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Journal articles on the topic 'Mechanical Vibration'
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1
Ragaišis, L., R. Jonušas, K. Ragulskis, and V. Jurėnas. "Research of Possibilities of Energy Transformation Using an Autovibrating System, Excited by Small Outer Excitement." Solid State Phenomena 113 (June 2006): 207–12. http://dx.doi.org/10.4028/www.scientific.net/ssp.113.207.
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There are lots of sources of disturbance in people’s surrounding environment - e.g. wind, sea, river flow, and intensive acoustic noise. These sources can cause auto vibrations of particular dynamic systems. Such phenomenon could be used for converting mechanical vibration energy to electrical energy. Solving this problem is topical because it could help to create autonomic sources of renewable energy. Dynamic model, described by a presumptive differential motion equation, of auto vibrating system, affected by airflow is made and inspected. Possible modes of vibrations and different states of nonlinear auto vibrating system are analyzed using methods of Newmark and Runge-Kutta. Auto vibration existence zones of the system are designated. Reliance on the existence of poly-solutions, stability or chaotic solutions of vibrating system is estimated. Consistencies of using electro dynamical principle of converting mechanical vibration energy to electric energy are inspected.
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Гапонюк, Т. О., Р. В. Кірчук, and Л. Ю. Забродоцька. "USING HYDRAULIC PARAMETRIC VIBRATION EXCITER IN AGRICULTURAL ENGINEERING." СІЛЬСЬКОГОСПОДАРСЬКІ МАШИНИ, no. 48 (October 31, 2022): 7–14. http://dx.doi.org/10.36910/acm.vi48.778.
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Vibration technology is widely used in mechanical engineering, construction, road building and different sectors of the manufacturing. In agriculture, it is used for dosing feed, cleaning and sorting seeds, digging up root crops, planting potatoes, and transporting bulk materials. Vibrations make the mechanical system more stable in relation to external force disturbances and do not change the technological properties of materials during its movement along the working surfaces. Also, the material passing through the vibration zone is not damaged. A wide range of frequency and amplitude of vibrations provides the possibility of vibration regime varying, and the characteristics of the movement of agricultural plant material on the vibrating working bodies. The analysis of possibility of application of vibrating hydraulic drives as elements of transmission of movement to working bodies of agricultural machines is executed. A historical excursion was conducted and the first mentions of the use of hydraulic drives were pointed out. The estimation of technological processes in agricultural production where it is expedient and possible to use vibration and vibrating drives is made. At the present stage of development of agricultural engineering, using vibrating hydraulic drive is accorded to the basic trends of agriculture machinery development. The stand for conduction of studies of amplitude-frequency characteristics of the vibrating drive with regulated perturbations is offered. A mathematical model is presented, which generally describes the course of the vibration process and estimates the stiffness of the mechanical system. The hydraulic parametric vibration exciter is recommended to use for studying and determination the conditions for the occurrence of parametric vibrations in working body of agricultural machines. Also, using a hydraulic drive makes it possible to simplify the kinematics, reduce metal consumption, increase accuracy, reliability and level of automation of working bodies of agricultural machines.
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Zhang, Yinquan, Kun Huang, and Changxing Zhang. "Nonlinear Vibrations of Carbon Nanotubes with Thermal-Electro-Mechanical Coupling." Applied Sciences 13, no. 4 (February 4, 2023): 2031. http://dx.doi.org/10.3390/app13042031.
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Carbon nanotubes (CNTs) have wide-ranging applications due to their excellent mechanical and electrical properties. However, there is little research on the nonlinear mechanical properties of thermal-electro-mechanical coupling. In this paper, we study the nonlinear vibrations of CNTs by a thermal-electro-mechanical coupling beam theory. The Galerkin method is used to discretize the partial differential equation and obtain two nonlinear ordinary differential equations that describe the first- and second-order mode vibrations. Then, we obtain the approximate analytical solutions of the two equations for the primary resonance and the subharmonic resonance using the multi-scale method. The results indicate the following three points. Firstly, the temperature and electric fields have a significant influence on the first-mode vibration, while they have little influence on the second-mode vibration. Under the primary resonance, when the load amplitude of the second mode is 20 times that of the first mode, the maximal vibrational amplitude of the second is only one-fifth of the first. Under the subharmonic resonance, it is more difficult to excite the subharmonic vibration at the second-order mode than that of the first mode for the same parameters. Secondly, because the coefficient of electrical expansion (CEE) is much bigger than the coefficient of thermal expansion (CTE), CNTs are more sensitive to changes in the electric field than the temperature field. Finally, under the primary resonance, there are two bifurcation points in the frequency response curves and the load-amplitude curves. As a result, they will induce the jump phenomenon of vibrational amplitude. When the subharmonic vibration is excited, the free vibration term does not disappear, and the steady-state vibration includes two compositions.
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Coelho, Andre Luiz de Freitas, Fábio Lúcio Santos, Francisco de Assis de Carvalho Pinto, and Daniel Marçal de Queiroz. "Detachment efficiency of fruits from coffee plants subjected to mechanical vibrations." Pesquisa Agropecuária Tropical 45, no. 4 (December 2015): 406–12. http://dx.doi.org/10.1590/1983-40632015v4536227.
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ABSTRACT The development of efficient machines for the mechanical harvesting of coffee plants requires the use of appropriate vibrational parameters. Thus, in order to detach less unripe fruits and decrease reharvesting, branch breakage and defoliation, it is important to choose the appropriate frequency, amplitude and vibration time. This study aimed at analyzing the detachment efficiency of fruits from coffee plants according to vibrational parameters and ripening stage. Fruit bunches were sampled at the green and mature stages and subjected to vibration, using a system composed by a signal generator, an amplifier and an electromagnetic vibrating machine. Tests combined different frequencies (16.4 Hz, 20.3 Hz, 24 Hz, 25.6 Hz, 30.0 Hz and 33.0 Hz), amplitudes (5.0 mm, 7.0 mm and 9.0 mm) and vibration times (10.0 s and 20.0 s). The vibration times did not affect the detachment efficiency. There was a trend for higher detachment efficiency in mature fruits than in green fruits. The detachment efficiency increased with increasing vibration frequency and amplitude.
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Beltran-Carbajal, Francisco, Hugo Francisco Abundis-Fong, Luis Gerardo Trujillo-Franco, Hugo Yañez-Badillo, Antonio Favela-Contreras, and Eduardo Campos-Mercado. "Online Frequency Estimation on a Building-like Structure Using a Nonlinear Flexible Dynamic Vibration Absorber." Mathematics 10, no. 5 (February 24, 2022): 708. http://dx.doi.org/10.3390/math10050708.
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The online frequency estimation of forced harmonic vibrations on a building-like structure, using a nonlinear flexible vibration absorber in a cantilever beam configuration, is addressed in this article. Algebraic formulae to compute online the harmonic excitation frequency on the nonlinear vibrating mechanical system using solely available measurement signals of position, velocity, or acceleration are presented. Fast algebraic frequency estimation can, thus, be implemented to tune online a semi-active dynamic vibration absorber to obtain a high attenuation level of undesirable vibrations affecting the main mechanical system. A semi-active vibration absorber can be tuned for application where variations of the excitation frequency can be expected. Adaptive vibration absorption for forced harmonic vibration suppression for operational scenarios with variable excitation frequency can be then performed. Analytical, numerical, and experimental results to demonstrate the effectiveness and efficiency of the operating frequency estimation, as well as the acceptable attenuation level achieved by the tunable flexible vibration absorber, are presented. The algebraic parametric estimation approach can be extended to add capabilities of variable frequency vibration suppression for several configurations of dynamic vibration absorbers.
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Shpachuk, V. P., M. A. Zasiadko, T. O. Suprun, and V. V. Dudko. "Variation coefficient of torsional vibrations of the connection nodes of vibrating machines." Naukovyi Visnyk Natsionalnoho Hirnychoho Universytetu, no. 6 (2021): 85–89. http://dx.doi.org/10.33271/nvngu/2021-6/085.
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Purpose. To formalize the dependence of the eigenfrequencies of translational and torsional vibrations of the structural elements of the vibrating machine articulated by the connection node on their design parameters and mechanical characteristics, as well as regulatory requirements for vibration activity, strength and accuracy. To develop a method for selecting the design parameters of the elastic band element of the package, taking into account the specified values of the amplitude and frequency characteristics of the dynamic loads reproduced by the supporting structure and the coefficient of variation of the natural frequencies of translational and torsional vibrations. Methodology. The research is based on fundamental approaches of applied mechanics, machine dynamics and vibration reliability. Findings. The dependences of the eigenfrequencies of torsional vibrations of the body parts of the vibrating machine connected by the connection node on their design parameters and mechanical characteristics are obtained and analyzed. Vibrations around an axis orthogonal to the working direction of the node are considered. A comparative analysis of the natural frequencies of the node in the direction of the transmitted vibration and its circular vibrations from the design parameters and mechanical characteristics of the elastic band elements, their number in the package and the number of packages in the connection node is performed. Originality. It is in the fact that for the first time the dependences describing the natural frequencies of translational and torsional vibrations of the body parts of a vibrating machine, articulated by a package of elastic band elements, are obtained. Also the paradigm for the choice of design parameters and mechanical characteristics of the elastic band element of the package, which is based on the results of a comparative analysis of the eigenfrequencies of vibrations in the working and connected directions through their coefficient of variation is innovative. This made it possible to include the criterion of vibration reproduction accuracy, which is formalized through the coefficient of frequency variation, together with the criteria of strength and rigidity, in the methodology of synthesis of the structural scheme of the vibrating machine. Practical value. The proposed methodological solutions for the calculation and selection of design parameters and mechanical characteristics of tape elastic elements ensure the achievement of vibration activity indicators of articulated parts, as well as the ratio of natural vibration frequencies in the working and related directions at the level of the requirements of normative documents when upgrading existing machines and creating new modern equipment. As a result, the reliability, durability, safety, productivity and load-bearing capacity of machines, equipment and mechanisms of mining engineering, aviation, transport and space technology are increased.
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Stosiak, Michał, Paulius Skačkauskas, and Adam Deptuła. "THE IMPACT OF MECHANICAL VIBRATIONS ON HYDRAULIC VALVES AND THE POSSIBILITY OF REDUCING THE EFFECTS." Aviation 28, no. 1 (March 28, 2024): 40–48. http://dx.doi.org/10.3846/aviation.2024.20904.
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The paper shows that mechanical vibrations occur in a wide frequency range in the hydraulic systems operating in the real world. Hydraulic valves are also exposed to these vibrations. The paper gives examples of vibration sources and suggests that the influence of vibrations on hydraulic valves could be reduced. Particular attention was paid to the vibrating proportional distributor. The amplitude-frequency spectrum of pressure pulsation in a hydraulic system with a vibrating proportional distributor was analysed. During the tests, the frequency of external mechanical vibrations acting on the proportional distributor and their direction was changed.
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Gunawan, Gani. "Penyelesaian khusus persamaan diferensial biasa ordo dua linier tak homogen dengan koefisien konstan untuk fungsi bagian demi bagian." Majalah Ilmiah Matematika dan Statistika 24, no. 1 (March 14, 2024): 1. http://dx.doi.org/10.19184/mims.v24i1.38240.
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Spring mechanical vibration motion system with a damped degree of freedom and influenced by external forces, is mathematically expressed as an ordinary differential equation of order of two linear constant coefficients that are not homogeneous. If an external force acts on a stationary system expressed as a continuous function f(t) for any time t, then the system will experience mechanical vibrational motion which mathematically the equation of motion can be expressed as a superposition. The equation consists of as a solution to a homogeneous form with mechanical vibrations as a solution to a particular form. In terms of the particular solution this article will show a mathematical way when f(t) is a continuous function section by part which is defined at an interval, such that the mechanical vibration motion equation is at the same time a special solution of the equation the mechanical vibration system.
Keywords: Vibration, Impulse Functions, ConvolutionMSC2020: 34A37
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Wang, Liping, Hung-Yao Hsu, Xu Li, and Cory J. Xian. "Effects of Frequency and Acceleration Amplitude on Osteoblast Mechanical Vibration Responses: A Finite Element Study." BioMed Research International 2016 (2016): 1–16. http://dx.doi.org/10.1155/2016/2735091.
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Bone cells are deformed according to mechanical stimulation they receive and their mechanical characteristics. However, how osteoblasts are affected by mechanical vibration frequency and acceleration amplitude remains unclear. By developing 3D osteoblast finite element (FE) models, this study investigated the effect of cell shapes on vibration characteristics and effect of acceleration (vibration intensity) on vibrational responses of cultured osteoblasts. Firstly, the developed FE models predicted natural frequencies of osteoblasts within 6.85–48.69 Hz. Then, three different levels of acceleration of base excitation were selected (0.5, 1, and 2 g) to simulate vibrational responses, and acceleration of base excitation was found to have no influence on natural frequencies of osteoblasts. However, vibration response values of displacement, stress, and strain increased with the increase of acceleration. Finally, stress and stress distributions of osteoblast models under 0.5 g acceleration inZ-direction were investigated further. It was revealed that resonance frequencies can be a monotonic function of cell height or bottom area when cell volumes and material properties were assumed as constants. These findings will be useful in understanding how forces are transferred and influence osteoblast mechanical responses during vibrations and in providing guidance for cell culture and external vibration loading in experimental and clinical osteogenesis studies.
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Trtík, Tomáš, Roman Chylík, Josef Fládr, and Jitka Vašková. "The Analysis of the Intensity and Vibration Time on the Mechanical Properties of Hardened Concrete." Solid State Phenomena 322 (August 9, 2021): 28–34. http://dx.doi.org/10.4028/www.scientific.net/ssp.322.28.
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In order to achieve optimal physical and mechanical properties of hardened concrete, it is necessary to determine the right intensity and vibration time of fresh concrete during casting. Since concrete is considered as a polydisperse substance and various aggregate grains move randomly during vibration, it is very difficult to describe this stochastic phenomenon using exact physical equations and it is more advantageous to apply an experimental approach to verify the effects of vibration on fresh concrete. The effect of vibrations on fresh concrete increases the speed gradient of individual grains and thus reduces the viscosity of the cement paste. The intensity of vibration is determined mainly by the frequency, amplitude and centrifugal force of the eccentric of the vibrating machine. The optimal vibration time is generally considered to be the "minimum required". Insufficient vibration caused by an unsuitable vibrating machine or a short vibration time can result in insufficient compaction of the aggregate grains, non-release of accumulated air from the fresh concrete mixture, formation of cavities or poor-quality casting of parts of the structure with a higher degree of reinforcement. Vibration with excessive intensity or time can also be considered dangerous. The over-compaction of concrete is most often demonstrated by segregation of aggregates. The presented research deals with the determination of the optimal time and intensity of vibration of fresh concrete mixture to achieve the required physical properties of concrete, i.e. high compressive strength and modulus of elasticity of hardened concrete while reducing the negative effects of vibration, especially segregation of aggregates.
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Kadoura, A., N. A. Abdul Jalil, M. Arumugam, and M. A. Azman. "A short review on the effect of mechanical vibration in the evaluation and replacement of bone cement-anchored implants in human bone." Journal of Physics: Conference Series 2721, no. 1 (March 1, 2024): 012003. http://dx.doi.org/10.1088/1742-6596/2721/1/012003.
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Abstract Mechanical vibration can be defined as the regular or irregular repetitive movement that makes the body leave its resting state. Mechanical vibrations have an important role in keeping the bones and joints healthy. This review study aimed to investigate the effect of mechanical vibration in the evaluation and replacement of bone cement-anchored implants in human bone. The empirical studies related to mechanical vibrations and bone cement-anchored implants were reviewed. The combinations used to search for studies related to the topic included mechanical vibrations, evaluation, replacement, bone, cement-anchored implants, and human bone. The reviewed studies show that mechanical vibration, either local or whole-body, promotes bone growth in and around the implant. The stimulation of bone growth is important for the strength and durability of cement-anchored bone implants. Through the reviewed studies, it was concluded that local or whole-body mechanical vibration improves the stability and durability of bone and bone implants. Mechanical vibration achieves this effect by increasing bone formation in and around the implants and by improving the contact between the implant and the bone.
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Bernardo-Filho, Mario, Debra Bemben, Christina Stark, and Redha Taiar. "Biological Consequences of Exposure to Mechanical Vibration." Dose-Response 16, no. 3 (July 1, 2018): 155932581879961. http://dx.doi.org/10.1177/1559325818799618.
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A special issue of the journal Dose-Response entitled “Biological Consequences of Exposure to Mechanical Vibration” is proposed. When there is the interaction of physical agents, such as mechanical vibration to a body, physiological stress can be generated leading to expected and unexpected consequences. The aim is to describe effects due to the stress generated by the energy delivered in biological systems by mechanical vibration produced by different sources through studies involving human beings and experimental models. The evaluation of effects in molecular, cellular, and systemic level will contribute to increase the medical and biological knowledge about the interaction of mechanical vibration, as well as the understanding of the stress and mechanisms of the biological responses of the mechanical vibrations. The main topics will be related to neurophysiological responses to mechanical vibration generated in different sources, clinical approaches of the mechanical vibration generated in oscillating/vibratory platform, undesirable effect of the mechanical vibration generated in oscillating/vibratory platform, mechanical vibration in occupational activities, biological effects of ultrasound and infrasound, and quantification and physical approaches of the mechanical vibration.
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Suryawanshi, Sagar. "A Review on Mechanical Motion Rectifier for Energy Harvesting." International Journal for Research in Applied Science and Engineering Technology 9, no. 8 (August 31, 2021): 2007–16. http://dx.doi.org/10.22214/ijraset.2021.37680.
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Abstract: The conventional vehicle suspension dissipates the mechanical vibration energy in the form of heat which waste considerable energy. The regenerative suspensions have attracted much attention in recent years for the improvement of vibration attenuating performance as well as the reduction of energy dissipation. In fact, the vibrations in some situations can be very large, for example, the vibrations of tall buildings, long vehicle systems, railroads and ocean waves. With the global concern on energy and environmental issues, energy harvesting from large-scale vibrations is more attractive. This paper introduces the existing research and significance of regenerative shock absorbers and reviews the potential of automotive vibration energy recovery techniques; then, it classifies and summarizes the general classifications of regenerative shock absorbers. Keywords: Mechanical vibration, regenerative suspension, energy dissipation, railroads, ocean waves, vehicle.
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Korotych, Yuriy. "VIBRATION TABLE MATHEMATICAL MODEL COMPOSING." TECHNICAL SCIENCES AND TECHNOLOGIES, no. 3(33) (2023): 83–96. http://dx.doi.org/10.25140/2411-5363-2023-3(33)-83-96.
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In this article, a mathematical model is obtained, which combines the design and technological parameters of the technological set of equipment for the concrete goods production (vibrating table), in which the vibrating exciter is fixed on the lever vertically in the center under the plate compactor. This equipment is used for the manufacture of small-sized concrete products. The mathematical model is composedwith the help of Lagrange equations of the second kind, which are the most common method for solving problems about the motion of a mechanical system. Methods of mathematical physics and physical and mathematical modeling by methods of applied mechanics were used in the compilation.To determine the position and describe the free motions of the material bodies that make up the mechanical system under consideration, an orthogonal vi-brational reference system of three coordinate systems was used. Analyzing the kinematic diagram of the vibration table, it is determined that the position in space of all material bodies of the mechanical system, which simulates the specified vibrating table, can be uniquely set by the following independent parameters: Cartesian coordinates, vibration angles and the angle of rotation of debalance.Thus, the mechanical system in question has seven degrees of freedom with seven generalized coordi-nates.As a result, a mathematical model of a vibrating table for concrete products manufacturing in the form of seven second order differential equations system, which describes the vibrating table spatial motion surface, is obtained.The theoretical values of the vibrating table vibrations amplitude at variable lever length were also determined and compared with experi-mental data at the same initial parameters. The difference was 15%, which confirms the adequacy of the created mathematical model to the real technological process on the vibrating table, which is being studied.Analyzing the change in the vibration oscillations amplitude on the vibrating table working surface from the change in the lever length on which the vibrating exciter is fixed, it was found that the lever fixation allows an almost linear increase in the amplitude of vibration oscillations due to an increase in the lever length. This, in turn, makes it possible to reduce energy consumption when compacting the concrete mixture.
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Ikeda, Keigo, Kota Kamimori, Ikkei Kobayashi, Jumpei Kuroda, Daigo Uchino, Kazuki Ogawa, Ayato Endo, et al. "Basic Study on Mechanical Vibration Suppression System Using 2-Degree-of-Freedom Vibration Analysis." Vibration 6, no. 2 (May 1, 2023): 407–20. http://dx.doi.org/10.3390/vibration6020025.
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Mechanical vibrations adversely affect mechanical components, and in the worst case, lead to serious accidents by breaking themselves. To suppress vibrations, various studies have been conducted on vibration isolation, suppression, and resistance. In addition, technologies to actively suppress vibration have been rapidly developed in recent years, and it has been reported that vibrations can be suppressed with higher performance. However, these studies have been conducted mostly for low-order systems, and few studies have employed control models that consider the complex vibration characteristics of multi-degree-of-freedom (DOF) systems. This study is a basic study that establishes a control model for complex control systems, and the vibration characteristics of a 2-DOF system are calculated using the vibration analysis of a multi-DOF system. Furthermore, the vibration suppression performance of the 2-DOF system is investigated by performing vibration experiments.
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Qin, Bin, Md Mahbub Alam, and Yu Zhou. "Free vibrations of two tandem elastically mounted cylinders in crossflow." Journal of Fluid Mechanics 861 (December 21, 2018): 349–81. http://dx.doi.org/10.1017/jfm.2018.913.
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The paper presents an experimental investigation on the flow-induced vibrations of two tandem circular cylinders for spacing ratio $L/D=1.2{-}6.0$ and reduced velocity $U_{r}=3.8{-}47.8$, where $L$ is the cylinder centre-to-centre spacing and $D$ is the cylinder diameter. Both cylinders are allowed to vibrate only laterally. Extensive measurements are conducted to capture the cylinder vibration and frequency responses, surface pressures, shedding frequencies and flow fields using laser vibrometer, hotwire, pressure scanner and PIV techniques. Four vibration regimes are identified based on the characteristics and generation mechanisms of the cylinder galloping vibrations. Several findings are made on the mechanisms of vibration generation and sustainability. First, the initial states (vibrating or fixed) of a cylinder may have a pronounced impact on the vibration of the other. Second, alternating reattachment, detachment, rolling up and shedding of the upper and lower gap shear layers all contribute to the vibrations. Third, the gap vortices around the base surface of the upstream cylinder produce positive work on the cylinder, sustaining the upstream cylinder vibration. Fourth, reattachment, detachment and switching of the gap shear layers result in largely positive work on the downstream cylinder, playing an important role in sustaining its vibration.
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Chen, Chuan Xiong. "Research on Stress Acoustic Model in the Process of Mechanical Self-Excited Vibration Based on Finite Element Method." Applied Mechanics and Materials 443 (October 2013): 189–93. http://dx.doi.org/10.4028/www.scientific.net/amm.443.189.
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The self-excited vibration of machinery is a common vibration in mechanical vibrations. Mechanical self-excited vibration destroys the normal working of the mechanical device and leads to mechanical fatigue damage. If the self-excited vibration reaches to the vibration frequency of machinery, it can produce the resonance and result in the scrapping of mechanical devices. The study of mechanical self-excited vibration has great significance. According to mathematical finite element methods, this paper establishes the mathematical model of the mechanical natural frequency through the finite volume method and gives the mathematical derivation formula of mechanical devices self-vibrated frequency. The second part of the paper simulates self-vibrated process of machinery using the professional software ANSYS software. First, it establishes a three-dimensional model of the mechanical device through the pre-processing module and analyzes mechanical self-excited vibration through calculation module and gets the frequency modal map of self-excited vibration process. It studies the mechanism of the mechanical self-excited vibration combining with modern signal analysis techniques--wavelet analysis. It gets the vibration source location which provides a reliable theoretical basis for the study of mechanical self-excited vibration.
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Dong, Jie, Yue Yang, and Zhi-Hui Wu. "Propagation characteristics of vibrations induced by heavy-haul trains in a loess area of the North China Plains." Journal of Vibration and Control 25, no. 4 (October 9, 2018): 882–94. http://dx.doi.org/10.1177/1077546318802980.
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To study heavy train-related vibration, this paper examines the world's largest heavy-freight railway – the Daqin Railway – to study the impacts of the seasonally frozen soil layer on vibrational acceleration. With increasing axle weight, the peak and mean values of the acceleration increased. Vibration acceleration attenuated the most from the shoulder to the embankment footing (51%–71%), while the vibrations at 70 m were attenuated by more than 90%. Certain measures must be taken by those living within 70 m of the railway shoulder. In addition, the acceleration peak caused by trains running in parallel after meeting amplified the vibration by 10%–39%. Moreover, the overall vibrations attenuate with increasing distance, whereas the local vibrations fluctuate. During the freezing period, the acceleration is 13%–26% greater than that of the unfrozen period. The vibration acceleration spectrum is comparatively wider, and is dominated by high-frequency components. Finally, using a three-dimensional model verified by field measurements, the vibrational features were analyzed at different embankment and foundation depths.
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Lai, Wei, Keping Zhou, Feng Gao, Zheng Pan, and Xiu Gao. "Experimental Study on Dense Settlement of Full-Tail Mortar under Mechanical Vibration." Minerals 13, no. 8 (August 13, 2023): 1077. http://dx.doi.org/10.3390/min13081077.
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There are some problems in the application of slurry preparation technology, such as wide fluctuation range of underflow concentration, long settling time and low efficiency of solid–liquid separation. This is an important basis for researching the thick settling law of tailings slurry under the action of mechanical vibration and its influencing factors to solve these problems. To this end, a small vibration thickening testing machine and vibrating rod were designed and developed. Physical simulation experiments were conducted to analyze the settling characteristics of tailings slurry under different vibration duration, start time, vibration frequency, and vibration inertia single factors. The results show that: (1) Mechanical vibration can effectively accelerate the settling speed of tailings particles, but the relationship between them is a non-positive correlation, and mechanical vibration time control with in 5 mins is the best. With the delay of starting the vibration time, the final mass concentration first increases and then decreases. (2) As the vibration frequency increases, the final mass concentration of tailings settlement first increases and then decreases. When the eccentric vibrator speed is 6000 r/min, the best slurry settlement effect is achieved. (3) When the vibration inertia of the eccentric oscillator is 0.158 g·cm2 and the final mass concentration reaches 70.1%, the settling time only takes 210 min. (4) The lower the slurry concentration, the faster the settling speed. As the initial concentration increases, the final thickening time is also gradually prolonged. The research results provide some insights for the rapid thickening technology of rake-free paste thickeners.
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Beltran-Carbajal, Francisco, Hugo Yañez-Badillo, Ruben Tapia-Olvera, Antonio Favela-Contreras, Antonio Valderrabano-Gonzalez, and Irvin Lopez-Garcia. "On Active Vibration Absorption in Motion Control of a Quadrotor UAV." Mathematics 10, no. 2 (January 13, 2022): 235. http://dx.doi.org/10.3390/math10020235.
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Conventional dynamic vibration absorbers are physical control devices designed to be coupled to flexible mechanical structures to be protected against undesirable forced vibrations. In this article, an approach to extend the capabilities of forced vibration suppression of the dynamic vibration absorbers into desired motion trajectory tracking control algorithms for a four-rotor unmanned aerial vehicle (UAV) is introduced. Nevertheless, additional physical control devices for mechanical vibration absorption are unnecessary in the proposed motion profile reference tracking control design perspective. A new dynamic control design approach for efficient tracking of desired motion profiles as well as for simultaneous active harmonic vibration absorption for a quadrotor helicopter is then proposed. In contrast to other control design methods, the presented motion tracking control scheme is based on the synthesis of multiple virtual (nonphysical) dynamic vibration absorbers. The mathematical structure of these physical mechanical devices, known as dynamic vibration absorbers, is properly exploited and extended for control synthesis for underactuated multiple-input multiple-output four-rotor nonlinear aerial dynamic systems. In this fashion, additional capabilities of active suppression of vibrating forces and torques can be achieved in specified motion directions on four-rotor helicopters. Moreover, since the dynamic vibration absorbers are designed to be virtual, these can be directly tuned for diverse operating conditions. In the present study, it is thus demonstrated that the mathematical structure of physical mechanical vibration absorbers can be extended for the design of active vibration control schemes for desired motion trajectory tracking tasks on four-rotor aerial vehicles subjected to adverse harmonic disturbances. The effectiveness of the presented novel design perspective of virtual dynamic vibration absorption schemes is proved by analytical and numerical results. Several operating case studies to stress the advantages to extend the undesirable vibration attenuation capabilities of the dynamic vibration absorbers into trajectory tracking control algorithms for nonlinear four-rotor helicopter systems are presented.
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Jiang, Shijie, Tiankuo Dong, Yang Zhan, Weibing Dai, and Ming Zhan. "Experimental Study on Improving the Mechanical Properties of Material Extrusion Rapid Prototyping Polylactic Acid Parts by Applied Vibration." Applied Sciences 11, no. 4 (February 18, 2021): 1820. http://dx.doi.org/10.3390/app11041820.
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Due to the stratified nature of the manufacturing process, material extrusion (ME) parts have lower mechanical properties than those fabricated by traditional technology. This is one of the most significant defects hindering the development and application of this rapid prototyping technique. In this paper, vibration was applied to the ME process by using piezoelectric ceramics for the first time to improve the mechanical properties of the built parts. The vibrating ME equipment was established, and the specimens processed in different build directions were individually fabricated without applied vibration and with different applied vibrations. To quantify the effect of applied vibration on their mechanical properties and to summarize the influencing rule, a series of experimental tests were then performed on these specimens. A comparison between the testing results shows that the tensile strength and plasticity of the specimens, especially those processed in the Z direction, can be obviously improved by applied vibration. The orthogonal anisotropy is decreased obviously. The improvement becomes greater with increasing vibration frequency or amplitude. From the microscopic point of view, it can be seen that applied vibration can reduce the part’s defects of porosity and inclusion as well as separation between layers and, thereby, improve the bonding strength.
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Uechi, Schun T., and Hiroshi Uechi. "A Mechanical Vibration-induced Electric Energy Generation (MVEG) and Applications to Ride Quality of Vehicles and International Roughness Index (IRI)." Studies in Engineering and Technology 6, no. 1 (May 28, 2019): 59. http://dx.doi.org/10.11114/set.v6i1.4301.
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A mechanical vibration-induced, electric energy harvesting method is discussed with applications to vibration analyses of systems of vehicles, motorboats, trains, machines and bridges, etc.. The research has evolved from the analysis of International Roughness Index (IRI), which studies roughness of road-surface as longitudinal vibrational motions in a vehicle measured with a quarter-car simulation (QCS) or Global Positioning System (GPS) with sensors such as gyro sensor and magnetometer sensor. The electric energy-convertible vibrations with information of roughness of road surface are extracted by way of an mechanoelectric energy conversion, and an energy harvesting technology suitable for the system of vehicles is discussed. The mechanical vibration-induced electric current is also suitable for IRI information measurement as well as a measure for ride quality of vehicles.
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Cieplok, Grzegorz. "Estimation of the resonance amplitude in machines with inertia vibrator in the coast-down phase." Mechanics & Industry 19, no. 1 (2018): 102. http://dx.doi.org/10.1051/meca/2017035.
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The work concerns mechanical systems with transient resonance formed as a result of an unbalanced rotating mass passing through an area of the system's natural frequency. In particular, this concerns over-resonant vibrating machines driven by inertia vibrators, which during start-up and coast-down pass through the natural frequency area related to the vibrating mass – flexible suspension system. The work analyses a system consisting of a soft-mounted machine body excited into vibrations by means of the inertia vibrator in order to designate the amplitude of resonant vibration, taking into consideration strong coupling between movements of the body and vibrator. The research results are presented in the form of nomograms and approximation formulas expressed in terms of relative parameters. The results of the theoretical research were verified on the laboratory model and industrial machines.
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Shimose, Shigeru, Kanjuro Makihara, and Junjiro Onoda. "Comparison of Analog and Digital Self-Powered Systems in Multimodal Vibration Suppression." Smart Materials Research 2012 (February 21, 2012): 1–9. http://dx.doi.org/10.1155/2012/287128.
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This paper compares our analog and digital self-powered systems for vibration suppression, and shows experimental results of multimodal vibration suppression for both self-powered systems. The experimental results are evaluated in light of the damping performance and adaptability under various vibrational conditions. We demonstrate various examples of our innovative vibration suppression method, called “digital self-powered.” Proper status switching of an electric circuit made up of an inductor and a selective switch connected to a piezoelectric transducer attenuates the vibrations. The control logic calculation and the switching events are performed with a digital microprocessor that is driven by the electrical energy converted from the mechanical vibration energy. Therefore, this vibration suppression system runs without any external power supply. The self-powering feature makes this suppression method useful in various applications. To realize an ideal vibration suppression system that is both self-powered and effective in suppressing multimode vibration, sophisticated control logic is implemented in the digital microprocessor. We demonstrate that our digital self-powered system can reduce the vibrational displacements of a randomly excited multimodal structure, by as much as 35.5%.
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Shikar Mammadov, Gunel Karimova, Shikar Mammadov, Gunel Karimova. "EFFECT OF VIBRATION ON CENTRIFUGAL COMPRESSOR." PAHTEI-Procedings of Azerbaijan High Technical Educational Institutions 39, no. 04 (April 15, 2024): 442–49. http://dx.doi.org/10.36962/pahtei39042024-442.
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Centrifugal compressors play a critical role in various industrial applications, including oil and gas, petrochemical, and aerospace industries. These machines are subjected to various operating conditions, including mechanical vibrations, which can significantly affect their performance, reliability, and longevity. Centrifugal compressors often face challenges related to mechanical vibrations, which can compromise performance and reliability. This article provides a comprehensive review of the effects of vibration on centrifugal compressors, covering the mechanisms of vibration generation, its impact on compressor components, and explores the application of active vibration control systems as a solution to mitigate vibration-induced issues in centrifugal compressors. Specifically, the implementation of active magnetic bearings (AMBs) is emphasized for its ability to actively suppress vibrations and enhance compressor stability. Through theoretical analysis and simulation results, the effectiveness of AMBs in reducing vibration levels and improving compressor performance is demonstrated. Keywords: compressors, centrifugal compressors, vibration, vibration effect on compressors.
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Pshinko, Oleksandr, Olena Hromova, and Dmytro Rudenko. "Study of Rheological Properties of Modified Concrete Mixtures at Vibration." Materials Science Forum 968 (August 2019): 96–106. http://dx.doi.org/10.4028/www.scientific.net/msf.968.96.
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Study of rheological properties of concrete mixtures based on modified cement systems in order to determine process parameters. Methodology. To study structural-mechanical properties of modified concrete mixtures of different consistency at their horizontal vibrating displacement an oscillatory viscometer was designed. Results. The optimization of the process of vibration displacement of concrete mixtures with the specification of parameters of vibration impacts taking into account structural-mechanical properties of the mixture is performed. It has been established that the viscosity of the modified cement system of the concrete mixture is a variable quantity, which depends on the parameters of the vibration impacts. Scientific novelty. The mechanism of interaction of the modified concrete mixture with the form and the table vibrator during its vibration compaction is determined. On the basis of this, a model of concrete laying process control is proposed, that allows to predict the ability to form a dense concrete structure. Practical significance. Disclosed physical nature of the process of vibrating displacement of modified concrete mixtures using the principles of physical-chemical mechanics of concrete allows reasonably choose the best options for vibration impacts.
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Spirin, Anatoly, Dmytro Borysiuk, Oleksandr Tsurkan, and Igor Tverdokhlib. "NFLUENCE OF VIBRATION ON THE ERGONOMIC INDICATORS OF THE PRODUCTION PROCESS." Vibrations in engineering and technology, no. 1 (108) (May 1, 2023): 45–56. http://dx.doi.org/10.37128/2306-8744-2023-1-5.
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Features of the impact of industrial vibration, the nature, depth and direction of physiological changes of various body systems depend on the level, frequency composition of vibrations and physiological properties of the human body. Vibration is one of the main causes of occupational diseases. The study of the sources of production vibration, the ways of its propagation, the specifics of the impact on the human body and protection against harmful effects is currently an urgent issue. The analysis of the latest sources shows that the majority of works consider individual elements of a complex system of ergonomic provision of safe working conditions in case of vibrational impact on workers. Therefore, there is a need to deepen the study of this issue, comprehensive consideration of the causes of vibration, its characteristics and specific effects on the worker's body, planning measures and means to minimize the consequences of its negative effects. There are two types of vibration: local, which primarily affects those organs of the human body that are in direct contact with vibrating elements, and general vibration, which causes the body to move in space and affects the entire body. The main parameters of vibration are amplitude and frequency of oscillations, speed and vibration acceleration. The effect of general vibration on the central nervous system leads to a disturbance in the balance between excitation and inhibition. Under the influence of vibration, workers become irritable, get tired quickly, feel drowsy (and sometimes, on the contrary, insomnia), work capacity decreases, the time it takes to complete production tasks increases, and the time of simple and complex reactions increases. The fight against the harmful effects of mechanical vibrations in most cases boils down to compliance with existing norms and rules. Also, a special role is played by means of protecting workers from the harmful effects of vibration. First of all, this is the improvement of the design of vehicles, machines, mechanisms and tools.
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Han, Feng Qi, Zhi Zun Li, and De Yuan Zhang. "Study on Oblique Cam Type Mechanical Torsional Vibrator." Applied Mechanics and Materials 215-216 (November 2012): 37–41. http://dx.doi.org/10.4028/www.scientific.net/amm.215-216.37.
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Vibrator is the key part of vibration tapping machine. In this paper, a kind of oblique cam type mechanical vibrator was designed. The vibrator has the advantages of simple structure and easy manufacturing, and the output amplitude of the vibrator can be adjusted by changing the inclination angle of oblique cam. It is verified by experiments that the process is successful when the oblique cam type vibrator is used to machine big thread holes, and compared with common continuous tapping, the torque of vibration tapping decreases significantly.
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Dohnal, F. "Experimental studies on damping by parametric excitation using electromagnets." Proceedings of the Institution of Mechanical Engineers, Part C: Journal of Mechanical Engineering Science 226, no. 8 (March 1, 2012): 2015–27. http://dx.doi.org/10.1177/0954406212439515.
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Transient vibrations in mechanical systems are a common problem in engineering. Several theoretical studies have shown analytically and numerically that a vibrating system can be stabilised or its vibrations can be reduced when excited close to a specific parametric combination resonance frequency. At this operation, the transient vibrations are effectively damped by parametric excitation. The basic step in exploiting this method is its experimental implementation in mechanical systems. In this review, recent experiments are discussed for a simple chain mass system, a continuous cantilever and a flexible rotor system. The parametric excitation is realised by electromagnetic variable-stiffness actuators driven by a periodic open-loop control. It is demonstrated experimentally that a parametrically excited structure can exhibit enhanced damping properties. A certain level of the excitation amplitude has to be exceeded to achieve the damping effect in which the existing damping in the system is artificially amplified. Upon exceeding this value, the additional artificial damping provided to the system is significant and most effective for vibration suppression of the lower vibration modes.
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Jurevicius, M., V. Vekteris, V. Turla, A. Kilikevicius, and G. Viselga. "Investigation of the dynamic efficiency of complex passive low-frequency vibration isolation systems." Journal of Low Frequency Noise, Vibration and Active Control 38, no. 2 (January 3, 2019): 608–14. http://dx.doi.org/10.1177/1461348418822230.
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In this study, the theoretical and experimental investigations of the dynamics of complex passive low-frequency vibration systems are described. It is shown that a complex system consisting of a vibrating platform, an optical table and a vibration isolation system of quasi-zero stiffness loaded by a certain mass may isolate low-frequency vibrations in a narrow frequency range only. In another case, the system does not isolate vibrations; it even operates as an amplifier. The frequencies that ensure the top efficiency of the vibration damping system of quasi-zero stiffness were established.
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Shi, Lian, and Lei Liu. "Vibration Test Measures for Pump Fault Diagnosis." Journal of Electronic Research and Application 5, no. 6 (November 30, 2021): 6–10. http://dx.doi.org/10.26689/jera.v5i6.2683.
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The vibration measuring standard for compound machinery utilized in modern industrial production will be employed for the application of detecting technologies. The vibration intensity can be obtained by selecting the detecting method to obtain the speed of mechanical vibration, and technicians can examine whether the vibrating machinery is in a proper functioning state based on the value of vibration intensity, allowing for thorough fault diagnosis. In order to provide useful diagnosis ideas for technicians, this study examines the measurement of mechanical vibration and investigates the calculating method of mechanical vibration intensity.
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VISELGA, Gintas, Vytautas TURLA, Ina TETSMAN, and Jan Radek KAMINSKI. "Dynamic Research on Low-frequency Vibration Isolation Tables." Mechanics 29, no. 3 (June 17, 2023): 207–13. http://dx.doi.org/10.5755/j02.mech.32385.
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In the paper, an establishment of dynamic characteristics of tabletops of the newly-developed optical tables is being discussed upon. Low-frequency vibration isolation systems are reviewed. Theoretical and experimental tests have been performed. Dynamic models of an optical table on a vibrating platform at different excitations have been developed, the dynamic displacement and the resonance frequencies of the system have been established and vibration transmissibility curves have been presented. The obtained dynamic characteristics of the mechanical passive low-frequency vibration isolation system show that such a system is able to isolate the vibrations effectively. The results of the performed experimental tests confirm the data of the theoretical research.
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Mkrtychev, O. V. "Vibration effect on mechanical vibration systems." Journal of the Novorossiysk Branch of the Belgorod V. G. Shukhov State Technological University. Series: Mechanics and Mathematics 1, no. 3 (2021): 15–19. http://dx.doi.org/10.51639/2713-0657_2021_1_3_15.
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Lu, Qin-Qin, Da-Chuan Yin, Yong-Ming Liu, Xi-Kai Wang, Peng-Fei Yang, Zheng-Tang Liu, and Peng Shang. "Effect of mechanical vibration on protein crystallization." Journal of Applied Crystallography 43, no. 3 (April 15, 2010): 473–82. http://dx.doi.org/10.1107/s0021889810009313.
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Mechanical vibration often occurs during protein crystallization; however, it is seldom considered as one of the factors influencing the crystallization process. This paper reports an investigation of the crystallization of five proteins using various crystallization conditions in a temperature-controlled chamber on the table of a mechanical vibrator. The results show that mechanical vibration can reduce the number of crystals and improve their optical perfection. During screening of the crystallization conditions it was found that mechanical vibration could help to obtain crystals in a highly supersaturated solution in which amorphous precipitates often normally appear. It is concluded that mechanical vibration can serve as a tool for growing optically perfect crystals or for obtaining more crystallization conditions during crystallization screening.
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Barros, Everaldo de, Carlos d'Andrade Souto, Leandro Ribeiro de Camargo, and Mauro Hugo Mathias. "Application of a computer sound card for measurement of mechanical vibrations." Revista Brasileira de Ensino de Física 37, no. 4 (December 2015): 4313–1. http://dx.doi.org/10.1590/s1806-11173742036.
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This paper presents a data acquisition and analysis system based on a computer sound card for measuring and processing random vibration signals. This system turns the computer into a two-channel measurement instrument which provides sample rate, simultaneous sampling, frequency range, filters and others essential capabilities required to perform random vibrations measurements. An easy-to-use software was developed for vibration monitoring and analysis, including facilities for data recording, digital signal processing and real time spectrum analyzer. Since the tasks of vibration data acquisition frequently require expensive hardware and software, this versatile system provides students a very accurate and inexpensive solution for experimental studying mechanical vibrations.
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Zhou, Yu, Qiongqiong Tang, Shulei Zhang, and Dajun Zhao. "The Mechanical Properties of Granite under Ultrasonic Vibration." Advances in Civil Engineering 2019 (January 20, 2019): 1–11. http://dx.doi.org/10.1155/2019/9649165.
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The new technique of using ultrasonic vibration to break hard rock is still in the experimental stage, but it has significant potential for improving the efficiency of hard rock crushing. We have analyzed the mechanical properties of granite under ultrasonic vibration and the characteristics of the damage produced. This was achieved by using an ultraloading device to apply continuous and discontinuous ultrasonic vibrations, respectively, to 32 mm diameter and 72 mm high granite samples. An ultradynamic data acceptor combined with strain gauges was used to monitor the strain of the granite in real time, and the elastic-plastic deformation behavior of the granite under ultrasonic vibration was observed. The results of this experiment indicate that the granite samples underwent elastic deformation, plastic deformation, and damage during this process. The samples first experienced compressive deformation with no obvious rupturing. As the vibration continued, the deformation finally became tensile, and significant fragmentation occurred. The mechanical properties of granite under ultrasonic vibration are analyzed in detail on the basis of these results, and the basis for selecting a vibration frequency is discussed.
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Linh, N. N., V. A. Tuan, N. V. Tuan, and N. D. Anh. "Response analysis of undamped primary system subjected to base excitation with a dynamic vibration absorber integrated with a piezoelectric stack energy harvester." Vietnam Journal of Mechanics 44, no. 4 (December 30, 2022): 490–99. http://dx.doi.org/10.15625/0866-7136/17948.
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Dynamic vibration absorber (DVA) integrated with a piezoelectric stack energy harvesting subjected to base excitation is introduced in this paper. The system of dynamic vibration absorber and piezoelectric stack energy harvesting system (DVA-PSEH) has two functions, the first is to reduce vibrations for the primary system, and the second is to convert a part of the vibrational energy into electricity through the piezoelectric effect. The mechanical and electrical responses of the electromechanical system are determined by the complex amplitude method, then the numerical simulations are carried out to investigate the characteristics of DVA-PSEH.
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Chomette, Baptiste, and Jean-Jacques Sinou. "On the Use of Linear and Nonlinear Controls for Mechanical Systems Subjected to Friction-Induced Vibration." Applied Sciences 10, no. 6 (March 19, 2020): 2085. http://dx.doi.org/10.3390/app10062085.
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Friction-Induced Vibration and noisE (FIVE) is still a complex and nonlinear physical phenomenon which is characterized by the appearance of instabilities and self-sustained vibrations. This undesirable vibrational phenomenon is encountered in numerous industrial applications and can cause major failures for mechanical systems. One possibility to limit this vibration phenomenon due to the appearance of instabilities is to add a controller on the system. This study proposes to discuss the efficiency but also limitations of an active control design based on full linearization feedback. In order to achieve this goal, a complete study is performed on a phenomenological mechanical system subjected to mono or multi-instabilities in the presence of friction. Transient and self-excited vibrations of the uncontrolled and controlled systems are compared. More specifically, contributions of linear and nonlinear parts in the control vector for different values of friction coefficient are investigated and the influence of the control gain and sensitivity of the controller to the signal-to-noise ratio are undertaken.
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Li, Jinyu, Xiaoyan Lei, Zhongqiu Zuo, and Yi Xiong. "Vibration Model of a Power Capacitor Core under Various Harmonic Electrical Excitations." Energies 15, no. 5 (March 2, 2022): 1848. http://dx.doi.org/10.3390/en15051848.
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Power capacitors are widely used in power transmission systems. During their operation, an electric force acting on the electrodes of the power capacitors actuates mechanical vibrations and radiates an audible noise. Considering a power capacitor as a general system, the frequency response with the electric force as the input and mechanical vibration as the output have been measured by engineers in recent years and used to evaluate the acoustic and mechanical features of products. Accidentally, it was found that the frequency of the capacitor vibration was not consistent with its excitation due to electro-mechanical coupling. This electro-mechanical coupling had not been considered in previous vibration models of power capacitors. Therefore, a new vibration model of power capacitors was built up in this paper and a so-called multi-frequency vibration characteristic was revealed. A theoretical analysis showed that the electric force and mechanical vibration of the power capacitors were coupled, which resulted in the multi-frequency vibration. The vibration frequency response was measured and the result was consistent with the vibration model proposed in this paper. Once the frequency of the electric force was near half the natural frequency of the power capacitor, a predominant multi-frequency vibration was triggered and the power capacitor was in a superharmonic resonance.
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Hajduk, Mikuláš, Dan Florin Niculescu, Adrian Olaru, Marek Vagaš, and Adrian Ghionea. "Research on Vibratory Behavior Assessment and Maintenance of Drilling and Threading Machine VA20A." Applied Mechanics and Materials 436 (October 2013): 205–12. http://dx.doi.org/10.4028/www.scientific.net/amm.436.205.
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Vibrations due to mechanical defects,are transmitted within the entire structure of the equipment, are amplified during its dynamical operation, having a direct impact on the accuracy of the processed surfaces. Spectral components need vibration analysis is required. In order to determine the operation state and the vibration level caused by the mechanical failures , the FFT (Fast Fourier Transform Method) method has been used. The vibrations measurements is repeated at constant intervals; It specify the measured vibration limits; It compares the values in ISO-sites exist for determining optimal predictive maintenance intervals.
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Xuan, Yan, Linyun Xu, Guanhua Liu, and Jie Zhou. "The Potential Influence of Tree Crown Structure on the Ginkgo Harvest." Forests 12, no. 3 (March 19, 2021): 366. http://dx.doi.org/10.3390/f12030366.
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Ginkgo biloba L. has significant health benefits and considerable economic value, but harvesting the fruit is highly labor-intensive. Mechanical vibration harvesting has been shown effective in harvesting various fruit types. In the study of vibration harvesting, the research on the vibration characteristics of fruit trees focuses on the natural frequency (resonance frequency), model, and damping coefficient, which are the main factors affecting the vibration characteristics of trees. But field harvesting experiments have shown that the tree structure may have an impact on the vibration characteristics of the fruit tree and the efficiency of mechanical harvesting. In addition, the research on the damping coefficient of fruit trees is mainly low-frequency damping, and the relevant results cannot be applied to the actual vibration harvesting frequency range. Applying a natural frequency with low damping coefficient to excite a tree can reduce additional energy dissipation. This study explored the influence of ginkgo crown structure on the vibration characteristics and the law of damping changes with frequency. After counting 273 ginkgo trees, two typical ginkgo crown structures, monopodial branching and sympodial branching, were selected to be analyzed for vibration spectrum and damping coefficient. The vibration models for different crown-shaped ginkgo trees were simulated to analyze the vibration state at different frequencies. For sympodial branching ginkgo trees, the consistency of natural frequencies at different branches was better than monopodial branching ginkgo trees. The finite element model analysis shows that monopodial branching ginkgo trees have mainly partial vibrations at different branches when vibrating at high frequencies. The high-frequency vibrations in sympodial branching reflect the better overall vibration of the canopy. The damping coefficients for the two crown types decreased with the increase in frequency. The monopodial branching damping coefficient was 0.0148–0.0298, and the sympodial branching damping coefficient was slightly smaller at 0.0139–0.0248. Based on the test results, the sympodial branching ginkgo tree has better vibration characteristics. The results indicate that controlling the crown structure of fruit trees to be sympodial branching by pruning may help improve the overall vibration characteristics of fruit trees.
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Rao, B. V. A., and S. Narayanan. "Mechanical vibration analysis." Journal of Sound and Vibration 153, no. 3 (March 1992): 565–66. http://dx.doi.org/10.1016/0022-460x(92)90387-d.
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Ding, Hu, and J. C. Ji. "Vibration control of fluid-conveying pipes: a state-of-the-art review." Applied Mathematics and Mechanics 44, no. 9 (September 2023): 1423–56. http://dx.doi.org/10.1007/s10483-023-3023-9.
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AbstractFluid-conveying pipes are widely used to transfer bulk fluids from one point to another in many engineering applications. They are subject to various excitations from the conveying fluids, the supporting structures, and the working environment, and thus are prone to vibrations such as flow-induced vibrations and acoustic-induced vibrations. Vibrations can generate variable dynamic stress and large deformation on fluid-conveying pipes, leading to vibration-induced fatigue and damage on the pipes, or even leading to failure of the entire piping system and catastrophic accidents. Therefore, the vibration control of fluid-conveying pipes is essential to ensure the integrity and safety of pipeline systems, and has attracted considerable attention from both researchers and engineers. The present paper aims to provide an extensive review of the state-of-the-art research on the vibration control of fluid-conveying pipes. The vibration analysis of fluid-conveying pipes is briefly discussed to show some key issues involved in the vibration analysis. Then, the research progress on the vibration control of fluid-conveying pipes is reviewed from four aspects in terms of passive control, active vibration control, semi-active vibration control, and structural optimization design for vibration reduction. Furthermore, the main results of existing research on the vibration control of fluid-conveying pipes are summarized, and future promising research directions are recommended to address the current research gaps. This paper contributes to the understanding of vibration control of fluid-conveying pipes, and will help the research work on the vibration control of fluid-conveying pipes attract more attention.
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Alphin, M. S., J. Paul Chandra Kumar, and B. Jain A. R. Tony. "Biomechanical Response of the Human Foot Model Exposed to Vibrations: A Finite Element Analysis." Journal of Biomaterials and Tissue Engineering 11, no. 11 (November 1, 2021): 2097–108. http://dx.doi.org/10.1166/jbt.2021.2748.
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Prolonged exposure to mechanical vibration has been associated with many musculoskeletal, vascular and sensorineural disorders of the foot from simple Plantar fasciitis and Achilles Tendonitis to complex ones as Tarsal tunnel syndrome (TTS) and Vibration white feet/toes. Foot-transmitted vibrations (FTV) are exposed to the occupants using vibrating equipment’s or standing on vibrating platforms. Prolonged exposure to foot-transmitted vibrations (FTV) can lead to syndromes like vibration white feet/toes may result in tingling sensation, blanching of the toes and even numbness in the feet and toes. A multi-layered two dimensional, plane strain finite element model is developed from the actual cross-section of the human foot to study the stresses and strains developed in the skin and soft tissues. The foot is assumed to be in contact with a steel plate, mimicking the interaction between the foot and the work platform. The skin and the subcutaneous tissue are considered as hyperelastic and viscoelastic. The effects of loading in the form of displacements and the frequency of sinusoidal vibration on a time-dependent stress/strain distribution at various depths in the subcutaneous tissue of the foot are investigated. The simulations indicate that lower frequency vibrations penetrate deep into the subcutaneous tissue while higher frequencies are concentrated in the outer skin layer. The present biomechanical model may serve as a valuable tool to study the response of foot of those who work on a vibrating platform.
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Bobba, Sujith, Sambasiva Rao Mukkollu, Z. Leman, and Harish Babu Bachina. "Experimental Investigation on the Effect Due to Mould Vibrations on Mechanical and Metallurgical Properties of Aluminum Alloy (A-1050)." International Journal of Surface Engineering and Interdisciplinary Materials Science 9, no. 1 (January 2021): 77–86. http://dx.doi.org/10.4018/ijseims.2021010105.
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In the current research work performed, the consequences caused in the casting aluminum alloy specimen due to mechanical mould vibrations are examined. Mould vibration throughout the casting provides decreased rate of shrinkage, good morphology, surface finish and lesser probability of hot tear. In this research work, the effect of mould vibration during solidification of Aluminum A-1050 alloys for dissimilar values of wavelengths at a permanent pouring temperature has been investigated to understand the modification in microstructure and mechanical properties after casting. The Al A-1050 casting has been made in a metal mould with different vibrations. The frequencies are varied from 15Hz to 50 Hz during the casting process. A casting has been made with different vibration as well to compare the results of castings with vibration frequencies. The experimental outcomes exhibited substantial grain refinement and significant increase in tensile strength and hardness of the castings with mechanical mould vibration during the duration and after solidification.
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El-Kafrawy, A. E., A. Kandil, and A. Omar. "Vibration isolation of a symmetric and asymmetric rigid bar using struts subject to axial static and dynamic excitation." Proceedings of the Institution of Mechanical Engineers, Part C: Journal of Mechanical Engineering Science 225, no. 2 (June 23, 2010): 334–46. http://dx.doi.org/10.1243/09544062jmes2125.
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Many developed modern machineries such as compressors, engines, and presses represent a serious source of undesirable, uncomfortable, and uncontrollable vibrations leading to harmful failure and loss of machine availability. Therefore, research of mechanical engineers in maintenance sections in the industry has been devoted to the control, isolation, and minimi-zation of harmful effects of such vibrations. The objective of the present paper is to study the influence of using a specific type of vibration isolator based on using post-buckled elastic clamped—clamped struts as an effective solution tool to relieve vibrating machines from these harmful effects. A model that consists of post-buckled struts acting as vibration isolators used to support symmetric and asymmetric rigid bars is introduced. The proposed clamped—clamped struts are subject to axial harmonic excitation at the base. The isolated bar is allowed to displace laterally. Displacement transmissibility is selected as the governing optimization variable of the isolator's effectiveness with the main objective to minimize vibrations transmitted from the base to the rigid bar. The transmissibility is calculated over a wide range of frequencies and plotted in the form of design charts to determine its effect on the vibration behaviour of struts. The lateral motion of the bar is considered. These plots are used to recognize the range of frequencies, for which full isolation is maintained. The frequencies at which resonance occurs in the system can then be depicted from the design graphs. The study reveals that at resonance frequencies, the most effective transmissibility is well below unity. Vibration characteristics are determined at specific frequencies, such that the physical performance of the vibrating system can be studied. All variables used in the analysis are normalized, such that the results are not dependent on any geometric of material property, such as the modulus of elasticity of the material, the section modulus of the profile used, or the length of the strut. In this way, the obtained results can be applied over a wide range of elastic materials, regardless of the type of material or section properties.
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Craifaleanu, Andrei, Cristian Dragomirescu, Nicolaie Orăşanu, and Adrian Costache. "Study on Vibration Transmission, with Application to the Calibration of a Measuring Stand." Applied Mechanics and Materials 430 (September 2013): 153–57. http://dx.doi.org/10.4028/www.scientific.net/amm.430.153.
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The paper studies the vibration transmitted by a mechanical oscillating system to its fixing device. The influence of the mechanical characteristics (inertial and elastic) of the device on the quantities specific to the free and forced vibration, respectively, of the principal system, is analyzed. In this context, the paper investigates the possibility to correlate the vibrations of the mechanical system with the vibrations measured on the fixing device. The conclusions of this study can be used for the calibration of vibration measuring stands. In the final part, a practical application is presented, aimed to compare the theoretical results with the data obtained by measurements performed on an experimental model built by the authors.
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Shen, Maoliang, Xuexi Chen, and Yong Xu. "Effect of Mechanical Vibration with Different Frequencies on Pore Structure and Fractal Characteristics in Lean Coal." Shock and Vibration 2021 (September 21, 2021): 1–14. http://dx.doi.org/10.1155/2021/5587592.
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The mechanical vibrations caused by underground operations can easily lead to coal and gas outbursts in coal mines. Using the MVGAD-I experimental platform that we designed, the raw coal (0 Hz) was treated with vibration frequencies of 25, 50, 75, and 100 Hz, and the coal samples with different frequency vibrations were obtained. The total pore volume (TPV), specific surface area (SSA), pore size distribution, and the pore fractal dimension (PFD) of five coal samples were analyzed by mercury intrusion porosimetry and low-pressure nitrogen adsorption data. We found that the TPV, SSA, and PFD of the coal samples fluctuate with the increase of vibration frequency. The changes of the TPV and SSA of coal samples treated with 25 and 75 Hz vibrations were significantly greater than those subjected to vibrations of 50 and 100 Hz. Compared with the raw coal (0 Hz), the TPV and SSA of macropores, mesopores, and micropores increased the most in 75 Hz vibration coal sample. Therefore, the 75 Hz vibration excitation can improve the permeability of a body of coal mass and is conducive to the diffusion and seepage of coalbed methane and its production.. The influence of 25 Hz vibration on the TPV and SSA of macropores and mesopores is not obvious, but the TPV and SSA of minipores and micropores decrease significantly, which is not conducive to gas diffusion and adsorption. In addition, 25 and 75 Hz vibrations obviously damaged the fractal characteristics of both mesopores and micropores, resulting in the change of gas adsorption and diffusion ability. The rational use of a 75 Hz vibration is beneficial to both the production of gas and the prevention of outbursts, while a 25 Hz vibration should be avoided. The results are expected to reveal the microscopic mechanism of a vibration-induced outburst and provide theoretical guidance for employing the appropriate frequency of vibration to improve the rate of gas drainage and reduce the risk of outbursts.
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BIENIEK, Piotr, Grzegorz KOWALIK, and Karol ŁYSIAK. "Influence of Technological Instruments on the Course of Vibration Tests Carried Out on the Inductor of Vibrations for 120 mm Mortar Cartridges." PROBLEMY TECHNIKI UZBROJENIA 159 (May 16, 2022): 47–71. http://dx.doi.org/10.5604/01.3001.0015.8553.
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The paper deals with a proper selection of technological instruments for fixing 120 mm mortar cartridges into the vibrations inductor at laboratory testing. The work was aimed to find out the influence of modified technological instruments on the course of vibration tests in comparison to an original design which had been changed along with performed trials to take into account the fixation on the vibrations inductor and matching with the tested sample. Aspects connected with the improvement of the technological handle, which is a transitional device between the vibrating system and tested sample, have essential impact into the course of vibration tests which were conducted both on the head and the sliding table of the inductor for comparison. Each test is burdened by actions of adverse effects which are partially caused by the design of the vibrating system, and hence the experience of operator and selection of suitable technological handle are also important for coping with difficulties. For this reason it may be helpful to use some recommendations described in the paper for balancing disproportions connected with the limitations of the vibration inductor and fabrication and fixation of the handle for 120 mm mortar cartridge. The way of coping with encountered difficulties is presented directly with proposed solutions on the base of vibration tests examining the resistance of 120 mm mortar cartridges against mechanical loads in the form of sinusoidal vibrations.
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Bialas, Katarzyna. "Reduction of vibrations in mechanical systems using piezoelectric elements." MATEC Web of Conferences 178 (2018): 06023. http://dx.doi.org/10.1051/matecconf/201817806023.
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The aim of study is to visualize not only the primary and active element but also sensors, returning the current state of the system. The work shows the use of piezoelectric accelerometer sensors in the active vibration reduction. In addition to the elements reduction of vibrations also are necessary elements with which it will be possible to constantly test and measure vibration. It is necessary to generate the force to appropriate executive to reduce the effects of vibration. It will be also shows how to design basic system in something special way which is the synthesis of mechanical systems.