ORIGINAL_ARTICLEIn this article, two positions of a lobe-shaped nozzle intended for the ejector mixing process are compared. The objective of the experiments was the identification of the cross-shaped nozzle flow pattern. The measurements of nozzle velocity profiles were conducted at a pressure of 2 kPa. Separate nozzle velocity profiles were measured from the nozzle mouth up to the distance of 90 mm and 180 mm, in 15 mm or 30 mm intervals respectively. In this way, 10 velocity profiles were measured per each nozzle position and consequently used for the final diagram. An important principle for the recommendation of a nozzle for the mixing process was the characteristics of cross-shaped nozzle velocity profiles measured at different positions, using the modern contactless measurement method - Laser Doppler Anemometry (LDA). Based on the measured data, the cross-shaped nozzle velocity profiles were described in detail. Defects of the cross-shaped nozzle were identified by the experiments and thus its unsuitability for the ejector mixing process.https://acc-ern.tul.cz/archiv/PDF/ACC_2011_1_01.pdf2011-06-30714PetrDolejš1AUTHOR

ORIGINAL_ARTICLEIn this paper, the graph-based models of planetary gears are discussed. The considered methods are as follows: linear (Hsu’s) graph, contour (Marghitu’s) graphs and bondgraphs. The original rules for the use of graph based methods were modified by the authors making them more adequate and more useful. The selected planetary gear was analyzed to show a course of calculations for the proposed methods in comparison with the traditional Willis method. The advantages of the graph based method consist in submission of an algebraic structure of a gear – which allows for an application of some AI approaches. Bondgraphs models of a subgear were presented. It additionally allows for algorithmic generation not only kinematical equations but also for relationships according to forces and accelerations or power.https://acc-ern.tul.cz/archiv/PDF/ACC_2011_1_02.pdf2011-06-301524JózefDrewniak1AUTHORJerzyKopeć2AUTHORStanisławZawiślak3AUTHOR

ORIGINAL_ARTICLEThe paper describes one of the principles of the backlash-free gear using tooth wheels. A design of a backlash-free gearbox with countershafts is solved in detail. Backlashes in a gear of tooth wheels and bearings are determined by a preloaded torsion-bar spring. A dependence of reaction forces applied to the tooth system and bearings on the torque bar preload is examined. Using a computer program created in the Maple environment, a loaded gear run is simulated in the speed reversal. The results are used to checkthe strength, material fatigue, and service life of dynamically loaded gear components.https://acc-ern.tul.cz/archiv/PDF/ACC_2011_1_03.pdf2011-06-302531Backlash-free geargearingtorsion-bar springpreloadaccurate position control systemVojtěchKlouček1AUTHOR

ORIGINAL_ARTICLEThe theoretical part of the paper deals with basic information about repair of gas pipeline with steel repair sleeves and simulation programme SYSWELD. The experimental part includes analysis of boundary conditions in two-pass fillet welding joint. By analyzing the boundary conditions welding speed, temperature cycles, macrosctructural analysis and its digitization can be determined. Using these boundary conditions welding process in programme SYSWELD was simulated. The results of the simulation are illustrated by means of temperature fields and temperature cycles.https://acc-ern.tul.cz/archiv/PDF/ACC_2011_1_04.pdf2011-06-303242RadoslavKoňár1AUTHORJaromírMoravec2AUTHORMilošMičian3AUTHOR

ORIGINAL_ARTICLECast aluminum-silicon alloys are used in a number of automotive and industrial weight sensitive applications because of their low weight and very good castability. Modifiers are usually added to molten aluminum-silicon alloys to refine the eutectic phase particle shape and improve the mechanical properties of the final cast products and Al-Si alloys cast properties. In terms of aluminum-silicon, this usually involves the addition of strontium (Sr), sodium (Na) or antimony (Sb). The cast properties fluidity and mould filling capacity play a key role in the production of thin-section and geometrically complex cast parts. The presence of trapped gas or shrinkage pores in certain locations within castings has been shown to influence fatigue life. In this paper the influence of Sb on the gas content and flowability of AlSi6Cu4 has been researched.https://acc-ern.tul.cz/archiv/PDF/ACC_2011_1_05.pdf2011-06-304351DušanMedlen1AUTHORIvaNová2AUTHORDanaBolibruchová3AUTHORDušanUrgela4AUTHOR

ORIGINAL_ARTICLEIn this research, the evaporation resistance Ret [m2Pa/W] of knitted fabrics made from different core elastic ratios have been investigated; these fabrics have been extended to different levels and the evaporation resistance have been measured under these variations of extensions. It was found, that the evaporation resistance for the knitted fabric from elastic core yarn under the study decreased with the increase of the extension in the course direction.https://acc-ern.tul.cz/archiv/PDF/ACC_2011_1_06.pdf2011-06-305259M.Motawe1AUTHORAntonínHavelka2AUTHORZdeněkKůs3AUTHOR

ORIGINAL_ARTICLEThe article is concerned with the dynamic analysis of the mechanism of the needle transfer, which has been carried out by means of Lagrange equations of the second kind, with the purpose to determine kinematic magnitudes of the individual elements. There have been established geometrical and physical properties of the individual elements, and the initial conditions have been determined. Furthermore, there have been compiled motion equations, and they have been complemented with the boundary conditions providing for the proper function of the mechanism. A program for the solution of the proper motion equations has been generated in the environment of Matlab Simulink, including the boundary and initial conditions. The results of the dynamic analysis have been processed graphically.https://acc-ern.tul.cz/archiv/PDF/ACC_2011_1_07.pdf2011-06-306070KarelPejchar1AUTHORJaroslavBeran2AUTHOR

ORIGINAL_ARTICLEVibrating conveyors as components of assembly lines are used in various technical branches, especially in the automotive industry. They do not only provide mechanical handling of differently shaped and sized parts, but they also allow the transport of loose materials. Hereby the main principle for the transportation of parts is based on the oscillating movements of the carrying element which, at the same time, imparts the vertical and horizontal velocity to the transported item. The vibration conveyors are driven by means of mechanical exciters or electromagnetic components. The mechanical exciters, based on the rotation of an unbalanced object, are either directly attached to the carrying element of the conveyer or are connected to the element that is joined to the conveyor by a flexible linkage. The electromagnetic components induce periodic power or moments between the carrying element and the frame. Generally, it is aimed to tune the system in a way to have the natural frequency according to the main transportation movement matching or nearly matching with the exciter frequency. The transport performance in relation to the energetic requirements of the drive is highest in the resonance zone.https://acc-ern.tul.cz/archiv/PDF/ACC_2011_1_08.pdf2011-06-307179MarekPešík1AUTHOR

ORIGINAL_ARTICLECurrently, the car manufacturers are dealing with optimization of seats, especially by reduction of weight and height, considering energy and ecological aspects of the used materials, at the same time maintaining or improving the existing parameters of the seat and back seat. Much emphasis is given to parameters of seating comfort and safety of car seats during a car crash. One possibility of seat weight reduction is by changing the construction of the seat cushion by incorporating viscoelastic composite reinforcement. Experimental quasi- static and dynamic tests were performed for samples of viscoelastic composite reinforcement materials for evaluation of mechanical properties. For deformation analysis of viscoelastic reinforcement, dummies (virtual human body) were loaded in a car seat and FEM simulation models were applied.https://acc-ern.tul.cz/archiv/PDF/ACC_2011_1_09.pdf2011-06-308088MichalPetrů1AUTHOROndřejNovák2AUTHOR

ORIGINAL_ARTICLEThe behavior in compression and the elastic recovery of highsloft materials can be described by a Kelvin-Maxwell rheological model. The proposed model is a serial combination of the Kelvin model (parallel connection of Newtonian viscous fluids and elastic materials) and the Maxwell model (serial combination of Newtonian viscous fluids and elastic materials). This combination is able to cover the plastic deformation and relaxation behavior.||In this paper an algorithm for the determination of the input parameters of the proposed rheological model based on experimental data on condition that the load phase is carried out||at constant stress for the time t0 will be presented.https://acc-ern.tul.cz/archiv/PDF/ACC_2011_1_10.pdf2011-06-308993JanaPřívratská1AUTHORKatarinaZelová2AUTHOR

ORIGINAL_ARTICLEThe paper deals with dynamic analysis of the driving system of small diameter knitting machines. Its main object is the description and analysis of the existing structural configuration of the drive. The present arrangement of the drive provides for a coupled motion of the needle cylinder and the dial, realized by a single driving unit. From the technological point of view, it is necessary to provide for a minimum deviation of swinging of principal parts of the machine during an operating cycle. The paper describes the compilation of a mathematical model. The motion equations have been devised by means of Lagrange equations of the second kind. They have been solved by means of the software Matlab and its superstructure Simulink. As the result, there have been obtained the courses of kinematic variables of basic parts of the driving system.https://acc-ern.tul.cz/archiv/PDF/ACC_2011_1_11.pdf2011-06-3095101JosefSkřivánek1AUTHORMartinBílek2AUTHOR