joint were created and analyzed. Computational model with that implant was compared with given physiological state of elbow articulation. The influence of friction and material characteristics of bone tissue and cartilage on changes in contact pressure (and therefore to the abrasion) were analyzed using this model.
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Napěťová analýza radiální náhrady a Souterovy endoprotézy v loketním kloubu
Hlavoň, Pavel ; Kolář, M.
Upon the initiative of the medical team at Traumatological Hospital in Brno, efforts are invested to create possible partial joint replacements of the proximal end of the radius and also proper design of Souter’s endoprothesis in the elbow articulation that would suitably replace the patient’s missing bone tissue and, at the same time, to preserve the same functionality of the radio-humeral connection. This paper speaks about potential geometrical and computational models of a partial joint replacement, Souter’s implant and their stress analysis.
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Calculation of the Ceramics Material Parameters from the Testing Destructions of the Heads
Fuis, Vladimír ; Návrat, Tomáš ; Hlavoň, Pavel
This paper deals with increasing of the computation modelling level of the reliability problem of ceramic heads of total hip joint endoprostheses. The solution to this problem was invoked by recent more frequent failures of these heads in clinical practice. Results of computational and experimental modelling have shown a substantial influence of shape deviations in the conical connection between stem and head on the initiation of ceramic head fractures. The fracture probability was evaluated step by step for various macroscopic shape deviations in the conical connection and then for microscopic shape deviations superposed on the macroscopic deviations.
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Stress-strain analyze of en elbow joint
Hlavoň, Pavel ; Fuis, Vladimír ; Florian, Z.
Summary: In traumatology demolition of elbow joint there are in many cases, where the surfaces of the joint are damaged. These parts of the joint have been removed during the operation. Function of the joint isn’t away but it nevertheless causes a really strong pain in the patient’s wrist. There is mentioned in the paper stress-strain analyze of the elbow joint in FEM and also geometric model of partial aloplastic for proximal part of radius.
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