Journal of Engineering and Thermal Sciences
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Stable parametric identification of vibratory diagnostics objects
Get PDFA common model of vibratory diagnostics objects is the stochastic difference schemes, and theirs parametrical identification is carried out least squares and least absolute deviations techniques. It is well known that these techniques are unstable under stochastic heterogeneity of observable process, specifically, in the presence of outliers. One way to make the stable parametrical identification of vibratory diagnostics objects is implementation of generalized least absolute deviations method based on concave loss function. Obtained requirements to the loss function guaranteeing the steadiness evaluation, algorithms of identification and examples are presente
Application of piezoactive material/rheological fluid composite structures in engineering
Get PDFActive materials are rapidly expanding their variety as well as applications due to their promising high–tech potential. Composite structures of active materials enable researchers to develop mechatronic systems and devices with inherent intelligence features and increased level of integration. A composite structure consisting of piezoactive material and electrorheological fluid is proposed, and its possibilities in developing self-adjusting and adaptive systems are discusse
A flat compound piezoelectric actuator of a type “a shaking beam”
Get PDFIt is investigated piezoelectric actuator, consisting of two flat converters of longitudinal fluctuations which ends are close by the hence – « a shaking beam ». Also is resulted the principle of work actuator in quality stator of the motor, and also as the ultrasonic concentrator of fluctuations. Additionally is made research of it actuator with the help of programs computer modeling. And is carried out optimization of the sizes driver hence actuator. Theoretical researches are confirmed experimentally, with the help of the precision laser equipmen
Computer-aided modeling of the adaptive intelligent vehicle safety systems
Get PDFThe paper presents classification of type of movement of motor vehicles and reports on computer-aided modeling and virtual design of active safety systems. An algorithm of identification of the moment of transition of wheel sliding from a steady range of sliding to unstable is described as well. In the presented research work results of computeraided modeling of anti-lock braking systems (ABS) that are based on a force principle are discussed and important questions of modeling and design of active safety system in CoDeSys environment are considere
Low – frequency acoustic instability of the working process in the combustion chamber of the solid propellant rocket engine
Get PDFThe following problems is investigated by statement of direct numerical experiment in offered paper. 1) The real oscillatory process is reproduced. 2) The mechanism of occurrence and refill of low-frequency acoustic instability in the combustion chamber of the solid propellant rocket.. The direct numerical modeling of low-frequency acoustic instability will be carried out by a Davydov’s method. This powerful numerical method was discovered by Yuri M. Davydov 40 years ago as the method of large particles The further modern complex improvement of this numerical technique was titled Davydov’s method. It is good itself recommending at the decision of many tasks of the mechanics of continuous media. The description of physical and mathematical model of flow in the rocket engine combustion chamber is given. The results of numerical modeling are resulted. The hydrodynamical deeply nonlinear nature of low-frequency fluctuations connected to structure and character of current in the combustion chamber of the solid propellant rocket engine proves to be tru
Dynamic orientation of systems for excitation of transverse and longitudinal waves
Get PDFA theoretical and numerical analysis of dynamic systems for excitation of longitudinal and transverse waves with a self-direction is carried out. Formulas for definition of excitation frequency and a difference of phases depending on system parameters are obtained. Conditions for existence and stability of the steady-state motion regimes are define
Research of nonlinear electromechanical and vibro-impact interactions in electrostatically driven microactuator
Get PDFThis paper provides results of dynamic numerical analysis of nonlinear electromechanical and vibro-impact interactions in electrically-actuated contact-type microactuator, which is a common component in such devices as microswitches. Mathematical modeling was performed by means of finite element method, representing microactuator as a 3D cantilever microstructure and taking into account influence of bending forces generated by electrostatic field, damping forces due to squeezed air-film in the gap as well as bouncing of the microactuator tip upon its contact with substrate. Electrostatic-structural simulations were performed in order to predict actuation (pull-in) voltages of fabricated microswitches as well as to study influence of various system parameters on the value of the voltage. Results of these simulations were compared with experimental findings obtained by using electrical probe measurements of fabricated microswitches. Numerical analysis of free impact vibrations was carried out and allowed determination of effect of ambient air pressure and intermolecular adhesive interactions on the phenomenon of contact bouncin
Analysis of holographic interferogram of microelectromechanical system with non harmonic cycles excitation
Get PDFRecent technological trends based on miniaturization of mechanical, electromechanical and photonic devices to the microscopic scale have led to the development of microelectromechanical systems (MEMS). Effective development of MEMS components requires the synergy of advanced design, analysis, and fabrication methodologies as well as application of quantitative metrology techniques for characterizing their performance, reliability and integrity during design stage. In this paper, we describe analysis of holographic interferograms of MEMS links which includes interferometric fringes related to deformation appearing because of the non-harmonic excitation of MEMS link
Vibratory alignment of the parts during robotized assembly
No full textPaper deals with vibratory alignment of the components during robotized assembly as one of the parts is gripped by the robotic gripper and provided with vibratory excitation along the assembly direction. Numerical simulation of parts alignment was carried out. The dependencies of vibratory alignment duration on dynamic system and excitation parameters were determined. Existing areas of parameter sets, where reliable alignment is taking place, were defined. Results of numerical simulation were verified experimentally. Obtained results of numerical simulation and experiments demonstrated that under properly chosen system and excitation parameters, vibratory method may be successfully applied in robotized assembly for peg-hole parts alignmen
Analysis of the dynamics of the vibratory valve-injector
Get PDFConstruction of a novel vibratory valve-injector and its design optimization is presented in the paper. The principle of the system operation is based on the effect of dynamic positioning of a steel ball in a vibrating tube. Theoretical analysis of the stability of this non-linear system is coupled together with the experimental study of an operating valve. Laser holographic interferometry is used for the identification and optimization of working regimes of the syste