Development of Endoprosthesis.

Tato bakalářská práce se zabývá problematikou vývoje totálních endoprotéz. V práci je popsána historie vývoje endoprotéz a popis v současné době vyráběných a používaných typů endoprotéz. V závěru je nastíněn současný vývoj kloubních implantátů.This bachelor’s thesis deals with the problems of the development of total endoprosthesis. The work contains the history of endoprosthesis and the present day description of made and used types of endoprosthesis. In the conclusion there is foreshadowed the development of joints’ surgical implants.

Strain stress analysis of BS splint

Tato diplomová práce se zabývá řešením deformačně napěťových stavů u kyčelního spojení s aplikovanou totální endoprotézou s Burch-Schneiderovou dlahou. Stěţejním prvkem celé práce bylo řešení deformačně napěťových stavů u jiţ zmíněné Burch- -Schneiderovy dlahy. V práci je popsán postup tvorby geometrie celé soustavy, materiály prvků či okrajové podmínky, jeţ jsou nutné pro výpočet řešení. Závěrem práce jsou prezentovány dosaţené výsledky u vypočtených variant. V první variantě, která byla počítána, byl uvaţován případ kostní tkáně, u které vlivem namáhání nedojde k zhoršení mechanických vlastností pod implantovanou dlahou. V určitých případech, kdy je kostní tkáň nevhodně zatěţována, však dochází k nekróze kostní tkáně pod částí Burch-Schneiderovy dlahy. Tato moţnost je postihnuta v druhé variantě modelu. Pro kaţdou z variant byl vypočten případ s aplikovanými šrouby a bez nich. Ve všech variantách byly uvaţovány zhoršené mechanické vlastnosti spongiózní kostní tkáně a vliv jejich změny na dosaţené výsledky. Problém byl řešen výpočtovým modelováním v programu Ansys Workbench 12.0.This master‘s thesis deals with strain-stress analysis of hip joint together with the final applied total endoprosthesis with Burch-Schneider cage. The main point of my work was to find the solution of stress–strain analysis state, which has been mentioned before in connection with Burch-Schneider cage. I describe the technique of geometric creation of whole body system, component´s materials or conditions which are neccessary for calculation. In coclusion there are results achieved in variants. In the first option the case of bone tissue was considered, which don’t reach degradation mechanical properties effect straining under Burch-Schneider cage. In some cases when the bone tissue is untimely forced, the necrosis of bone tissue takes place under Burch-Schneider cage. This possibility is described in the second option of type. For every option there was a case which was calculated with applied screw or without it. In all option mechanical features of cancellous bone tissue and their change influence on achieved results were considered. This problem was solved computational simulation in commercial software Ansys Workbench 12.0.

Experimental verification of the power required for the movement of the tracked vehicle

This article deals with the experimental verification of the power requirements of the tracked vehicle power unit while driving on a flat terrain. Requirements are based on results of a dynamic simulation. At first, the article presents the description of the simulation model, including the virtual terrain, on which the vehicle was moved. Second, a description of the experiment performed directly on the real prototype is presented. Measured variables were flow rates and pressures in the hydraulic system, whereby the power transmission from the engine to drive sprockets of four tracked undercarriages is ensured. Finally, there is the comparison of the calculated and measured time-power characteristics. The results correspond to each other

Determination of the modal parameters on the thin flat structures

This paper presents the investigation of modal parameters using the different approaches. The object of the examination is the simple structure such as flat rectangle plate is. Before starting the measurement, there have been calculated natural frequencies of the plate by analytical approach. Subsequently, the experiment part is performed. The appropriate measuring apparatus has to be applicated for the experimental analysis. First, there are evaluated modal parameters of the specimen, the so-called “frequency sweep” is used as the input signal for excitation. After that, the experimental harmonic analysis is performed according the obtained eigen frequencies from the modal analysis. In the final stage, the data from simulations and experimental measurement are compared

Investigating the influence of computational model complexity on noise and vibration modeling of powertrain

The paper presents advanced computational models suitable for the development of a modern powertrain in the field of noise and vibration. The aim is to decide how detailed the model should be to correctly describe the vibrational and acoustic performance of the powertrain. In general, the advanced computational model of the powertrain – a virtual powertrain – is developed as a powerful tool for the solution of structural and also thermal and fatigue problems. Main results from the field of vibrations are verified by technical experiments using laser vibration technique and strain gauges. Afterwards, the simpler computational models are compared with the virtual powertrain and the results are discussed. The virtual powertrain is assembled, as well as numerically solved, in Multi Body System extended by user written subroutines. The virtual engine results are validated by measurements performed on compression ignition in-line six-cylinder engine

Complex strategy for a development of highly elastic couplings

This paper presents complex strategy for a development of highly elastic couplings. There are presented methods how to determine the dynamics characteristic of the coupling. The highly elastic coupling is applied to the connection of an in-line six-cylinder natural gas engine and an electrical generator. Loading forces are applied based on the values of combustion pressures measured in an engine cylinder. Experimental verification of the computational model results was carried out by measuring the values on a testing engine using non-contact laser measuring technique

Heavy-Duty Transmission Gear Shift Investigation by Virtual Prototypes

This paper deals with application of virtual prototype to the heavy-duty vehicles gearbox concept. Used methodology was developed and validated on the single stage gearbox concept. Afterwards the virtual prototype was applied to complex gearbox and extended for gear shift. Gear shift has a significant influence on comfort of vehicle and also for its lifetime. The gear shift process has to be fast and smooth as much as possible, which is very difficult. This paper deals with using virtual prototype to see the effect of different gear shift process on the vibration of gearbox. The validation by the experimental approach of gearshift has not been performed yet

Parameter effecting the experimental determination of modal properties

The investigation of structure dynamic behavior can be done by finding modal properties, which are based on the relation of force and vibration response. The information about exact force value is in most application unknown, but the investigation can be done for unit magnitude of force. In case of using modal exciter, the force applied to structure is transferred by connection between modal exciter and structure. The stiffness of connection part can affect the dynamic behavior and change the modal properties, or response of investigated part, because of additional modal properties of connection part. This article is focused on the influence of two different rod stiffness during modal properties identification. The modal exciter is used to find potential critical frequency during decreasing frequency. The affect is evaluated on the surface normal velocity as well as acoustic pressure. The stiffness of rod significantly affects the dynamic response of structure and based on that can add frequency, when the emitted noise is high

Transmission error analysis for heavy-duty gearbox

This paper deals with an analysis of the transmission error. For this purpose, the measuring loop was assembled from two gear boxes. Subsequently, angles, torque and shaft speed were set or measured. For the evaluation a calculation method was used and the impact of the different transmitted torque was evaluated. The measuring loop enables to test at different operation conditions of torque and shaft rotation direction. In this paper, the static transmission error analysis for braking mode at 50 rpm shaft speed and torque range from 600 to 2400 Nm is described