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1
Lian, Jijian, Yan Zheng, Chao Liang, and Bin Ma. "Analysis for the Vibration Mechanism of the Spillway Guide Wall Considering the Associated-Forced Coupled Vibration." Applied Sciences 9, no. 12 (June 25, 2019): 2572. http://dx.doi.org/10.3390/app9122572.
Анотація:
During the flood discharge in large-scale hydraulic engineering projects, intense flow-induced vibrations may occur in hydraulic gates, gate piers, spillway guide walls, etc. Furthermore, the vibration mechanism is complicated. For the spillway guide wall, existing studies on the vibration mechanism usually focus on the vibrations caused by flow excitations, without considering the influence of dam vibration. According to prototype tests, the vibrations of the spillway guide wall and the dam show synchronization. Thus, this paper presents a new vibration mechanism of associated-forced coupled vibration (AFCV) for the spillway guide wall to investigate the dynamic responses and reveal coupled vibrational properties and vibrational correlations. Different from conventional flow-induced vibration theory, this paper considers the spillway guide wall as a lightweight accessory structure connected to a large-scale primary structure. A corresponding simplified theoretical model for the AFCV system is established, with theoretical derivations given. Then, several vibrational signals measured in different structures in prototype tests are handled by the cross-wavelet transform (XWS) to reveal the vibrational correlation between the spillway guide wall and the dam. Afterwards, mutual analyses of numeral simulation, theoretical derivation, and prototype data are employed to clarify the vibration mechanism of a spillway guide wall. The proposed mechanism can give more reasonable and accurate results regarding the dynamic response and amplitude coefficient of the guide wall. Moreover, by changing the parameters in the theoretical model through practical measures, the proposed vibration mechanism can provide benefits to vibration control and structural design.
2
Zhao, Ming Hui. "Vibration Analysis of a Shell Structure by Finite Element Method." Advanced Materials Research 591-593 (November 2012): 1929–33. http://dx.doi.org/10.4028/www.scientific.net/amr.591-593.1929.
Анотація:
Plate-shell structures, especially cylindrical shells and spherical shells, are widely used in engineering fields, such as aircraft and tanks, missiles, submarines, ships, hydraulic pumps, infusion pipelines and gas pipelines, and so on. These structures are usually in a fluid medium, which are related to the structure fluid-solid coupling and acoustic radiation field. As many experiments show that enclosed air in a thin walled structure, just like the violin, affects some modes of vibration significantly, air coupling between vibrating sides of the structure cannot be neglected. In order to explore the sound pressure distribution of vibrational frequencies, this paper, considering the material anisotropy, analyzes a typical complex shell structure of the violin by finite element method, including acoustic-structure coupling analysis and post-processing, especially sound pressure vibration frequency extraction. Finally, we get the conclusion that the distribution of sound pressure vibration frequency is similar to the normal distribution.
3
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.
Анотація:
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.
4
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.
Анотація:
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.
5
Trujillo-Franco, Luis Gerardo, Nestor Flores-Morita, Hugo Francisco Abundis-Fong, Francisco Beltran-Carbajal, Alejandro Enrique Dzul-Lopez, and Daniel Eduardo Rivera-Arreola. "Oscillation Attenuation in a Building-like Structure by Using a Flexible Vibration Absorber." Mathematics 10, no. 3 (January 18, 2022): 289. http://dx.doi.org/10.3390/math10030289.
Анотація:
This is a theoretical, numerical, and experimental study on the vibration attenuation capability of the dynamic response of a building-like structure using a dynamic vibration absorber in cantilever flexible beam configuration, taking into account gravitational effects associated with its mass. The dynamic model of the primary vibrating structure with the passive vibration control device is obtained using the Euler–Lagrange formulation considering the flexible vibration absorber as a generalized system of one degree of freedom. The application of the Hilbert transform to the frequency response function to determine the tuning conditions between this nonlinear flexible beam vibration absorber and the primary system is also proposed. In this fashion, Hilbert transform analysis is then carried out to show that nonlinearities present in the dynamic model do not significantly contribute to the performance of the implemented absorber. Therefore, it is valid to linearize the equations of motion to obtain the tuning condition in which the flexible vibration absorber can attenuate undesirable harmonic vibrations that are disturbing to the building-like flexible structure. Thus, the present study shows that the Hilbert transform can be applied to obtain tuning conditions for other configurations of dynamic vibration absorbers in nonlinear vibrating systems. Simulation and experimental results are included to demonstrate the efficient performance of the presented vibration absorption scheme.
6
Szulej, Jacek, and Paweł Ogrodnik. "Determining the level of damping vibration in bridges and footbridges." Budownictwo i Architektura 15, no. 1 (April 1, 2016): 095–103. http://dx.doi.org/10.24358/bud-arch_16_151_10.
Анотація:
While designing slim and slender structures such as cable-stayed, suspended and arch bridges and footbridges, data on the dynamic behavior of structure are required. One of the main quantities, included in the calculations, is the damping parameter of vibration of the structure whose corresponding value has a direct impact on the proper behavior of the facility. One of currently applied approaches in the case of complex constructions, is the use of methods defining the equivalent damping coefficient which refers to the given form of natural vibrations. Among these methods, the collocation method and energy method can be distinguished. The collocation method refers to the existing facilities and requires performing measurements of vibration and spectral processing of time course of vibrations. The energy method requires the creation of FEM model of construction and it estimates the kinetic energy of the vibrating system. The above- mentioned methods are used in the calculations of the damping level of vibration of two structures, i.e.: arch John Paul II Bridge in Pulawy and a footbridge located in Lublin.
7
Sugakov, V. I. "Fine structure of thermoluminescence assisted by molecular vibrations in disordered organic semiconductors." Journal of Physics: Condensed Matter 34, no. 18 (March 2, 2022): 185703. http://dx.doi.org/10.1088/1361-648x/ac50d9.
Анотація:
Abstract The article deals with the issue of the influence of a separate mode of molecular vibrations on the formation of the thermoluminescence from disordered systems with quasi-continuous spectra of localized carriers. The contribution of vibrations is noticeable if the energy of their quanta is close to the depth of some localized carriers and the transition of the carrier into the conductive region occurs via absorption of these quanta. At some value of a carrier–vibration interaction, the effect manifests itself in the appearance of a fine discrete structure on the generally smooth thermoluminescence curve. The thermoluminescence of polymers is calculated using the model of non-adiabatic transitions, in which the carrier–vibrational interaction is determined by the displacements of nuclei in the presence of the carrier. The dependence of the arising discrete structure of the thermoluminescence curve on a number of parameters of the system like the magnitude of the carrier–vibration interaction, the width of vibrational levels, the parameters of the conductive region is investigated. The processes with participation of multiple quanta of vibrations are investigated and the formation of repetitive structures on the thermoluminescence curve has been shown owing to the absorption of several vibrational quanta. Analysis of a number of experiments is presented using the suggested theory.
8
Xu, Yuan, Hui Li, Jue Hou, Liming Zhu, and Lingkun Chen. "Newly Constructed Subway on Over-Track Bridge Safety and Vibration Reduction Measure." Advances in Civil Engineering 2024 (May 16, 2024): 1–12. http://dx.doi.org/10.1155/2024/5851849.
Анотація:
Primarily generated at the interface between the wheel and the rail, railroad vibrations then propagate through the supporting soil. If these vibrations reach nearby bridges and buildings, they amplify the vibration nuisance and cause ground noise, which has detrimental effects on nearby residents, sensitive equipment, and historic structures. By analyzing measured data from metro vibration field vibration experiments, this article attempts to contribute to the body of knowledge on environmental vibration propagation patterns by offering insightful conclusions. Before analyzing the deformation response of the metro jet system (MJS) vibration isolation piles to the structure and the ground, we investigated the effect of MJS vibration isolation piles in the ground of the existing subway tunnel structure on the control of vibration of the proximate structure and conducted dynamic tests on the vibration of bridges without vibration isolation measures caused by operating subway trains. The tests determined that the acceleration of the bridge’s lateral vibration exceeded the code limit; one of the contributing factors was that the bridge’s structure had already sustained damage. The utilization of MJS isolation piles was also discovered to safeguard the extant bridge pile foundations. The paper presents an innovation in the form of economically viable vibration mitigation strategies that were implemented subsequent to the identification that the lateral vibration acceleration of the preexisting bridge surpassed the prescribed code standards. Considerable insight is gained regarding the design and implementation of vibration control systems for structures situated near caverns, encompassing deep foundation works.
9
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.
Анотація:
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.
10
Shen, Y. X., Ke Hua Zhang, Y. C. Chen, H. W. Zhu, and K. Fei. "Numerical Simulation Analysis of Vibrating Screen’s Structure Vibration Property." Advanced Materials Research 215 (March 2011): 272–75. http://dx.doi.org/10.4028/www.scientific.net/amr.215.272.
Анотація:
Vibrating screen sifts materials via screen mesh, vibration displacement and velocity. In order to completing optimal design of vibrating screen’s vibration frequency. Firstly, Using the CAD function of the three dimensional software UG NX 6.0 to achieve vibrating screen modeling. Secondly, modal simulation analysis was carried out using the simulation soft NX NASTRAN. Numerical simulation experimental result indicates: this designed vibrating screen’s natural vibration frequency are 27.79Hz, 32.58 Hz, and 46.39Hz, consequently, designing this vibrating screen should avoid identical or approaching these natural vibration frequencies as far as possible, while choosing the vibration frequency.
11
Hujare, Pravin P., and Anil D. Sahasrabudhe. "Effect of Thickness of Damping Material on Vibration Control of Structural Vibration in Constrained Layer Damping Treatment." Applied Mechanics and Materials 592-594 (July 2014): 2031–35. http://dx.doi.org/10.4028/www.scientific.net/amm.592-594.2031.
Анотація:
The reduction of noise and vibration is a major requirement for performance of any vibratory system. Passive damping technology using viscoelastic materials is classically used to control vibrations. Viscoelastic material among the damping materials is widely used to dissipate the structural vibration energy. Three-layer sandwich beams, made of two elastic outer layers and a viscoelastic layer sandwiched between them, are considered as damping structural elements. This paper presents the effect of thickness of constrained damping material on modal loss factor of vibrating structures. Measurements are performed on sandwich beam structure. In order to understand the effectiveness of the sandwich structures, the dynamics of beam with constrained viscoelastic layers are investigated. Comparisons of the experimental and the Numerical results confirm that the damping levels and the natural frequencies of damped structures are well corroborated.
12
Shen, Xiaoyan, Jing Yu, Jianlong Yin, and Dongsheng Li. "Experimental Study of See-Saw Mode Nano-Vibration on Orifice-Type Restrictors." Applied Sciences 11, no. 11 (June 6, 2021): 5265. http://dx.doi.org/10.3390/app11115265.
Анотація:
Slide stability is key to the aerostatic guide in ultra-precise machines; thus, it has garnered plenty of attention. Macro-scale studies are commonplace, but micro- and nano-vibration issues require more attention. Microscope vibration is mainly caused by tiny changes in the fluid parameters of lubricating gas film, which is complex and has no verdict. In this case, slide-gas interaction should be considered. In this study, the widely used orifice-type restrictor was investigated for its nano-vibration performance. A Comsol finite-element-method fluid–structure interaction model was used to simulate and analyze an orifice-type restrictor, and orifice-restrictor vibration characteristics at the nanometer scale were inspected using a high-performance laser vibrometer. The results demonstrate that see-saw mode vibrations occur in the restrictors, growing stronger with increased air-supply pressure. The see-saw vibration’s axis is speculatively determined based on orifice and restrictor structures, and the vibration type is related to the number of orifices. The results also show that the vibration is random with natural frequencies at the kilohertz level. The newly provided research results are beneficial for better understanding the nano-vibrations of orifice-type restrictors.
13
Abdullah, Nurfaezah, Kasrul Abdul Karim, Raja Nor Firdaus Raja Othman, Auzani Jidin, and Tole Sutikno. "Investigation on various stator structure towards noise and vibration." International Journal of Power Electronics and Drive Systems (IJPEDS) 14, no. 3 (September 1, 2023): 1403. http://dx.doi.org/10.11591/ijpeds.v14.i3.pp1403-1413.
Анотація:
<span lang="EN-US">This research analyses the noise and vibration characteristics of permanent magnet motors (PMM) with the electromagnetic characteristics, with an emphasis on high-speed motor segmented closed slot stator. The interaction between the stator, rotor, and magnets can cause a vibration that results in the loud sound due to the high magnetic energy. Even if there aren't many vibrations to contend with, the fluctuation of motor vibrations causes more serious harm. The studies covered slotted stator, closed slot stator, and segmented with closed slot stator. The objective is to analyze the cogging torque relation towards vibration and the effect of natural frequency at steady-state behavior of the structure. ANSYS finite element analysis (FEA) is used to generate electromagnetic analysis performance whilst ANSYS mechanical used to simulate the modal and harmonic analysis at the stator tooth tips surface to define the structure when </span><span lang="EN-US">the steady-state condition under vibrational stimulation. Anticipation on this work shows, the lowest cogging torque produce less radiated sound. Thus, the result indicates the cogging torque profiles had good agreement with the equivalent radiated power level (ERPL) waterfall diagram.</span>
14
Mohammadi, Nader, and Mehrdad Nasirshoaibi. "Optimization of vibrational absorber rested on linear structures under arbitrary vibrations." International Journal of Engineering & Technology 4, no. 3 (August 8, 2015): 446. http://dx.doi.org/10.14419/ijet.v4i3.4784.
Анотація:
Vibrational absorber is one of the common approaches for vibration control in structures. In this article, optimization criteria for mechanical systems under arbitrary vibrations is presented based on a multi-purpose method whose objective function vector collects the efficiency of arbitrary reliability and indexes of structure costs. The criterion is different from conventional criteria and standards used to design structures subjected to arbitrary vibrations and is based on minimizing the changes in displacement or response acceleration of the main structure, regardless of the required function for the failure. In this study, multi-purpose optimization approach to the design of vibrational an absorber is investigated to control non-uniform structural vibrations stimulating mechanical a mechanical structure based on an arbitrary acceleration process. It is performed based on bee optimization algorithm. In the following, a numerical example is shown for a simple vibrational absorber by this way. It shows the results of cost increase for decreased possibility of deconstruction, and therefore, allows appropriate decision making and selection based on need and cost.
15
Dekui, Xu. "The Research Of Fluid-structure Interaction Of The Hydrocyclone Under The Condition Of Vibration." E3S Web of Conferences 118 (2019): 02075. http://dx.doi.org/10.1051/e3sconf/201911802075.
Анотація:
During the operation of the hydrocyclone, vibrations are often generated by internal fluids and external disturbances resulting in fluid-structure interaction, causing the spatiotemporal evolution of the flow field and the movement of the structure. In this paper, the flow characteristic and the structural motion of the periodic vibrating hydrocyclones are studied. The bidirectional fluid-solid model of hydrocyclone under vibration condition is established. The flow field and structure motion under different vibration frequencies and structure resonances are studied. It shows that the velocities in the three directions oscillate positively and negatively with the motion of structure, the amplitude of the oscillation is the largest on resonance, the skewing of the velocity in the flow field is smaller than the structure; the tangential velocity is asymmetric and the radial velocity is increased significantly, the deformation of the structure is different on the different vibration frequencies, which causes the flow field of distribution of each section to be different. This study will provide the theoretical guidance for the application of hydrocyclone under the vibration conditions.
16
Hudeček, Leopold, Jiří Svoboda, and Jan Kramný. "Reducing the Negative Effects of City Railways on Houses in Ostrava." Advanced Materials Research 1041 (October 2014): 432–35. http://dx.doi.org/10.4028/www.scientific.net/amr.1041.432.
Анотація:
The paper discusses measures to reduce the negative effects of tram traffic on residential house in Ostrava, where the tram line passes through the street area located under the structure of the house see Figure 1.Fig.1HouseNo.1340inOstravaaffectedbyvibrationsfromrailtransportThe lines of urban railways are often kept at densely built-up areas, often in close proximity to the buildings. It is necessary to put a high emphasis on protection against noise and vibration. In case of structures for residential buildings it has a negative effect on residents. An efficient way to reduce the vibration levels of the protected structure and thus the secondary noise is elastic foundation structure as a whole to its support structure. But in practice, we need to solve the problem of the ex post, i.e. when the structure of a residential building already exists.To reduce the transmission of vibrations to the structure was carried out technical measures for vibration attenuation along the route of the spread it is the path from the source to the protected structure. Railway track was imposed on rubber anti-vibration mats under gravel bed of tram line. Furthermore, the test sections were established in order to test the application of different materials used as a grout space between the rails and the surrounding environment and the reference section to compare the resulting data.Subsequently was held the measurement of noise and vibration. Vibrations were measured on the own construction of the house, also on the communication - vertical vibration near the track (30 cm far from the running rail track), these data present the transmission of vibration from the rail and sleepers in the immediate surroundings, measuring the vertical vibrations of the road (150 cm far from the running rail track in place that was not affected by reconstruction), these data present the transmission of vibration to the subsoil neighborhood.
17
Cha, Woon-Yong. "Study on Dynamic Characterization and Vibration Reduction of Scrubber Structures Using Fluid Structure Interaction Analysis." Applied Sciences 12, no. 10 (May 21, 2022): 5207. http://dx.doi.org/10.3390/app12105207.
Анотація:
A scrubber is an important structure in post-semiconductor processes. It is impossible to completely modify the entire structure of an already installed and operating scrubber if a vibration problem occurs. Therefore, it is essential to determine the cause of vibrations and reinforce the structure. Vibration is majorly caused by the pump, and as considerable vibration is generated around the pump, it is essential to analyze it. However, as various equipment is operated in buildings where scrubbers are installed, the vibration data measured by attaching sensors are invalid owing to surrounding problems. Therefore, in this study, vibration data on the periphery of a pump according to the pump driving force was confirmed using a two-way fluid structure interaction analysis. To this end, a case run was conducted within a changeable design range, and an efficient design for vibration reduction was suggested by comparing the data with a change in the design factor.
18
Khomenko, Andrei P., Sergey K. Kargapoltsev, and Andrey V. Eliseev. "Development of Approaches to Creation of Active Vibration Control System in Problems of the Dynamics for Granular Media." MATEC Web of Conferences 148 (2018): 11004. http://dx.doi.org/10.1051/matecconf/201814811004.
Анотація:
The article deals with the development of mathematical models and evaluation criteria of the vibration field in the dynamic interactions of the elements of the vibrational technological machines for the processes of vibrational strengthening of long-length parts with help of a steel balls working medium. The study forms a theoretical understanding of the modes of motions of material particles in interaction with a vibrating surface of the working body of the vibration machine. The generalized approach to the assessment of the dynamic quality of the work of vibrating machines in multiple modes of tossing, when the period of free flight of particles is a multiple of the period of the surface oscillations of the working body, is developed in the article. For the correction of vibration field of the working body, the characteristics of dynamic interactions of granular elements of the medium are taken into account using original sensors. The sensors that can detect different particularities of interaction of the granular medium elements at different points of the working body are proposed to evaluate the deviation from a homogeneous and one-dimensional mode of vibration field. Specially developed sensors are able to register interactions between a single granule, a system of granules in filamentous structures, and multipoint interactions of the elements in a close-spaced cylindrical structure. The system of regularization of the structure of vibration fields based on the introduction of motion translation devices is proposed using the multi-point sensor locations on the working body. The article refers to analytical approaches of the theory of vibration displacements. For the experimental data assessment, the methods of statistical analysis are applied. It is shown that the peculiar features of the motion of granular medium registered by the sensors can be used to build active control systems of field vibration.
19
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.
Анотація:
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.
20
Tho, Nguyen Chi, Nguyen Tri Ta, and Do Van Thom. "New Numerical Results from Simulations of Beams and Space Frame Systems with a Tuned Mass Damper." Materials 12, no. 8 (April 23, 2019): 1329. http://dx.doi.org/10.3390/ma12081329.
Анотація:
In working processes, mechanical systems are often affected by both internal and external forces, which are the cause of the forced vibrations of the structures. They can be destroyed if the amplitude of vibration reaches a high enough value. One of the most popular ways to reduce these forced vibrations is to attach tuned mass damper (TMD) devices, which are commonly added at the maximum displacement point of the structures. This paper presents the computed results of the free vibration and the vibration response of the space frame system under an external random load, which is described as a stationary process with white noise. Static and dynamic equations are formed through the finite element method. In addition, this work also establishes artificial neural networks (ANNs) in order to predict the vibration response of the first frequencies of the structure. Numerical studies show that the data set of the TMD device strongly affects the first frequencies of the mechanical system, and the proposed artificial intelligence (AI) model can predict exactly the vibration response of the first frequencies of the structure. For the forced vibration problem, we can find optimal parameters of the TMD device and thus obtain minimum displacements of the structure. The results of this work can be used as a reference when applying this type of structure to TMD devices.
21
Janas, Lucjan. "Experimental Study on Vibration and Noise Characteristics of Steel-Concrete Railway Bridge." Sensors 21, no. 23 (November 29, 2021): 7964. http://dx.doi.org/10.3390/s21237964.
Анотація:
The paper presents the results of vibroacoustic tests of a plate girder railway bridge consisting of two parallel dilated structures and a common ballast trough. The requirements currently set for railway bridges relate to, among others, vibrations considered as one of the criteria for traffic safety and to noise emissions that may pose a threat to the environment. In this article, the results of tests conducted on vibrations of elements of the analyzed structure are presented, and the level of these vibrations in terms of meeting the requirements of the European standards is assessed. Vibrating criteria of structure performance were checked, and safety was assessed. The results of noise measurements in the vicinity of the analyzed bridge are also presented, and the environmental impact of this structure is determined. The test results show that the bridge meets the requirements for vibration acceleration and noise. An increased acoustic emission in the analyzed case does not pose a significant threat, but if this type of structure was on high supports in an urbanized area, it would be a nuisance to the environment.
22
He, Hong Lin, Dong Mei Wu, and Wen Guang Liu. "A Linear Piezoelectric Linear Motor Driven by the in-Plane Longitudinal and Bending Vibrations of an H-Shaped Vibrator." Advanced Materials Research 472-475 (February 2012): 2824–27. http://dx.doi.org/10.4028/www.scientific.net/amr.472-475.2824.
Анотація:
In order to develop theoretical instructions for design of high performance linear motor, a piezoelectric linear motor based on an H-shaped vibrator is proposed, which employed the vibrator’s 2nd bending vibration mode and 1st longitudinal planar vibration to drive the motor in this paper. Firstly, the driving principle of the motor is presented, and the elliptical motion generated on the driving end of the vertical bars of the vibrator is proved. Then, FEM simulation model is built for the vibrator, which is used to calculate the vibrator’s working modes and to execute harmonic response analysis and sensitivity analysis for the vibrator. Furthermore, the vibration’s optimal size is given and the motor assembly structure is designed. Finally, modal test is done for the vibrator to validate the anticipated work modes vibration and the bending vibration and longitudinal planar vibration could be 1.4μm and1.2μm under normal drive.
23
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.
Анотація:
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.
24
Mohamed, Khaled Saad, Fatin Amri, Mostafa Mohamed Elboraey, N. H. Diyana Nordin, and Asan Gani Abdul Muthalif. "Adaptive Electromagnetic Vibration Absorber for a Multimode Structure." Strojniški vestnik - Journal of Mechanical Engineering 68, no. 3 (March 25, 2022): 191–99. http://dx.doi.org/10.5545/sv-jme.2021.7458.
Анотація:
All structures experience vibrations due to external dynamic force excitations, such as earthquakes and wind loadings. At resonance, the impact of this natural dynamic force on structures may lead to structural failures. Hence, an absorber is mounted to absorb vibrations from the primary system. Unfortunately, passive tuned mass absorbers can only target a single frequency. Since structural buildings possess multiple modes, an adaptive or tune-able vibration absorber is needed to attenuate the vibration in a multi-degree of freedom (MDOF) system. In this work, an adaptive electromagnetic vibration absorber (AEMVA) is proposed to eliminate the effects of vibrations and is dynamically tuned using electromagnets. By varying the current supplied to the coil, the stiffness of the AEMVA can be adjusted, resulting in a varying absorber frequency. A mathematical description of the AEMVA on a three-story prototype model building is also presented. The three-story benchmark model was used to demonstrate the effectiveness of AEMVA in absorbing multiple vibration modes, both analytically and experimentally. It is shown that 68.81 %, 50.49 %, and 33.45 % of vibration amplitude reductions were achieved at the first, second, and third modes, respectively.
25
Hambric, Stephen. "Tutorial on Acoustic Fluid Loading of Structures." INTER-NOISE and NOISE-CON Congress and Conference Proceedings 263, no. 6 (August 1, 2021): 1–19. http://dx.doi.org/10.3397/in-2021-1002.
Анотація:
Any vibrating structure is loaded by the fluid surrounding it. Whether air, water, or something else, the fluid loading adds a spatially distributed resistance (in phase with the vibration) and reactance (out of phase with the vibration) over the structural surfaces. The resistance absorbs energy, and damps structural vibrations. The reactance is either mass-like, effectively adding to the structural density, reducing resonance frequencies and vibration amplitudes; or stiffness-like, increasing resonance frequencies. Usually, mass-like reactance is caused by fluids external to a structure, and stiffness-like reactance is caused by enclosed volumes of fluids. This tutorial uses analytic methods to compare and contrast external and internal fluid loading on a flat rectangular plate and demonstrates the effects of fluid loading on plate vibration and radiated sound. The well-known stiffening effect of the internal Helmholtz resonance is demonstrated for a thin panel and a shallow entrained cavity. The differences between heavy (water) and light (air) external fluid loading are also demonstrated, with significant reductions in resonance frequencies and peak vibration amplitudes for water loading.
26
Onoda, Junjiro. "Some Advances in Energy Recycling Semiactive Vibration Suppression." Advances in Science and Technology 56 (September 2008): 345–54. http://dx.doi.org/10.4028/www.scientific.net/ast.56.345.
Анотація:
This paper summarizes some studies performed by the author's group on energy-recycling semiactive vibration suppression using piezoelectric transducers embedded in the vibrating structures and shunted on switched inductive circuits. Basic idea of this method is to suppress the vibration by controlling the switch in the shunt circuit, which was first introduced by Richard C., et al. This idea has been upgraded by introducing (1) a multiple-input-multiple-output (MIMO) control method for the switches in the shunt circuits, (2) a self-sensing method to estimate the state of structure from the voltage across the piezoelectric transducer, so that any additional sensors can be neglected, and (3) a self-powered shunt circuit that performs the semiactive vibration suppression without any power supply. Several numerical and experimental results showed that the method works well against transient, sinusoidal, and random multi-modal vibrations and suppresses the vibrations effectively. It was also shown that the method is very robust, and, with it, the system is always stable. Studies for various applications of this method are also discussed.
27
Ray, Tony, Jasmin Kaljun, and Aleš Straže. "Comparison of the Vibration Damping of the Wood Species Used for the Body of an Electric Guitar on the Vibration Response of Open-Strings." Materials 14, no. 18 (September 14, 2021): 5281. http://dx.doi.org/10.3390/ma14185281.
Анотація:
Research show that the vibrations of the strings and the radiated sound of the solid body electric guitar depend on the vibrational behavior of its structure in addition to the extended electronic chain. In this regard, most studies focused on the vibro-mechanical properties of the neck of the electric guitar and neglected the coupling of the vibrating strings with the neck and the solid body of the instrument. Therefore, the aim of the study was to understand how the material properties of the solid body could affect the stiffness and vibration damping of the whole instrument when comparing ash (Fraxinus excelsior L.) and walnut (Juglans regia L.) wood. In the electric guitar with identical components, higher modal frequencies were confirmed in the structure of the instrument when the solid body was made of the stiffer ash wood. The use of ash wood for the solid body of the instrument due to coupling effect resulted in a beneficial reduction in the vibration damping of the neck of the guitar. The positive effect of the low damping of the solid body of the electric guitar made of ash wood was also confirmed in the vibration of the open strings. In the specific case of free-free vibration mode, the decay time was longer for higher harmonics of the E2, A2 and D3 strings.
28
Karimov, Komolkhan, Bakhtiyor Mardonov, Azamat Akhmedov, and Murtoza Toirov. "Prospects for mathematical modeling in mining system development: accounting for global oscillations and seismic waves." E3S Web of Conferences 525 (2024): 05017. http://dx.doi.org/10.1051/e3sconf/202452505017.
Анотація:
The article discusses the potential of mathematical modeling in understanding the impact of vibrations and seismic waves, aiming at enhancing the sustainability of systems within the mining industry. It explores the dynamic response of a tall, elastic structure with a uniform cross-section and a fixed cylindrical fluid reservoir, subject to various complex boundary conditions. The study delves into the vibrational behavior of the structure when exposed to seismic and harmonic forces, calculating frequency, vibration periods, and deriving formulas for stress, tension, deformation, bending moments, and shear forces in different parts of the structure through both theoretical and experimental approaches. Additionally, the article derives the differential equation for the free oscillation of a tall hydraulic structure in pure bending with an incorporated mass load under appropriate boundary conditions, identifying specific vibration frequencies and periods. The forced vibration scenario is also examined, focusing on the structure's foundation movement due to external harmonic forces. Numerical computation technology is utilized to analyze the change laws of principal quantities that describe both free and forced vibrational movements of the hydraulic structure, showcasing the applicability of these models in predicting and mitigating the effects of seismic activities on mining infrastructure.
29
Cveticanin, Livija, Miljana Prica, and Sanja Vujkov. "Influence of the elasticity variation of the 3D printed PMMA structure on the axial tooth vibration." Journal of the Serbian Chemical Society, no. 00 (2024): 29. http://dx.doi.org/10.2298/jsc240118029c.
Анотація:
Recently, 3D printing with poly methyl methacrylate (PMMA) has been widely used in dentistry: 3D printing is a suitable method for producing any complex three-dimensional shape, and PMMA is a material that has suitable properties in the oral cavity environment. That is why 3D printing is very often used to make PMMA teeth. There is the impact between teeth during chewing that causes shape variation and tooth vibration. As cyclic vibrations adversely affect the durability of PMMA teeth, they must be eliminated. The object of this work is to study the axial vibrations of a 3D printed tooth, as well as to give recommendations for modifying the PMMA structure with the aim of vibration dampening. Tooth vibration is mathematically modeled and analytically solved. The obtained result provides a link between the vibrational properties and the elasticity variation of the PMMA material. The function that defines the change in elasticity of PMMA depends on the "slow time". (The term "slow time" implies a product of time and a parameter that is less than one). For a decreasing elasticity function, the vibration is of damped type: for higher is the elasticity reduction, the faster is the vibration decay. Based on the determined elasticity function, the modification of the PMMA structure can be realized. Authors propose the application of the obtained elasticity variation function for programming 4D printing with modified PMMA.
30
Martin, Vincent, Marie-Hélène Moulet, and Saül Mapagha. "Prediction of Forces Applied on a Receiver by Two Vibrating Structures Installed in Series; Application to an Engine Cooling Fan Mounted on a Car Chassis." Acta Acustica united with Acustica 97, no. 5 (September 1, 2011): 877–89. http://dx.doi.org/10.3813/aaa.918467.
Анотація:
Prediction of vibration and/or acoustic radiation of machines is an old problem which has in part been solved via a linear vibrations approach. Equipment mounted on a host structure, or receiver, is often responsible for vibration and radiation of the latter. The equipment is called source (electrical motor, ventilation system, cylinder and vibrating laminae in a music box . . . ). The host structure is passive (receiver structure of an engine, building supporting the ventilation system, music box itself. . . ). Beyond the case where one source structure is coupled with a host structure, there are a great number of configurations where the source structure excites an intermediary structure, itself mounted on the receiver. Our contribution pertains to such cases with an application to a car engine cooling fan system: the fan (source) is attached via elastic connections to a plate (intermediary structure), which excites the chassis (receiver) through rigid and elastic links. The vibratory behaviour of the assembled structure depends on those of the structures, which are known either by their technical specifications or because they are physically obtainable. According to the situation, there may or may not be a choice between different methods to predict the vibration and/or acoustic radiation of the host structure. In cases where choice exists, the predictions obtained by different methods vary and this paper attempts to show how to obtain the best prediction of forces imposed on the receiver structure. The originality is to be found in a metrological procedure more apt than another to predict the vibratory behaviour of an assembly in series of three structures in an industrial context. Indeed, when inertance matrices necessary for the prediction are measured on isolated structures, the prediction is of lesser quality than when a certain number of them are measured on coupled structures. This echoes a similar conclusion drawn recently from academic configurations.
31
Wu, Da Fang, Lin Zhu, Yue Wu Wang, Shou Gen Zhao, and Ying Pu. "Study on Vibration Characteristics of the Vehicles Wing Structure in High Temperature Environment." Applied Mechanics and Materials 482 (December 2013): 200–206. http://dx.doi.org/10.4028/www.scientific.net/amm.482.200.
Анотація:
During the flight of the long-range cruise missiles, aerodynamic heating can cause the temperature of the wing structure, fairing, missile body and other components to rise rapidly, along with serious structural vibrations. The thermal environment generated by aerodynamic heating significantly changes the mechanical properties of the materials and structure, including the elastic modulus, stiffness, and so on. The complex flight maneuver process will also produce high-temperature gradients, which affect the thermal stress field. Both of these impacts significantly affect the characteristics of the missile structures natural vibration. In this paper, thermal vibration joint testing was performed on two different wing structures of a high-speed missile under a thermal environment, and the vibration characteristics of the wing structure (e.g., the natural frequency) at various temperatures were obtained. The experimental results can provide a reliable basis for the safety design of the wing structure of missiles under high-speed thermal vibration conditions.
32
Krajewski, A., W. Włosiński, T. Chmielewski, and P. Kołodziejczak. "Ultrasonic-vibration assisted arc-welding of aluminum alloys." Bulletin of the Polish Academy of Sciences: Technical Sciences 60, no. 4 (December 1, 2012): 841–52. http://dx.doi.org/10.2478/v10175-012-0098-2.
Анотація:
Abstract The structure and hardness of the surface-welds and fusion-welds made on a 2017A aluminum alloy waveguide using the MIG and TIG methods with and without the participation of ultrasonic vibrations were examined. Cross-sections of the fusions and surface-welds thus obtained were observed in a microscope and the hardness distributions were determined. The aim of the study was to analyze the effects of the ultrasonic vibrations applied to the melted metal pool by a vibrating substrate which in our experiments was a waveguide. The interactions of the ultrasonic vibrations with the molten metal during its solidification and also with the heat-affected zone were examined at various phases of the vibration wave. The ultrasonic vibrations affected the structure of a weld. These changes are strongly depended on the wave phase.
33
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.
Анотація:
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.
34
Timms, David, Graham Brown, and Damian McGuckin. "Comparison of FEA and SEA methods for predicting railway-induced vibration propagation through over-station developments." Journal of the Acoustical Society of America 154, no. 4_supplement (October 1, 2023): A302—A303. http://dx.doi.org/10.1121/10.0023602.
Анотація:
The design process for Over-Station Developments (OSDs) includes consideration of the potential impacts of railway-induced vibrations to ensure that structure-borne noise and occupant comfort standards are maintained during railway operations. Should an OSD be identified as sensitive to railway operational structure-borne noise or vibration impacts, the inclusion of adequate track vibration isolation measures becomes essential for mitigation. This paper presents a comparative study of two methodologies for predicting vibration propagation through structures and consequent structure-borne noise levels—Finite Element Analysis (FEA) and Statistical Energy Analysis (SEA). Specifically, this study provides an indication of the range of predicted results and emphasizes the computational efficiency and scalability of these methods when determining track isolation requirements for structures.
35
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.
Анотація:
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%.
36
ZHANG, LIXIANG, WENQUAN WANG, and YAKUN GUO. "NUMERICAL SIMULATION OF FLOW FEATURES AND ENERGY EXCHANGE PHYSICS IN NEAR-WALL REGION WITH FLUID-STRUCTURE INTERACTION." International Journal of Modern Physics B 22, no. 06 (March 10, 2008): 651–69. http://dx.doi.org/10.1142/s0217979208038806.
Анотація:
Large eddy simulation is used to explore flow features and energy exchange physics between turbulent flow and structure vibration in the near-wall region with fluid–structure interaction (FSI). The statistical turbulence characteristics in the near-wall region of a vibrating wall, such as the skin frictional coefficient, velocity, pressure, vortices, and the coherent structures have been studied for an aerofoil blade passage of a true three-dimensional hydroturbine. The results show that (i) FSI greatly strengthens the turbulence in the inner region of y+ < 25; and (ii) the energy exchange mechanism between the flow and the vibration depends strongly on the vibration-induced vorticity in the inner region. The structural vibration provokes a frequent action between the low- and high-speed streaks to balance the energy deficit caused by the vibration. The velocity profile in the inner layer near the vibrating wall has a significant distinctness, and the viscosity effect of the fluid in the inner region decreases due to the vibration. The flow features in the inner layer are altered by a suitable wall vibration.
37
Grosu, C., and M. Blaga. "OVERVIEW OF THE KNITTED MATERIALS WITH VIBRATIONS DAMPING CAPACITY." TEXTEH Proceedings 2021 (October 22, 2021): 342–47. http://dx.doi.org/10.35530/tt.2021.54.
Анотація:
Textile materials are often subjected to different stresses, acting on them in two phases: during the knitting phase, when the yarns and the obtained structure are subjected to cyclic stress, but also during the use phase, when the knitted structures are subjected to various stresses. The dynamic behaviour of knitted fabrics in a vibrating environment is usually evaluated by standardized methods, such as the method using vibration exciters (e.g., ISO 10819:2013). However, in recent years, the authors' collective has carried out research to characterize the behaviour of knitted structures in a vibrating environment, using a well-known method for generating vibrations by impact excitation, which is specific to the mechanical field but also has a high potential for application in the textile field. This method refers to the determination of the free vibrations of an elastic system. Its measurement in the design phase of the system is considered a crucial step, since by knowing the frequency range of the system, the resonance phenomenon in the operational phase can be avoided. Similar results obtained by applying standardized methods for measuring vibration transmissibility and the currently adapted method from the field of mechanics to the field of textiles, represent a validation for this type of investigation process and also show the high potential of knitwear to be used in the vibration environment.
38
Wang, Ying, James Brownjohn, Jose Alfonso Jiménez Capilla, Kaoshan Dai, Wensheng Lu, and Ki Young Koo. "Vibration investigation for telecom structures with smartphone camera: case studies." Journal of Civil Structural Health Monitoring 11, no. 3 (April 5, 2021): 757–66. http://dx.doi.org/10.1007/s13349-021-00478-9.
Анотація:
AbstractTelecom structures such as high guyed masts are tall and flexible, so that not only the main structure but also the components (i.e., guy cable and antenna) suffer from vibrations induced by wind or earthquakes. The installation of contact inertial accelerometers for high guyed mast cables or antenna can be logistically challenging and the original vibration state may be influenced by these sensors. With convenient implementation and acceptable accuracy, computer vision technologies have been applied for vibration tests both in labs and field. In this paper, videos taken with smartphone cameras are processed to extract guy cable and antenna vibration information for telecom structures and, as a result, providing an efficient cost-effective method for vibration investigation of this type of structure. The video processing method can also be used in similar cases for other structures.
39
Liu, Xia, Likun Wang, Chao Zhong, Yanjun Zhang, Shaohua Hao, and Ruiqing Sun. "Piezoelectric Composite Vibrator with a Bilaminated Structure for Bending Vibration." Applied Sciences 9, no. 19 (October 8, 2019): 4191. http://dx.doi.org/10.3390/app9194191.
Анотація:
A piezoelectric composite vibrator with a bilaminated structure is designed and fabricated, in this work by applying bending vibration to increase vibration displacement and reduce resonance frequency. The finite element software ANSYS (ANSYS, Inc. USA) is used to simulate the 2-2 and 1-3 piezoelectric composite bilaminated vibrators under free boundary condition and optimize their design. Simulation results show that the vibration displacement of the 2-2 vibrator is higher than that of the 1-3 vibrator, and the resonance frequency of the former is lower than the latter. Five pieces each of the 2-2 and piezoelectric ceramic vibrators are prepared. In addition, simulation and experimental results indicate that the vibration displacement of the 2-2 vibrator increases by 2.3 times, whereas its resonance frequency decreases by nearly 100 Hz, in comparison with those of the piezoelectric ceramic bilaminated vibrator.
40
Talib EH. Elaikh, HaiderJ. Abed, Kadhim M. Abed, Salah M. Swadi, and Kadhim Karim M. "Vibration and Kinematic Analysis of Scara Robot Structure." Diyala Journal of Engineering Sciences 6, no. 3 (September 1, 2013): 127–43. http://dx.doi.org/10.24237/djes.2013.06309.
Анотація:
This paper presents a procedure for assessing the vibration analysis of type SCARA robots. The motion and running conditions of such robots are very complicated that leads to produce vibration and shock which are generated by arm profile in running conditions .In this study the vibration analysis gives the feasibility of the preview control was examined to improve the performance of the SCARA robots system. As it is important for containment the robot arm trajectories generated by the model to show satisfactory safe performance under vibration occurrence phenomena so that they completely avoid errors, the results obtained from such vibration analysis assessment procedure are considered to be valuable and reliable process not only with respect to vibration risk assessment but also for predicting kinematic analysis by investigating the robot arm motion using the kinematic and vibration methods. Forced vibrations is studied analytically help the designer to predict the behavior and design the robot hardware or control system. Theoretical results show reduction in both vibration amplitude and time history response.
41
Jia, Di, Fuhao Peng, Tao Zhou, Xueren Wang, Qingliang Lu, and Yiwan Wu. "Experimental Research on Vibration Reduction of Cantilever Structure in High-Temperature Environments." Shock and Vibration 2021 (January 4, 2021): 1–15. http://dx.doi.org/10.1155/2021/8833460.
Анотація:
To reduce the vibration of a cantilever steel plate in high-temperature environments (25°C–500°C), a new composite structure with entangled metallic wire material (EMWM) core was proposed. The damping performance of the EMWM under different temperatures was investigated. The results show that when the temperature does not exceed 260°C, the damping property of the EMWM is not affected by temperature. When the temperature exceeds 260°C, the damping property of the EMWM decreases with the increase of temperature. A thermal-vibration joint test system was set up to verify the energy dissipation mechanism of the composite structure with EMWM core and to research the effect of vibration reduction under different temperatures. The displacement deviation between the baseplate (steel plate) and constraining plate was sufficient to cause frictional energy dissipation of the EMWM core. The thermal-vibration joint test results indicated that the EMWM core had a positive impact on the damping properties of the cantilever structure. Adding EMWM core and constraining plate can significantly increase the damping ratio and reduces the vibration of the cantilever structures under different temperatures. This research is helpful to control the structural vibrations of cantilever structures in high-temperature environments.
42
Lian, Jijian, Hongzhen Wang, and Haijun Wang. "Study on Vibration Transmission among Units in Underground Powerhouse of a Hydropower Station." Energies 11, no. 11 (November 2, 2018): 3015. http://dx.doi.org/10.3390/en11113015.
Анотація:
Research on the safety of powerhouse in a hydropower station is mostly concentrated on the vibration of machinery structure and concrete structure within a single unit. However, few studies have been focused on the vibration transmission among units. Due to the integrity of the powerhouse and the interaction, it is necessary to study the vibration transmission mechanism of powerhouse structure among units. In this paper, field structural vibration tests are conducted in an underground powerhouse of a hydropower station on Yalong River. Additionally, the simplified mechanical models are established to explain the transmission mechanism theoretically. Moreover, a complementary finite element (FE) model is built to replicate the testing conditions for comprehensive analysis. The field tests results show that: (1) the transmission of lateral-river vibration is greater than those of longitude-river vibration and vertical vibration; (2) the vibration transmission of the vibrations that is caused by the low frequency tail fluctuation is basically equal to that of the vibrations caused by rotation of hydraulic generator. The transmission mechanism is demonstrated by the simplified mechanical models and is verified by the FE results. This study can provide guidance for further research on the vibration of underground powerhouse structure.
43
Bae, Jae-Sung, Jai-Hyuk Hwang, Dong-Gi Kwag, Jeanho Park, and Daniel J. Inman. "Vibration Suppression of a Large Beam Structure Using Tuned Mass Damper and Eddy Current Damping." Shock and Vibration 2014 (2014): 1–10. http://dx.doi.org/10.1155/2014/893914.
Анотація:
For a few decades, various methods to suppress the vibrations of structures have been proposed and exploited. These include passive methods using constrained layer damping (CLD) and active methods using smart materials. However, applying these methods to large structures may not be practical because of weight, material, and actuator constraints. The objective of the present study is to propose and exploit an effective method to suppress the vibration of a large and heavy beam structure with a minimum increase in mass or volume of material. Traditional tuned mass dampers (TMD) are very effective for attenuating structural vibrations; however, they often add substantial mass. Eddy current damping is relatively simple and has excellent performance but is force limited. The proposed method is to apply relatively light-weight TMD to attenuate the vibration of a large beam structure and increase its performance by applying eddy current damping to a TMD. The results show that the present method is simple but effective in suppressing the vibration of a large beam structure without a substantial weight increase.
44
Yu, Jianda, Zhibo Duan, Xiangqi Zhang, and Jian Peng. "Wind-Induced Vibration Control of High-Rise Structures Using Compound Damping Cables." Shock and Vibration 2021 (April 22, 2021): 1–9. http://dx.doi.org/10.1155/2021/5537622.
Анотація:
Based on the vibration reduction mechanism of compound damping cables, this study focuses on the wind-induced vibration control of high-rise structures with additional mass at the top. The differential equation of motion of the system under the action of the composite damping cable is established, and the analytical solution of the additional damping ratio of the structure is deduced, which is verified by model tests. The vibration response of the structure under the action of simple harmonic vortex excitation and randomly fluctuating wind loads is studied, and the effect of different viscous coefficients of the dampers in the composite damping cable and different installation heights of the damping cable on the vibration control is analyzed. The results show that a small vortex excitation force will cause large vibrations of low-dampened towering structures, and the structure will undergo buffeting under the action of wind load pulse force. The damping cable can greatly reduce the amplitude of structural vibration. The root means square of structural vibration displacement varies with damping. The viscosity coefficient of the device and the installation height of the main cable of the damping cable are greatly reduced.
45
Javed, A., J. Park, H. Lee, B. Kim, and Y. Han. "EPIPOLAR LINE-BASED LATERAL VIBRATION MEASUREMENT BY USING TWO CAMERAS." International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences XLIII-B2-2022 (May 30, 2022): 539–44. http://dx.doi.org/10.5194/isprs-archives-xliii-b2-2022-539-2022.
Анотація:
Abstract. Vibration measurement techniques can be categorized into contact-type and non-contact-type techniques. These types of techniques can add mass-loading to a lightweight structure resulting in the negative performance of a structure, because sensors, high contrast speckles or targets should be mounted on a structure. Moreover, non-contact-type vibration measurement techniques have only been tested to detect vibrations using a single camera. As the vibrations occurring at the opposite sides of a rotating structure in a region of interest (ROI) can be different from each other. For 3-dimensional (3D) vibration measurement, the same position in videos acquired from two cameras should be used. Because the videos acquired by two cameras placed perpendicular to the structure can be used to detect the vibrations in the x-direction as well as y-direction. In this study, an epipolar line-based corresponding point selection on a rotating cylindrical structure was performed, to extract the same ROIs from videos recorded by two cameras. A fundamental matrix was constructed by using the targets attached on the structure and in the background. The coordinates of the mid-pixel of the ROI in a video acquired by one camera was used to determine the epipolar line for the same ROI in the video acquired by another camera. Then an edge-based vibration measurement technique was applied to measure the vibration in the extracted ROIs. The results were used to reconstruct a 3D vibration signal. The 3D vibration measurement results can be used to effectively recognize the deformations resulting in the negative performance of a structure.
46
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.
Анотація:
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.
47
Son, Taehwan, Seongmin Park, and Wonju Jeon. "Damping vibration of platform structure using modified acoustic black holes." Journal of the Acoustical Society of America 154, no. 4_supplement (October 1, 2023): A200. http://dx.doi.org/10.1121/10.0023259.
Анотація:
We propose waveguide absorbers (WGAs) to dampen structural vibrations of platforms supporting vibrating systems. The waveguide absorber is designed by modifing a spiral acoustic black hole (ABH) to improve its damping performance while saving installation space and weight. The proposed WGA absorbs the flexural wave propagating in a platform to its end, resulting in vibration damping in the platform. To maximize the damping capability of WGA, we analyze the structural intensity field of the platform and attach the WGA based on the intensity field. Numerical and experimental results show that large reductions of peaks in mobility are achieved using the WGAs, showing the possibility to utilize the WGA in practice.
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Landolsi, Fakhreddine, Slim Choura, and Ali H. Nayfeh. "Control of 2D Flexible Structures by Confinement of Vibrations and Regulation of Their Energy Flow." Shock and Vibration 16, no. 2 (2009): 213–28. http://dx.doi.org/10.1155/2009/727236.
Анотація:
In this paper, we investigate the control of 2D flexible structures by vibration confinement and the regulation of their energy flow along prespecified spatial paths. A discretized-model-based feedback strategy, aiming at confining and suppressing simultaneously the vibration, is proposed. It is assumed that the structure consists of parts that are sensitive to vibrations. The control design introduces a new pseudo-modal matrix derived from the computed eigenvectors of the discretized model. Simulations are presented to show the efficacy of the proposed control law. A parametric study is carried out to examine the effects of the different control parameters on the simultaneous confinement and suppression of vibrations. In addition, we conducted a set of simulations to investigate the flow control of vibrational energy during the confinement-suppression process. We found that the energy flow can be regulated via a set of control parameters for different confinement configurations.
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Enríquez-Zárate, Josué, Hugo Francisco Abundis-Fong, Ramiro Velázquez, and Sebastián Gutiérrez. "Passive vibration control in a civil structure: Experimental results." Measurement and Control 52, no. 7-8 (May 13, 2019): 938–46. http://dx.doi.org/10.1177/0020294019847715.
Анотація:
The problem of vibrations in civil structures is common; nevertheless, its negative effects can be significantly reduced using structural control methods with intention of maintaining structural welfare as much as possible. This work deals with the study of structural vibration control in a model of a civil-like structure, which consists of three-level building with a tuned mass damper implemented as a passive vibration absorber, mounted on the top of the structure, to attenuate the harmonic vibrations provided by an electromagnetic actuator connected at the base of the primary system. The action of the tuned mass damper is evaluated from an energy approach. The dissipation of energy in the overall system is conducted in an experimental way, where the passive control technique is designed to minimize the undesirable forced dynamic response of the main structure via the tuned mass damper. Experimental results are provided to show the effective performance of the proposed passive vibration absorption scheme to suppress resonant frequency harmonic excitations disturbing the primary system, evaluating the performance energy and contribution of the dissipative device for the energy release in the overall system.
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Ansari, Meisam, Fabiola Tartaglione, and Carsten Koenke. "Experimental Validation of Dynamic Response of Small-Scale Metaconcrete Beams at Resonance Vibration." Materials 16, no. 14 (July 16, 2023): 5029. http://dx.doi.org/10.3390/ma16145029.
Анотація:
Structures and their components experience substantially large vibration amplitudes at resonance, which can cause their failure. The scope of this study is the utilization of silicone-coated steel balls in concrete as damping aggregates to suppress the resonance vibration. The heavy steel cores oscillate with a frequency close to the resonance frequency of the structure. Due to the phase difference between the vibrations of the cores and the structure, the cores counteract the vibration of the structure. The core-coating inclusions are randomly distributed in concrete similar to standard aggregates. This mixture is referred to as metaconcrete. The main goal of this work is to validate the ability of the inclusions to suppress mechanical vibration through laboratory experiments. For this purpose, two small-scale metaconcrete beams were cast and tested. In a free vibration test, the metaconcrete beams exhibited a larger damping ratio compared to a similar beam cast from conventional concrete. The vibration amplitudes of the metaconcrete beams at resonance were measured with a frequency sweep test. In comparison with the conventional concrete beam, both metaconcrete beams demonstrated smaller vibration amplitudes. Both experiments verified an improvement in the dynamic response of the metaconcrete beams at resonance vibration.