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Journal articles on the topic 'Mechanics - Vibration'
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1
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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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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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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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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Pelmear, P. L., and D. K. N. Leong. "EU Directive on Physical Agents — Vibration." Journal of Low Frequency Noise, Vibration and Active Control 21, no. 3 (September 2002): 131–39. http://dx.doi.org/10.1260/026309202321164702.
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Vibrations that arouse human health concerns are classified into two main categories: (1) hand-arm vibrations (HAV) and (2) whole-body vibrations (WBV). Hand-transmitted vibration from a power or impact tool affects the upper extremities of the body. WBV affects the entire body and is transmitted from a vibrating seat, bed or floor to a person who is in a sitting, Iying or standing position. The EU Directive April 5, 2002 provides exposure limit and action values for both HAV and WBV. These values have taken into consideration recent advances in knowledge and the political judgment of the Member States so are at variance with the present Health and Safety Executive (HSE) values and the ACGIH TLVs. This paper reviews the development of international standards for vibration and the requirements of the EU Directive.
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SHEVTSOVA, VALENTINA, ILYA I. RYZHKOV, DENIS E. MELNIKOV, YURI A. GAPONENKO, and ALIAKSANDR MIALDUN. "Experimental and theoretical study of vibration-induced thermal convection in low gravity." Journal of Fluid Mechanics 648 (April 7, 2010): 53–82. http://dx.doi.org/10.1017/s0022112009993442.
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Vibrations acting on a fluid with density gradient induced by temperature variations can cause relative flows. High-frequency vibration leads to the appearance of time-averaged (mean) flows (or streaming flows), which can essentially affect heat and mass transfer processes. This phenomenon is most pronounced in the absence of other external forces (in particular, static gravity). In this work, an extensive experimental and computational study of thermal vibrational convection in a reduced-gravity environment of a parabolic flight is performed. The transient evolution of the temperature field in a cubic cell subjected to translational vibration is investigated by optical digital interferometry. The mean flow structures previously reported in numerical studies are confirmed. The transition from four-vortex flow to a pattern with a large diagonal vortex and two small vortices is observed in the transient state. The experiments reveal a significant enhancement of heat transfer by vibrational mean flows with increasing the vibrational strength. Three-dimensional direct numerical simulation with real microgravity profile and two-dimensional numerical modelling based on averaging approach provide a very good agreement with the experimental results. The influence of residual gravity on heat transfer and bifurcation scenario is first investigated numerically and correlated with the experimental data. It is demonstrated that gravity effects on non-uniformly heated fluids can be reproduced in weightlessness by applying vibrations to the system.
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Dymarek, Andrzej, Tomasz Dzitkowski, Krzysztof Herbuś, Piotr Ociepka, and Agnieszka Sękala. "Use of active synthesis in vibration reduction using an example of a four-storey building." Journal of Vibration and Control 26, no. 17-18 (January 13, 2020): 1471–83. http://dx.doi.org/10.1177/1077546319898970.
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The article presents a method of active vibration reduction of vibrating mechanical systems. This method is based on the properties of positive rational functions, which in the case of discrete dynamical systems correspond to the characteristic function describing such systems. The method formalized uses methods for decomposing positive rational functions. The advantage of this approach is taking into account the analytical form of a characteristic function of the system being tested and the vibration-reducing force, as well as the conditions that the system should meet in the event of an active vibration-reducing force. In addition, in the proposed method, the desired dynamic properties of the system and the vibration-reducing force can be defined in such a way that the determined parameters of the active force affect all forms of the natural vibrations of the examined system. Based on the formalized methodology, the force reducing the vibrations of a four-storey frame to the desired displacement amplitude was determined. The impact of the place of application of the specific active force on the reduction of vibration of the tested object was also taken into account. The vibrations of the tested structure’s model were caused by kinematic excitation with a harmonic course and an amplitude corresponding to an earthquake of a magnitude of 5 on the Richter scale. To verify the determined force reducing the vibrations of the object and to create a visualisation of the analysed phenomenon, a dynamic analysis of the building structure was carried out using PLM Siemens NX 12 software.
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Choi, S. H., J. Glienicke, D. C. Han, and K. Urlichs. "Dynamic Gear Loads Due to Coupled Lateral, Torsional and Axial Vibrations in a Helical Geared System." Journal of Vibration and Acoustics 121, no. 2 (April 1, 1999): 141–48. http://dx.doi.org/10.1115/1.2893956.
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In this paper we investigate the rotordynamics of a geared system with coupled lateral, torsional and axial vibrations, with a view toward understanding the severe vibration problems that occurred on a 28-MW turboset consisting of steam turbine, double helical gear and generator. The new dynamic model of the shaft line was based on the most accurate simulation of the static shaft lines, which are influenced by variable steam forces and load-dependent gear forces. The gear forces determine the static shaft position in the bearing shell. Each speed and load condition results in a new static bending line which defines the boundary condition for the dynamic vibration calculation of the coupled lateral, torsional and axial systems. Rigid disks and distributed springs were used for shaft line modeling. The tooth contact was modeled by distributed springs acting normally on the flank surfaces of both helices. A finite element method with distributed mass was used for lateral and torsional vibrations. It was coupled to a lumped mass model describing the axial vibrations. The forced vibrations due to unbalances and static transmission errors were calculated. The eigenvalue problem was solved by means of a stability analysis showing the special behavior of the coupled system examined. The calculation was successfully applied, and the source of the vibration problem could be located as being a gear-related transmission error. Several redesign proposals lead to a reliable and satisfactory vibrational behavior of the turboset.
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Gong, Man Feng, Zhong Li, and Jue Dong. "Mechanics Analysis of Reinforcing Rib Structure in Aluminum Heating-Plate Automatic Casting System." Advanced Materials Research 538-541 (June 2012): 1755–61. http://dx.doi.org/10.4028/www.scientific.net/amr.538-541.1755.
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Reinforcing rib structure in the aluminum heating-plate automatic casting system was modeled by ANSYS, the static and dynamical problems were studied. Deformation and stress were calculated by static analysis, the front ten orders inherent frequency, critical rotating-speed and vibration modes were analyzed by modal analysis technology, vibration amplitude responses were obtained by harmonic response analysis. The maximum deformation value of reinforcing rib structure was less than 2mm (irrespective of the structure self-weight); the maximum equivalent stress was about 64.8MPa. It showed that the reinforcing rib structure could effectively avoid the resonance region, and the maximum vibration mode according to its inherent frequency appeared at the edge of the structure, some vibration modes were orthogonal, the main vibration modes appeared in the forms of bending, torsion, but the stretching vibration mode was scarce. The low orders inherent frequency greatly effected more than the high orders inherent frequency by harmonic response analysis, and the maximum deformation value was 25μm in low order vibrations. The conclusion is that the reinforcing rib structure fulfills design requirements and operates softly.
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Guerra-Bravo, Esteban, Han-Joo Lee, Arturo Baltazar, and Kenneth J. Loh. "Vibration Analysis of a Piezoelectric Ultrasonic Atomizer to Control Atomization Rate." Applied Sciences 11, no. 18 (September 9, 2021): 8350. http://dx.doi.org/10.3390/app11188350.
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In this work, a mechanical vibrational analysis of an ultrasonic atomizer is carried out to control its atomization mass transfer rate. An ultrasonic atomizer is a device constructed with a piezoelectric ring coupled to a metallic circular thin plate with micro-apertures. The mechanism of mass transfer by atomization is a complex phenomenon to model because of the coupling effect between the fluid transfer and dynamic mechanics controlled by a piezoelectric vibrating ring element. Here, the effect of the micro-apertures shape of the meshed thin plate coupled to a piezoelectric ring during vibration, as well as the resonance frequency modes, are numerically studied using a finite element analysis and compared with theoretical and experimental results. Good correlations between the predicted and experimental results of the resonant frequencies and atomization rates were found.
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Wang, Hong Ying. "Study on Electromechanical Coupling Vibration of Simulation Technology Based on the Drive System." Advanced Materials Research 676 (March 2013): 289–92. http://dx.doi.org/10.4028/www.scientific.net/amr.676.289.
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Study the mechanical and electrical system,according to the mechanical system of the coupling mechanics principle, the AC drive system is simplified as many degrees of freedom "spring - mass - damper" system,the quality of construction of three two-axis system,established the two shafts electromechanical coupling vibration mathematical model; Using the electromechanical coupling vibration simulation model, the parameters of the current regulator, damping, harmonic disturbances, gap and load disturbance of electromechanical coupling factors such as vibrations caused by dynamic process.Improve the dynamic performance of the system is significant, have the great value for the parameters of the system design and fault diagnosis on this study.
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Felszeghy, Stephen F. "Steady-State Residual Vibrations in High-Speed, Dwell-Type, Rotating Disk Cam-Follower Systems." Journal of Vibration and Acoustics 127, no. 1 (February 1, 2005): 12–17. http://dx.doi.org/10.1115/1.1855928.
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Followers driven by high-speed, dwell-type, rotating disk cams can exhibit undesirable residual vibrations during dwell. These vibrations have been studied with linear models mostly using results from transient vibration analysis, assuming quiescent initial conditions. Here, the residual vibrations are studied with closed-form solutions to the steady-state vibrations obtained with a circular convolution integral. The steady-state vibrations, which can extend over the entire cam cycle, are periodic and continuous. It is shown that significant differences exist between the residual vibration results obtained from steady-state analysis and those obtained from transient analysis. The undamped steady-state vibrations exhibit resonances. Away from the resonance conditions, the steady-state residual vibration amplitudes are consistently smaller than those predicted by transient analysis. The results from the two approaches agree quantitatively only for relatively stiff and damped follower systems.
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JAMES, A. J., B. VUKASINOVIC, MARC K. SMITH, and A. GLEZER. "Vibration-induced drop atomization and bursting." Journal of Fluid Mechanics 476 (February 10, 2003): 1–28. http://dx.doi.org/10.1017/s0022112002002835.
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A liquid drop placed on a vibrating diaphragm will burst into a fine spray of smaller secondary droplets if it is driven at the proper frequency and amplitude. The process begins when capillary waves appear on the free surface of the drop and then grow in amplitude and complexity as the acceleration amplitude of the diaphragm is slowly increased from zero. When the acceleration of the diaphragm rises above a well-defined critical value, small secondary droplets begin to be ejected from the free-surface wave crests. Then, quite suddenly, the entire volume of the drop is ejected from the vibrating diaphragm in the form of a spray. This event is the result of an interaction between the fluid dynamical process of droplet ejection and the vibrational dynamics of the diaphragm. During droplet ejection, the effective mass of the drop–diaphragm system decreases and the resonance frequency of the system increases. If the initial forcing frequency is above the resonance frequency of the system, droplet ejection causes the system to move closer to resonance, which in turn causes more vigorous vibration and faster droplet ejection. This ultimately leads to drop bursting. In this paper, the basic phenomenon of vibration-induced drop atomization and drop bursting will be introduced, demonstrated, and characterized. Experimental results and a simple mathematical model of the process will be presented and used to explain the basic physics of the system.
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Meehan, Paul A. "Vibration Instability in Rolling Mills: Modeling and Experimental Results." Journal of Vibration and Acoustics 124, no. 2 (March 26, 2002): 221–28. http://dx.doi.org/10.1115/1.1456457.
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Models for the occurrence of the vibrational instability during rolling known as third octave chatter are presented and discussed. An analysis of rolling mill chatter was performed for the purpose of identifying characteristics of the vibrations and to determine any dependency on the rolling schedule. In particular, a stability criterion for the critical rolling speed is used to predict the maximum rolling speed without chatter instability on schedules from a 5 stand tandem mill rolling thin steel product. The results correlate well with measurements of critical speed occurring on the mill using a vibration monitor. This research provides significant insights into the chatter phenomena and has been used to investigate control methods for suppression of the instability.
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Iurlova, N. A., D. A. Oshmarin, N. V. Sevodina, and M. A. Iurlov. "Numerical algorithm for searching for layouts of electroelastic bodies with external electric circuits for obtaining the best damping properties." PNRPU Mechanics Bulletin, no. 3 (December 15, 2020): 108–24. http://dx.doi.org/10.15593/perm.mech/2020.3.11.
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This paper presents an algorithm which allows finding such layouts of electromechanical systems that provide the best vibration damping whether for one mode or a set of vibration modes within some continuous frequency ranges. The basis for the algorithm is the problem solution about natural vibrations. An elastic structure with a piezoelectric element located on its surfaces, which electrodes are connected to a passive external electric circuit, is treated as an electromechanical system. The piezoelectric elements shunted with an electric circuit are the devices where energy dissipation occurs, thus leads to damping of vibrations. A change in damping properties of such systems can be reached by a proper choice of parameters of the electric circuits and corresponding location of the piezoelectric element, which provides the highest energy withdrawal into the electric circuit. The paper presents the mathematical formulation of the natural vibrations problem for piecewise-homogeneous electroelastic bodies shunted with passive external electric circuits. Within the proposed mathematical statement, the problem solution of natural vibrations for such objects is based on values of complex natural vibration frequencies. Real parts of the complex natural vibration frequencies are the circular frequency of vibrations, and the imaginary parts are the damping indices of vibrations. We proposed techniques aimed at determining the location of the piezoelectric element and selecting parameters of shunting the external electric circuit. These approaches are based on values of the complex natural vibration frequencies obtained as results of solving the natural vibrations problem. The proposed approach is demonstrated using a specimen of a thin-walled shell in the semi-cylinder form. The piezoelectric element has a form of a segment of a ring made of PZT-4 piezoceramics. Electrodes of the piezoelectric element are connected to the series resonant RL -circuit. The formulated problem is solved numerically using the finite element method and ANSYS commercial package.
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Brennan, M. J., R. J. Pinnington, and S. J. Elliott. "Mechanisms of Noise Transmission through Helicopter Gearbox Support Struts." Journal of Vibration and Acoustics 116, no. 4 (October 1, 1994): 548–54. http://dx.doi.org/10.1115/1.2930462.
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Helicopter gearbox support struts are structural members designed to take large compressive and tensile mechanical loads. They also act as vibration transmission paths connecting the major noise and vibration generators of the main rotor and gearbox to the fuselage and cabin. In this paper the mechanisms of vibration transmission through these struts are examined. The differences between the low frequency behavior that is important in the transmission of the rotor vibrations, and the high frequency behavior that is important in the transmission of gear noise are discussed. A flexible element is introduced in series with the strut, and the limitations of this simple passive measure in attenuating longitudinal and flexural vibrations are highlighted. The analysis shows that there is a difference in the mechanisms of vibration transmission between low and high frequencies, and that there are difficulties in applying effective passive vibration isolation measures to this system.
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Zhu, Xuezhi, Zhaobo Chen, and Yinghou Jiao. "Optimizations of distributed dynamic vibration absorbers for suppressing vibrations in plates." Journal of Low Frequency Noise, Vibration and Active Control 37, no. 4 (August 15, 2018): 1188–200. http://dx.doi.org/10.1177/1461348418794563.
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Dynamic vibration absorber is an ideal device for vibration control at specific frequencies. In order to get a robust vibration control performance, multiple or distributed dynamic vibration absorbers are usually used for suppressing vibrations in plate structures. Optimization methods for the single dynamic vibration absorber in various vibration systems had been proposed many years ago. However, the analytical optimization solutions with respect to the distributed dynamic vibration absorbers for the plate structures have not been found. In this paper, the optimization problems of the distributed dynamic vibration absorbers for suppressing vibrations in plates are studied. Vibration equations of the plate carrying distributed dynamic vibration absorbers are established using modal superposition method. The similarities of vibration shapes of the dynamic vibration absorbers and mode shapes of the plate are revealed. According to the characteristics of the vibration shapes of dynamic vibration absorbers, the vibration equations of the plate carrying distributed dynamic vibration absorbers are transformed into a form of equations of a two degree of freedom system. The analytical optimization formulas of the distributed dynamic vibration absorbers for suppressing vibrations in plates are derived by applying the fixed-points theory. The effectiveness of the optimization formulas is verified through numerical simulations. The simulation results also show that a brilliant multi-mode vibration control can be realized by using the optimized distributed dynamic vibration absorbers.
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Xu, Zhaogang, Yu Lou, and Liu Chen. "Vibration Measurement and Prediction for Foundation Slab Design of a High-Tech Lab Based on In Situ Testing." Shock and Vibration 2020 (October 28, 2020): 1–12. http://dx.doi.org/10.1155/2020/8892597.
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Reduction of road traffic-induced vibrations has gained importance with rapid development of high-tech industry and nanotechnology. This study focuses on the in situ vibration measurement and transmissibility-based vibration prediction for the foundation slab design of a high-tech lab subjected to truck-induced vibrations. The truck-induced vibrations come from a proposed road 30 m away from the high-tech lab. The allowable vertical vibration velocity for the foundation slab of the high-tech lab was 60 μm/s in the frequency range of 5–50 Hz. The truck-induced ground vibrations in the proximity of an existing road with the same design as the proposed road were taken as the vibration source response used in the foundation design. The ground vibration transmissibility from the proposed road area to the high-tech lab area was determined by conducting frequency sweep tests in the free field. Based on the vibration source response and the ground vibration transmissibility, two antivibration foundation prototypes with different thicknesses were constructed at the site. The vibration transmissibility from the subgrade soil to the surfaces of the two foundation prototypes was obtained by measuring the ground vibrations at the high-tech lab area and the surface vibrations of the two foundation prototypes. The vertical vibration velocities of the two foundation prototypes were predicted based on the measured transmissibility and the vibration source response. The final thickness of the antivibration foundation was determined by comparing the predicted vibration velocities with the allowable vibration velocity. After construction of the high-tech lab and the road, vibration tests were conducted to assess the performance of the actual antivibration foundation. The results showed that the actual antivibration foundation was able to reduce the vibration levels at the high-tech lab to acceptable levels.
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Papadopoulos, C. A., and A. D. Dimarogonas. "Coupled Vibration of Cracked Shafts." Journal of Vibration and Acoustics 114, no. 4 (October 1, 1992): 461–67. http://dx.doi.org/10.1115/1.2930285.
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The coupling of vibration modes of vibration of a clamped-free circular cross-section Timoshenko beam with a transverse crack is investigated in this paper. A 6 × 6 local flexibility matrix is used to simulate the crack. The nondiagonal terms of this matrix cause coupling between the longitudinal, torsional, and bending vibrations. Coupling is apparent in all spectra obtained with a harmonic sweeping excitation throughout the frequency range. The method is very sensitive even for small cracks.
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Mroz, A., A. Orlowska, and J. Holnicki-Szulc. "Semi-Active Damping of Vibrations. Prestress Accumulation-Release Strategy Development." Shock and Vibration 17, no. 2 (2010): 123–36. http://dx.doi.org/10.1155/2010/126402.
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New method for semi-active control of vibrating structures is introduced. So-called Prestress Accumulation-Release (PAR) strategy aims at releasing of the strain energy accumulated in the structure during its deformation process. The strain energy is converted into kinetic energy of higher modes of vibration which is suppressed with structural damping or by means of a damping device. The adaptation process essentially affects the first mode vibrations by introducing an elastic force that opposes the movement. Numerical simulations as well as experimental results prove that the strategy can be very effective in mitigating of the fundamental mode of a free – vibrating structure. In a numerical example 95% of the vibration amplitude was mitigated after two cycles. An experimental demonstrator shows 85% reduction of the amplitude in a cantilever free- vibrations. In much more complex practical problems smaller portion of total energy can be released from the system in each cycle, nevertheless the strategy could be applied to mitigate the vibrations of, for example, pipeline systems or pedestrian walkways.
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Tumer, Irem Y., and Edward M. Huff. "Analysis of Triaxial Vibration Data for Health Monitoring of Helicopter Gearboxes." Journal of Vibration and Acoustics 125, no. 1 (January 1, 2003): 120–28. http://dx.doi.org/10.1115/1.1526130.
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Research on the nature of the vibration data collected from helicopter transmissions during flight experiments has led to several crucial observations believed to be responsible for the high rates of false alarms and missed detections in aircraft vibration monitoring systems. This work focuses on one such finding, namely, the need to consider additional sources of information about system vibrations. In this light, helicopter transmission vibration data, collected using triaxial accelerometers, are explored in three different directions, analyzed for content, and then combined using Principal Components Analysis (PCA) to analyze changes in directionality. The frequency content of the three different directions is compared and analyzed using time-synchronously averaged vibration data. To provide a method for analysis and monitoring purposes, the triaxial data are decorrelated using a mathematical transformation, and compared to the original axes to determine their differences. The benefits of using triaxial data for vibration monitoring and diagnostics are explored by analyzing the changes in the direction of the principal axis of vibration formed using all three axes of vibration. The statistical variation introduced due to the experimental variables is further analyzed using an Analysis of Variance approach to determine the effect of each variable on the overall signature. The results indicate that triaxial accelerometers can provide additional information about the frequency content of helicopter gearbox vibrations, and provide researchers and industry with a novel method of capturing and monitoring triaxial changes in the baseline vibration signatures.
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Muhammad, Adnan. "Technical Review: Indirect Tire Pressure Monitoring Systems and Tire Vibrations." Tire Science and Technology 47, no. 2 (April 1, 2019): 102–17. http://dx.doi.org/10.2346/tire.18.460403.
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ABSTRACT Indirect tire pressure monitoring systems (ITPMSs) have been an active area of research for the past 2 decades. Researchers worldwide have strived to develop estimation techniques for the detection of the change in tire pressure by using the vibration information present in the speed signal. Different groups have used a torsional vibration model for the tire, owing to its torsional stiffness and rotational moment of inertia. The standard antilock braking system (ABS) speed sensor signal is analyzed for these vibrations. Different estimation algorithms try to detect the change in this vibration frequency, which indicates the change in the torsional stiffness of the tire as a result of variation in the pressure. Tire vibrations have been studied in great detail for the past 5 decades, and there are various models of tire vibrations available in the literature. These models range from physics-based analytical models to finite element models (FEMs). Analytical models take benefit from the mathematics developed for rotating elastic thin shells and plates, whereas FEMs use simulation tools to develop vibration models of the tire. A detailed literature survey of ITPMSs and tire vibration models reveals that there is no correlation between the vibrations detected in the speed signal and the vibrations predicted in the tire vibration models. Researchers have developed tire vibration models that do not take into consideration the effects of vibrations on the speed signal; although, to the best of our knowledge, signal processing and estimation experts who have developed methods for ITPMSs have not validated the true source of observed vibrations in the speed signal and could not present a viable theoretical explanation. In this review, a comprehensive study of the ITPMS techniques and tire vibration models is presented, with an aim to find a correlation between them. The review begins with a brief introduction to the topic followed by state of the art, then a detailed review of ITPMSs and the methods for their realizations in the automotive industry. Finally, tire vibration models are presented in detail, and possible links between vibration models and ITPMS vibrations are sorted.
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Choy, F. K., J. Padovan, and Y. F. Ruan. "Coupling of Rotor-Gear-Casing Vibrations During Extreme Operating Events." Journal of Pressure Vessel Technology 114, no. 4 (November 1, 1992): 464–71. http://dx.doi.org/10.1115/1.2929256.
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During extreme operating environments (i.e., seismic events, base motion-induced vibrations, etc.), the coupled vibrations developed between the rotors, bearings, gears and enclosing structure of gear-driven rotating equipment can be quite substantial. Generally, such large vibrational amplitudes may lead to failures in both the rotor-gearing system and/or the casing structure. This paper simulates the dynamic behavior of rotor-bearing-gear system resulting from motion of the enclosed structure. The modal synthesis approach is used in this study to synthesize the dynamics of the rotor systems with the vibrations of their casing structure in modal coordinates. Modal characteristics of the rotor-bearing-gear systems are evaluated using the matrix transfer technique, while the modal parameters for the casing structure are developed through a finite element model using NASTRAN. The modal accelerations calculated are integrated through a numerical algorithm to generate modal transient vibration analysis. Vibration results are examined in both time and frequency domains to develop representations for the coupled dynamics generated during extreme operating conditions. Typical three-rotor bull gear-driven power plant equipment (compressors, pumps, etc.) is used as an example to demonstrate the procedure developed.
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Kubo, Yoshinobu. "Prospects for the Suppression of Aeroedynamic Vibrations of a Long-Span Bridge Using Boundary-Layer Control." Journal of Vibration and Control 10, no. 9 (September 2004): 1359–73. http://dx.doi.org/10.1177/1077546304042050.
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Aerodynamic vibrations inherently occur on a long-span-length bridge. The vibrations are roughly classified into vortex-excited vibration and self-excited vibration both are induced by separation flow from the leading edge of the structure. As aerodynamic vibrations frequently cause fatal damage to the structure, the suppression method of vibration has been studied for a long time. Two methods have been proposed for suppression of the vibrations: a structural method and an aerodynamic method. The former is a tuned mass damper or a tuned liquid damper, and the latter is a separation flow control using a certain device of flap or faring. As the aerodynamic method is one of the solutions to eliminate the cause of aeroelastic vibration, the aerodynamic method is more useful than the structural method from the point of view of the suppression of vibrations. Sometimes, however, it may be more costly. This paper deals with the prospects for active control of separation flow to suppress vibrations for the girders and towers of a long-span-length bridge.
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Natsiavas, S., and J. L. Beck. "Almost Classically Damped Continuous Linear Systems." Journal of Applied Mechanics 65, no. 4 (December 1, 1998): 1022–31. http://dx.doi.org/10.1115/1.2791896.
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The dynamic response of a general class of continuous linear vibrating systems is analyzed which possess damping properties close to those resulting in classical (uncoupled) normal modes. First, conditions are given for the existence of classical modes of vibration in a continuous linear system, with special attention being paid to the boundary conditions. Regular perturbation expansions in terms of undamped modeshapes are then utilized for analyzing the eigenproblem as well as the vibration response of almost classically damped systems. The analysis is based on a proper splitting of the damping operators in both the field equations and the boundary conditions. The main advantage of this approach is that it allows application of standard modal analysis methodologies so that the problem is reduced to that of finding the frequencies and mode shapes of the corresponding undamped system. The approach is illustrated by two simple examples involving rod and beam vibrations.
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Othman, M. O., and A. Seireg. "A Procedure for Evaluating the Friction Properties of Hertzian Contacts Under Reciprocating Sliding Motion." Journal of Tribology 112, no. 2 (April 1, 1990): 361–64. http://dx.doi.org/10.1115/1.2920265.
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The study reported in this paper presents an empirical procedure for evaluating the frictional properties in Hertzian contacts subjected to sinusoidal sliding motion. It utilizes the friction induced lateral vibration of a rod to evaluate the parameters of the frictional function using a gradient search which minimize the error between the analytical response and the friction-induced experimental vibrations. The use of sinusoidal sliding motion at the resonant frequencies of the vibrating rod is found to considerably minimize the effect of external vibrations on the experimental results.
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Peng, Er Bao, Hong Ge Zhang, and Hong Ying Wang. "Mechanics and Pretreatment Research of Vibration Signals for the Numerical Control Machine." Advanced Materials Research 676 (March 2013): 162–65. http://dx.doi.org/10.4028/www.scientific.net/amr.676.162.
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To study vibration signals processing mechanics and the analysis method of the numerical control machine. vibration signals analysis method include time and frequent domain analysis: the time domain analysis mainly has the statistical analysis and the correlation function analysis. frequency domain analysis include spectral analysis, cepstrum analysis, data envelopment analysis. vibration signals pretreatment is the most commonly used and effective method on the mechanical device condition monitor and the failure diagnosis.
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Rothberg, S. J., and N. A. Halliwell. "Vibration Measurements on Rotating Machinery Using Laser Doppler Velocimetry." Journal of Vibration and Acoustics 116, no. 3 (July 1, 1994): 326–31. http://dx.doi.org/10.1115/1.2930432.
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This paper explores the use of laser vibrometry for vibration measurement directly from a rotating component. The presence of a surface velocity component due to the rotation itself is shown to create a strong measurement dependency on vibration perpendicular to the intended measurement direction. Particular ambiguity results at synchronous frequencies. A mathematical means to resolve the genuine vibration components from two simultaneous laser vibrometer measurements is presented and shown to be effective in the study of nonsynchronous rotor vibrations.
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Patil, Sushil S. "Grass trimmer hand-arm vibration reduction using multi-axial vibration absorber." Noise & Vibration Worldwide 50, no. 8 (August 12, 2019): 245–53. http://dx.doi.org/10.1177/0957456519869926.
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In this investigation, the novel multi-axial vibration absorber is proposed to reduce the handle vibration of petrol engine grass trimmer. The proposed vibration absorber is designed using Dunkerley’s equation and fabricated for testing. The experimental modal analysis of absorber is conducted to find resonance frequencies of the absorber and to validate the results obtained from equations. The experimental tests are carried on grass trimmer with absorber attached near handle location to find effectiveness of absorber in reducing hand-arm vibrations in the x, y and z directions. The result indicated that the total vibration value measured at the handle of grass trimmer is reduced by substantial level with the attachment of multi-axial vibration absorber.
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Li, Lifeng, and Jhon Silva-Castro. "Synthesis of single-hole signatures by group delay for ground vibration control in rock blasting." Journal of Vibration and Control 26, no. 13-14 (December 24, 2019): 1273–84. http://dx.doi.org/10.1177/1077546319892435.
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Prediction and control of ground vibrations become essential as with the development of neighborhoods in the proximity of active mining operations or the need for new infrastructure in urban centers, both requiring the use of blasting. Novel ground vibration prediction models attempt to reproduce a whole vibration waveform from a blast and are based, in most cases, on the collection of vibrational information from a single blasthole. A single blasthole should have the same characteristics (geometry and weights of explosives) as the blastholes used in production shots. In some cases, the collection of the fundamental information (the signature) is straightforward. In more complex cases, the fundamental information from ground vibration data is collected from previous production shots. This study presents a novel methodology to assess the fundamental ground vibration information (the signature) using known information such as one event waveform (a production shot waveform) and the timing sequence used (the comb function) for the shot. The methodology is based on the analysis of group delay, a concept widely used in signal processing, and is modified here for the analysis of ground vibration waveforms. The methodology is developed using real data collected in coal and quarry mining operations, and at the end of this document, one case study with step-by-step calculations is presented to show the benefits of the methodology.
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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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Chondros, T. G., and A. D. Dimarogonas. "Vibration of a Cracked Cantilever Beam." Journal of Vibration and Acoustics 120, no. 3 (July 1, 1998): 742–46. http://dx.doi.org/10.1115/1.2893892.
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A continuous cracked bar vibration model is developed for the lateral vibration of a cracked Euler-Bernoulli cantilevered beam with an edge crack. The Hu-Washizu-Barr variational formulation was used to develop the differential equation and the boundary conditions for the cracked beam as an one-dimensional continuum. The crack was modelled as a continuous flexibility using the displacement field in the vicinity of the crack found with fracture mechanics methods. The results of three independent evaluations of the lowest natural frequency of lateral vibrations of an aluminum cantilever beam with a single-edge crack are presented: the continuous cracked beam vibration model, the lumped crack model vibration analysis, and experimental results. Experimental results fall very close to the values predicted by the continuous crack formulation. Moreover, the continuous cracked beam theory agrees better with the experimental results than the lumped crack flexibility theory.
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Long, Y. G., K. Nagaya, and H. Niwa. "Vibration Conveyance in Spatial-Curved Tubes." Journal of Vibration and Acoustics 116, no. 1 (January 1, 1994): 38–46. http://dx.doi.org/10.1115/1.2930394.
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The problem of inserting a long optical fiber into a long helical steel tube by means of vibration is modelled as a block repeatedly sliding and jumping inside a vibrating long tube which is in a spatial curved-line shape. Analytical models and equations are established by considering three kinds of motion states involved: relative sliding motion, flying motion, and bumping. Thorough investigations are carried out for the inclined friction with component velocities and for the oblique impact. The detailed motion of the whole response, called the “subperiodic motion,” is revealed through numerical solutions. Fundamental influences of some basic parameters on the motion of the system are discussed. Appropriate ranges for both the frequency and the amplitudes of vibration are discovered to be very narrow. Conveying materials inside vibrating tubes is quite different from, or opposite to, conveying materials on vibrating plates in ordinary use. Experimental studies confirm the theoretical analyses presented.
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Wang, T. "Dynamic Forcing Function for Flow-Acoustic-Induced Vibration." Journal of Pressure Vessel Technology 111, no. 4 (November 1, 1989): 361–70. http://dx.doi.org/10.1115/1.3265692.
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Vibration problems in piping systems can manifest themselves in two forms: excessive noise generated from wall flexural vibrations, that in combination with jet noise itself may exceed OSHA limits, and piping system vibration, which could lead to fatigue failure at stress risers. Thus, a comprehensive dynamic forcing function for flow-acoustic-induced vibration on piping system needs to consider both the flexural and system excitation sources. Jet column instabilities and acoustic standing waves are utilized to identify the vibration sources in a large-capacity steam piping system. Initial noise generation originates from approximately six jet diameters downstream of a control valve. It consists of two sharply defined high-frequency sources, the shock cells and the large-scale axisymmetric coherent turbulent structure generated from the nonlinear shear layer instability. These sources effectively excite wall flexural vibrations because of their nonzero net dynamic forcing on pipe “shells.” The compact shock and instability wave noise sources further excite the low-frequency acoustic standing wave in the acoustic duct formed by the discharge piping. The low-frequency acoustic standing wave excites the piping system vibration axially. The piping system was also excited transversely by a more potent vibration source incurred by the spiral mode provoked by a piping elbow. Field observation and measurement of the vibration problem of a large-diameter piping system confirm the prediction.
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Ding, Zhi Hua, Zheng Bao Lei, and Mu Xi Lei. "Research on Damping Characteristics of New Recycling Vibrational Energy Hydraulic Damping System." Advanced Materials Research 308-310 (August 2011): 610–13. http://dx.doi.org/10.4028/www.scientific.net/amr.308-310.610.
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A vibrational energy-recycling vibration damper is introduced which can recycle some vibrational energy by exporting pressurized oil from rebound cavity to energy accumulator. Pressurized oil can be used for HPS, hydraulic power braking and so on which saves energy. Nonlinear parameterized model of damping characteristics is constructed by fluid mechanics theory, and simulation is made under MATLAB. The results show that damping characteristics of the vibration damper is better than conventional dampers.
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Zhang, Ting, and Hongguang Li. "Adaptive modal vibration control for smart flexible beam with two piezoelectric actuators by multivariable self-tuning control." Journal of Vibration and Control 26, no. 7-8 (January 6, 2020): 490–504. http://dx.doi.org/10.1177/1077546319889842.
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It has been popular for decades that the vibrations of space structures are suppressed with smart actuators. However, the higher mode vibrations are often motivated when a control strategy is applied to attenuate the vibration for the smart structures. Moreover, if the multi-mode vibration of a smart structure is suppressed with multi-actuators, a proper multivariable control law will be adopted to solve the coupling problem caused by the multi-actuators of the smart structure. Therefore, in the paper, a decoupling technique for two modal vibrations of a smart flexible beam with two piezoelectric patches is adopted by adaptive control. The proposed control law is designed with a multivariable minimum variance self-tuning control. Considering the first two orders of modal vibrations, two piezoelectric patches are configured on the flexible beam according to the strain of the first two orders of modal vibrations along the longitudinal direction of the beam. A dynamical model for the flexible beam with two piezoelectric actuators is constructed by the mode superposition method. With the dynamical model, simulations are implemented to suppress the free vibration of the flexible beam. Moreover, experiments are carried out to verify the effectiveness of the multivariable minimum variance self-tuning control for vibration suppression of the flexible structure. The control results clearly show that the free vibration amplitude of the cantilevered beam with two control voltages applied to the two piezoelectric patches is less than that with one control voltage applied to the first piezoelectric actuator. Thus, multivariable minimum variance self-tuning control is a more efficient approach for suppressing multimodal vibration for a smart flexible beam with two piezoelectric actuators compared with the conventional velocity feedback control.
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Yabui, Shota, and Tsuyoshi Inoue. "Development of optimal controller design method to compensate for vibrations caused by unbalanced force in rotor system based on Nyquist diagram." Journal of Vibration and Control 25, no. 4 (September 4, 2018): 793–805. http://dx.doi.org/10.1177/1077546318797173.
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In this paper, an optimal controller design method is proposed to compensate for vibrations caused by unbalanced force in the rotor system. The vibrations caused by unbalanced force are the major root cause of excessive whirling vibration in the rotor system, and it is important to compensate for the vibration to maintain its stable operation. The proposed design method can optimize a performance of the controller based on the vector locus of open loop characteristics on the Nyquist diagram. To verifiy the effectiveness, the proposed design method was employed for three typical active vibration control methods. The experimental results show that the proposed method can design the optimal parameters to compensate for the whirling vibrations of the rotor system.
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Atta, C. W. Van, and M. Gharib. "Ordered and chaotic vortex streets behind circular cylinders at low Reynolds numbers." Journal of Fluid Mechanics 174 (January 1987): 113–33. http://dx.doi.org/10.1017/s0022112087000065.
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We report some experiments undertaken to investigate the origin of ordered and chaotic laminar vortex streets behind circular cylinders at low Reynolds numbers. We made simultaneous measurements of near wake longitudinal velocity and cylinder lateral vibration amplitude spectra for cylinder Reynolds numbers in the range from 40 to 160. For a non-vibrating cylinder the velocity energy spectra contained only a single peak, at the Strouhal frequency. When the cylinder was observed to vibrate in response to forcing by the vortex wake, additional dominant spectral peaks appeared in the resulting ‘ordered’ velocity spectra. Cylinder vibrations too small to be noticed with the naked eye or from audible Aeolian tones produced a coupled wake-cylinder response with dramatic effects in hot-wire and cylinder vibration detector signals. The velocity spectra associated with these coupled motions had dominant peaks at the Strouhal frequency fs, at a frequency fc proportional to the fundamental cylinder vibration frequency, and at sum and difference combinations of multiples of fs and fc. In windows of chaos the velocity spectra were broadened by switching between different competing coupling modes. The velocity spectra were very sensitive to the nature of the boundary conditions at the ends of the cylinder. Our measurements strongly suggest that the very similar regions of ‘order’ and ‘chaos’ observed by Sreenivasan and interpreted by him as transition through quasi-periodic states in the sense of the Ruelle, Takens, and Newhouse theory were also due to aeroelastic coupling of the vortex wake with cylinder vibration modes.
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Lin, Zefeng, Junhong Zhang, Jinlu Li, Weitan Yin, Chi Liu, and Jiewei Lin. "Biodynamic Response of Seated Human Body to Roll Vibration and Correlation between Roll and Lateral Directions." Shock and Vibration 2020 (November 3, 2020): 1–12. http://dx.doi.org/10.1155/2020/8839363.
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Within 30 Hz, the discomfort caused by whole-body vibration in rotational direction is higher than vertical vibration at similar equivalent magnitude. Roll vibration, in particular, produces greater discomfort comparing with pitch and yaw vibrations. It is critical to understand the biodynamic characteristics of seated human body under roll vibration for both comfort assessment and vibration control. Experiments are carried out to obtain the biodynamic response of seated human body under random roll vibrations at four r.m.s. magnitude levels. It is found that the principal resonance in the roll apparent inertia is about 1 Hz, but varied from 0.7 to 1.5 Hz depending on the magnitude of vibration (0.5 to 2.0 rad/s2), and the secondary resonance locates around 3 Hz with a much lower modulus. It is noted that the human response to roll vibration has some features in common with that in the lateral direction. Two lumped parameter models are developed and calibrated to study the correlation between the two excitation axials. The equivalent relationships of magnitude and phase between roll and lateral vibrations are obtained on condition that they produce similar rotational responses of the upper human body. It suggests an equivalence approach between translational and rotational vibrations that can benefit the comfort assessment when exposed to multiaxial excitations.
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Hua, Jun, Yuhui Zhang, and Xiaxia Wu. "Vibration analysis of defective graphene based on the molecular structural mechanics method." International Journal of Computational Materials Science and Engineering 05, no. 01 (March 2016): 1650002. http://dx.doi.org/10.1142/s2047684116500020.
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A molecular structural mechanics method has been implemented to investigate the vibrational characteristics of single-layer graphene (SLG) with defects. By adopting the lumped mass unit to replace carbon atoms, and the beam element with circular cross-section to mimic C–C covalent bonds, SLG is modeled as a space framework. The simulation results show that the chirality almost has no effect on the natural frequency and the vibration mode of SLG, while boundary conditions have great influences. The influences of defects with different number and location on the natural frequencies are also studied. It is concluded that vibration mode is insensitive to the vacancy defect, small hole and short flaw, but large holes and long flaws can affect the vibration characteristics. So the graphene sheet even with small defect effects might be selected as the nanosensor material as well as pristine graphene. The conclusions in this paper may provide some references for the design of nanosensor.
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Anigbogu, Winner, and Hamzeh Bardaweel. "A Metamaterial-Inspired Structure for Simultaneous Vibration Attenuation and Energy Harvesting." Shock and Vibration 2020 (June 13, 2020): 1–12. http://dx.doi.org/10.1155/2020/4063025.
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In this article, a magnetomechanical metamaterial structure capable of simultaneous vibration attenuation and energy harvesting is presented. The structure consists of periodically arranged local resonators combining cantilever beams and permanent magnet-coil systems. A prototype of the metamaterial dual-function structure is fabricated, and models are developed. Results show good agreement between model simulation and experiment. Two frequency bandgaps are measured: 205–257 Hz and 587–639 Hz. Within these bandgaps, vibrations are completely attenuated. The level of vibration attenuation in the first bandgap is substantially larger than the level of vibration attenuation observed in the second bandgap. Mode shapes suggest that bending deformations experienced by the local resonators in the second bandgap are less than the deformations experienced in the first bandgap, and most vibrational energy is localized within the first bandgap where the fundamental resonant frequency is located, i.e., 224 Hz. The ability of the fabricated metamaterial structure to harvest electric power in these bandgaps is examined. Results show that vibration attenuation and energy harvesting characteristics of the metamaterial structure are coupled. Stronger vibration attenuation within the first bandgap has led to enhanced energy harvesting capabilities within this bandgap. Power measurements at optimum load resistance of 15 Ω reveal that maximum power generated within the first bandgap reaches 5.2 µW at 245 Hz. Compared with state-of-the-art, the metamaterial structure presented here shows a significant improvement in electric power generation, at considerably lower load resistance, while maintaining the ability to attenuate undesired vibrations within the frequency bandgap.
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Lee, Sangdeok, and Seul Jung. "Detection and control of a gyroscopically induced vibration to improve the balance of a single-wheel robot." Journal of Low Frequency Noise, Vibration and Active Control 37, no. 3 (July 3, 2017): 443–55. http://dx.doi.org/10.1177/0263092317716075.
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In this article, an experimental investigation of the detection of a gyroscopically induced vibration and the balancing control performance of a single-wheel robot is presented. The balance of the single-wheel robot was intended to be maintained by virtue of the gyroscopic effect induced from a highly rotating flywheel. Since the flywheel rotates at a high speed, an asymmetrical structure of a flywheel causes an irregular rotation and becomes one of the major vibration sources. A vibration was detected and suppressed a priori before applying control algorithms to the robot. Gyroscopically induced vibrations can empirically be detected with different rotational velocities. The detection of the balancing angle of the single-wheel robot was accomplished by using an attitude and heading reference system. After identifying the vibrating frequencies, a notch filter was designed to suppress the vibration at the typical frequencies identified through experiments. A digital filter was designed and implemented in a digital signal processor(DSP) along with the control scheme for the balance control performance. The performance of the proposed method was verified by the experimental studies on the balancing control of the single-wheel robot. Experimental results confirmed that the notch filter designed following the detection of the flywheel’s vibration actually improved the balancing control performance. A half of the vibration magnitude was reduced by the proposal.
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Beikmann, R. S., N. C. Perkins, and A. G. Ulsoy. "Nonlinear Coupled Vibration Response of Serpentine Belt Drive Systems." Journal of Vibration and Acoustics 118, no. 4 (October 1, 1996): 567–74. http://dx.doi.org/10.1115/1.2888336.
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This theoretical and experimental study identifies a key nonlinear mechanism that promotes strongly coupled dynamics of serpentine belt drive systems. Attention is focused on a prototypical three-pulley system that contains the essential features of automotive serpentine drives having automatic (spring-loaded) tensioners. A theoretical model is presented that describes pulley and tensioner arm rotations, and longitudinal and transverse belt vibration response. A recent investigation demonstrates that infinitesimal belt stretching creates a linear mechanism that couples transverse belt vibration to tensioner arm rotation. Here, it is further demonstrated that finite belt stretching creates a nonlinear mechanism that may lead to strong coupling between pulley/tensioner arm rotation and transverse belt vibration, in the presence of an internal resonance. Theoretical and experimental results confirm the existence of this nonlinear coupling mechanism. In particular, it is shown that very large transverse belt vibrations can result from small resonant torque pulses applied to the crankshaft or accessory pulleys. These large amplitude transverse vibrations are particularly sensitive to seemingly small changes in the rotational mode characteristics.
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Gronskii, V. I., and A. M. Tikhomirov. "Automation of the analysis of resonance vibrations of mechanical systems in vibration tests." Soviet Applied Mechanics 26, no. 7 (July 1990): 686–92. http://dx.doi.org/10.1007/bf00889410.
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Wi, Daehan, and Angela Sodemann. "Vibration analysis for the development of resonant microbeam high-resolution vibrotactile haptic display." Journal of Vibration and Control 25, no. 2 (May 28, 2018): 362–72. http://dx.doi.org/10.1177/1077546318778672.
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One type of assistive device for the blind has attempted to convert visual information into information that can be perceived through another sense, such as touch or hearing. A vibrotactile haptic display assistive device consists of an array of vibrating elements placed against the skin, allowing the blind individual to receive visual information through touch. However, these approaches have two significant technical challenges: large vibration element size and the number of microcontroller pins required for vibration control, both causing excessively low resolution of the device. Here, we propose and investigate a type of high-resolution vibrotactile haptic display which overcomes these challenges by utilizing a ‘microbeam’ as the vibrating element. These microbeams can then be actuated using only one microcontroller pin connected to a speaker or surface transducer. We propose that this approach could solve the low-resolution problem currently present in all haptic displays. In this paper, we present the results of an investigation into the manufacturability of such a device, simulation of the vibrational characteristics, and prototyping and experimental validation of the device concept.
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A.M., Lipanov, Rusyak I.G., and Sufiyanov V.G. "A STUDY ON THE EFFECTS OF GUN BARREL VIBRATIONS ON THE FIRING ANGLE OF A PROJECTILE." Vestnik Tomskogo gosudarstvennogo universiteta. Matematika i mekhanika, no. 68 (2020): 80–94. http://dx.doi.org/10.17223/19988621/68/8.
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The problem of longitudinal and transverse vibrations of an artillery gun barrel during firing is considered. Unsteady stress-strain equations for the gun barrel are solved together with equations of internal ballistics. Ballistic parameters and dynamics of the projectile motion inside a gun bore are determined using a thermodynamic approach. Formulation of the vibration problem accounts for the initial gravitational deflection of the barrel, mass forces, varying distribution of the propellant gas pressure, and the effect of moving projectile mass on gun barrel vibrations. To solve the equations for longitudinal and transverse gun barrel vibrations, difference schemes are obtained by integro-interpolation method. It has been revealed that the solution to the problem in a one-dimensional formulation is almost as accurate as the results obtained in a three-dimensional formulation. Moreover, the former case is significantly less time consuming. The decay time of the barrel longitudinal vibrations after shot is shown to be much less than the time between shots in the burst. Deviations of the transverse barrel vibrations from the initial firing angle are more significant, and the vibration decay time is longer than the time between shots, which affects the accuracy of single shots and the dispersion of shells in the burst mode. Thus, when firing from a 30 mm gun at the range of 1 km, lateral vibrations lead to a change in the height of target hit point by 8.7 m.
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Guo, Tong, Zhiliang Cao, Zhiqiang Zhang, and Aiqun Li. "Numerical simulation of floor vibrations of a metro depot under moving subway trains." Journal of Vibration and Control 24, no. 18 (August 9, 2017): 4353–66. http://dx.doi.org/10.1177/1077546317724322.
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With the development of subway lines in urban areas, building structures are sometimes subjected to train-induced vibrations, and there is a need to develop prediction models to evaluate the vibration serviceability. In this paper, a new type of subway-depot system is investigated, where subway trains run through the top story of a 3-story metro depot, while the first two stories were developed for offices and shops to avoid the waste of large city areas. Considering the increasing use of such a structural system and the possible serviceability problems, the floor vibrations of a metro depot under moving subway trains were numerically simulated, where the train-track system was treated as the vibration source and studied separately, and the influence of train speed and fastener configuration on the vibration response was discussed. The metro depot was modeled taking the stiffness of the partition walls into account, and vibration responses of the building at different locations were compared and validated through field tests. Besides, vibration level of the second floor was evaluated using an acceleration index that considers frequency weighting. Finally, parameter analysis was carried out so as to provide some references to the vibration control.
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Huang, Zi-Gui, and Zheng-Yu Chen. "Analysis of Excitation and Dead Vibration Modes of Quartz Resonators." Advances in Acoustics and Vibration 2014 (February 10, 2014): 1–9. http://dx.doi.org/10.1155/2014/746847.
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This study uses the finite element method (FEM) to analyze the excitation and dead vibration modes of two-dimensional quartz plates. We first simplify three-dimensional quartz plates with plane strain simplification and then compare the modes of the simplified three-dimensional plates to those of two-dimensional plates. We then analyze quartz vibrating elements of AT-cut plates and SC-cut plates. To understand the regularity of the resonance frequency of plates that are excitable by voltage loading, we compare the natural vibrations of quartz plates with the excitation frequency generated after the plates are excited by voltage loading.
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Berardi, Umberto, and Gino Iannace. "Additive manufacturing for minimizing vibration damages in the water-stop tray of washing machines." Journal of Low Frequency Noise, Vibration and Active Control 36, no. 2 (June 2017): 193–99. http://dx.doi.org/10.1177/0263092317712017.
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The present work aims to study the water-stop tray, a front-loading component of a washing machine. As most of the components of washing machines, the water-stop tray suffers significant vibrations especially when the spin speed increases. A vibrational analysis of the current typical design was realized. Then, four modified trays were investigated and a hammer impulse response was recorded using 13 accelerometers in order to measure the frequency response of each tray. The results allow to identify the key parameters that affect the vibrational response of a water-stop tray. Finally, the comparative analysis among the different designs allows to select the tray with the lowest vibration amplitude.
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Palazzolo, A. B., S. Jagannathan, A. F. Kascak, G. T. Montague, and L. J. Kiraly. "Hybrid Active Vibration Control of Rotorbearing Systems Using Piezoelectric Actuators." Journal of Vibration and Acoustics 115, no. 1 (January 1, 1993): 111–19. http://dx.doi.org/10.1115/1.2930303.
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The vibrations of a flexible rotor are controlled using piezoelectric actuators. The controller includes active analog components and a hybrid interface with a digital computer. The computer utilizes a grid search algorithm to select feedback gains that minimize a vibration norm at a specific operating speed. These gains are then downloaded as active stiffnesses and dampings with a linear fit throughout the operating speed range to obtain a very effective vibration control.