Multidimensional Vibrations of Cable-Harnessed Beam Structures with Periodic Pattern: Modeling and Experiment

The dynamics of space structures is significantly impacted by the presence of power and electronic cables. Robust physical model is essential to investigate how the host structure dynamics is influenced by cable harnessing. All the developed models only considered the decoupled bending motion. Initial studies by authors point out the importance of coordinate coupling in structures with straight longitudinal cable patterns. In this article, an experimentally validated mathematical model is developed to analyze the fully coupled dynamics of beam with a more complex cable wrapping pattern which is periodic in nature. The effects of cable wrapping pattern and geometry on the system dynamics are investigated through the proposed coupled model. Homogenization-based mathematical modeling is developed to obtain an analogous solid beam that represents the cable wrapped system. The energy expressions obtained for fundamental repeating segment are transferred into the global coordinates consisting of several periodic elements. The coupled partial differential equations (PDE) are obtained for an analogous solid structure. The advantage of the proposed analytical model over the existing models to analyze the vibratory motion of beam with complex cable wrapping pattern has been shown through experimental validation.

Measurement of Vibrating Tympanic Membrane in an In Vivo Mouse Model Using Doppler Optical Coherence Tomography

Optical coherence tomography (OCT) has a micro-resolution with a penetration depth of about 2 mm and field of view of about 10 mm. This makes OCT well suited for analyzing the anatomical and internal structural assessment of the middle ear. To study the vibratory motion of the tympanic membrane (TM) and its internal structure, we developed a phase-resolved Doppler OCT system using Kasai’s autocorrelation algorithm. Doppler optical coherence tomography is a powerful imaging tool which can offer the micro-vibratory measurement of the tympanic membrane and obtain the micrometer-resolved cross-sectional images of the sample in real-time. To observe the relative vibratory motion of individual sections (malleus, thick regions, and the thin regions of the tympanic membrane) of the tympanic membrane in respect to auditory signals, we designed an experimental study for measuring the difference in Doppler phase shift for frequencies varying from 1 to 8 kHz which were given as external stimuli to the middle ear of a small animal model. Malleus is the very first interconnecting region between the TM and cochlea. In our proposed study, we observed that the maximum change in Doppler phase shift was seen for the 4 kHz acoustic stimulus in the malleus, the thick regions, and in the thin regions of the tympanic membrane. In particular, the vibration signals were higher in the malleus in comparison to the tympanic membrane.

The Basic Parameters of Vibration Settings for Sealing Horizontal Surfaces

Are examined and defined pattern vibratory motion to form horizontal surfaces on the basis of the account of wave phenomena and bias voltages. Given numerical values screeds and rheological characteristics of sealing concrete.Based on the analysis of the energy balance, motion qualities limits are defined. Analytical dependences for the estimation of main parameters of the effective vibroimpact mode are suggested as well as the motion stability layout of the analyzed system is cited.

Modifying the Shape of Blades of a Flexible Reed in a Vibration Beat-up Mechanism – Theoretical Investigation

The beat-up mechanism of a loom with exciters for vibrating motion of the reed is presented . With the placing of exciters at regular distances across the width of the reed, certain differences can be observed in the amplitudes of the vibratory motion of individual blades. Undercutting is proposed here as a method of reducing these differences. The permissible distance between the exciters was determined taking into account the undercut reed. The undulation of the reed in the process of thickening of the wefts is shown to be a consequence of undercutting. For a distance between the exciters of L = 200 mm and relative depth of the undercut h0/h = 0.8, differences in the amplitudes of individual blades do not exceed 10%.

On Improvement of Operation Bandwidth of Duffing-Like Vibration-Based Harvesters Using a Mechanical Motion Rectifier

A novel vibration-based energy harvester which consists of a monostable Duffing oscillator connected to an electromagnetic generator with a mechanical motion rectifier (MMR-Duffing) is studied. The mechanical motion rectifier converts the bi-directional vibratory motion from ambient environments into uni-directional rotation to the generator and causes the harvester to periodically switch between a larger- and small-inertia system, resulting in nonlinearity in inertia. By means of the method of averaging, it is analytically shown that the proposed Duffing-MMR harvester outperforms traditional monostable Duffing oscillator energy harvesters in twofold. First of all, it increases the bandwidth of energy harvesting, given identical nonlinear stiffness. Second of all, it mitigates the jump phenomenon due to nonlinear stiffness and thus exploits more potential bandwidth of energy harvesting without inducing any jump phenomenon. Finally, the analytical analyses are verified via numerical simulations of a prototype of the proposed Duffing-MMR harvester.

INFLUENCE OF THE GRANULAR MIXTURE PARTICLES SIZES AND OSCILLATION FREQUENCY ON THE SEPARATION PROCESS AT THE CONICAL SIEVES WITH OSCILLATING MOVEMENT

<p>The paper presents the results of experimental researches on the working process and his efficiency for a sieve with external conical surface with alternative periodic motion. The sieve is suspended at the top and bottom with three elastic threads (of silk), with thread diameter f1.5<em> </em>mm and is provided with circular apertures of f4.2<em> </em>mm. Vibratory motion was obtained with an eccentric mechanism, placed horizontally and acting on tangential direction to the sieve at adjustable distance. . Was thus obtained amplitude oscillation of 3.58, 3.74, 3.91 and 4.10 mm. The oscillation frequencies used were 250, 520 and 790 osc/min. The sieve was used for sorting of canola seeds having sizes between f1.25 mm and f2.5 mm, in percent of 95 %.</p><p>It was found that seeds are separated closer to the feeding point of sieve the more so as the oscillation frequency is smaller. Seeds of a size less than 1.5 mm is separated close to the axis of rotation. Also, the sieve orifices can properly calibrate a seeds mix for all oscillation frequencies analyzed.</p>

The Manipulator Tool Fault Diagnostics Based on Vibration Analysis in the Frequency Domain

The issues presented in the article, relate to the detection of damage of a cutting tool used in robotised machining. Due to the time saving requirements, it is desirable to carry out the current control of the tool mounted in the holder of the robotic manipulator. The tool is a ceramic fiber brush used for grinding. A typical damage of the brush is fiber breakage, which leads to an unbalance of the tool and vibrations. The phenomenon of vibrations and parameters of the vibratory motion of the tool have been used as a carrier of information about the state of the tool. On the basis of the measurement data, obtained during tests of tools with varying degrees of damage, classifiers of the tool state were built. Two types of classifiers were tested: decision trees and artificial neural networks. The results confirm that it is possible to build a classifier of the tool state with high effectiveness reaching up to 99,875%.