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Journal of Sound and Vibration
Journal Prestige (SJR): 1.36
Citation Impact (citeScore): 3
Number of Followers: 202  
 
  Hybrid Journal Hybrid journal (It can contain Open Access articles)
ISSN (Print) 0022-460X - ISSN (Online) 1095-8568
Published by Elsevier Homepage  [3185 journals]
  • A novel approach for vibration analysis of fractional viscoelastic beams
           with attached masses and base excitation
    • Abstract: Publication date: Available online 18 September 2019Source: Journal of Sound and VibrationAuthor(s): Stepa Paunović, Milan Cajić, Danilo Karlićić, Marina Mijalković The Galerkin method is widely applied for finding approximate solutions to vibration problems of beam and plate structures and for estimating their dynamic behavior. Most studies employ the Galerkin method in the analysis of the undamped systems, or for simple structure models with viscous damping. In this paper, a novel approach of using the Galerkin method and Fourier transform to find the solution to the problem of vibration of fractionally damped beams with an arbitrary number of attached concentrated masses and base excitation is presented. The considered approach is novel and it lends itself to determination of the impulse response of the beam and leads to the solution of the system of coupled fractional order differential equations. The proposed approximate solution is validated against the exact solution for a special case with only one tip mass attached, as well as against the Finite Element Method Solution for a special case with classical viscous damping model. Numerical analysis is also given, including the examples of vibration analysis of viscoelastic beams with different fractional derivative orders, retardation times, and the number, weight and position of the attached masses.
       
  • Experimental and numerical investigation of noise generation due to
           acoustic resonance in a cavitating valve
    • Abstract: Publication date: Available online 18 September 2019Source: Journal of Sound and VibrationAuthor(s): Stefan Semrau, Romuald Skoda, Walther Wustmann, Klaus Habr In order to study cavitation induced noise generation in a hydraulic system, cavitation is generated at a planar orifice. The sudden condensation (implosion) of vapor results in shock waves which excite the connected hydraulic pipes with pressure fluctuations. The synchronization between the continuous condensation and evaporation process and shock wave reflection can result in a stationary wave with superelevated pressure amplitudes. The fluid-borne sound is transferred through the mechanical structure into the air, where it can be perceived as a distracting whistling noise. A high-speed camera is used to visualize the void volume. Dynamic pressure signals are recorded in the vicinity of the orifice to analyze the pressure pulsation. The operating point is varied, the orifice geometry is changed and the reflection properties of the pipe on the up- and downstream sides are changed too. In addition, CFD (Computational Fluid Dynamics) simulations of the test bench are used to investigate the root cause of the whistling noise. With regards to representative operating points, the numerical results confirm the measured shedding vapor frequency, particularly the pressure pulsation frequency in the pipe and its amplitude. The conjunction of the experimental and numerical investigations provides the following findings: By reducing the discharge pressure, the void volume increases, which leads to a reduction of the resonance frequency of the pipe downstream of the orifice. For large void volumes, the pressure wave reflection at the void volume can be identified in the amplitude spectrum. The whistling noise depends on the history of the flow field. So, the increase and the reduction of the discharge pressure level leads to different whistling ranges. The whistling range decreases with the increasing length of the pipe resonator. Besides that, the order of the dominant resonance frequency increases. The experimental and numerical results indicate that the whistling noise only occurs, when the jet downstream of the orifice and hence the vapor is perpendicular to the sound propagation in the pipe resonator.Graphical abstractImage 1
       
  • Characterization and suppression of cutting vibration under the coupling
           effect of varied cutting excitations and position-dependent dynamics
    • Abstract: Publication date: Available online 18 September 2019Source: Journal of Sound and VibrationAuthor(s): Yili Peng, Bin Li, Xinyong Mao, Hongqi Liu, Fangyu Peng, Xuchu Jiang Vibration characteristics of cutting vary with the change of the cutting excitation and the change of structure dynamics. To analysis and reduce the vibration, this paper presents a method of identifying the principal mode of vibration to analysis the coupling effect of cutting excitation and position-dependent structure dynamics on cutting vibration. Next, the modal mass distributions corresponding to the principal modes at different positions are calculated to optimize the selection of machining position and reduce vibration. The method is verified through simulation and cutting tests. The vibration can be reduced through the optimally selected cutting position based on the proposed method.
       
  • A tri-stable nonlinear energy sink with piecewise stiffness
    • Abstract: Publication date: Available online 18 September 2019Source: Journal of Sound and VibrationAuthor(s): Hongliang Yao, Yanbo Cao, Yuwei Wang, Bangchun Wen A tri-stable nonlinear energy sink (NES) with negative stiffness and positive piecewise linear stiffness is presented for broad band vibration suppression of small vibrations of host structural system. The negative stiffness of the NES is produced by permanent magnets and the piecewise linear stiffness is produced by a combination of elastic beams. The structure and the mechanism of the NES is firstly introduced, and then the dynamic model of the main system with the NES is built. The vibration suppression ability of the considered NES under transient and steady state excitations are numerically studied and experimentally verified. The results show that the proposed NES has efficient vibration suppression ability, the dissipating speed increases 6.89 times in transient vibration suppression and vibration suppression rate reaches to 71% in steady state vibration suppression. And also, the NES has the ability to attenuate vibrations less than 1 mm.
       
  • A methodology for measurement-system design combining information from
           static and dynamic excitations for bridge load testing
    • Abstract: Publication date: Available online 16 September 2019Source: Journal of Sound and VibrationAuthor(s): Numa J. Bertola, Ian F.C. Smith Managing infrastructure assets is challenging for developed countries because of demand for increases in capacity, the scarcity of economic and environmental resources as well as ageing. Due to conservative approaches to construction design and practice, infrastructure often has hidden reserve capacity and its estimation may improve asset-management decisions. Static and dynamic bridge load testing has the potential to support engineers in their evaluation of infrastructure reserve capacity if monitoring data are associated with a robust structural-identification methodology. As choices of sensor types and locations directly influence structural-identification outcomes, sensor-placement methodologies have recently been developed to ensure successful model-updating results. Due to the nature of static and dynamic measurements, sensor-placement methodologies are usually developed independently. However, both types of load testing are used to update the same bridge behavior model. Therefore, when sensor-placement strategies are established independently, redundant sensor information is likely. In this study, two measurement-system design methodologies are proposed. First, a new methodology for sensor-placement for dynamic load testing is presented, where expected information gain of natural frequencies is used to prioritize sensor-location selections. Then, a measurement-system-design methodology combining information of both static and dynamic load testing is proposed. Finally, the methodology is evaluated using a full-scale bridge. A well-designed measurement system based on expected information gain enhances system identification and reserve-capacity estimation.
       
  • Damping mistuning identification of coated blisks by means of vibrational
           test
    • Abstract: Publication date: Available online 16 September 2019Source: Journal of Sound and VibrationAuthor(s): Kunpeng Xu, Wei Sun, Xianfei Yan, Jin Wang In order to accurately capture the damping mistuning of each sector of coated blisks, a novel identification method was proposed. Based on component mode mistuning (CMM) method, a dynamic model for damping mistuning identification of coated blisks is established. The novelty of this model is that it can predict and quantify the damping mistuning of blisk substrate and coating through the frequency deviations between coated blades and nominal cantilever blades. Based on this dynamic model, the identification algorithm of damping mistuning was obtained. The mass and stiffness mistuning of the blisk substrate and coating are considered in this algorithm, and the damping mistuning of blisk substrate and coating can be identified independently. A six-step identification procedure of damping mistuning for coated blisks is then proposed, where the operation sequence of theoretical simulations and vibration tests is introduced, as well as the method of using input parameters in each step. In addition, the damping mistuning identifications of a numerical case and an actual case are carried out to verify the feasibility of the developed algorithm and the identification procedure.
       
  • Efficient automated extraction of local defect resonance parameters in
           fiber reinforced polymers using data compression and iterative amplitude
           thresholding
    • Abstract: Publication date: Available online 16 September 2019Source: Journal of Sound and VibrationAuthor(s): Joost Segers, Saeid Hedayatrasa, Erik Verboven, Gaétan Poelman, Wim Van Paepegem, Mathias Kersemans Local defect resonance (LDR) employs a specific high frequency, the LDR frequency, to get a localized strong resonant activation of the defect. However, one of the major difficulties for applying LDR as a non-destructive testing technique, is the proper identification of the required LDR frequency, and the subsequent LDR localization.In this study, post-processing methods in both time and frequency domain are applied to low-power broadband vibration data in view of automated extraction of LDR parameters, i.e. LDR frequency and LDR location. In order to reduce the computational effort for large datasets (>1 GB), various data compression methods have been considered: power spectral density (PSD), principal component analysis (PCA) and operational modal analysis (OMA). The actual LDR parameter extraction from the (compressed) data is based on an iterative procedure to threshold the vibrational amplitudes. The LDR parameter extraction procedure is demonstrated on different carbon fiber reinforced polymers with various defect types: flat bottom holes, inserts and low velocity impact damage. It is further demonstrated that the procedure can equally handle multiple defects. A comparison of the performance of the various data compression methods is provided.
       
  • Structural vibrations and acoustic radiation of
           blade–shafting–shell coupled system
    • Abstract: Publication date: Available online 16 September 2019Source: Journal of Sound and VibrationAuthor(s): Yang Liu, Jiyuan Han, Zengyuan Xue, Ye Zhang, Qiang Yang Structural vibrations and radiation noise are common problems in the blade–shafting–shell coupled system. To research this problem, a coupled system consisting of a five-leaf blade, shaft, bearing, and shell was established using a dynamic equilibrium equation. To describe the dynamic behaviour, a blade excitation force model consisting of transverse and vertical excitation forces generated by the blade was established using a quasi-steady method. It was found that the transverse excitation force resulted in more complex frequency components than the vertical excitation force. The frequency components of the blade frequency doubling (2.5fr) and the blade frequency (5fr) in the spectrogram were mainly produced by the transverse excitation force (where fr is the rotational frequency of the shafting). In addition, in the acoustic analysis section of this paper, a finite element model of the coupled system was established. Blade excitation forces were applied to the model, and the vibrational response data of the coupling model's nodes were obtained. Using the acoustic boundary element method, the coupled system's acoustic response was calculated from the surface node vibration velocity data of the coupling model. The effects of the transverse and vertical excitation forces on the acoustic radiation of the coupled system were considered. Finally, dynamic and acoustic experiments of the blade–shafting–shell coupled system were conducted. The results verified the accuracy of the simulation model.Graphical abstractThe boundary conditions of the finite element model and the analytical model was determined by the experiment. The excitation force applied to the finite element model is calculated by the analytical model. Then calculate the vibration velocity of housing's surface nodes. Then the acoustic boundary element method was used to analysis the acoustic response of the system. At last, the accuracy of the simulation model was verified respectively by the dynamics and acoustic experiments of the blade-shafting-shell coupled system.Image 1
       
  • Observation and diagnosis of chaos in nonlinear acoustic waves using
           phase-space domain
    • Abstract: Publication date: Available online 14 September 2019Source: Journal of Sound and VibrationAuthor(s): Sina Zamen, Ehsan Dehghan-Niri Thorough understanding of complex nonlinear behavior of ultrasound wave propagation is a challenging task in concrete. Concrete is an inhomogeneous brittle composite material that is susceptible to several physical and chemical processes that induce micro-cracks. There are numerous methods in time and frequency domains to analyze ultrasound nonlinearities in concrete material. However, existing literature of complex nonlinear dynamical systems expose the limitation of time and frequency domains as unreliable mathematical methods for revealing the complete state and behavior of a nonlinear systems. This study considers a mathematical framework for analyzing the behavior of ultrasonic waves’ nonlinearities due to load-induced cracks with loaded interfaces in concrete materials. The proposed framework uses phase-space domain that is essential in chaos analysis, which is the main contribution of the following article. To verify chaotic behavior, three mathematical tools are exploited. First, Poincaré map is used to verify aperiodic behavior of ultrasonic waves in phase-space domain. Next, Recurrence plot as well as recurrence quantification analysis are performed to verify deterministic behavior of ultrasound waves. Finally, Maximal Lyapunov exponent is leveraged as a factor to verify sensitivity of trajectories of phase-space portraits to initial conditions. For the first time, chaotic behavior of ultrasonic waves due to loaded induced cracks is verified.Furthermore, phase-space analysis highlights the limitations of current nonlinear models, which are based on nonlinear differential equations, to accurately represent all observed responses in a phase-space domain. It is also shown that nonlinear model classification can be substantially enhanced in phase-space domain. It is concluded that phase-space domain analysis of ultrasound waves is a powerful method to reveal complex nonlinear behavior, and consequently, to discover new mathematical models to improve the inability of existing models, based on time and frequency domains, to reveal complex acoustic nonlinearities such as chaos.
       
  • Hybrid numerical model for acoustic propagation through sheared flows
    • Abstract: Publication date: Available online 14 September 2019Source: Journal of Sound and VibrationAuthor(s): Karim Hamiche, Sophie Le Bras, Gwénaël Gabard, Hadrien Bériot Simulating the propagation of sound in non-uniform flows remains challenging, especially for large, three-dimensional problems. To account for the sound refraction due to gradients of velocity and temperature, one has to solve the Linearised Euler Equations (LEE) which can be computationally expensive in three dimensions. Alternatively, one can use the Linearised Potential Equation (LPE) which is much cheaper but is limited to potential, isentropic flows. In this paper, a hybrid model combining the LEE and the LPE is proposed in order to simulate the sound propagation in sheared flows at a reasonable computational cost. The LEE are applied only in regions with strong sheared mean flows, the LPE is used everywhere else. The coupling between the LEE and the LPE consists in imposing relations for the characteristic waves propagating at the interface between the LEE and the LPE regions. In this study, the hybrid model is implemented in a high-order finite element solver in the frequency domain. Its performance is first assessed by simulating the propagation of planes waves in a uniform mean flow and the acoustic radiation from a semi-infinite duct in a strongly sheared non-isothermal jet flow. No significant spurious noise is produced at the LEE-LPE interfaces. The applicability of the hybrid model to industrial problems is then demonstrated by simulating the propagation of fan noise through the jet flow exiting from a turbofan exhaust. The use of the proposed hybrid model does not affect the propagation of the sound field while reducing the memory footprint by more than one order of magnitude compared to a full three-dimensional LEE simulation.Graphical abstractImage 1
       
  • Simulation of wheel–rail impact load and sleeper–ballast contact
           pressure in railway crossings using a Green's function approach
    • Abstract: Publication date: Available online 13 September 2019Source: Journal of Sound and VibrationAuthor(s): X. Li, J.C.O. Nielsen, P.T. Torstensson A method for the simulation of dynamic vehicle–track interaction and evaluation of measures to improve the design of railway crossings is presented. To accurately represent the high-frequency dynamics and non-linear contact conditions of the vehicle–track system, the vertical interaction between a wheelset and the crossing is simulated in the time domain using a Green's function approach based on extensive finite element models of track and wheelset in combination with an implementation of Kalker's variational method to solve the non-Hertzian, and potentially multiple, wheel–rail contact. Both wheels of the wheelset in simultaneous contact with the crossing rail and the outer rail are considered. Rigid and flexible wheelset models are compared. The sampled contact geometry of the crossing, including the discrete irregularity between the wing rail and the crossing nose, is used to determine a three-dimensional surface geometry between each pair of adjacent rail cross-sections. A parameter study is performed to investigate the influence of crossing design on the maximum vertical wheel–rail contact force and the contact pressure generated at the sleeper–ballast interface. It is concluded that a design with a combination of increased sleeper width, softer rail pads and implementation of under sleeper pads (USP) will reduce the track stiffness gradients in the crossing panel and mitigate the risk of differential track settlement by lowering the sleeper–ballast contact pressure.
       
  • Forced acoustic analysis and energy distribution for a theoretical model
           of coupled rooms with a transparent opening
    • Abstract: Publication date: Available online 13 September 2019Source: Journal of Sound and VibrationAuthor(s): Shuangxia Shi, Kongchao Liu, Bin Xiao, Guoyong Jin, Zhigang Liu This study presents a forced acoustic analysis and investigation of the energy distribution of a theoretical model of coupled rooms with a transparent coupling aperture. The energy principle is employed in combination with a 3D modified Fourier cosine series approach to formulate the theoretical model. The sound pressures inside individual subrooms are expanded as 3D Fourier cosine series supplemented with auxiliary functions, which are introduced to ensure the uniform convergence of the solution over the entire solution domain. Both the energy transmission through the coupling interface and the work done by the external load are considered as the external work in the energy expressions for the coupled system. The theoretical results are verified using the experimental results obtained for the room with a transparent opening. The influences of the coupling aperture and boundary conditions on the acoustic behaviors and energy distribution inside the coupled room system are investigated, including: opening positions, opening size, and impedance boundaries.
       
  • Study of damped vibrations of a vibroacoustic interior problem with
           viscoelastic sandwich structure using a High Order Newton solver
    • Abstract: Publication date: Available online 13 September 2019Source: Journal of Sound and VibrationAuthor(s): B. Claude, L. Duigou, G. Girault, J.M. Cadou The aim of this study is to compute damped eigenfrequencies and modes of a vibroacoustic interior problem with fluid-structure coupling. Damping is introduced using a sandwich structure with viscoelastic core. In this paper, the coupled problem is solved by a High Order Newton (HON) solver, based on homotopy and perturbation techniques. Thus, the initial non-linear problem is turned into a set of linear algebraic systems, easier to solve. Comparison of the results obtained by the HON solver with those obtained by the Newton classical method highlights the efficiency of the proposed method. Finally, the mechanical behavior of the coupled damped problem is studied.
       
  • Deformation study of an in-plane oscillating dielectric elastomer actuator
           having complex modes
    • Abstract: Publication date: Available online 12 September 2019Source: Journal of Sound and VibrationAuthor(s): Kun Jia, Tongqing Lu, Tiejun Wang Due to the deformation ability over a wide frequency range, dielectric elastomer actuators (DEAs) under an alternating electric load have received increasing attention. In the theoretical analysis of an in-plane oscillating DEA (edge clamped membrane without a pressure load), the assumption of homogeneous deformation is applied, which conflicts with the observed non-uniform deformation under a combination of pressure and voltage load. To validate the simplification, experimental and theoretical studies of a circular DEA under alternating voltage are reported here. A laser Doppler vibrometer is used to acquire the full-field oscillating response of the DEA fabricated by commercial VHB4905 with hydrogel electrodes. The measured amplitude and phase illustrate that the assumption of homogeneous deformation only works at low frequencies, whereas the non-uniform deformation dominates the oscillation with the increase of excitation frequency. In addition, the in-plane oscillating DEA behaves as a complex mode system. Accordingly, the motion equation is proposed by considering the general viscous damping effect. The experimentally observed transition (from uniform to non-uniform deformation) is analyzed numerically. The normalized upper frequency, under which the deformation field can be treated as uniform, is also obtained based on full-wave simulations.
       
  • Longitudinal wave propagation in one-dimensional waveguides with
           sinusoidally varying depth
    • Abstract: Publication date: Available online 11 September 2019Source: Journal of Sound and VibrationAuthor(s): S. Gopalakrishnan, Manish Suresh Raut In this paper, longitudinal elastic wave propagation in one-dimensional waveguides with sinusoidally varying depth is investigated. Furthermore, different types of such waveguide designs are explored to understand their capability to attenuate the group speeds as well as the velocity amplitudes. The plane waveguide configurations with sinusoidally varying depth, of three types, namely Convex, Concave and Full, along with their combinations and variants, whose segmental depth along the length of the waveguide is modeled by a sine function having an amplitude parameter α and the half-period p, which leads to a governing differential equation with variable coefficients, are considered in this study. To study the longitudinal wave propagation in these inhomogenous waveguides, a novel superconvergent finite element formulation is developed, which gives an exact stiffness matrix. In addition to the wave propagation analysis, static and free vibration behaviors in these waveguides are also studied. The implemented superconvergent finite element formulation for these studies is validated with the commercial finite element software Abaqus. In the first part of the wave propagation analysis, abilities of the three plane waveguide configurations with sinusoidally varying depth to attenuate high amplitude and frequency waves are investigated for different values of α. Next, four different waveguides composed of Convex-Concave combinations are studied with an aim to get better attenuation. Following this, the waveguides' segmental parameters, α and p, are varied across the segments along the length of the waveguide, using a sine function and polynomial power law to see if such graded variations give better energy absorption properties compared to the plane waveguides whose parameters are unvarying. In the last part, a developed inhomogenous rod of a certain length is inserted in the middle of a uniform waveguide to study the possibility of changing the longitudinal wave propagation characteristics of the uniform waveguide. The results from the analyses show that the group speed and amplitude of the longitudinal wave in these configurations change significantly with space as well as with frequencies, especially for high values of α. The Concave and Full waveguides delay the propagation of longitudinal waves significantly, which translates into the reflected waves appearing later in the chosen large time window. The Convex waveguide and its variants reduce the wave amplitudes significantly. Building on these results, some waveguides with notable attenuation characteristics are proposed.
       
  • Influence of structural modifications of automotive brake systems for
           squeal events with kriging meta-modelling method
    • Abstract: Publication date: Available online 10 September 2019Source: Journal of Sound and VibrationAuthor(s): E. Denimal, J.-J. Sinou, S. Nacivet Squeal noise is an important issue in the automotive industry since it is one of the main reasons for the return of vehicles to the customer service. Hence, it is essential to predict it in the design stage of a brake system. The Complex Eigenvalue Analysis (CEA) remains the most widely used method to predict squeal noise in the automotive industry. The numerical cost associated to this method is important enough to make impossible the use of parametric studies. The present study proposes the use of the kriging method to surrogate the eigenvalues computed by the CEA by taking into consideration different uncertain parameters, namely the friction coefficient and two small masses added to the caliper that correspond to a classical choice of structural modifications used in the final phase of a brake design to avoid squeal noise. Thus, it is possible to assess the influence of the structural modifications on the stability of the brake system and to get information to choose the best brake design. Finally, uncertainty propagation is performed to get a robust design of the brake.
       
  • Numerical analysis on thermoacoustic prime mover
    • Abstract: Publication date: Available online 9 September 2019Source: Journal of Sound and VibrationAuthor(s): Dongwei Zhang, Erhui Jiang, Chao Shen, Junjie Zhou, Weiwei Yang, Yaling He A two-dimensional numerical model based on compressible SIMPLE algorithm was developed to simulate the evolution process of self-excited oscillation in a thermoacoustic engine at two different heating conditions. Moreover, the performance analysis of the thermoacoustic engine was researched. On one hand, the influence of stack parameters and charge pressure on the onset temperature of self-excited thermoacoustic oscillation was exhibited and analyzed. On the other hand, the impact of different gas types on the onset temperature difference was investigated. The results indicated that the self-excited thermoacoustic oscillation happened with the same performance for both two heating conditions. The minimum onset temperature difference can be achieved when the dimensionless stack length and position are Lr = 0.055–0.06 and Xr = 0.14–0.16, respectively. For a detail, the optimal stack plate thickness is 33% of the stack channel width when the computational width is 3 times as large as the thermal penetration depth of the working gas. Furthermore, the onset temperature difference increased with the increasing of the charge pressure in prime mover. For different working gas, the onset temperature difference was the highest for argon, which was followed by helium and nitrogen. Finally, the performance was improved with the increase of the temperature difference between the two exchangers in the prime mover.
       
  • Passive control of nonlinear aeroelasticity in hypersonic 3-D wing with a
           nonlinear energy sink
    • Abstract: Publication date: Available online 8 September 2019Source: Journal of Sound and VibrationAuthor(s): Wei Tian, Yueming Li, Ping Li, Zhichun Yang, Tian Zhao Nonlinear aeroelastic behaviors of a three-dimensional (3-D) trapezoidal wing coupled with a nonlinear energy sink (NES) in hypersonic flow are investigated. A NES is used to suppress the wing flutter and mitigate the aeroelastic responses. Based on the von Karman large deformation theory and the third-order piston theory, the nonlinear aeroelastic governing equations of trapezoidal wing-like plate with a NES are built by using the Rayleigh-Ritz approach combined with the affine transformation. The energy transfer mechanism of NES is analyzed by an energy-based approach. The comparisons of bifurcation diagrams between the trapezoidal wing-like plates without and with NES show that the NES has a stabilizing effect on the system in the pre-flutter regime and enhances the flutter boundary. The NES can absorb and dissipate the energy provided by the airflow though resonance capture, and the nonlinear responses of the wing-like plate can be suppressed completely in the post-flutter regime. However, the passive control performance of the NES degrades for a higher dynamic pressure, and the NES is even no longer capable of mitigating aeroelastic responses especially for chaotic motions. Furthermore, a parametric design is conducted to evaluate the influences of the NES's parameters on its performance. The results reveal that the NES-based structure design has good effectiveness for delaying the onset of wing flutter and reducing vibration amplitude.
       
  • Parameters optimization and performance evaluation for the novel
           inerter-based dynamic vibration absorbers with negative stiffness
    • Abstract: Publication date: Available online 8 September 2019Source: Journal of Sound and VibrationAuthor(s): Xiaoran Wang, Tian He, Yongjun Shen, Yingchun Shan, Xiandong Liu In order to enhance the performance of dynamic vibration absorber (DVA), inerter-based DVA and DVA with negative stiffness have received considerable attention in structural vibration reduction. However, the characteristic of DVA which includes inerter and negative stiffness concurrently remains unclear. In this paper, four kinds of novel inerter-based dynamic vibration absorber with negative stiffness (IN-DVAs) are proposed and analytically researched in detail. The closed-form optimal parameters of four kinds of IN-DVAs are obtained based on the classical fixed-points theory. Analysis of the optimal parameters of the IN-DVAs demonstrates that the coupling relationships between inerter and negative stiffness are distinct for various structural forms of the IN-DVAs. The comparison of the performances of IN-DVAs with those of the existing DVAs shows that IN-DVAs have superior performance. Besides, the effective frequency bandwidth is wider than those of the existing DVAs. Moreover, the results also exhibit that RIN (one of the IN-DVAs in this paper) performs the best under harmonic and random excitations.
       
  • Interval and subinterval perturbation finite element-boundary element
           method for low-frequency uncertain analysis of structural-acoustic systems
           
    • Abstract: Publication date: Available online 7 September 2019Source: Journal of Sound and VibrationAuthor(s): F. Wu, M.Q. Gong, J. Ji, G.L. Peng, L.Y. Yao, Y.L. Li, W. Zeng Uncertainties exist widely in the structural-acoustic systems, due to the physical imperfections, model inaccuracies and system complexities. To deal with the uncertainties, the interval perturbation and subinterval perturbation techniques, for the first time, are extended and integrated into the hybrid finite element-boundary element method (IPFEM/BEM) in this work. Firstly, the structural part of structural-acoustic systems is modeled using finite element method (FEM) and acoustic cavity is modeled by boundary element method (BEM). Then the interval perturbation technique is introduced to establish the interval perturbation equations of the system. For large uncertainty levels, the interval of parameters is divided into smaller sub-intervals to improve the accuracy of proposed IPFEM/BEM (sub-interval perturbation finite element-boundary element method, SIPFEM/BEM). The proposed IPFEM/BEM and SIPFEM/BEM are verified by two numerical examples. The results obtained by IPFEM/BEM, SIPFEM/BEM and Monte-Carlo method are compared. It is found that IPFEM/BEM and SIPFEM/BEM is reliable for the frequency response analysis of structural-acoustic systems with small or large uncertain levels.
       
  • A group sparse representation method in frequency domain with adaptive
           parameters optimization of detecting incipient rolling bearing fault
    • Abstract: Publication date: Available online 5 September 2019Source: Journal of Sound and VibrationAuthor(s): Kai Zheng, Dewei Yang, Bin Zhang, Jingfeng Xiong, Jiufei Luo, Yanfang Dong The periodic impulses are the most important signatures of rolling bearing failure, which are often buried by excessive background noise. It is challenging to extract the incipient periodic impulses in the vibration fault signal. In this paper, we propose a group sparse representation denoising method in frequency domain of extracting the incipient periodic impulses for rolling bearings fault diagnosis. First, we reveal the sparsity within and across groups (SWAG) property of the bearing fault signal in frequency domain. Afterwards, a penalty function promoting SWAG is employed to construct the denoising model in frequency domain. To achieve better feature extraction results, a guided periodic information index is proposed to construct the objective function of Moth-Flame optimization (MFO) algorithm for adaptively optimizing regularization parameters of the proposed denoising model. Lastly, simulation and experimental results indicate that the proposed method can accurately maintain the weak fault feature while suppressing the noise effectively. Compared with other state-of-art methods, the proposed method shows better performance of extracting the incipient fault feature of rolling bearings.
       
  • Nonlinear dispersion relation in anharmonic periodic mass-spring and
           mass-in-mass systems
    • Abstract: Publication date: Available online 3 September 2019Source: Journal of Sound and VibrationAuthor(s): R. Zivieri, F. Garescì, B. Azzerboni, M. Chiappini, G. Finocchio The study of wave propagation in chains of anharmonic periodic systems is of fundamental importance to understand the response of dynamical absorbers of vibrations and acoustic metamaterials working in the nonlinear regime. Here, we derive an analytical nonlinear dispersion relation for periodic chains of anharmonic mass-spring and mass-in-mass systems resulting from considering the hypothesis of factorization for the spatial and temporal parts of the solution and a periodic distribution function as ansatz of a general solution of the temporal part of the nonlinear equations of motion. A comparison with numerical simulations shows the range of validity of this expression. This work provides a tool to design and study nonlinear dynamics for some classes of seismic metamaterials such as composite foundations, perturbative metamaterials, and metasurfaces.
       
  • Robust two-scale command shaping for residual vibration mitigation in
           nonlinear systems
    • Abstract: Publication date: Available online 31 August 2019Source: Journal of Sound and VibrationAuthor(s): J. Justin Wilbanks, Michael J. Leamy This paper develops robust two-scale command shaping (TSCS) for vibration mitigation in nonlinear systems. Recursive least-squares (RLS) and extended Kalman filtering (EKF) approaches are used to estimate uncertain system parameters alongside robust command shaping methods to decrease the impact of vibration mode variations on TSCS efficacy. For full implementation, the TSCS strategy requires input parameters to characterize the nonlinear system for which it is being applied, which may be a) difficult to quantify, and/or b) uncertain due to their dependence on environmental considerations or operating conditions. To alleviate these issues a parameter estimation technique can be used to help define these required input parameters. Additionally, robust command shaping methods can be leveraged to decrease the impact of variations in system vibration modes on the efficacy of the command shaping portion of TSCS. A motivating problem for adding robustness to TSCS is the mitigation of vibration-related issues during internal combustion engine (ICE) restart. TSCS applied to engine restart is used as an example to develop the techniques to add robustness to the strategy. It is shown that both the RLS and EKF algorithms can be used to estimate the necessary ICE parameters and increase effectiveness of the TSCS strategy. Robust command shaping is then used to reduce the effect of variations in the chassis and powertrain vibration modes on the efficacy of TSCS during ICE restart.
       
  • Improving material damping characterization of a laminated plate
    • Abstract: Publication date: Available online 31 August 2019Source: Journal of Sound and VibrationAuthor(s): M. Wesolowski, E. Barkanov Laminated composite structures have considerably higher ability for the vibration damping than structures made of conventional materials. On the other hand the prediction of damping of composite structures is not straightforward due to their anisotropic behaviour. The anisotropic nature of composites brings the need for the accurate measurement of the damping parameters which are used for the prediction of the dynamic response. The present study concerns with the effectiveness and efficiency improvements of the inverse technique used for the identification of material damping coefficients of a laminated plate. The evaluated identification method combines numerical and experimental analyses. The effectiveness improvement of the method is realized by application of a vacuum chamber for dynamic tests in order to reduce the influence of the air damping on the identified damping coefficients. The efficiency improvement of the method is gained by proper definition of the minimization process with the use of the experiment design, the response surface methodology, and the strain energy approach for damping modelling. The Finite Element Modelling is realized using ABAQUS software and the minimization problem is defined using Isight environment.Graphical abstractImage 1
       
  • Direct method for second-order sensitivity analysis of modal strain energy
    • Abstract: Publication date: Available online 31 August 2019Source: Journal of Sound and VibrationAuthor(s): Sheng Lei, Li Li, Wei Tian, Min Lei This paper proposed a Lagrange-based method for calculation of the second-order sensitivity of modal strain energy (MSE) values. According to scheme of the direct method, a Lagrange functional of the element MSE, which added the eigenproblem and the normalization augmented by Lagrange multipliers as constraints, is constructed firstly. After that, the Lagrange multipliers can be decided by setting variations of the Lagrange functional with respect to state variables to zeros. And then, the sensitivity of MSE can be yielded by derivative of the Lagrange functional easily. The accuracy of the new method and the affection of normalization criterion are verified by the numerical instances of a simply supported beam and a truss structure. A portal frame is employed to testify the prediction ability of both the first-order and the second-order sensitivities of MSE values. As the numerical example of the portal frame shows, the computation complexity of the new method can be reduced significantly in comparison of indirect methods at similar accuracy.
       
  • Visualization of travelling waves propagating in a plate equipped with 2D
           ABH using wide-field holographic vibrometry
    • Abstract: Publication date: Available online 29 August 2019Source: Journal of Sound and VibrationAuthor(s): Laure Lagny, Mathieu Secail-Geraud, Julien LE. Meur, Silvio Montresor, Kevin Heggarty, Charles Pezerat, Pascal Picart This paper presents a method for wide-field vibrometry based on high-speed digital holographic interferometry. We demonstrate the possibility of measuring transient vibrations of structures at 100 kHz frame rate when providing 46600 quantitative data on 380 cm2 rectangular spot at the object surface. Investigation of travelling acoustic waves propagating in alloy plate equipped with a two-dimensional acoustic black hole (ABH) is considered. Such a structure leads to localized vibrations of high amplitude and constitutes a good candidate for methodology testing. The wave front is generated by a short shock with duration about 50 μs' The time sequence of the vibration field obtained after the shock is depicted and exhibits the propagation of the wave front in the plate and inside the ABH. It follows that the observation of the modification of the wave propagation can be observed at very short time scale. The modification of the wave front due to the gradient in elastic properties related to the ABH area is also highlighted.
       
  • Vibrations, 3rd edition, Balakumar Balachandran, Edward B. Magrab. (2019)
    • Abstract: Publication date: 24 November 2019Source: Journal of Sound and Vibration, Volume 461Author(s): Emiliano Rustighi
       
  • On the acoustic optimality of leading-edge serration profiles
    • Abstract: Publication date: Available online 29 August 2019Source: Journal of Sound and VibrationAuthor(s): Benshuai Lyu, Lorna J. Ayton, Paruchuri Chaitanya Leading-edge serrations are studied extensively as a way of reducing leading-edge noise and have been shown to be able to reduce leading-edge noise significantly. Previous experiments showed that different serration geometries have different noise reduction capabilities. However, the optimal serration geometry has not been known. Consequently, there are no guides that can be used at the design stage of serrations. In this paper, by performing an asymptotic analysis, we show that in order to achieve greater noise reduction in the high frequency regime (k1h ≫ 1, where k1 denotes the streamwise hydrodynamic wavenumber and h half of the root-to-tip amplitude of serrations), the serration profile cannot have stationary points. Therefore, piecewise smooth profiles free of stationary points are more desirable. Moreover, we show that greater noise can be achieved in the high frequency regime by using serrations that are sharper around the non-smooth points. The underlying physical mechanisms of these findings are discussed. Based on these findings, a new type of serration profile is proposed, and analytical model evaluations confirm its improved acoustic performance in the frequency range of interest. At low frequencies, a slight deterioration may be expected, but this is often negligible. To verify the conclusion drawn from the analysis, we perform an experimental study to investigate the acoustic performance of this new serration design. The results show that it is indeed superior than conventional sawtooth serrations. For example, a remarkable 7 dB additional noise reduction is observed in the intermediate frequency range with no perceivable noise increase elsewhere. The trends predicted by the analysis are well validated by the experiment. It is expected that these findings can serve as an essential guide for designing serrations, and lead to more acoustically optimized serration geometries.
       
  • Nonlinear dynamics of directional drilling with fluid and borehole
           interactions
    • Abstract: Publication date: Available online 29 August 2019Source: Journal of Sound and VibrationAuthor(s): Quang-Thinh Tran, Khac-Long Nguyen, Lionel Manin, Marie-Ange Andrianoely, Régis Dufour, Mohamed Mahjoub, Stéphane Menand In rotary drilling, a drillstring is an assembly of slender pipes. It is used to transmit the driving torque of a motor at the drilling surface to the drill bit at the bottom hole of a 3D well. Numerous vibratory phenomena are induced during the drilling: whirling, stick-slip, bit-bouncing, lateral instability, inducing in particular reduction of the rate of penetration and mean time between failures. For the rotordynamics prediction of such a structure, the drillpipes are modelled with Timoshenko beam elements, containing 12° of freedom, equipped with distributed radial stop-ends. The rotary motion is assumed to have a constant speed of rotation imposed at the top of the drillstring. The drilling mud is taken into account by using a fluid-structure interaction model. The numerical simulations concern a real 3D-borehole and a parametric analysis is carried out for determining the role of the mud density and of the flows rate on the drillstring dynamics. It is shown that increasing the flow rate and densifying the drilling fluid reduce the fluid damping effect that increases drillstring lateral vibrations.
       
  • An augmented free-interface-based modal substructuring for nonlinear
           structural dynamics including interface reduction
    • Abstract: Publication date: Available online 26 August 2019Source: Journal of Sound and VibrationAuthor(s): Morteza Karamooz Mahdiabadi, Andreas Bartl, Duo Xu, Paolo Tiso, Daniel Jean Rixen This work proposes two novel aspects for modal substructuring of geometrical nonlinear structural dynamics. Firstly, we present a non-intrusive model order reduction technique for substructures using an augmented free-interface method with residual flexibility attachment modes. Non-intrusive model reduction methods are beneficial, because they do not require to access substructures' closed form equations of motion while building nonlinear reduced models. Therefore, they can be easily combined with commercial finite element packages. Generally, the interface of substructures can contain many degrees-of-freedom leading to reduced order models, which are still computationally expensive. As a second novel point, the nonlinear reduced models of substructures are developed when the augmented free-interface-based method is combined with three interface reduction techniques (one system-level and two local-level), which so far have only been used with the fixed-interface method of Hurty/Craig-Bampton. The proposed methods are compared in terms of accuracy and computational efficiency with the two existing non-intrusive-based modal substructuring methods: nonlinear free-interface and nonlinear Hurty/Craig-Bampton methods. The performance of the improved free-interface method is examined on two different geometrically nonlinear structures by applying random pressure on them and comparing displacement spectral densities. The dynamic results show a remarkable improvement of accuracy compared to the nonlinear free-interface method and a slightly improved accuracy compared to the nonlinear Hurty/Craig-Bampton method. This improvement is achieved while the online computational costs are not increased significantly.
       
  • Effect of symmetrical broken wires damage on mechanical characteristics of
           stay cable
    • Abstract: Publication date: Available online 24 August 2019Source: Journal of Sound and VibrationAuthor(s): Jun Xu, Huahuai Sun, Shunyao Cai Broken wires are a common damage in stay cables due to aging and harsh environment. However, the analytical method to study the effect of broken wires on the mechanical characteristics of stay cables is still limited. Therefore, based on the microstructural mechanical model of damaged multi-wire cable, this paper proposes an analytical method for the static and dynamic characteristics of cables with broken wires. The broken wire damage is equalised to the axial stiffness reduction in the end-sliding region and recovery region of the broken wire. Governing equations for static configuration and in-plane free vibration of damaged multi-wire cable are then established. Cables with different physical parameters are studied to research the effect of broken wire damage on the static and dynamic characteristics. The results reveal that an increase in the number of symmetrical broken wires linearly decreases the horizontal component of cable tension in piecewise, linearly increases the sag and decreases the in-plane natural vibration frequency in piecewise. Besides, the cable sag is sensitive to the location of broken wire damage, while the horizontal component of cable tension and natural frequency are not sensitive to the location of the broken wire damage. Under the same broken wire damage, the closer the damage is to the support, the greater the sag is. When the broken wire percentage reaches 18.9% at the mid-span, the relative reduction in horizontal component of cable tension is 1.7%, the relative increase in sag is 1.7% and the relative decrease in the in-plane natural vibration frequency is about 0.85% for 100 m long cable. Meanwhile, broken wire damage hardly alters the static characteristics of the initial slack cable with an aspect ratio greater than 1.002. However, the effect of the broken wire on the static characteristics of the initial taut cable nonlinearly increases with a decreasing aspect ratio. Moreover, the effect of broken wire damage on this cable's static characteristics nonlinearly decreases when the cable length increases. Hence, broken wire damage remarkably influences the static characteristics of short cable.
       
  • Compensation of inherent bias errors in using the three-dimensional
           acoustic intensimetry for sound source localization
    • Abstract: Publication date: Available online 24 August 2019Source: Journal of Sound and VibrationAuthor(s): In-Jee Jung, Jeong-Guon Ih The three-dimensional acoustic intensimetry has not been found useful for the sound source localization, although it was developed a long time ago. One of the leading causes is the significant amount of inherent bias error in the measured intensity vector. In addition to the well-known phase mismatch and finite difference errors, the two crucial bias error mechanisms exist yet. Both of them are principally caused by employing the limited number of microphones in estimating the direction-of-arrival vector. One is the spectral bias error exhibiting a significant fluctuation in the intensity spectrum, which is due to the time-delay of the incident and reflected sounds travelling between microphones. The other is the spatial bias error exhibiting the intensity variation depending on the probe orientation, which is due to the spatial inhomogeneity of the microphone distribution. In this work, two parameters are considered in the compensation of spectral bias error: the phase of cross-spectrum and the time contents of cross-correlation function. Also, an error map associated with the incident direction of sound is calculated for a sphere surrounding the probe to compensate for the spatial bias error. Experiments are conducted with two different source types emitting a band-limited noise and an impulsive sound, and also varying the source positions to investigate the effect of main parameters. A tetrahedral intensity probe consisted of 4 pressure microphones with 30-mm spacing is used for the test in a reverberant space. The result shows that the mean localization error is less than 3° for 0.3 
       
  • Mode matching to enhance nonlinear response of local defect resonance
    • Abstract: Publication date: Available online 24 August 2019Source: Journal of Sound and VibrationAuthor(s): Igor Solodov, Marc Kreutzbruck Activation of mechanical resonance in localized inclusions and defects enables to route the input acoustic energy directly to the defect that dramatically increases its vibration amplitude and shifts into nonlinear regime. The higher harmonics generated in such a nonlinear resonator excited at a fundamental mode are, however, not matched to the higher-order resonances that prevents full development of the maximal higher harmonic response of the resonator. In the experiments, the nonlinear resonant response is studied for a simulated defect of a circular flat-bottomed hole in a Plexiglas plate. Conventional second and third higher harmonic responses for excitation at the fundamental resonance frequency are measured and used to evaluate background nonlinearity parameters of the resonator. An increase by orders of magnitude in these parameters is then obtained as the excitation frequencies are changed in order the second and third harmonics match the higher-order resonances. A similar result is also obtained for a subharmonic excitation: the second harmonic in this case always matches the fundamental resonance frequency and thus manifests the maximum efficiency.
       
  • A spectral collocation method for acoustic scattering by multiple elastic
           plates
    • Abstract: Publication date: Available online 23 August 2019Source: Journal of Sound and VibrationAuthor(s): Matthew J. Colbrook, Lorna J. Ayton This paper presents a new approach to solving acoustic scattering problems: the Unified Transform method. This spectral, boundary-based collocation method can be readily applied to acoustic scattering by disjoint two-dimensional structures, and, for the purposes of this paper, is illustrated in the case of multiple flat plates, which also addresses the additional difficulty of mathematical singularities in the scattered field due to diffraction at sharp edges. Fluid-structure interaction may also be incorporated into the method, such as plate elasticity, which when applied to aerofoil trailing edges, is known to reduce aerodynamic noise. While a range of examples are illustrated to show the versatility of the method, attention is in particular given to the scattering of quadrupole sources by rigid plates with finite elastic extensions. It is seen that whilst a fully elastic plate is most beneficial acoustically, plates with only small extensions can considerably reduce the far-field sound power versus a fully rigid plate.
       
  • An analytical method for dynamic analysis of a ball bearing with offset
           and bias local defects in the outer race
    • Abstract: Publication date: Available online 23 August 2019Source: Journal of Sound and VibrationAuthor(s): Jing Liu, Zidan Xu, Yajun Xu, Xihui Liang, Ruikun Pang Ball bearings are the critical essential bodies in different industrial machinery. An in-depth recognition of the vibrations of defective ball bearings can be useful for the progress of defect detection approaches of the machinery. In this paper, an improved time dependent displacement excitation (TDDE) model is proposed to consider the parallel, offset or bias local defects in the outer race of ball bearing. The contact relationship between the parallel defect and ball, that between the offset defect and ball, and that between the bias defect and ball are deeply analyzed. The TDDE model for the parallel, offset, and bias defect cases is established by using a piecewise function model including the rectangular and half-sine functions. A dynamic model in the previous study is improved to consider the effects of the offset and bias local defects. The Hertzian contact theory is adopted to calculate the bearing contact stiffness. The effects of defect sizes, defect offset distance, and defect bias angle on the vibrations of a ball bearing are analyzed. Comparison results among the parallel, offset, and bias defect cases show the advantage of established method in this study. The obtained results show that the given method can provide a more accurate and reasonable analytical method for studying the vibrations of ball bearing with a local offset defect.
       
  • Effect of trailing-edge boundary conditions on acoustic feedback loops in
           high-pressure turbines
    • Abstract: Publication date: Available online 23 August 2019Source: Journal of Sound and VibrationAuthor(s): R.D. Sandberg, A.P.S. Wheeler The occurrence and sensitivity of acoustic feedback loops was investigated for a linear high-pressure turbine (HPT) vane cascade at realistic operating conditions, i.e. isentropic exit conditions of Re = 570, 000 and M = 0.92. Forced compressible Navier–Stokes simulations were conducted to study the temporal response of various base flows to an initial small-amplitude pulse. One of the objectives was to assess the impact the quality of the base flow has on the instability behaviour, i.e. whether base flows obtained from computationally more affordable approaches such as Reynolds-averaged Navier–Stokes (RANS) produce similar results as those obtained from highly resolved large-eddy simulations (LES). Using base flows obtained from both LES and RANS of a high-pressure turbine vane with no-slip trailing-edge boundary conditions, the temporal pulse response revealed the presence of an unstable acoustic feedback loop, i.e. with amplitude increasing quickly over time. It was also found that the base flows were globally unstable with respect to three-dimensional instabilities, regardless of the perturbation location. However, the stability analysis performed on the RANS generated base flow exhibited much increased growth rates due to the recirculation region downstream of the blade trailing edge featuring a higher reverse velocity.In order to understand the sensitivity of the acoustic feedback loop to modifications of the trailing-edge boundary conditions, additional stability analyses were conducted on base flows obtained from simulations of the same HPT vane configuration with trailing-edge ejection at two different rates. For the base flows with added trailing-edge ejection, the pulse responses did not exhibit pressure waves originating from the trailing edge impinging on the suction side of the adjacent blade. More importantly, although an acoustic feedback loop was also present in these cases, the amplitude decayed over time, thus the flow was stable with regards to two- and three-dimensional disturbances. The results suggest that it is primarily the reduction in reverse flow velocity, or even the full removal of the trailing-edge recirculation region when applying trailing-edge ejection, that is responsible for the suppression of the acoustic feedback loop and the growth of three-dimensional instabilities.
       
  • Influence of uneven loading condition on the sound radiation of starved
           lubricated full ceramic ball bearings
    • Abstract: Publication date: Available online 23 August 2019Source: Journal of Sound and VibrationAuthor(s): H.T. Shi, X.T. Bai, K. Zhang, Y.H. Wu, G.D. Yue The effect of ball diameter difference is quite obvious in full ceramic bearings due to the great stiffness, and leads to the problem of uneven loading in starved lubricated conditions. This paper takes the uneven loading condition into consideration in the dynamic model, and a verification experiment is carried out for the assessment of calculation accuracy. The factors of ball diameter tolerance, the arrangements of balls and the number of balls have impact on the interactions between the inner ring and the loaded balls, and the trends of sound radiation are studied in depth. The amplitude of sound radiation is used to show the interaction between the elements, and uneven loading conditions can be evaluated by the sound directivity. Results show that the tolerance is a key factor that has impact on the sound radiation, and the sound radiation and directivity have obvious change with the ball diameter tolerance. The arrangements of balls have impact on the sound radiation by changing the diameter difference between adjacent balls, and the loaded area of each loaded ball varies with the number of balls. The cases with different numbers of loaded balls are discussed, and the relations between the uneven loading conditions and sound radiation are investigated. This study proposes a method for the study of uneven loading conditions, and provides theoretical basis for the optimal design of full ceramic bearings.
       
  • Control of ground-borne underground railway-induced vibration from
           double-deck tunnel infrastructures by means of dynamic vibration absorbers
           
    • Abstract: Publication date: Available online 23 August 2019Source: Journal of Sound and VibrationAuthor(s): Behshad Noori, Robert Arcos, Arnau Clot, Jordi Romeu The aim of this study is to investigate the efficiency of Dynamic Vibration Absorbers (DVAs) as a vibration abatement solution for railway-induced vibrations in the framework of a double-deck circular railway tunnel infrastructure. A previously developed semi-analytical model of the track-tunnel-ground system is employed to calculate the energy flow resulting from a train pass-by. A methodology for the coupling of a set of longitudinal distributions of DVAs over a railway system is presented as a general approach, as well as its specific application for the case of the double-deck tunnel model. In the basis of this model, a Genetic Algorithm (GA) is used to obtain the optimal parameters of the DVAs to minimize the vibration energy flow radiated upwards by the tunnel. The parameters of the DVAs set to be optimized are the natural frequency, the viscous damping and their positions. The results show that the DVAs would be an effective countermeasure to address railway induced ground-borne vibration as the total energy flow radiated upwards from the tunnel can be reduced by an amount between 5.3 dB and 6.6 dB with optimized DVAs depending on the type of the soil and the train speed.
       
  • Free vibration analysis of a rotating pre-twisted beam subjected to
           tendon-induced axial loading
    • Abstract: Publication date: Available online 23 August 2019Source: Journal of Sound and VibrationAuthor(s): V. Ondra, B. Titurus The main objective of this paper is to investigate free vibration of a rotating pre-twisted beam with bending-bending-torsion coupling that is axially loaded by a tendon. The tendon is connected to the tip of the beam, passes through its body, and is fixed and loaded at the axis of rotation. Due to their connection, the motion of the beam influences the motion of the tendon and vice versa. The equations of motion of the beam-tendon system are introduced and solved numerically by a combination of a boundary value problem solver and differential quadrature method to obtain the natural frequencies and mode shapes of the system. The numerical implementation is firstly validated against literature for a non-rotating beam-tendon system and a rotating pre-twisted blade. Then, the effect of the tendon on the free vibration of the system is studied for a wide range of loading cases and rotation speeds. From the computed modal characteristics, it is found that the presence of a tendon leads to the frequency shift of beam's natural frequencies as well as frequency loci veering between the beam-dominated and tendon-dominated modes. Both of these effects strongly depend on the beam-tendon rotation speed.
       
  • The impact of damping on the sound transmission loss of locally resonant
           metamaterial plates
    • Abstract: Publication date: Available online 23 August 2019Source: Journal of Sound and VibrationAuthor(s): Lucas Van Belle, Claus Claeys, Elke Deckers, Wim Desmet Vibro-acoustic locally resonant metamaterials with structural stop band behaviour can lead to a strongly increased sound transmission loss in a targeted frequency range. This work assesses the impact of damping in the constituents of metamaterial plates on their acoustic insulation performance by means of infinite periodic and finite structure modelling. Besides applying the hybrid Wave Based - Finite Element unit cell method for infinite plates and the Finite Element Method for finite plates, qualitative dispersion curve based predictions are extended to quantitative sound transmission loss approximations by introducing a dispersion curve based equivalent plate method. Both an idealised and a realisable locally resonant metamaterial plate are analysed. Damping in the resonators in particular is found to have an important impact in and around the stop band, reducing the sound transmission loss peak, but improving the subsequent dip and reducing resonant transmission in a broadening frequency range around the stop band. The damping influenced sound transmission loss predictions for the realisable locally resonant metamaterial plate are experimentally validated by means of insertion loss measurements. It is shown that, by including damping in the infinite periodic structure modelling, acoustic insulation performance predictions with improved accuracy are obtained.
       
  • An engineering model for the prediction of the sound radiation from a
           railway track
    • Abstract: Publication date: Available online 22 August 2019Source: Journal of Sound and VibrationAuthor(s): Xianying Zhang, David Thompson, Erika Quaranta, Giacomo Squicciarini Models for predicting railway rolling noise such as TWINS are well-established and have been validated against field measurements. However, there are still some areas where improvements are required. In particular, the radiation from the rail is based on a model of a rail in free space whereas in reality the rail is located close to the ground; there are also limitations in the existing model for the sound radiation from the sleepers. Besides, the influence of the ballast absorption on the sound power radiated by the track is neglected. This paper draws on recent research into the effects of the proximity of the rail and sleeper to an absorptive ground on their sound radiation, based on the boundary element method. In reality, the rail is located above the ballast over part of its length, and attached periodically to the concrete sleepers elsewhere. The sound radiation of the rail for those two situations can be predicted using the 2D boundary element method. In order to obtain a realistic rail radiation model for engineering applications, a method to combine those two results is proposed and the resulting average rail radiation is verified by using a 3D boundary element model. An improved sleeper radiation model is also proposed and verified using the 3D boundary element model. These new engineering models for the rail and sleeper radiation have been used together with TWINS to predict the sound radiation from operational tracks and the results have been compared with field measurements. Compared with the TWINS model, the rail radiation is found to be increased below 300 Hz, but decreased above 1 kHz; the sound radiation from the sleeper is reduced compared with the TWINS model below 600 Hz.
       
  • Broadband low-frequency sound absorption by periodic metamaterial
           resonators embedded in a porous layer
    • Abstract: Publication date: Available online 22 August 2019Source: Journal of Sound and VibrationAuthor(s): Xing-Feng Zhu, Siu-Kit Lau, Zhenbo Lu, Wonju Jeon Broadband absorption of the audible sound wave at low frequency has been achieved by using periodic acoustic metamaterial resonators (AMRs) embedded inside a porous layer. A single AMR embedded in a porous layer could reach perfect absorption (PA) at the resonance frequency, and it can be easily tuned by adjusting the inner radius of AMR. With four AMRs in the porous layer, a high absorption (>80%) is obtained in the frequency range from 180 Hz to 550 Hz, while the thickness of the porous layer is only 1/10 of the relevant wavelength at 300 Hz. The broadband and high absorption performances are due to the interferences of the low-frequency resonances of the AMRs and the energy trapping between the AMRs and the rigid backings. The finite element simulations are experimentally validated. Moreover, the broadband low-frequency absorption is robust under various oblique incidence even at large incident angles. The effects of the acoustic parameters of the porous layer on the absorption properties are also discussed. The absorbers should have high potential for the practical applications in buildings, aircrafts and automobiles due to their ease of fabrication, ultra-thin, and robust high-efficiency.
       
  • An efficient computation of cascade-gust interaction noise based on a
           hybrid analytical and boundary element method
    • Abstract: Publication date: Available online 22 August 2019Source: Journal of Sound and VibrationAuthor(s): Siyang Zhong, Hanbo Jiang, Wei Ying, Xin Zhang, Xun Huang This paper presents a hybrid analytical and boundary element method to compute the airfoil cascade-gust interaction noise. We assume that the acoustic response of an airfoil to the oncoming gust depends on the locally non-uniform mean flow such that the analytical solution based on a generalised Prandtl-Glauert transformation is utilised to compute the sound generation. The radiation of sound from an airfoil is scattered by other airfoils, which is resolved by a high-efficiency boundary element method. An averaging approach is proposed to efficiently compute the periodic Green's function due to the cascade. The predicted results are validated against numerical simulations for flat plate cascades, and the results match reasonably well. The cut-off properties due to the geometry restriction are discussed, and the critical gust wavelengths for the different orders of acoustic mode are derived. The low-frequency components are trapped in the space between the blades if the stagger angle is zero, while the plane waves are likely to propagating otherwise. For cascades with real airfoil geometry, the background mean flows are computed based on the potential theory. The omission of the refraction effect and approximation errors in the analytical solution of the acoustic response can cause errors for real airfoils, but the hybrid method can capture the sound reduction due to the finite thickness, and yield closer agreement with the numerical solution than the flat plate.
       
  • Damage detection in one- and two-dimensional structures using residual
           error method
    • Abstract: Publication date: Available online 21 August 2019Source: Journal of Sound and VibrationAuthor(s): Iqbal Alshalal, Faten Al Zubaidi, Alaa Elsisi, Z.C. Feng Damage detection at the early stages of structural design is crucial to prevent the occurrence of unpredictable failures. The residual error method can be used to detect damage by monitoring the changes it induces in the equation of motion. The residual error method was originally applied to beam structures, but in this study, it is adapted to detect and locate damage in two-dimensional structures such as plates. To demonstrate this method, the damage is modeled as a reduction in stiffness while the mass is maintained at a constant value. The effect of damage on the equation of motion of the intact structure is then quantified by substituting the eigenmodes and eigenvalues of the damaged structure; the residual error then pinpoints the location of the damage and its relative severity. Thorough finite element method simulations are performed to assess the robustness and limitations of the method in several scenarios with single and multiple damages. Furthermore, the sensitivity of the method to various noise levels is tested. Finally, a comparison is drawn between the residual error method and the absolute difference mode shape curvature method. The obtained results show that the residual error method is able to detect and locate damage in one- and two-dimensional structures.
       
  • Development and validation of a simple two degree of freedom model for
           predicting maximum fundamental sloshing mode wave height in a cylindrical
           tank
    • Abstract: Publication date: Available online 20 August 2019Source: Journal of Sound and VibrationAuthor(s): Vikas Sharma, C.O. Arun, I.R. Praveen Krishna The present paper proposes a new and simple mechanical model for predicting the maximum sloshing wave height (MSWH) in a partially filled, laterally excited cylindrical tank. The proposed model is a linear, two degree of freedom spring-mass-damper system which consists of two masses representing the sloshing and non-sloshing mass of the partially filled cylindrical tank. The model is validated through a series of experiments conducted on a cylindrical tank filled with water which is mounted in a slosh test rig. The proposed model successfully captures the beating phenomenon observed in sloshing wave height, when the tank is laterally excited near the resonant frequency of the liquid. The present study leads to a simpler, accurate and faster mechanical model which can predict the MSWH, frequency of sloshing liquid and the lateral sloshing force. The model can be readily used by the design engineers, instead of time consuming numerical models like computational fluid dynamics and smoothed particle hydrodynamics, in the preliminary design phase of any structure involving lateral sloshing and provide quick results which will substantially lead to shorter design cycle time.
       
  • Amplitude distortion of measured leak noise signals caused by
           instrumentation: Effects on leak detection in water pipes using the
           cross-correlation method
    • Abstract: Publication date: Available online 17 August 2019Source: Journal of Sound and VibrationAuthor(s): M.J. Brennan, Y. Gao, P.C. Ayala, F.C.L. Almeida, P.F. Joseph, A.T. Paschoalini A common way to detect and locate leaks in buried water pipes is to use leak noise correlators. Vibration or acoustic signals are measured on or in the pipe using sensors placed either side of the leak, and the difference in the leak noise arrival times (time delay) at the sensors is estimated from the peak in the cross-correlation function of these signals. Over many years, much effort has been spent on improving the quality of the leak noise signals with the aim of improving the time delay estimate. In this paper it is shown that even if the signals suffer from severe amplitude distortion through either clipping or quantization, then an accurate time delay estimate can be obtained provided that the zero crossings in the noise data are preserved. This is demonstrated by using polarity co-incidence correlation on simulated and measured data. The use of random telegraph theory is also used as an approximation to allow the derivation of approximate analytical solutions for the cross-correlation function and cross spectral density of clipped noise to facilitate further insight into the effects of severe clipping.
       
  • Modeling and analysis of in-plane and out-of-plane elastic wave
           propagation in a phononic-crystal circular beam
    • Abstract: Publication date: Available online 14 August 2019Source: Journal of Sound and VibrationAuthor(s): M. Liu, W.D. Zhu An efficient formulation of a circular Timoshenko beam is developed for static, vibration, and wave propagation problems. The B-spline wavelet on the interval (BSWI) interpolation functions are used to construct wavelet-based elements, which have analytical expressions at all levels and sufficient continuity. This paper derives static equilibrium, vibration, and wave propagation wavelet-based finite element models of in-plane and out-of-plane motions of circular beams according to the Hamilton's principle. Wave propagation characteristics of in-plane and out-of-plane waves in a phononic-crystal (PC) circular beam are analyzed using the wavelet-based finite element method (WFEM) based on the Bloch theorem. Effects of geometric parameters and material properties on in-plane and out-of-plane wave propagation characteristics of the PC circular beam are discussed. Numerical simulations show that the WFEM is more effective for static, vibration, and wave propagation problems than the traditional finite element method (TFEM). The WFEM can achieve the same accuracy as the TFEM with much fewer elements and degrees of freedom. It is shown that both in-plane and out-of-plane elastic wave band gaps exist in the PC circular beam, which exhibits some interesting phenomena due to coupling effects. This study can provide good support for wave filtering and vibration control of PC circular beam structures.
       
  • Analysis on nonlinear vibration of breathing cracked beam
    • Abstract: Publication date: Available online 12 August 2019Source: Journal of Sound and VibrationAuthor(s): Chenxi Wei, Xinchun Shang The nonlinear behaviors of breathing cracked beam vibration are investigated. A continuous model based on Timoshenko beam theory is established, whose breathing effect is described by signal function in mathematics to simulate bilinear stiffness. A semi-analytical approach to solve the problem is developed by spatial difference discretization and transfer matrix method, in which local linearization and the Padé approximation are employed. The numerical results of validated examples have good agreement with experiments and FEM. As a typical indicator to breathing crack, the super-resonance responses under harmonic and fast frequency-sweep excitation are analyzed, such as waveforms, phase portraits and FFT results.
       
  • Stochastic response analysis of elastic and inelastic systems with
           uncertain parameters under random impulse loading
    • Abstract: Publication date: Available online 12 August 2019Source: Journal of Sound and VibrationAuthor(s): Anil Kumar, Sandip Kumar Saha, Vasant A. Matsagar Response analysis of structural systems under impulse loading is extremely important for appropriate design against accidental loads such as blast. Herein, the response of elastic and inelastic single degree of freedom (SDOF) systems with uncertain parameters under random impulse loadings is investigated. Four different types of impulse loading profiles (rectangular-, half-sine wave-, and two triangular-shaped), having same duration and impulse, are applied to the SDOF systems with varying fundamental periods of vibration. Non-sampling stochastic simulation procedure based on the generalized polynomial chaos (gPC) expansion technique is used to model the dynamic response of the SDOF systems duly considering the uncertainties. Effects of uncertainty levels in the input parameters on the peak response and sensitivity of the peak response to the uncertain input parameters are investigated in detail. It is concluded that the propagation of uncertainties from the inputs to the response quantities is more prominent in stiffer systems. Amongst the impulse profiles considered, those pulses with sudden rise in force lead to higher deviations in response of the systems for a given uncertainty scenario. Further, it is observed that the shock response spectra of all the impulse loads are more sensitive to the uncertainties when time periods are less than or close to the loading duration. Furthermore, the gPC expansion-based simulation technique is observed to be an efficient alternative to computationally demanding conventional Monte Carlo (MC) simulation for quantifying the uncertainties.
       
  • The identification of gearbox vibration using the meshing impacts based
           demodulation technique
    • Abstract: Publication date: Available online 2 August 2019Source: Journal of Sound and VibrationAuthor(s): Shuiguang Tong, Yuanyuan Huang, Yongqing Jiang, Yanxiang Weng, Zheming Tong, Ning Tang, Feiyun Cong Gearboxes are at the heart of most rotating machines and they are considered as one of the main sources of vibration. As a key element in rotating machines, it is important to extract the gearbox vibration part from the mechanical system signal to assess the health state of the gearbox. In general, the gear meshing frequency part contains rich information which reflects its health state. In this paper, the authors find that in some cases when gearboxes work under heavy load, the meshing frequency part cannot be detected easily from the frequency spectrum. We think that the meshing frequency part may be modulated to the higher frequency band as the meshing impacts. To prove this point, a Multi-Input Single-Output (MISO) model is proposed to identify the local resonance excited by gear meshing impacts. In our method, a Meshing Impact Energy Distribution (MIED) graph is obtained through iteration to determine the demodulated frequency band. Experimental vibration data acquired form a healthy gearbox are illustrated to validate the performance of the proposed method. The forklift is taken as an example in the paper. Forklifts usually work in heavy load condition, and the gearbox vibration of a forklift is generally mixed with the ignition impacts of the diesel engine. The experiment result shows that for forklift machine system working in heavy load condition, its meshing frequency part of gearbox vibration signal is modulated into high frequency band. Further, the result shows that the proposed method is good at extracting the meshing frequency component when it is modulated into high frequency band especially when it is in heavy load condition.
       
  • Quasi-periodic motions of high-dimensional nonlinear models of a
           translating beam with a stationary load subsystem under harmonic boundary
           excitation
    • Abstract: Publication date: Available online 31 July 2019Source: Journal of Sound and VibrationAuthor(s): J.L. Huang, W.J. Zhou, W.D. Zhu Bifurcations and quasi-periodic motions of high-dimensional nonlinear models of a translating beam with a stationary load subsystem under harmonic boundary excitation, where there are combined parametric and forcing excitations, are investigated. It is demonstrated that by adjusting the frequency of the boundary excitation beyond bifurcation points, the nonlinear system exhibits quasi-periodic motion rather than the periodic response reported in an earlier publication. Particular attention is paid to the nonlinear dynamics of models with five and six included trial functions, where quantitative and qualitative results of frequency responses and quasi-periodic motions are significantly different from each other. The nonlinear governing equations of motion of the translating beam are established by using the Newton's second law. The Galerkin method is used to truncate the governing partial differential equation into a set of nonlinear ordinary differential equations. The incremental harmonic balance (IHB) method is used to solve for periodic responses of the high-dimensional models of the translating beam. The Floquet theory along with the precise Hsu's method is used to investigate stability of the periodic responses. The IHB method with two time scales developed earlier is extended to analyze quasi-periodic motion of the nonlinear system with combined parametric and forcing excitations whose spectrum contains uniformly spaced sideband frequencies. Quasi-periodic motion obtained from the IHB method with two time scales is in excellent agreement with that from numerical integration using the fourth-order Runge-Kutta method.
       
 
 
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