Journal of Engineering and Thermal Sciences
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Investigation of vibrations of a tape in the printing device
Get PDFStability and controllability of a welding arc have a large influence on both the weld quality and welding productivity in the process of welding. Metal fusing and weld forming depend on the forces affecting the arc. Welding current creates electromagnetic forces, which basically define the influence of arc forces on molten metal. While estimating the magnitude of the influence of electromagnetic forces, it is necessary to investigate the radial distribution of arc pressure on the surface of a weld pool and take into account the dependence of distribution of electromagnetic forces on the non-consumable electrode tip geometry
Investigation of vibrations of a sheet of paper in the printing machine
Get PDFIt is assumed that a sheet of paper performs transverse vibrations as a plate having additional stiffness due to static tension in its plane. The first eigenmodes are determined. The setup for experimental investigation of the nodal lines of the standing waves and for the determination of eigenmodes using projection moire is created for the analysis of unsymmetric loading of the paper. The comparison of the theoretical and experimental results of investigations is performed. The obtained results could be used in the process of design of the elements of the printing devic
Vibration dampers for transmission of mechatronic systems
Get PDFThe paper reviews original torsional vibration dampers retaining their efficiency in a wide disturbing frequency band. Some potential design alternatives are considered. The basic structural element of the damper is a rotary flexible ring. The mathematical model of the system estimates inertia, flexible and gyroscopic terms. The equations to calculate the system motion are derived and stability conditions for the system dynamic balance are formulated, proper consideration is given to other possible stability loss forms and regions of the flexible ring. The analysis of the system natural frequencies is made. Efficiency estimation of the damper versus various parameters is effected following the expression of the equivalent inertia moment and its limit value
Usage of the powder metallurgy method for fabrication of titanium implant alloy
Get PDFIn the paper research of the new implant titanium alloy obtained by powder metallurgy method were presented. The Ti15Mo2,8Nb alloy was fabricated from pure alloying component powders. The structure was observed by scanning electron microscope and analyzed by X-ray diffraction. The effect of grinding time of mixtures as well as the size of titanium powder grain on compatibility, compression strength and yield point of sintered alloys was analysed. It was found that grain size has a significant effect on strength properties of the alloy. However, the prolonging of grinding time caused deterioration of compatibility as well as mechanical properties of sinter
Directional conjugate smoothing for analysis of axi-symmetric fluid vibrations
Get PDFNumerical implementation of the Abel transform for the construction of digital fluid holographic images is analyzed in this paper. Volumetric strains are obtained from the numerical calculations using the displacement formulation by the method of finite elements. Then the field of volumetric strain is obtained by using the procedure of conjugate approximation with smoothing. Numerical procedure is developed for the calculation of the Abel transform on the basis of the right rectangle numerical integration rule and thus the digital holographic image is constructed. The obtained digital holographic images are used in the hybrid experimental – numerical procedure for the determination of the correlation with the experimental holographic image
The research of characteristics of electric arc on weld pool formation
Get PDFStability and controllability of a welding arc have a large influence on both the weld quality and welding productivity in the process of welding. Metal fusing and weld forming depend on the forces affecting the arc. Welding current creates electromagnetic forces, which basically define the influence of arc forces on molten metal. While estimating the magnitude of the influence of electromagnetic forces, it is necessary to investigate the radial distribution of arc pressure on the surface of a weld pool and take into account the dependence of distribution of electromagnetic forces on the non-consumable electrode tip geometry
Interaction of vibrating and translational motions
Get PDFThe mathematical model describing the interaction of a vibrating system and a system performing translational motion is proposed. Such motions take place in vibromotors. The main characteristics of the dynamic motion are defined. The model is investigated numerically and a number of graphical relationships are obtained. They are used in the process of design of systems with vibromotors like a walking inpipe robot
The advanced structural materials for living beings implants
Get PDFThe paper deals with development of bioinert and bioactive biomaterials, different application of structural materials, including metallic materials, nanomaterials, nanostructured materials, biomaterials, ceramics, polymers, hybrid materials, functional graded materials, composites. Also are discussed multi-functional engineering materials with gradient properties, engineering materials for challenging application conditions, including aggressive environment and lightweight, multi-material (hybrid) systems where advanced materials are combined with more conventional / structural materials and materials production or joining technologies. Interdisciplinary approach to biomedicine materials research and production is very promising and horizontal cooperation of different national technology platforms is discusse
The evaluation of resonant frequencies of rotary system with adaptive segmental sliding bearings by orbits of rotor rotation axis
Get PDFThis paper is based on research of work parameters of rotary systems with segmental sliding bearings, working system in the resonant regime. Primary signals are given doing experimental researches, they are analyzed with special programmable pockets and different formats of data are given. Evaluation of work state of rotary system is done in the resonant and in the normal regime by getting orbits of rotor rotation. The principal scheme of researching system is given in this work and its technical characteristics and principle of working are described. Methodology of experimental researches is given. The gained results are described in graphs and a comparison of obtaining results and its discussio
Development of threshold based EMG prosthetic hand
Get PDFThere is a real need of EMG (Electromyogram) based prosthetic hand for the amputee which should be economical as well as reliable. The cheap prosthetic hand available in market works passively. In those cases the patient does not feel the feeling of natural human hand. EMG based prosthetic hand provides the amputee feeling of natural human hand. The work that has been discussed here is to develop a prosthetic hand with one degree of freedom. The two motions developed were open and close. Most of the work is done at electronic level. The main work was to acquire the noiseless EMG signal and further to convert it into control signal for prosthetic hand, after suitable processing. For classification a threshold based technique has used rather than any classification technique like Artificial Neural Network (ANN), Fuzzy Logic and Genetic Algorithm (GA). It was tried to use the minimum hardware, without making any compromise with performance. It was done so, to achieve the target of developing a economical and reliable prosthetic hand. The threshold value used was variable and was controllable from outside by just varying the knob of potentiometer. This adds an additional dimension for tuning the device and scope to adjust the threshold according to muscle activity of subject. So the same prosthetic hand can be used by different amputees by just changing the threshold values only. The mechanical hand was having only two fingers to grasp the objects. The work was also extended to develop the frequency based Prosthetic hand. The scheme was to find out the frequency bands where the amplitude of open and close motions is different. The FFTs (Fast Fourier Transform) of EMG signal were calculated in MATLAB. The DSO (Digital Storage oscilloscope) was also having the facility of displaying the FFT of signal. It was found that there is certain possible frequency band which classifies the open and close motion of han