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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
Evaluation of cracked construction elements durability and estimation of structural strength under vibrations
Get PDFThe manuscript deals with the research of relevant problems of cracked elements under cyclic loading. In contrast to the majority of published research work that is dedicated to the case of symmetrical cyclic loading, this paper proposes a methodology for evaluation of influence of asymmetric cyclic loading. First part of the manuscript is concerned with straight crack growth dependence on loading parameters using probabilistic analysis. Speed of crack growth and stress intensity factor values are obtained from experimental studies. Assessment of these parameters can be made using method of Monte Carlo however it is not common and the current research is carried out by applying a more simple averaging method. For elements under asymmetrical loading a general-purpose equation is proposed. Symmetrical cycle and pulsing cycle parameters are used. As a result of these two parameters a general equation is obtained for computational number of loading cycles. This technique enables estimation of durability of elements under various types of loadings with the defined size of the crac
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
Tool edge geometry’ and wear’ recognition by using contact method
No full textThe aim of this paper is to present a device to measure non-destructively the geometry of cutting edges as well as to detect the wear. This might sound easy. One might propose a usual optical way where an edge is illuminated by an inclined beam and observed from the top. Another might try to use a surface roughness measurement device. However, those were all tested in the past and ended up with a total failure or severe limitation in application. The major reason consists in the size of roundness. For the case of a lancet or shaving knife the roundness is of the order of 2 – 5 µm and varies along the periphery covering over 300 degrees. This paper presents a non-destructive method, which consists of a mechanical device and software package for performing reading and mathematical calculations as well as obtaining practical knowledge on the relationship between the sharpness and performance of various sharp edges according to their purpose
Vibration based research into temperature influence on circular saw parameters
Get PDFThe study presents the research results of transverse sawing circular saws in conjunction with the oscillatory research of a non-rotating circular saw. It reveals that amplitude-frequency characteristics, resonance frequencies and modes were established and operative heating regimes of the saws were modelled. It was determined that the form of the main modes insignificantly changes when the saw is heated. At the same time heating temperature considerably influences the value of both high and low resonance frequencies, as well as the size of amplitude. During the examination damping coefficient within temperature interval was estimated and both surface and deep hardness of the saw were determined. The study shows that the temperature of the saw significantly changes its surface hardness, but its deep hardness remains less changed. The research results allow forecasting the behaviour of saws during operatio
Failure analysis of destructive coils
Get PDFThe failure of the destructive pulsed power coils has been investigated. The destructive coil is the key element of the laboratory system which generates half-period abrupt magnetic field pulses with the amplitudes up to 45 T. The transient coupled non-linear magneto-mechanical model has been applied for finite element simulations. The mechanical behavior and operation threshold of the coil have been examined. It has been found that operation threshold of the coil with relatively thin cylindrical reinforcement could be characterized by the opening of the plastic hinge and estimated numerically. Good agreement with experimental results has been observe
Experimental researches of a flexible waveguide of ultrasound vibrations
No full textIn this paper we report the results of experimental research of a new flexible and variable-rigidity waveguide, which operation is based on ultrasound vibrations. The tested waveguide is a combination of conical-stepped-cylindrical waveguides, which enables significant improvement of dynamic characteristics with respect to various existing static loads. The resonant frequency for excitation of the waveguide is in the range of 24-26 kHz. The measurements presented in this paper were performed on a STANDA vibration-isolation honeycomb-type table by means of the POLYTEC laser Doppler vibrometer system MSV-400 consisting of a laser interferometer OFV-512, vibrometer controller OFV-5000 and analog-to-digital converter ADC-2424 (PICO,GB) as well as by using HYTEC holographic interferometry system PRIS
Concept and methods of adaptive vibration protection and stabilization
Get PDFThe paper considers the concept, the general formulation of problems and the algorithms of adaptive real-time control of multivariate vibration protection and stabilization of multi-axis chassis position in space, which provide in general case the solution of the problems of oscillations moderation and motion stabilit
Thermaly mechanisms in electrostaticaly actuated microelectromechanical structures
Get PDFThe paper reports results of the performed research work related to the deformations and stability of Al-Si parallel-plate electrostatic microactutors fabricated on silicon-on-insulator (SOI) wafer and subjected to uniform temperature changes. Presented research includes measurements of the deformation of Si beam with deposited Al thin-film microstructures as a function of temperature changes using Electronics Speckle Pattern Interferometry (ESPI) and a custom-built thermal module that is covered by optical beam splitter window to allow optical acces
Mechatronic structure of modern test bench for precise angle calibration
Get PDFMany optoelectronic measuring instruments, vibro-scanning devices and deflection systems have angular sensors or circular scales as a reference measure for angle determination. Most of angle measuring devices must be tested or calibrated with a relevant precision therefore a special test rig for these purposes is needed. At current technical level the precision of measurements of vibro-displacement, amplitudes or frequency of vibrations implies not only precise manufacturing and assembly but also a necessity to incorporate modern computer technologies enabling automation of the measuring process. All these components of modern technologies can be accomplished by using mechatronic constituents. This paper presents a brief review of the angle testing/calibration equipment with the integrated mechatronic device