Journal of Vibroengineering
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Dynamics of tactile device drive
Full text linkA study of novel tactile device transient processes that occurs during the information transmission has been described. Mathematical model has been presented and investigation of pin drive dynamics were performed. Results of investigations allowed us to evaluate the influence of drive parameters and operating regimes on the pin motion, and may be used in engineering practice for tactile device developmen
Possibilities of assessment of reliability of an anthropotechnical system
Full text link"Reliability and safety characteristics [7] of an anthropotechnical system are the basic information about the correctness of relation between a man (e.g. pilot) and a helicopter (machine). Methods of defining them are still an open problem. The article presents an innovative way of definition of reliability characteristics of a pilot and a helicopter engine as well as an entire anthropotechnical system. Described are theoretical bases of this method, which are various configurations of the ""equation of state"" describing relations pilot – helicopter and helicopter – pilot [8, 9]. Defined was the set of ""numbers of limit state violations"" of the parameter of pilot’s physical condition aP and technical state of the helicopter aS, which as ""premises of damage"" were used for calculation of estimators of reliability characteristics. It is noteworthy that these characteristics could be particularly useful in the process of comparing different pilots and helicopters in various situations appearing in the course of utilisation
Analysis of insertion process for robotic assembly
Full text linkInsertion process of cylindrical parts with clearance for robotic assembly using vibratory excitation is analyzed in the paper. Mathematical model of vibratory parts insertion process, which determines peg contact with the chamfer of the bush, peg one point and two point contact with the bush hole, was formed. Simulation of cylindrical parts insertion process was performed. The influence of vibrations on the insertion process, when mobile based peg is kinematically excited in axial direction, was determined. The combinations of excitation and system parameters, under which insertion process duration is the shortest and the process is the most reliable, were detecte
Validation of vibration analysis using photo-elastic coatings
Full text linkThe analysis of vibrations is performed using a plate bending element assuming that a coating has no effect to the motion of the plate. The stresses in the coating are calculated by using the procedure of conjugate approximation. Then the relative error norms for the finite elements are determined. They are represented graphically and serve for validation of the results of calculations in hybrid experimental - numerical procedures
CFAR vibration signal change test and its applications to real-time recognition of developing cracks in jet engine rotors
Full text linkThis paper introduces a new technique for early identification of fatigue cracks, namely the constant false alarm rate (CFAR) test. This test works on the null hypotheses that a target vibration signal is statistically similar to a reference vibration signal. In effect, this is a time-domain signal processing technique that compares two signals, and returns the likelihood whether the two signals are similar or not. The system monitors the vibration signal of the rotor as it cycles, and compares that vibration signal with, say, the original vibration signal. The difference vector reflects the change in vibration over time. As a crack develops, the vector changes in a characteristic way. Thus, it is possible, during CFAR test, to determine whether the two signals are similar or not. Therefore, by comparing a given vibration signal to a number of reference vibration signals (for several crack scenarios) it is possible to state which is the most likely condition of the rotor under analysis. The CFAR test not only successfully identifies the presence of the fatigue cracks but also gives an indication related to the advancement of the crack. This test, despite its simplicity, is an extremely powerful method that effectively classifies different vibration signals, allowing for its safe use as another condition monitoring techniqu
Vibrations of a double wall plane adaptive to electrorheological materials
Full text linkAn analytical study of vibrations response and control capabilities of an Electrorheological (ER) material-filled double wall plate to random excitation pressure is presented. The governing equations of motion are developed by incorporating the ER material constitutive relations to thin face plate equations. A three-parameter viscoelastic model is used to characterize ER material behaviour in pre-yield regime. The effect of electric field strength on the response of the double wall sandwich plate with ER material is investigated. Numerical results include response spectral densities and modal frequencies for several ER material core thicknesses and different electric field level
Surgical treatment of the vertebrae fractures in the lower-breast and lumbar localization with the contemporary technologies
Full text link"The absence of the unique approach to a problem of treatment of fragmented fracture of the lowest thoracic and lumbic part of a spinal column makes the given problem very actual. The purpose of the work is to mark the surgical methods applied to patients with fragmented fracture of the lowest thoracic and lumbic part of a spinal column. The material of research is based on the given supervision over the patients with the given pathology, operated on in clinic of the Traumotology and Orthopedi on the basis of UZ ""GKO"" ""SMP"" in Grodno. The decompressive-stabilizing operations with the use of transpeduncular fixators were applied in treatment. Offer new way of surgical treatment of traumas of a spinal column: combined spondilodezis with the use of transpeduncular fixators and deminiralizating bone matrix. While analyzing the results of treatment good results were revealed
Measurement of sportsman‘s jump psychomotoric reaction
Full text linkFor representatives of sport games are very important components of physical abilities – spring and rate of psychomotoric reaction. For the following sportsman’s especially important is the rate of psychomotoric reaction, which defines reaction to the constantly changing ambience, similar to the sport action. Testing system, which simulates the situation of sports game, was created in the department of Informatics and biomechanics of LKKA. This system allows estimating the physical capabilities of player – spring and the speed of psychomotoric reaction. The speed of psychomotoric reaction is evaluated by making the jump-up. The influence of the height of jump-up on the spring and speed of reaction of sportsman is investigated. Considering the results of experiments and statistical analysis some recommendations are given and conclusions withdraw
The advanced structural materials for living beings implants
Full text linkThe 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