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Journal Cover Journal of Sound and Vibration
  [SJR: 1.494]   [H-I: 121]   [190 followers]  Follow
    
   Hybrid Journal Hybrid journal (It can contain Open Access articles)
   ISSN (Print) 0022-460X - ISSN (Online) 1095-8568
   Published by Elsevier Homepage  [3089 journals]
  • Damage assessment in a sandwich panel based on full-field vibration
           measurements
    • Authors: F. Seguel; V. Meruane
      Pages: 1 - 18
      Abstract: Publication date: 17 March 2018
      Source:Journal of Sound and Vibration, Volume 417
      Author(s): F. Seguel, V. Meruane
      Different studies have demonstrated that vibration characteristics are sensitive to debonding in composite structures. Nevertheless, one of the main restrictions of vibration measurements is the number of degrees of freedom that can be acquired simultaneously, which restricts the size of the damage that can be identified. Recent studies have shown that it is possible to use high-speed three-dimensional (3-D) digital image correlation (DIC) techniques for full-field vibration measurements. With this technique, it is possible to take measurements at thousands of points on the surface of a structure with a single snapshot. The present article investigates the application of full-field vibration measurements in the debonding assessment of an aluminium honeycomb sandwich panel. Experimental data from an aluminium honeycomb panel containing different damage scenarios is acquired by a high-speed 3-D DIC system; four methodologies to compute damage indices are evaluated: mode shape curvatures, uniform load surface, modal strain energy and gapped smoothing.

      PubDate: 2017-12-12T10:43:23Z
      DOI: 10.1016/j.jsv.2017.11.048
      Issue No: Vol. 417 (2017)
       
  • The level crossing rates and associated statistical properties of a random
           frequency response function
    • Authors: Robin S. Langley
      Pages: 19 - 37
      Abstract: Publication date: 17 March 2018
      Source:Journal of Sound and Vibration, Volume 417
      Author(s): Robin S. Langley
      This work is concerned with the statistical properties of the frequency response function of the energy of a random system. Earlier studies have considered the statistical distribution of the function at a single frequency, or alternatively the statistics of a band-average of the function. In contrast the present analysis considers the statistical fluctuations over a frequency band, and results are obtained for the mean rate at which the function crosses a specified level (or equivalently, the average number of times the level is crossed within the band). Results are also obtained for the probability of crossing a specified level at least once, the mean rate of occurrence of peaks, and the mean trough-to-peak height. The analysis is based on the assumption that the natural frequencies and mode shapes of the system have statistical properties that are governed by the Gaussian Orthogonal Ensemble (GOE), and the validity of this assumption is demonstrated by comparison with numerical simulations for a random plate. The work has application to the assessment of the performance of dynamic systems that are sensitive to random imperfections.

      PubDate: 2017-12-12T10:43:23Z
      DOI: 10.1016/j.jsv.2017.12.001
      Issue No: Vol. 417 (2017)
       
  • In-plane modal frequencies and mode shapes of two stay cables
           interconnected by uniformly distributed cross-ties
    • Authors: Haiquan Jing; Xuhui He; Yunfeng Zou; Hanfeng Wang
      Pages: 38 - 55
      Abstract: Publication date: 17 March 2018
      Source:Journal of Sound and Vibration, Volume 417
      Author(s): Haiquan Jing, Xuhui He, Yunfeng Zou, Hanfeng Wang
      Stay cables are important load-bearing structural elements of cable-stayed bridges. Suppressing the large vibrations of the stay cables under the external excitations is of worldwide concern for the bridge engineers and researchers. Over the past decade, the use of crosstie has become one of the most practical and effective methods. Extensive research has led to a better understanding of the mechanics of cable networks, and the effects of different parameters, such as length ratio, mass-tension ratio, and segment ratio on the effectiveness of the crosstie have been investigated. In this study, uniformly distributed elastic crossties serve to replace the traditional single, or several cross-ties, aiming to delay “mode localization.” A numerical method is developed by replacing the uniformly distributed, discrete elastic cross-tie model with an equivalent, continuously distributed, elastic cross-tie model in order to calculate the modal frequencies and mode shapes of the cable-crosstie system. The effectiveness of the proposed method is verified by comparing the elicited results with those obtained using the previous method. The uniformly distributed elastic cross-ties are shown to significantly delay “mode localization.”

      PubDate: 2017-12-12T10:43:23Z
      DOI: 10.1016/j.jsv.2017.12.004
      Issue No: Vol. 417 (2017)
       
  • Multiple spatially localized dynamical states in friction-excited
           oscillator chains
    • Authors: A. Papangelo; N. Hoffmann; A. Grolet; M. Stender; M. Ciavarella
      Pages: 56 - 64
      Abstract: Publication date: 17 March 2018
      Source:Journal of Sound and Vibration, Volume 417
      Author(s): A. Papangelo, N. Hoffmann, A. Grolet, M. Stender, M. Ciavarella
      Friction-induced vibrations are known to affect many engineering applications. Here, we study a chain of friction-excited oscillators with nearest neighbor elastic coupling. The excitation is provided by a moving belt which moves at a certain velocity v d while friction is modelled with an exponentially decaying friction law. It is shown that in a certain range of driving velocities, multiple stable spatially localized solutions exist whose dynamical behavior (i.e. regular or irregular) depends on the number of oscillators involved in the vibration. The classical non-repeatability of friction-induced vibration problems can be interpreted in light of those multiple stable dynamical states. These states are found within a “snaking-like” bifurcation pattern. Contrary to the classical Anderson localization phenomenon, here the underlying linear system is perfectly homogeneous and localization is solely triggered by the friction nonlinearity.

      PubDate: 2017-12-12T10:43:23Z
      DOI: 10.1016/j.jsv.2017.11.056
      Issue No: Vol. 417 (2017)
       
  • Dynamical modeling and free vibration analysis of spinning pipes conveying
           fluid with axial deployment
    • Authors: Feng Liang; Xiao-Dong Yang; Wei Zhang; Ying-Jing Qian
      Pages: 65 - 79
      Abstract: Publication date: 17 March 2018
      Source:Journal of Sound and Vibration, Volume 417
      Author(s): Feng Liang, Xiao-Dong Yang, Wei Zhang, Ying-Jing Qian
      In this paper, a dynamical model of simply-supported spinning pipes conveying fluid with axial deployment is proposed and the transverse free vibration and stability for such a doubly gyroscopic system involving time-dependent parameters are investigated. The partial differential equations of motion are derived by the extended Hamilton principle and then truncated by the Galerkin technique. The time-variant frequencies, mode shapes and responses to initial conditions are comprehensively investigated to reveal the dynamical essence of the system. It is indicated that the qualitative stability evolution of the system mainly depends on the effect of fluid-structure interaction (FSI), while the spinning motion will enhance the pipe rigidity and eliminate the buckling instability. The dynamical evolution of a retracting pipe is almost inverse to that of the deploying one. The pipe possesses different mode configurations of spatial curves as the pipe length increases and some modal and response characteristics of the present system are found rather distinct from those of deploying cantilevered structures.

      PubDate: 2017-12-12T10:43:23Z
      DOI: 10.1016/j.jsv.2017.12.005
      Issue No: Vol. 417 (2017)
       
  • Probabilistic assessment of the dynamic interaction between multiple
           pedestrians and vertical vibrations of footbridges
    • Authors: Federica Tubino
      Pages: 80 - 96
      Abstract: Publication date: 17 March 2018
      Source:Journal of Sound and Vibration, Volume 417
      Author(s): Federica Tubino
      The effect of human-structure interaction in the vertical direction for footbridges is studied based on a probabilistic approach. The bridge is modeled as a continuous dynamic system, while pedestrians are schematized as moving single-degree-of-freedom systems with random dynamic properties. The non-dimensional form of the equations of motion allows us to obtain results that can be applied in a very wide set of cases. An extensive Monte Carlo simulation campaign is performed, varying the main non-dimensional parameters identified, and the mean values and coefficients of variation of the damping ratio and of the non-dimensional natural frequency of the coupled system are reported. The results obtained can be interpreted from two different points of view. If the characterization of pedestrians' equivalent dynamic parameters is assumed as uncertain, as revealed from a current literature review, then the paper provides a range of possible variations of the coupled system damping ratio and natural frequency as a function of pedestrians' parameters. Assuming that a reliable characterization of pedestrians' dynamic parameters is available (which is not the case at present, but could be in the future), the results presented can be adopted to estimate the damping ratio and natural frequency of the coupled footbridge-pedestrian system for a very wide range of real structures.

      PubDate: 2017-12-12T10:43:23Z
      DOI: 10.1016/j.jsv.2017.11.057
      Issue No: Vol. 417 (2017)
       
  • Investigation of PDC bit failure base on stick-slip vibration analysis of
           drilling string system plus drill bit
    • Authors: Zhiqiang Huang; Dou Xie; Bing Xie; Wenlin Zhang; Fuxiao Zhang; Lei He
      Pages: 97 - 109
      Abstract: Publication date: 17 March 2018
      Source:Journal of Sound and Vibration, Volume 417
      Author(s): Zhiqiang Huang, Dou Xie, Bing Xie, Wenlin Zhang, Fuxiao Zhang, Lei He
      The undesired stick-slip vibration is the main source of PDC bit failure, such as tooth fracture and tooth loss. So, the study of PDC bit failure base on stick-slip vibration analysis is crucial to prolonging the service life of PDC bit and improving ROP (rate of penetration). For this purpose, a piecewise-smooth torsional model with 4-DOF (degree of freedom) of drilling string system plus PDC bit is proposed to simulate non-impact drilling. In this model, both the friction and cutting behaviors of PDC bit are innovatively introduced. The results reveal that PDC bit is easier to fail than other drilling tools due to the severer stick-slip vibration. Moreover, reducing WOB (weight on bit) and improving driving torque can effectively mitigate the stick-slip vibration of PDC bit. Therefore, PDC bit failure can be alleviated by optimizing drilling parameters. In addition, a new 4-DOF torsional model is established to simulate torsional impact drilling and the effect of torsional impact on PDC bit's stick-slip vibration is analyzed by use of an engineering example. It can be concluded that torsional impact can mitigate stick-slip vibration, prolonging the service life of PDC bit and improving drilling efficiency, which is consistent with the field experiment results.

      PubDate: 2017-12-12T10:43:23Z
      DOI: 10.1016/j.jsv.2017.11.053
      Issue No: Vol. 417 (2017)
       
  • Analytical validation of an explicit finite element model of a rolling
           element bearing with a localised line spall
    • Authors: Sarabjeet Singh; Carl Q. Howard; Colin H. Hansen; Uwe G. Köpke
      Pages: 94 - 110
      Abstract: Publication date: 3 March 2018
      Source:Journal of Sound and Vibration, Volume 416
      Author(s): Sarabjeet Singh, Carl Q. Howard, Colin H. Hansen, Uwe G. Köpke
      In this paper, numerically modelled vibration response of a rolling element bearing with a localised outer raceway line spall is presented. The results were obtained from a finite element (FE) model of the defective bearing solved using an explicit dynamics FE software package, LS-DYNA. Time domain vibration signals of the bearing obtained directly from the FE modelling were processed further to estimate time–frequency and frequency domain results, such as spectrogram and power spectrum, using standard signal processing techniques pertinent to the vibration-based monitoring of rolling element bearings. A logical approach to analyses of the numerically modelled results was developed with an aim to presenting the analytical validation of the modelled results. While the time and frequency domain analyses of the results show that the FE model generates accurate bearing kinematics and defect frequencies, the time–frequency analysis highlights the simulation of distinct low- and high-frequency characteristic vibration signals associated with the unloading and reloading of the rolling elements as they move in and out of the defect, respectively. Favourable agreement of the numerical and analytical results demonstrates the validation of the results from the explicit FE modelling of the bearing.

      PubDate: 2017-12-12T10:43:23Z
      DOI: 10.1016/j.jsv.2017.09.007
      Issue No: Vol. 416 (2017)
       
  • Experimental and theoretical investigation of an impact vibration
           harvester with triboelectric transduction
    • Authors: Alwathiqbellah Ibrahim; Abdallah Ramini; Shahrzad Towfighian
      Pages: 111 - 124
      Abstract: Publication date: 3 March 2018
      Source:Journal of Sound and Vibration, Volume 416
      Author(s): Alwathiqbellah Ibrahim, Abdallah Ramini, Shahrzad Towfighian
      There has been remarkable interest in triboelectric mechanisms because of their high efficiency, wide availability, and low-cost generation of sustainable power. Using impact vibrations, we introduce piece-wise stiffness to the system to enlarge frequency bandwidth. The triboelectric layers consist of Aluminum, which also serves as an electrode, and Polydimethylsiloxane (PDMS) with micro semi-cylindrical patterns. At the bottom of the PDMS layer, there is another Al electrode. The layers are sandwiched between the center mass of a clamped-clamped beam and its base. The center mass enhances the impact force on the triboelectric layers subjected to external vibrations. Upon impact, alternating current, caused by the contact electrification and electrostatic induction, flows between the Al electrodes. Because of the impact, the equivalent stiffness of the structure increases and as a result, the frequency bandwidth gets wider. The output voltage and power reach as large as 5.5 V , 15 μ W , respectively at 0.8 g vibrational amplitude. In addition, we report how the surface charge density increases with the excitation levels. The analysis delineates the interactions between impact vibrations and triboelectric transductions. The ability of the system to achieve wider bandwidth paves the way for efficient triboelectric vibrational energy harvesters.

      PubDate: 2017-12-12T10:43:23Z
      DOI: 10.1016/j.jsv.2017.11.036
      Issue No: Vol. 416 (2017)
       
  • Bryan's effect and anisotropic nonlinear damping
    • Authors: Stephan V. Joubert; Michael Y. Shatalov; Temple H. Fay; Alexander V. Manzhirov
      Pages: 125 - 135
      Abstract: Publication date: 3 March 2018
      Source:Journal of Sound and Vibration, Volume 416
      Author(s): Stephan V. Joubert, Michael Y. Shatalov, Temple H. Fay, Alexander V. Manzhirov
      In 1890, G. H. Bryan discovered the following: “The vibration pattern of a revolving cylinder or bell revolves at a rate proportional to the inertial rotation rate of the cylinder or bell.” We call this phenomenon Bryan's law or Bryan's effect. It is well known that any imperfections in a vibratory gyroscope (VG) affect Bryan's law and this affects the accuracy of the VG. Consequently, in this paper, we assume that all such imperfections are either minimised or eliminated by some known control method and that only damping is present within the VG. If the damping is isotropic (linear or nonlinear), then it has been recently demonstrated in this journal, using symbolic analysis, that Bryan's law remains invariant. However, it is known that linear anisotropic damping does affect Bryan's law. In this paper, we generalise Rayleigh's dissipation function so that anisotropic nonlinear damping may be introduced into the equations of motion. Using a mixture of numeric and symbolic analysis on the ODEs of motion of the VG, for anisotropic light nonlinear damping, we demonstrate (up to an approximate average), that Bryan's law is affected by any form of such damping, causing pattern drift, compromising the accuracy of the VG.

      PubDate: 2017-12-12T10:43:23Z
      DOI: 10.1016/j.jsv.2017.11.043
      Issue No: Vol. 416 (2017)
       
  • Modeling of automotive driveline system for reducing gear rattles
    • Authors: Wen-Bin Shangguan; Xue-Lai Liu; Yuming Yin; Subhash Rakheja
      Pages: 136 - 153
      Abstract: Publication date: 3 March 2018
      Source:Journal of Sound and Vibration, Volume 416
      Author(s): Wen-Bin Shangguan, Xue-Lai Liu, Yuming Yin, Subhash Rakheja
      A nonlinear torsional model for a driveline system with 4 degrees of freedom is proposed for studying gear rattle if a car is at idle. The time-varying meshing stiffness of geared teeth, gear backlash, and the damping from oil film are included in the model. The dynamic responses of the driveline system, such as clutch angular displacement, meshing force and relative displacement between geared teeth, are calculated using the presented model. The influences of stiffness and damping of a clutch on gear rattle of geared teeth in a generic transmission are investigated. Based on the calculation and analysis results, a design guideline to select clutch's stiffness and damping is developed to reduce gear rattle for a car at idle. Taking a generic driveline system of a passenger car as an example, the developed method is experimentally validated by comparing the baseline clutch and revised clutch, in terms of the measured noise inside engine compartment and cab and vibrations at transmission housing.

      PubDate: 2017-12-12T10:43:23Z
      DOI: 10.1016/j.jsv.2017.07.052
      Issue No: Vol. 416 (2017)
       
  • A general electromagnetic excitation model for electrical machines
           considering the magnetic saturation and rub impact
    • Authors: Xueping Xu; Qinkai Han; Fulei Chu
      Pages: 154 - 171
      Abstract: Publication date: 3 March 2018
      Source:Journal of Sound and Vibration, Volume 416
      Author(s): Xueping Xu, Qinkai Han, Fulei Chu
      The electromagnetic vibration of electrical machines with an eccentric rotor has been extensively investigated. However, magnetic saturation was often neglected. Moreover, the rub impact between the rotor and stator is inevitable when the amplitude of the rotor vibration exceeds the air-gap. This paper aims to propose a general electromagnetic excitation model for electrical machines. First, a general model which takes the magnetic saturation and rub impact into consideration is proposed and validated by the finite element method and reference. The dynamic equations of a Jeffcott rotor system with electromagnetic excitation and mass imbalance are presented. Then, the effects of pole-pair number and rubbing parameters on vibration amplitude are studied and approaches restraining the amplitude are put forward. Finally, the influences of mass eccentricity, resultant magnetomotive force (MMF), stiffness coefficient, damping coefficient, contact stiffness and friction coefficient on the stability of the rotor system are investigated through the Floquet theory, respectively. The amplitude jumping phenomenon is observed in a synchronous generator for different pole-pair numbers. The changes of design parameters can alter the stability states of the rotor system and the range of parameter values forms the zone of stability, which lays helpful suggestions for the design and application of the electrical machines.

      PubDate: 2017-12-12T10:43:23Z
      DOI: 10.1016/j.jsv.2017.11.050
      Issue No: Vol. 416 (2017)
       
  • A new hybrid observer based rotor imbalance vibration control via passive
           autobalancer and active bearing actuation
    • Authors: DaeYi Jung; Hans DeSmidt
      Pages: 1 - 24
      Abstract: Publication date: 17 February 2018
      Source:Journal of Sound and Vibration, Volume 415
      Author(s): DaeYi Jung, Hans DeSmidt
      Many researchers have explored the use of active bearings, such as non-contact Active Magnetic Bearings (AMB), to control imbalance vibration in rotor systems. Meanwhile, the advantages of a passive Auto-balancer device (ABD) eliminating the imbalance effect of rotor without using other active means have been recently studied. This paper develops a new hybrid imbalance vibration control approach for an ABD-rotor system supported by a normal passive bearing in augmented with an AMB to enhance the balancing and vibration isolation capabilities. Essentially, an ABD consists of several freely moving eccentric balancing masses mounted on the rotor, which, at supercritical operating speeds, act to cancel the rotor's imbalance at steady-state. However, due to the inherent nonlinearity of the ABD, the potential for other, non-synchronous limit-cycle behavior exists resulting in increased rotor vibration. To address this, the algorithm of proposed hybrid control is designed to guarantee globally asymptotic stability of the synchronous balanced condition. This algorithm also incorporates with a “Luenberger-like” observer that continuously estimates the states of a balancer ball circulating around within ABD. In particular, it is shown that the balanced equilibrium can be made globally attractive under the hybrid control strategy, and that the control power levels of AMB are significantly reduced via the addition of the ABD because the control is designed such that it is only switched on for the abnormal operation of ABD and will be disengaged otherwise. Moreover, unlike other imbalance vibration control applications based upon ABD such as rotor speed regulator [21,22], this approach enables the controller to achieve the desirable performance without altering rotor speed once the rotor initially reaches the target speed. These applications are relevant to limited power applications such as in satellite reaction wheels, flywheel energy storage batteries or CD-ROM application.

      PubDate: 2017-12-12T10:43:23Z
      DOI: 10.1016/j.jsv.2017.11.024
      Issue No: Vol. 415 (2017)
       
  • Reduction of sound transmission across plenum windows by incorporating an
           array of rigid cylinders
    • Authors: S.K. Tang
      Pages: 25 - 40
      Abstract: Publication date: 17 February 2018
      Source:Journal of Sound and Vibration, Volume 415
      Author(s): S.K. Tang
      The potential improvement of plenum window noise reduction by installing rigid circular cylinder arrays into the window cavity is investigated numerically using the finite-element method in this study. A two-dimensional approach is adopted. The sound transmission characteristics and propagation within the plenum window are also examined in detail. Results show that the installation of the cylinders in general gives rise to broadband improvement of noise reduction across a plenum window regardless of the direction of sound incidence. Such acoustical performance becomes better when more cylinder columns are installed, but it is suggested that the number of cylinder rows should not exceed two. Results also show that the cylinder positions relative to the nodal/anti-nodal planes of the acoustic modes are crucial in the noise reduction enhancement mechanisms. Noise reduction can further be enhanced by staggering the cylinder rows, such that each cylinder row supports the development of a different acoustic mode. For the simple cylinder arrangements considered in this study, the traffic noise reduction enhancement observed in this study can be as high as 4–5 dB, which is already comparable to or higher than the maximum achieved by installing sound absorption into a plenum window.

      PubDate: 2017-12-12T10:43:23Z
      DOI: 10.1016/j.jsv.2017.11.027
      Issue No: Vol. 415 (2017)
       
  • A two-step FEM-SEM approach for wave propagation analysis in cable
           structures
    • Authors: Songhan Zhang; Ruili Shen; Tao Wang; Guido De Roeck; Geert Lombaert
      Pages: 41 - 58
      Abstract: Publication date: 17 February 2018
      Source:Journal of Sound and Vibration, Volume 415
      Author(s): Songhan Zhang, Ruili Shen, Tao Wang, Guido De Roeck, Geert Lombaert
      Vibration-based methods are among the most widely studied in structural health monitoring (SHM). It is well known, however, that the low-order modes, characterizing the global dynamic behaviour of structures, are relatively insensitive to local damage. Such local damage may be easier to detect by methods based on wave propagation which involve local high frequency behaviour. The present work considers the numerical analysis of wave propagation in cables. A two-step approach is proposed which allows taking into account the cable sag and the distribution of the axial forces in the wave propagation analysis. In the first step, the static deformation and internal forces are obtained by the finite element method (FEM), taking into account geometric nonlinear effects. In the second step, the results from the static analysis are used to define the initial state of the dynamic analysis which is performed by means of the spectral element method (SEM). The use of the SEM in the second step of the analysis allows for a significant reduction in computational costs as compared to a FE analysis. This methodology is first verified by means of a full FE analysis for a single stretched cable. Next, simulations are made to study the effects of damage in a single stretched cable and a cable-supported truss. The results of the simulations show how damage significantly affects the high frequency response, confirming the potential of wave propagation based methods for SHM.

      PubDate: 2017-12-12T10:43:23Z
      DOI: 10.1016/j.jsv.2017.11.002
      Issue No: Vol. 415 (2017)
       
  • Dynamic balancing of super-critical rotating structures using slow-speed
           data via parametric excitation
    • Authors: Shachar Tresser; Amit Dolev; Izhak Bucher
      Pages: 59 - 77
      Abstract: Publication date: 17 February 2018
      Source:Journal of Sound and Vibration, Volume 415
      Author(s): Shachar Tresser, Amit Dolev, Izhak Bucher
      High-speed machinery is often designed to pass several “critical speeds”, where vibration levels can be very high. To reduce vibrations, rotors usually undergo a mass balancing process, where the machine is rotated at its full speed range, during which the dynamic response near critical speeds can be measured. High sensitivity, which is required for a successful balancing process, is achieved near the critical speeds, where a single deflection mode shape becomes dominant, and is excited by the projection of the imbalance on it. The requirement to rotate the machine at high speeds is an obstacle in many cases, where it is impossible to perform measurements at high speeds, due to harsh conditions such as high temperatures and inaccessibility (e.g., jet engines). This paper proposes a novel balancing method of flexible rotors, which does not require the machine to be rotated at high speeds. With this method, the rotor is spun at low speeds, while subjecting it to a set of externally controlled forces. The external forces comprise a set of tuned, response dependent, parametric excitations, and nonlinear stiffness terms. The parametric excitation can isolate any desired mode, while keeping the response directly linked to the imbalance. A software controlled nonlinear stiffness term limits the response, hence preventing the rotor to become unstable. These forces warrant sufficient sensitivity required to detect the projection of the imbalance on any desired mode without rotating the machine at high speeds. Analytical, numerical and experimental results are shown to validate and demonstrate the method.
      Graphical abstract image

      PubDate: 2017-12-12T10:43:23Z
      DOI: 10.1016/j.jsv.2017.11.029
      Issue No: Vol. 415 (2017)
       
  • The elastic properties of an actively controlled piezoelectric transducer:
           Measurement, analysis and tuning
    • Authors: Pavel Marton; Jakub Nečásek; Jan Václavík; Pavel Mokrý
      Pages: 78 - 90
      Abstract: Publication date: 17 February 2018
      Source:Journal of Sound and Vibration, Volume 415
      Author(s): Pavel Marton, Jakub Nečásek, Jan Václavík, Pavel Mokrý
      We report on the development of a method for the measurement of the effective stiffness of a piezoelectric transducer which is bonded to a vibration control system and operated using an approach known as active elasticity control (AEC). Using high-accuracy measurement techniques it is shown that the effective stiffness of the transducer can reach negative values in a certain frequency range, when a suitable active shunt circuit is connected to its electrodes. Extensive analysis proves the consistency of mechanical and electrical measurements of the dynamically loaded piezoelectric transducer compared with the AEC model. A method which allows the computation of adjustments to the active shunt circuit based on the vibration control device's measured mechanical transfer function is developed. The applicability of the method to a real vibration control system is also demonstrated.

      PubDate: 2017-12-12T10:43:23Z
      DOI: 10.1016/j.jsv.2017.11.017
      Issue No: Vol. 415 (2017)
       
  • Effects of random tooth profile errors on the dynamic behaviors of
           planetary gears
    • Authors: Chao Xun; Xinhua Long; Hongxing Hua
      Pages: 91 - 110
      Abstract: Publication date: 17 February 2018
      Source:Journal of Sound and Vibration, Volume 415
      Author(s): Chao Xun, Xinhua Long, Hongxing Hua
      In this paper, a nonlinear random model is built to describe the dynamics of planetary gear trains (PGTs), in which the time-varying mesh stiffness, tooth profile modification (TPM), tooth contact loss, and random tooth profile error are considered. A stochastic method based on the method of multiple scales (MMS) is extended to analyze the statistical property of the dynamic performance of PGTs. By the proposed multiple-scales based stochastic method, the distributions of the dynamic transmission errors (DTEs) are investigated, and the lower and upper bounds are determined based on the 3σ principle. Monte Carlo method is employed to verify the proposed method. Results indicate that the proposed method can be used to determine the distribution of the DTE of PGTs high efficiently and allow a link between the manufacturing precision and the dynamical response. In addition, the effects of tooth profile modification on the distributions of vibration amplitudes and the probability of tooth contact loss with different manufacturing tooth profile errors are studied. The results show that the manufacturing precision affects the distribution of dynamic transmission errors dramatically and appropriate TPMs are helpful to decrease the nominal value and the deviation of the vibration amplitudes.

      PubDate: 2017-12-12T10:43:23Z
      DOI: 10.1016/j.jsv.2017.11.022
      Issue No: Vol. 415 (2017)
       
  • Damage identification of supporting structures with a moving sensory
           system
    • Authors: X.Q. Zhu; S.S. Law; L. Huang; S.Y. Zhu
      Pages: 111 - 127
      Abstract: Publication date: 17 February 2018
      Source:Journal of Sound and Vibration, Volume 415
      Author(s): X.Q. Zhu, S.S. Law, L. Huang, S.Y. Zhu
      An innovative approach to identify local anomalies in a structural beam bridge with an instrumented vehicle moving as a sensory system across the bridge. Accelerations at both the axle and vehicle body are measured from which vehicle-bridge interaction force on the structure is determined. Local anomalies of the structure are estimated from this interaction force with the Newton's iterative method basing on the homotopy continuation method. Numerical results with the vehicle moving over simply supported or continuous beams show that the acceleration responses from the vehicle or the bridge structure are less sensitive to the local damages than the interaction force between the wheel and the structure. Effects of different movement patterns and moving speed of the vehicle are investigated, and the effect of measurement noise on the identified results is discussed. A heavier or slower vehicle has been shown to be less sensitive to measurement noise giving more accurate results.

      PubDate: 2017-12-12T10:43:23Z
      DOI: 10.1016/j.jsv.2017.11.032
      Issue No: Vol. 415 (2017)
       
  • Finite element based N-Port model for preliminary design of multibody
           systems
    • Authors: Francesco Sanfedino; Daniel Alazard; Valérie Pommier-Budinger; Alexandre Falcoz; Fabrice Boquet
      Pages: 128 - 146
      Abstract: Publication date: 17 February 2018
      Source:Journal of Sound and Vibration, Volume 415
      Author(s): Francesco Sanfedino, Daniel Alazard, Valérie Pommier-Budinger, Alexandre Falcoz, Fabrice Boquet
      This article presents and validates a general framework to build a linear dynamic Finite Element-based model of large flexible structures for integrated Control/Structure design. An extension of the Two-Input Two-Output Port (TITOP) approach is here developed. The authors had already proposed such framework for simple beam-like structures: each beam was considered as a TITOP sub-system that could be interconnected to another beam thanks to the ports. The present work studies bodies with multiple attaching points by allowing complex interconnections among several sub-structures in tree-like assembly. The TITOP approach is extended to generate NINOP (N-Input N-Output Port) models. A Matlab toolbox is developed integrating beam and bending plate elements. In particular a NINOP formulation of bending plates is proposed to solve analytic two-dimensional problems. The computation of NINOP models using the outputs of a MSC/Nastran modal analysis is also investigated in order to directly use the results provided by a commercial finite element software. The main advantage of this tool is to provide a model of a multibody system under the form of a block diagram with a minimal number of states. This model is easy to operate for preliminary design and control. An illustrative example highlights the potential of the proposed approach: the synthesis of the dynamical model of a spacecraft with two deployable and flexible solar arrays.

      PubDate: 2017-12-12T10:43:23Z
      DOI: 10.1016/j.jsv.2017.11.021
      Issue No: Vol. 415 (2017)
       
  • Using singular value decomposition of component eigenmodes for interface
           reduction
    • Authors: Hadrien Tournaire; Franck Renaud; Jean Luc Dion
      Pages: 1 - 14
      Abstract: Publication date: 3 February 2018
      Source:Journal of Sound and Vibration, Volume 414
      Author(s): Hadrien Tournaire, Franck Renaud, Jean Luc Dion
      The aim of this paper is to describe the development of a reduced order model for modal analysis in a design context. The design process of most industrial systems is based on the re-utilization of certain components. Here, we propose a reduction method involving component eigenmodes to recover the modal behaviour of an assembled structure. The contribution of this work is that it uses component eigenmodes to build an interface reduction basis. Lastly, the reduction methodology proposed is compared to the Craig and Bampton method by applying it to two case studies of which one is an industrial model of an open rotor blade.

      PubDate: 2017-11-16T14:40:50Z
      DOI: 10.1016/j.jsv.2017.05.029
      Issue No: Vol. 414 (2017)
       
  • On application of the Floquet theory for radially periodic membranes and
           plates
    • Authors: Alexander Hvatov; Sergey Sorokin
      Pages: 15 - 30
      Abstract: Publication date: 3 February 2018
      Source:Journal of Sound and Vibration, Volume 414
      Author(s): Alexander Hvatov, Sergey Sorokin
      The paper is concerned with the vibro-isolation effects in radially periodic membranes and plates. Alternative formulations of the canonical Floquet theory for analysis of wave propagation in these elastic structures are compared with each other. An extension of this theory beyond the applicability limits of the well-known theory of Bragg fiber is proposed. The similarities and differences in performance of infinite and finite structures periodic in Cartesian and polar coordinates are highlighted and explained.

      PubDate: 2017-11-16T14:40:50Z
      DOI: 10.1016/j.jsv.2017.11.003
      Issue No: Vol. 414 (2017)
       
  • Numerical and experimental analysis of a vibration isolator equipped with
           a negative stiffness system
    • Authors: E. Palomares; A.J. Nieto; A.L. Morales; J.M. Chicharro; P. Pintado
      Pages: 31 - 42
      Abstract: Publication date: 3 February 2018
      Source:Journal of Sound and Vibration, Volume 414
      Author(s): E. Palomares, A.J. Nieto, A.L. Morales, J.M. Chicharro, P. Pintado
      This paper presents a Negative Stiffness System (NSS) based on a set of two double–acting pneumatic linear actuators (PLA). The NSS is added to a system with a single degree of freedom, which consists of a sprung mass and a pneumatic spring. One end of each PLA is jointed to the sprung mass while the other end is jointed to the vibrating frame. In addition, the PLAs are symmetrically arranged so that they remain horizontal while the sprung mass is in static conditions. When the rear chamber is pressurised, the vertical component of the force applied by the PLAs will work against the pneumatic spring reducing the dynamic resonance frequency of the overall system. Experimental tests and simulations showed improvements regarding sprung mass isolation in comparison to the passive system without NSS, decreasing the resonance frequency by up to 58 % and improving the vibration attenuation for different experimental excitations.

      PubDate: 2017-11-16T14:40:50Z
      DOI: 10.1016/j.jsv.2017.11.006
      Issue No: Vol. 414 (2017)
       
  • Bearing fault diagnosis under unknown time-varying rotational speed
           conditions via multiple time-frequency curve extraction
    • Authors: Huan Huang; Natalie Baddour; Ming Liang
      Pages: 43 - 60
      Abstract: Publication date: 3 February 2018
      Source:Journal of Sound and Vibration, Volume 414
      Author(s): Huan Huang, Natalie Baddour, Ming Liang
      Under normal operating conditions, bearings often run under time-varying rotational speed conditions. Under such circumstances, the bearing vibrational signal is non-stationary, which renders ineffective the techniques used for bearing fault diagnosis under constant running conditions. One of the conventional methods of bearing fault diagnosis under time-varying speed conditions is resampling the non-stationary signal to a stationary signal via order tracking with the measured variable speed. With the resampled signal, the methods available for constant condition cases are thus applicable. However, the accuracy of the order tracking is often inadequate and the time-varying speed is sometimes not measurable. Thus, resampling-free methods are of interest for bearing fault diagnosis under time-varying rotational speed for use without tachometers. With the development of time-frequency analysis, the time-varying fault character manifests as curves in the time-frequency domain. By extracting the Instantaneous Fault Characteristic Frequency (IFCF) from the Time-Frequency Representation (TFR) and converting the IFCF, its harmonics, and the Instantaneous Shaft Rotational Frequency (ISRF) into straight lines, the bearing fault can be detected and diagnosed without resampling. However, so far, the extraction of the IFCF for bearing fault diagnosis is mostly based on the assumption that at each moment the IFCF has the highest amplitude in the TFR, which is not always true. Hence, a more reliable T-F curve extraction approach should be investigated. Moreover, if the T-F curves including the IFCF, its harmonic, and the ISRF can be all extracted from the TFR directly, no extra processing is needed for fault diagnosis. Therefore, this paper proposes an algorithm for multiple T-F curve extraction from the TFR based on a fast path optimization which is more reliable for T-F curve extraction. Then, a new procedure for bearing fault diagnosis under unknown time-varying speed conditions is developed based on the proposed algorithm and a new fault diagnosis strategy. The average curve-to-curve ratios are utilized to describe the relationship of the extracted curves and fault diagnosis can then be achieved by comparing the ratios to the fault characteristic coefficients. The effectiveness of the proposed method is validated by simulated and experimental signals.

      PubDate: 2017-11-16T14:40:50Z
      DOI: 10.1016/j.jsv.2017.11.005
      Issue No: Vol. 414 (2017)
       
  • Characterizing human activity induced impulse and slip-pulse excitations
           through structural vibration
    • Authors: Shijia Pan; Mostafa Mirshekari; Jonathon Fagert; Ceferino Gabriel Ramirez; Albert Jin Chung; Chih Chi Hu; John Paul Shen; Pei Zhang; Hae Young Noh
      Pages: 61 - 80
      Abstract: Publication date: 3 February 2018
      Source:Journal of Sound and Vibration, Volume 414
      Author(s): Shijia Pan, Mostafa Mirshekari, Jonathon Fagert, Ceferino Gabriel Ramirez, Albert Jin Chung, Chih Chi Hu, John Paul Shen, Pei Zhang, Hae Young Noh
      Many human activities induce excitations on ambient structures with various objects, causing the structures to vibrate. Accurate vibration excitation source detection and characterization enable human activity information inference, hence allowing human activity monitoring for various smart building applications. By utilizing structural vibrations, we can achieve sparse and non-intrusive sensing, unlike pressure- and vision-based methods. Many approaches have been presented on vibration-based source characterization, and they often either focus on one excitation type or have limited performance due to the dispersion and attenuation effects of the structures. In this paper, we present our method to characterize two main types of excitations induced by human activities (impulse and slip-pulse) on multiple structures. By understanding the physical properties of waves and their propagation, the system can achieve accurate excitation tracking on different structures without large-scale labeled training data. Specifically, our algorithm takes properties of surface waves generated by impulse and of body waves generated by slip-pulse into account to handle the dispersion and attenuation effects when different types of excitations happen on various structures. We then evaluate the algorithm through multiple scenarios. Our method achieves up to a six times improvement in impulse localization accuracy and a three times improvement in slip-pulse trajectory length estimation compared to existing methods that do not take wave properties into account.

      PubDate: 2017-11-16T14:40:50Z
      DOI: 10.1016/j.jsv.2017.10.034
      Issue No: Vol. 414 (2017)
       
  • Condition monitoring and fault diagnosis of motor bearings using
           undersampled vibration signals from a wireless sensor network
    • Authors: Siliang Lu; Peng Zhou; Xiaoxian Wang; Yongbin Liu; Fang Liu; Jiwen Zhao
      Pages: 81 - 96
      Abstract: Publication date: 3 February 2018
      Source:Journal of Sound and Vibration, Volume 414
      Author(s): Siliang Lu, Peng Zhou, Xiaoxian Wang, Yongbin Liu, Fang Liu, Jiwen Zhao
      Wireless sensor networks (WSNs) which consist of miscellaneous sensors are used frequently in monitoring vital equipment. Benefiting from the development of data mining technologies, the massive data generated by sensors facilitate condition monitoring and fault diagnosis. However, too much data increase storage space, energy consumption, and computing resource, which can be considered fatal weaknesses for a WSN with limited resources. This study investigates a new method for motor bearings condition monitoring and fault diagnosis using the undersampled vibration signals acquired from a WSN. The proposed method, which is a fusion of the kurtogram, analog domain bandpass filtering, bandpass sampling, and demodulated resonance technique, can reduce the sampled data length while retaining the monitoring and diagnosis performance. A WSN prototype was designed, and simulations and experiments were conducted to evaluate the effectiveness and efficiency of the proposed method. Experimental results indicated that the sampled data length and transmission time of the proposed method result in a decrease of over 80% in comparison with that of the traditional method. Therefore, the proposed method indicates potential applications on condition monitoring and fault diagnosis of motor bearings installed in remote areas, such as wind farms and offshore platforms.

      PubDate: 2017-11-16T14:40:50Z
      DOI: 10.1016/j.jsv.2017.11.007
      Issue No: Vol. 414 (2017)
       
  • A robust equal-peak method for uncertain mechanical systems
    • Authors: L. Dell'Elce; E. Gourc; G. Kerschen
      Pages: 97 - 109
      Abstract: Publication date: 3 February 2018
      Source:Journal of Sound and Vibration, Volume 414
      Author(s): L. Dell'Elce, E. Gourc, G. Kerschen
      The linear vibration absorber is a widely-used vibration mitigation device. However, when the absorber is tuned according to Den Hartog's equal-peak method, the resulting narrow bandwidth may decrease its effectiveness, especially when the host structure is uncertain or in the presence of environmental variability. In this paper, a new tuning strategy of the linear absorber, based on the concept of robust equal peaks, is introduced for mitigating a specific resonance of an uncertain mechanical system. Both analytical and numerical investigations are carried out to demonstrate the robustness of the proposed absorber. For 20% uncertainty in the stiffness of the host system, the performance improvement brought by the robust equal-peak method amounts to more than 30% with respect to Den Hartog's tuning rule.

      PubDate: 2017-11-16T14:40:50Z
      DOI: 10.1016/j.jsv.2017.10.038
      Issue No: Vol. 414 (2017)
       
  • Wave propagation modeling in composites reinforced by randomly oriented
           fibers
    • Authors: Pawel Kudela; Maciej Radzienski; Wieslaw Ostachowicz
      Pages: 110 - 125
      Abstract: Publication date: 3 February 2018
      Source:Journal of Sound and Vibration, Volume 414
      Author(s): Pawel Kudela, Maciej Radzienski, Wieslaw Ostachowicz
      A new method for prediction of elastic constants in randomly oriented fiber composites is proposed. It is based on mechanics of composites, the rule of mixtures and total mass balance tailored to the spectral element mesh composed of 3D brick elements. Selected elastic properties predicted by the proposed method are compared with values obtained by another theoretical method. The proposed method is applied for simulation of Lamb waves in glass-epoxy composite plate reinforced by randomly oriented fibers. Full wavefield measurements conducted by the scanning laser Doppler vibrometer are in good agreement with simulations performed by using the time domain spectral element method.

      PubDate: 2017-11-16T14:40:50Z
      DOI: 10.1016/j.jsv.2017.11.015
      Issue No: Vol. 414 (2017)
       
  • Sound transmission through a finite perforated panel set in a rigid
           baffle: A fully coupled analysis
    • Authors: Anoop Akkoorath Mana; Venkata R. Sonti
      Pages: 126 - 156
      Abstract: Publication date: 3 February 2018
      Source:Journal of Sound and Vibration, Volume 414
      Author(s): Anoop Akkoorath Mana, Venkata R. Sonti
      Sound transmission through a fluid-loaded finite perforated panel set in an infinite unperforated rigid baffle is considered. Using a fully coupled formulation in the 2-D wavenumber domain, the transmitted pressure due to an incident plane wave is obtained. The change in the panel resonances caused by the perforations is accounted for. The formulation also takes into account the self- and inter-modal coupling coefficients arising due to the fluid-loading effect. The derivation is almost entirely analytical with numerical computations done at the very end. Transmission loss (TL) curves are plotted for various cases and the physics is discussed. Along the way an uncoupled calculation is also done for the sake of comparison. The results are mainly for a light medium like air. For a light medium, in general, the perforate impedance is lower than the panel impedance. Thus, most of the transmission happens through the perforations. The panel velocity contribution is insignificant and hence the uncoupled calculation is adequate. In general, the absolute perforate impedance increases with increasing frequency. So does the TL. At low frequencies, because the resistive component of the hole impedance increases, the absolute perforate impedance rises. Thus, the TL curves rise at the lower frequencies. This effect is prominent for sub-millimeter hole radii, i.e., for micro-perforations. An important issue with the TL values for perforated panels is that they sometimes acquire negative values at low frequencies. This apparent anomaly is resolved by showing that at low frequencies there is an additional power component that flows from the baffle region onto the panel. Upon inclusion of this additional term, the TL values remain positive at all frequencies.

      PubDate: 2017-12-12T10:43:23Z
      DOI: 10.1016/j.jsv.2017.10.020
      Issue No: Vol. 414 (2017)
       
  • Vibration of a string against multiple spring-mass-damper stoppers
    • Authors: Ji-Hwan Shin; Ezdiani Talib; Moon K. Kwak
      Pages: 157 - 173
      Abstract: Publication date: 3 February 2018
      Source:Journal of Sound and Vibration, Volume 414
      Author(s): Ji-Hwan Shin, Ezdiani Talib, Moon K. Kwak
      When a building sways due to strong wind or an earthquake, the elevator rope can undergo resonance, resulting in collision with the hoist-way wall. In this study, a hard stopper and a soft stopper comprised of a spring-mass-damper system installed along the hoist-way wall were considered to prevent the string from undergoing excessive vibrations. The collision of the string with multiple hard stoppers and multiple spring-mass-damper stoppers was investigated using an analytical method. The result revealed new formulas and computational algorithms that are suitable for simulating the vibration of the string against multiple stoppers. The numerical results show that the spring-mass-damper stopper is more effective in suppressing the vibrations of the string and reducing structural failure. The proposed algorithms were shown to be efficient to simulate the motion of the string against a vibration stopper.

      PubDate: 2017-12-12T10:43:23Z
      DOI: 10.1016/j.jsv.2017.11.011
      Issue No: Vol. 414 (2017)
       
  • An identification method of orbit responses rooting in vibration analysis
           of rotor during touchdowns of active magnetic bearings
    • Authors: Tao Liu; Mindong Lyu; Zixi Wang; Shaoze Yan
      Pages: 174 - 191
      Abstract: Publication date: 3 February 2018
      Source:Journal of Sound and Vibration, Volume 414
      Author(s): Tao Liu, Mindong Lyu, Zixi Wang, Shaoze Yan
      Identification of orbit responses can make the active protection operation more easily realize for active magnetic bearings (AMB) in case of touchdowns. This paper presents an identification method of the orbit responses rooting on signal processing of rotor displacements during touchdowns. The recognition method consists of two major steps. Firstly, the combined rub and bouncing is distinguished from the other orbit responses by the mathematical expectation of axis displacements of the rotor. Because when the combined rub and bouncing occurs, the rotor of AMB will not be always close to the touchdown bearings (TDB). Secondly, we recognize the pendulum vibration and the full rub by the Fourier spectrum of displacement in horizontal direction, as the frequency characteristics of the two responses are different. The principle of the whole identification algorithm is illustrated by two sets of signal generated by a dynamic model of the specific rotor-TDB system. The universality of the method is validated by other four sets of signal. Besides, the adaptability of noise is also tested by adding white noises with different strengths, and the result is promising. As the mathematical expectation and Discrete Fourier transform are major calculations of the algorithm, the calculation quantity of the algorithm is low, so it is fast, easily realized and embedded in the AMB controller, which has an important engineering value for the protection of AMBs during touchdowns.

      PubDate: 2017-12-12T10:43:23Z
      DOI: 10.1016/j.jsv.2017.11.001
      Issue No: Vol. 414 (2017)
       
  • Separation and identification of structural modes in largely
           underdetermined scenarios using frequency banding
    • Authors: Roberto Castiglione; Jerome Antoni; Luigi Garibaldi
      Pages: 192 - 217
      Abstract: Publication date: 3 February 2018
      Source:Journal of Sound and Vibration, Volume 414
      Author(s): Roberto Castiglione, Jerome Antoni, Luigi Garibaldi
      In recent years, blind source separation (BSS) has gained significant interest in the context of operational modal analysis, as a non-parametric alternative to the identification of mechanical structures from output-only measurements. One persisting limitation of most BSS methods, however, is to they cannot identify more active modes than the number of simultaneously measured outputs. The aim of this work is to propose a solution to the largely underdetermined case – where many more modes are to be identified than the number of available measurements -- by dividing the frequency axis in subbands, such that each band provides an (over)determined problem where BSS can be applied separately. The approach comes with the proposal of a new second-order BSS that operates directly in the frequency domain and takes as an input the cross-spectral matrix of the data. A data augmentation technique is also devised to artificially increase the dimension of the measurements in severely undetermined scenarios. Finally, an identification algorithm is introduced that estimates the modal parameters of the separated structural modes. A remarkable aspect of these algorithms is that they are all based on the unified use of multi-filters designed in the frequency domain, yet with different frequency bandwidths. Another particularity of the present paper is to demonstrate the validity of the proposed approach on several benchmark databases with various degrees of difficulty including complex modes, high modal overlap, singular modes, and the presence of engine harmonics. In all cases, the proposed methodology was efficient and, above all, easy to deal with even in largely undetermined cases.

      PubDate: 2017-12-12T10:43:23Z
      DOI: 10.1016/j.jsv.2017.10.033
      Issue No: Vol. 414 (2017)
       
  • A new method of smart and optimal flutter control for composite laminated
           panels in supersonic airflow under thermal effects
    • Authors: Zhi-Guang Song; Feng-Ming Li; Erasmo Carrera; Peter Hagedorn
      Pages: 218 - 232
      Abstract: Publication date: 3 February 2018
      Source:Journal of Sound and Vibration, Volume 414
      Author(s): Zhi-Guang Song, Feng-Ming Li, Erasmo Carrera, Peter Hagedorn
      In most of the active flutter controls, the feedback control gains are selected arbitrarily or by trial and error. These methods are inaccurate and time-consuming. In the present study, a smart and optimal method is proposed to investigate the thermal flutter control of composite laminated panels in supersonic airflow based on a genetic algorithm (GA), in which the feedback control gains of all the piezoelectric actuators are represented by the chromosomes and the fitness is set to be the difference between the present flutter bound and the expected one. Then, according to the GA process, a set of optimal feedback control gains can be obtained, and the flutter bounds of the structural system can be suppressed to any expected values by means of the optimal control gains. Furthermore, the maximum flutter bound of the panel and the corresponding feedback control gains can also be obtained. In the investigations, the aerodynamic pressure is evaluated by the supersonic piston theory and the controller is designed by the displacement feedback method. The influences of the placements of piezoelectric patches on the active flutter control effects are analyzed. Some interesting phenomena are obtained and discussed.

      PubDate: 2017-12-12T10:43:23Z
      DOI: 10.1016/j.jsv.2017.11.008
      Issue No: Vol. 414 (2017)
       
  • Application of a movable active vibration control system on a floating
           raft
    • Authors: Zhen Wang; Cheuk Ming Mak
      Pages: 233 - 244
      Abstract: Publication date: 3 February 2018
      Source:Journal of Sound and Vibration, Volume 414
      Author(s): Zhen Wang, Cheuk Ming Mak
      This paper presents a theoretical study of an inertial actuator connected to an accelerometer by a local feedback loop for active vibration control on a floating raft. On the criterion of the minimum power transmission from the vibratory machines to the flexible foundation in the floating raft, the best mounting positions for the inertial actuator on the intermediate mass of the floating raft are investigated. Simulation results indicate that the best mounting positions for the inertial actuator vary with frequency. To control time-varying excitations of vibratory machines on a floating raft effectively, an automatic control system based on real-time measurement of a cost function and automatically searching the best mounting position of the inertial actuator is proposed. To the best of our knowledge, it is the first time that an automatic control system is proposed to move an actuator automatically for controlling a time-varying excitation.

      PubDate: 2017-12-12T10:43:23Z
      DOI: 10.1016/j.jsv.2017.11.026
      Issue No: Vol. 414 (2017)
       
  • Magnetostrictive patch sensor system for battery-less real-time
           measurement of torsional vibrations of rotating shafts
    • Authors: Jun Kyu Lee; Hong Min Seung; Chung Il Park; Joo Kyung Lee; Do Hyeong Lim; Yoon Young Kim
      Pages: 245 - 258
      Abstract: Publication date: 3 February 2018
      Source:Journal of Sound and Vibration, Volume 414
      Author(s): Jun Kyu Lee, Hong Min Seung, Chung Il Park, Joo Kyung Lee, Do Hyeong Lim, Yoon Young Kim
      Real-time uninterrupted measurement for torsional vibrations of rotating shafts is crucial for permanent health monitoring. So far, strain gauge systems with telemetry units have been used for real-time monitoring. However, they have a critical disadvantage in that shaft operations must be stopped intermittently to replace telemetry unit batteries. To find an alternative method to carry out battery-less real-time measurement for torsional vibrations of rotating shafts, a magnetostrictive patch sensor system was proposed in the present study. Since the proposed sensor does not use any powered telemetry system, no battery is needed and thus there is no need to stop rotating shafts for battery replacement. The proposed sensor consists of magnetostrictive patches and small magnets tightly bonded onto a shaft. A solenoid coil is placed around the shaft to convert magnetostrictive patch deformation by shaft torsional vibration into electric voltage output. For sensor design and characterization, investigations were performed in a laboratory on relatively small-sized stationary solid shaft. A magnetostrictive patch sensor system was then designed and installed on a large rotating propulsion shaft of an LPG carrier ship in operation. Vibration signals were measured using the proposed sensor system and compared to those measured with a telemetry unit-equipped strain gauge system.

      PubDate: 2017-12-12T10:43:23Z
      DOI: 10.1016/j.jsv.2017.11.023
      Issue No: Vol. 414 (2017)
       
  • Analytical solution for the transient wave propagation of a buried
           cylindrical P-wave line source in a semi-infinite elastic medium with a
           fluid surface layer
    • Authors: Zhendong Shan; Daosheng Ling
      Pages: 259 - 283
      Abstract: Publication date: 3 February 2018
      Source:Journal of Sound and Vibration, Volume 414
      Author(s): Zhendong Shan, Daosheng Ling
      This article develops an analytical solution for the transient wave propagation of a cylindrical P-wave line source in a semi-infinite elastic solid with a fluid layer. The analytical solution is presented in a simple closed form in which each term represents a transient physical wave. The Scholte equation is derived, through which the Scholte wave velocity can be determined. The Scholte wave is the wave that propagates along the interface between the fluid and solid. To develop the analytical solution, the wave fields in the fluid and solid are defined, their analytical solutions in the Laplace domain are derived using the boundary and interface conditions, and the solutions are then decomposed into series form according to the power series expansion method. Each item of the series solution has a clear physical meaning and represents a transient wave path. Finally, by applying Cagniard's method and the convolution theorem, the analytical solutions are transformed into the time domain. Numerical examples are provided to illustrate some interesting features in the fluid layer, the interface and the semi-infinite solid. When the P-wave velocity in the fluid is higher than that in the solid, two head waves in the solid, one head wave in the fluid and a Scholte wave at the interface are observed for the cylindrical P-wave line source.

      PubDate: 2017-12-12T10:43:23Z
      DOI: 10.1016/j.jsv.2017.11.018
      Issue No: Vol. 414 (2017)
       
  • Time-variant random interval natural frequency analysis of structures
    • Authors: Binhua Wu; Di Wu; Wei Gao; Chongmin Song
      Pages: 284 - 298
      Abstract: Publication date: 3 February 2018
      Source:Journal of Sound and Vibration, Volume 414
      Author(s): Binhua Wu, Di Wu, Wei Gao, Chongmin Song
      This paper presents a new robust method namely, unified interval Chebyshev-based random perturbation method, to tackle hybrid random interval structural natural frequency problem. In the proposed approach, random perturbation method is implemented to furnish the statistical features (i.e., mean and standard deviation) and Chebyshev surrogate model strategy is incorporated to formulate the statistical information of natural frequency with regards to the interval inputs. The comprehensive analysis framework combines the superiority of both methods in a way that computational cost is dramatically reduced. This presented method is thus capable of investigating the day-to-day based time-variant natural frequency of structures accurately and efficiently under concrete intrinsic creep effect with probabilistic and interval uncertain variables. The extreme bounds of the mean and standard deviation of natural frequency are captured through the embedded optimization strategy within the analysis procedure. Three particularly motivated numerical examples with progressive relationship in perspective of both structure type and uncertainty variables are demonstrated to justify the computational applicability, accuracy and efficiency of the proposed method.

      PubDate: 2017-12-12T10:43:23Z
      DOI: 10.1016/j.jsv.2017.11.009
      Issue No: Vol. 414 (2017)
       
  • Non-material finite element modelling of large vibrations of axially
           moving strings and beams
    • Authors: Yury Vetyukov
      Pages: 299 - 317
      Abstract: Publication date: 3 February 2018
      Source:Journal of Sound and Vibration, Volume 414
      Author(s): Yury Vetyukov
      We present a new mathematical model for the dynamics of a beam or a string, which moves in a given axial direction across a particular domain. Large in-plane vibrations are coupled with the gross axial motion, and a Lagrangian (material) form of the equations of structural mechanics becomes inefficient. The proposed mixed Eulerian-Lagrangian description features mechanical fields as functions of a spatial coordinate in the axial direction. The material travels across a finite element mesh, and the boundary conditions are applied in fixed nodes. Beginning with the variational equation of virtual work in its material form, we analytically derive the Lagrange's equations of motion of the second kind for the considered case of a discretized non-material control domain and for geometrically exact kinematics. The dynamic analysis is straightforward as soon as the strain and the kinetic energies of the control domain are available. In numerical simulations we demonstrate the rapid mesh convergence of the model, the effect of the bending stiffness and the dynamic instability when the axial velocity gets high. We also show correspondence to the results of fully Lagrangian benchmark solutions.
      Graphical abstract image

      PubDate: 2017-12-12T10:43:23Z
      DOI: 10.1016/j.jsv.2017.11.010
      Issue No: Vol. 414 (2017)
       
  • Extension of roughness noise to bluff bodies using the boundary element
           method
    • Authors: Antoni Alomar; David Angland; Xin Zhang
      Pages: 318 - 337
      Abstract: Publication date: 3 February 2018
      Source:Journal of Sound and Vibration, Volume 414
      Author(s): Antoni Alomar, David Angland, Xin Zhang
      A prediction model of roughness noise generated by bluff body flow at high Reynolds numbers is proposed. Howe's roughness noise theory extended by Liu and Dowling is used, and the boundary layer inputs to the theory have been modified for a bluff body. The scattering due to the bluff body has been accounted for by the boundary element method. The procedure to couple the roughness noise sources to the tailored Green's function is detailed for the case where the boundary element method mesh is orthogonal and aligned with the boundary layer outer velocity. The proposed method has been implemented and compared to experimental results for the particular case of a circular cylinder with large roughness. Two different estimations of the skin friction, which is an input to the roughness noise theory, are considered. One is a zero-pressure gradient model, and the second is based on published experimental data of the skin friction on a rough circular cylinder, but with smaller roughness than was used in the experiments. The zero-pressure gradient skin friction estimate leads to a better prediction of the effect of changes in the area covered by roughness elements. The success of the zero-pressure gradient skin friction estimate is encouraging as the only modifications that need to be made to the boundary layer model to account for a bluff body are the boundary layer outer velocity distribution and the location of separation.

      PubDate: 2017-12-12T10:43:23Z
      DOI: 10.1016/j.jsv.2017.09.021
      Issue No: Vol. 414 (2017)
       
  • Method development of damage detection in asymmetric buildings
    • Authors: Yi Wang; David P. Thambiratnam; Tommy H.T. Chan; Andy Nguyen
      Pages: 41 - 56
      Abstract: Publication date: 20 January 2018
      Source:Journal of Sound and Vibration, Volume 413
      Author(s): Yi Wang, David P. Thambiratnam, Tommy H.T. Chan, Andy Nguyen
      Aesthetics and functionality requirements have caused most buildings to be asymmetric in recent times. Such buildings exhibit complex vibration characteristics under dynamic loads as there is coupling between the lateral and torsional components of vibration, and are referred to as torsionally coupled buildings. These buildings require three dimensional modelling and analysis. In spite of much recent research and some successful applications of vibration based damage detection methods to civil structures in recent years, the applications to asymmetric buildings has been a challenging task for structural engineers. There has been relatively little research on detecting and locating damage specific to torsionally coupled asymmetric buildings. This paper aims to compare the difference in vibration behaviour between symmetric and asymmetric buildings and then use the vibration characteristics for predicting damage in them. The need for developing a special method to detect damage in asymmetric buildings thus becomes evident. Towards this end, this paper modifies the traditional modal strain energy based damage index by decomposing the mode shapes into their lateral and vertical components and to form component specific damage indices. The improved approach is then developed by combining the modified strain energy based damage indices with the modal flexibility method which was modified to suit three dimensional structures to form a new damage indicator. The procedure is illustrated through numerical studies conducted on three dimensional five-story symmetric and asymmetric frame structures with the same layout, after validating the modelling techniques through experimental testing of a laboratory scale asymmetric building model. Vibration parameters obtained from finite element analysis of the intact and damaged building models are then applied into the proposed algorithms for detecting and locating the single and multiple damages in these buildings. The results obtained from a number of different damage scenarios confirm the feasibility of the proposed vibration based damage detection method for three dimensional asymmetric buildings.

      PubDate: 2017-10-24T11:15:12Z
      DOI: 10.1016/j.jsv.2017.10.015
      Issue No: Vol. 413 (2017)
       
  • On the non-proportionality between wheel/rail contact forces and speed
           during wheelset passage over specific welds
    • Authors: Nekane Correa; Ernesto G. Vadillo; Javier Santamaria; Julio Blanco-Lorenzo
      Pages: 79 - 100
      Abstract: Publication date: 20 January 2018
      Source:Journal of Sound and Vibration, Volume 413
      Author(s): Nekane Correa, Ernesto G. Vadillo, Javier Santamaria, Julio Blanco-Lorenzo
      This study investigates the influence on the wheel-rail contact forces of the running speed and the shape and position of weld defects along the track. For this purpose, a vertical dynamic model in the space domain is used. The model is obtained from the transformation between the domains of frequency and space using a Rational Fraction Polynomials (RFP) method, which is modified with multiobjective genetic algorithms in order to improve the fitting of track receptance and to assist integration during simulations. This produces a precise model with short calculation times, which is essential to this study. The wheel-rail contact is modelled using a non-linear Hertz spring. The contact forces are studied for several types of characteristic welds. The way in which forces vary as a function of weld position and running speed is studied for each type of weld. This paper studies some of the factors that affect the maximum forces when the vehicle moves over a rail weld, such as weld geometry, parametric excitation and contact stiffness. It is found that the maximum force in the wheel-rail contact when the vehicle moves over a weld is not always proportional to the running speed. The paper explains why it is not proportional in specific welds.

      PubDate: 2017-12-12T10:43:23Z
      DOI: 10.1016/j.jsv.2017.10.031
      Issue No: Vol. 413 (2017)
       
  • Effect of thermal stresses on frequency band structures of elastic
           metamaterial plates
    • Authors: Ying Wu; Kaiping Yu; Linyun Yang; Rui Zhao; Xiaotian Shi; Kuo Tian
      Pages: 101 - 119
      Abstract: Publication date: 20 January 2018
      Source:Journal of Sound and Vibration, Volume 413
      Author(s): Ying Wu, Kaiping Yu, Linyun Yang, Rui Zhao, Xiaotian Shi, Kuo Tian
      We investigate the effect of thermal stresses on the band structure of elastic metamaterial plates by developing a useful finite-element based method. The thermal field is assumed to be uniform throughout the whole plate. Specifically, we find that the stiffness matrix of plate element is comprised of elastic and thermal stresses parts, which can be regarded as a linear function of temperature difference. We additionally demonstrate that the relative magnitudes between elastic properties and thermal stresses will lead to nonlinear effects on frequency band structures based on two different types of metamaterial plates made of single and double inclusions of square plates, respectively. Then, we validate the proposed approach by comparing the band structures with the frequency response curves obtained in finite periodic structures. We conduct sensitivity analysis and discuss in-depth the sensitivities of band structures with respect to temperature difference to quantitatively investigate the effect of thermal stresses on each band. In addition, the coupled effects of thermal stresses and temperature-dependent material properties on the band structure of Aluminum/silicone rubber plate have also been discussed. The proposed method and new findings in this paper extends the ability of existing metamaterial plates by enabling tunability over a wide range of frequencies in thermal environments.

      PubDate: 2017-12-12T10:43:23Z
      DOI: 10.1016/j.jsv.2017.10.014
      Issue No: Vol. 413 (2017)
       
  • Modelling and mitigation of wheel squeal noise amplitude
    • Authors: Paul A. Meehan; Xiaogang Liu
      Pages: 144 - 158
      Abstract: Publication date: 20 January 2018
      Source:Journal of Sound and Vibration, Volume 413
      Author(s): Paul A. Meehan, Xiaogang Liu
      The prediction of vibration amplitude and sound pressure level of wheel squeal noise is investigated using a concise mathematical model that is verified with measurements from both a rolling contact two disk test rig and a field case study. The model is used to perform an energy-based analysis to determine a closed form solution to the steady state limit cycle amplitude of creep and vibration oscillations during squealing. The analytical solution compares well with a numerical solution using an experimentally tuned creep curve with full nonlinear shape. The predicted squeal sound level trend also compares well with that recorded at various crabbing velocities (proportional to angle of attack) for the test rig at different rolling speeds. In addition, further verification is performed against many field recordings of wheel squeal on a sharp curve of 300 m. A comparison with a simplified modified result from Rudd [1] is also provided and highlights the accuracy and advantages of the present efficient model. The analytical solution provides insight into why the sound pressure level of squeal noise increases with crabbing velocity (or angle of attack) as well as how the amplitude is affected by the critical squeal parameters including a detailed investigation of modal damping. Finally, the efficient model is used to perform a parametric investigation into means of achieving a 6 dB decrease in squeal noise. The results highlight the primary importance of crabbing velocity (and angle of attack) as well as the creep curve parameters that may be controlled using third body control (ie friction modifiers). The results concur with experimental and field observations and provide important theoretical insight into the useful mechanisms of mitigating wheel squeal and quantifying their relative merits.

      PubDate: 2017-11-01T11:25:58Z
      DOI: 10.1016/j.jsv.2017.10.032
      Issue No: Vol. 413 (2017)
       
  • Dynamic properties and damping predictions for laminated plates: High
           order theories – Timoshenko beam
    • Authors: Bohdan Diveyev; Solomija Konyk; Malcolm J. Crocker
      Pages: 173 - 190
      Abstract: Publication date: 20 January 2018
      Source:Journal of Sound and Vibration, Volume 413
      Author(s): Bohdan Diveyev, Solomija Konyk, Malcolm J. Crocker
      The main aim of this study is to predict the elastic and damping properties of composite laminated plates. This problem has an exact elasticity solution for simple uniform bending and transverse loading conditions. This paper presents a new stress analysis method for the accurate determination of the detailed stress distributions in laminated plates subjected to cylindrical bending. Some approximate methods for the stress state predictions for laminated plates are presented here. The present method is adaptive and does not rely on strong assumptions about the model of the plate. The theoretical model described here incorporates deformations of each sheet of the lamina, which account for the effects of transverse shear deformation, transverse normal strain-stress and nonlinear variation of displacements with respect to the thickness coordinate. Predictions of the dynamic and damping values of laminated plates for various geometrical, mechanical and fastening properties are presented. Comparison with the Timoshenko beam theory is systematically made for analytical and approximation variants.

      PubDate: 2017-11-01T11:25:58Z
      DOI: 10.1016/j.jsv.2017.10.017
      Issue No: Vol. 413 (2017)
       
  • Fourier and wavelet analyses of intermittent and resonant pressure
           components in a slot burner
    • Authors: Tiziano Pagliaroli; Matteo Mancinelli; Guido Troiani; Umberto Iemma; Roberto Camussi
      Pages: 205 - 224
      Abstract: Publication date: 20 January 2018
      Source:Journal of Sound and Vibration, Volume 413
      Author(s): Tiziano Pagliaroli, Matteo Mancinelli, Guido Troiani, Umberto Iemma, Roberto Camussi
      In laboratory-scale burner it has been observed that the acoustic excitations change the flame topology inducing asymmetry and oscillations. Hence, an acoustic and aeroacoustic study in non reactive condition is of primary importance during the design stage of a new burner in order to avoid the development of standing waves which can force the flame. So wall pressure fluctuations inside and outside of a novel slot burner have been studied experimentally and numerically for a broad range of geometrical parameters and mass flow rates. Wall pressure fluctuations have been measured through cavity-mounted microphones, providing uni- and multi-variate pressure statistics in both the time and frequency domains. Furthermore, since the onset of combustion-driven oscillations is always presaged by intermittent bursts of high amplitude, a wavelet-based conditional sampling procedure was applied to the database in order to detect coherent signatures embedded in the pressure time signals. Since for a particular case the coherent structures identified have a multi-scale signature, a wavelet-based decomposition technique was proposed as well to separate the contribution of the large- and small-scale flow structures to the pressure fluctuation field. As a main outcome of the activity no coupling between standing waves and velocity fluctuations was observed, but only well localized pressure signatures with shape strongly affected by the neighbouring flow physics.

      PubDate: 2017-11-01T11:25:58Z
      DOI: 10.1016/j.jsv.2017.10.029
      Issue No: Vol. 413 (2017)
       
  • Modeling, design, and testing of a proof-of-concept prototype damper with
           friction and eddy current damping effects
    • Authors: Mohsen Amjadian; Anil K. Agrawal
      Pages: 225 - 249
      Abstract: Publication date: 20 January 2018
      Source:Journal of Sound and Vibration, Volume 413
      Author(s): Mohsen Amjadian, Anil K. Agrawal
      Friction is considered as one of the most reliable mechanisms of energy dissipation that has been utilized extensively in passive damping devices to mitigate vibration of civil engineering structures subjected to extreme natural hazards such as earthquakes and windstorms. However, passive friction dampers are well-known for having a highly nonlinear hysteretic behavior caused by stick-slip motion at low velocities, a phenomenon that is inherent in friction and increases the acceleration response of the structure under control unfavorably. The authors have recently proposed the theoretical concept of a new type of damping device termed as “Passive Electromagnetic Eddy Current Friction Damper” (PEMECFD) in which an eddy current damping mechanism was utilized not only to decrease the undesirable effects of stick-slip motion, but also to increase the energy dissipation capacity of the damping device as a whole. That study was focused on demonstration of the theoretical performance of the proposed damping device through numerical simulations. This paper further investigates the influence of eddy current damping on energy dissipation due to friction through modeling, design, and testing of a proof-of-concept prototype damper. The design of this damper has been improved over the design in the previous study. The normal force in this damper is produced by the repulsive magnetic force between two cuboidal permanent magnets (PMs) magnetized in the direction normal to the direction of the motion. The eddy current damping force is generated because of the motion of the two PMs and two additional PMs relative to a copper plate in their vicinity. The dynamic models for the force-displacement relationship of the prototype damper are based on LuGre friction model, electromagnetic theory, and inertial effects of the prototype damper. The parameters of the dynamic models have been identified through a series of characterization tests on the prototype damper under harmonic excitations of different frequencies in the laboratory. Finally, the identified dynamic models have been validated by subjecting the prototype damper to two different random excitations. The results indicate that the proposed dynamic models are capable of representing force-displacement behavior of the new type of passive damping device for a wide range of operating conditions.

      PubDate: 2017-11-01T11:25:58Z
      DOI: 10.1016/j.jsv.2017.10.025
      Issue No: Vol. 413 (2017)
       
  • Twin rotor damper for the damping of stochastically forced vibrations
           using a power-efficient control algorithm
    • Authors: Richard Bäumer; Richard Terrill; Simon Wollnack; Herbert Werner; Uwe Starossek
      Pages: 308 - 331
      Abstract: Publication date: 20 January 2018
      Source:Journal of Sound and Vibration, Volume 413
      Author(s): Richard Bäumer, Richard Terrill, Simon Wollnack, Herbert Werner, Uwe Starossek
      The twin rotor damper (TRD), an active mass damper, uses the centrifugal forces of two eccentrically rotating control masses. In the continuous rotation mode, the preferred mode of operation, the two eccentric control masses rotate with a constant angular velocity about two parallel axes, creating, under further operational constraints, a harmonic control force in a single direction. In previous theoretical work, it was shown that this mode of operation is effective for the damping of large, harmonic vibrations of a single degree of freedom (SDOF) oscillator. In this paper, the SDOF oscillator is assumed to be affected by a stochastic excitation force and consequently responds with several frequencies. Therefore, the TRD must deviate from the continuous rotation mode to ensure the anti-phasing between the harmonic control force of the TRD and the velocity of the SDOF oscillator. It is found that the required deviation from the continuous rotation mode increases with lower vibration amplitude. Therefore, an operation of the TRD in the continuous rotation mode is no longer efficient below a specific vibration-amplitude threshold. To additionally dampen vibrations below this threshold, the TRD can switch to another, more energy-consuming mode of operation, the swinging mode in which both control masses oscillate about certain angular positions. A power-efficient control algorithm is presented which uses the continuous rotation mode for large vibrations and the swinging mode for small vibrations. To validate the control algorithm, numerical and experimental investigations are performed for a single degree of freedom oscillator under stochastic excitation. Using both modes of operation, it is shown that the control algorithm is effective for the cases of free and stochastically forced vibrations of arbitrary amplitude.

      PubDate: 2017-11-01T11:25:58Z
      DOI: 10.1016/j.jsv.2017.10.007
      Issue No: Vol. 413 (2017)
       
  • Finite element modeling of temperature load effects on the vibration of
           local modes in multi-cable structures
    • Authors: Fabien
      Abstract: Publication date: 20 January 2018
      Source:Journal of Sound and Vibration, Volume 413
      Author(s): Fabien Treyssède
      Understanding thermal effects on the vibration of local (cable-dominant) modes in multi-cable structures is a complicated task. The main difficulty lies in the modification by temperature change of cable tensions, which are then undetermined. This paper applies a finite element procedure to investigate the effects of thermal loads on the linear dynamics of prestressed self-weighted multi-cable structures. Provided that boundary conditions are carefully handled, the discretization of cables with nonlinear curved beam elements can properly represent the thermoelastic behavior of cables as well as their linearized dynamics. A three-step procedure that aims to replace applied pretension forces with displacement continuity conditions is used. Despite an increase in the computational cost related to beam rotational degrees of freedom, such an approach has several advantages. Nonlinear beam finite elements are usually available in commercial codes. The overall method follows a thermoelastic geometrically non-linear analysis and hereby includes the main sources of non-linearities in multi-cable structures. The effects of cable bending stiffness, which can be significant, are also naturally accounted for. The accuracy of the numerical approach is assessed thanks to an analytical model for the vibration of a single inclined cable under temperature change. Then, the effects of thermal loads are investigated for two cable bridges, highlighting how natural frequencies can be affected by temperature. Although counterintuitive, a reverse relative change of natural frequency may occur for certain local modes. This phenomenon can be explained by two distinct mechanisms, one related to the physics intrinsic to cables and the other related to the thermal deflection of the superstructure. Numerical results show that cables cannot be isolated from the rest of the structure and the importance of modeling the whole structure for a quantitative analysis of temperature effects on the dynamics of cable bridges.

      PubDate: 2017-12-12T10:43:23Z
       
 
 
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