Journal of Sound and Vibration

Journal: Journal of Sound and Vibration

Abbreviation

J. Sound Vib.

Publisher

Elsevier

ISSN

0022-460X
1095-8568

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Publications 1 - 10 of 36

Mitigation of seismic waves: Metabarriers and metafoundations bench tested
Colombi, Andrea; Zaccherini, Rachele; Aguzzi, Giulia; et al. (2020)
Journal of Sound and Vibration
The article analyses two potential metamaterial designs, the metafoundation and the metabarrier, capable to attenuate seismic waves impact on buildings or structural components in a frequency band between 3.5 and 8 Hz. The metafoundation serves the dual purpose of reducing the seismic response and supporting the superstructure. Conversely the metabarrier surrounds and shields the structure from incoming waves. The two solutions are based on a cell layout of local resonators whose dynamic properties are tuned using finite element simulations combined with Bloch periodicity boundary conditions. To enlarge the attenuation band, a graded design where the resonant frequency of each cell varies spatially is employed. If appropriately enlarged or reduced, the metamaterial designs could attenuate lower frequency seismic waves or groundborne vibrations respectively. A sensitivity analysis over various design parameters including size, number of resonators, soil type and source directivity, carried out by computing full 3D numerical simulations in time domain for horizontal shear waves is proposed. Overall, the metamaterial solutions discussed here can reduce the spectral amplification of the superstructure by approx. 15–70% depending on several parameters such as the metastructure size and the properties of the soil. Pitfalls and advantages of each configuration are discussed in detail. The role of damping, crucial to avoid multiple resonant coupling, and the analogies between graded metamaterials and tuned mass dampers is also investigated. © 2020 Elsevier
A comparison of deterministic and Bayesian model updating frameworks for identifying offshore wind turbine foundation parameters
Simpson, Harry A.; Chatzi, Eleni; Chatzis, Manolis N. (2026)
Journal of Sound and Vibration
The rapid growth of the wind industry has resulted in larger wind turbines, whose modal properties lie in the lower frequency range. This has induced higher loads and stress cycles rendering accurate fatigue assessment increasingly important. Such assessment is highly affected by the precision in the estimation of turbine properties, including those related to the support conditions and foundation, which can be associated with high uncertainty. One approach to improve these estimates is to use structural monitoring data (e.g. from sensors mounted on the tower) to update the foundation parameters of offshore wind turbine models. However, the low identifiability of the parameters to be estimated can lead to divergent estimates across different fatigue estimation frameworks, which combined with the uncertainty inherent in the foundation properties, can compromise the reliable assessment of the remaining useful life. In this work, two Bayesian model updating frameworks are applied to update the foundation parameters of an offshore wind turbine and results are compared against a deterministic framework in a numerical example. The advantages and limitations of each framework are considered and the importance of accurately accounting for uncertainties as part of the model updating process is highlighted.
Experiments on sound reflection and production by choked nozzle flows subject to acoustic and entropy waves
Weilenmann, Markus; Noiray, Nicolas (2021)
Journal of Sound and Vibration
Perturbation theory of nonlinear, non-self-adjoint eigenvalue problems: Simple eigenvalues
Mensah, Georg A.; Orchini, Alessandro; Moeck, Jonas P. (2020)
Journal of Sound and Vibration
Structural identification with physics-informed neural ordinary differential equations
Lai, Zhilu; Mylonas, Charilaos; Nagarajaiah, Satish; et al. (2021)
Journal of Sound and Vibration
This paper exploits a new direction of structural identification by means of Neural Ordinary Differential Equations (Neural ODEs), particularly constrained by domain knowledge, such as structural dynamics, thus forming Physics-informed Neural ODEs, aiming at governing equations discovery/approximation. Structural identification problems often entail complex setups featuring high-dimensionality, or stiff ODEs, which pose difficulties in the training and learning of conventional data-driven algorithms who seek to unveil the governing dynamics of a system of interest. In this work, Neural ODEs are re-casted as a two-level representation involving a physics-informed term, that stems from possible prior knowledge of a dynamical system, and a discrepancy term, captured by means of a feed-forward neural network. The re-casted format is highly adaptive and flexible to structural monitoring problems, such as linear/nonlinear structural identification, model updating, structural damage detection, driving force identification, etc. As an added step, for inferring an explainable model, we propose the adoption of sparse identification of nonlinear dynamical systems as an additional tool to distill closed-form expressions for the trained nets, that embed a more straightforward engineering interpretation. We demonstrate the framework on a series of numerical and experimental examples, with the latter pertaining to a structural system featuring highly nonlinear behavior, which is successfully learned by the proposed framework. The proposed structural identification with Physics-informed Neural ODEs comes with the benefits of direct approximation of the governing dynamics, and a versatile and flexible framework for discrepancy modeling in structural identification problems.
Curve squealing of trains: Measurement, modelling and simulation
Glocker, Christoph; Cataldi-Spinola, Eric; Leine, Remco I. (2009)
Journal of Sound and Vibration
Curve squealing of railway wheels occurs erratically in narrow curves with a frequency of about 4 kHz. Squealing is caused by a self-excited stick-slip oscillation in the wheel-rail contact. The mechanism which activates squeal is still unexplained and will be analyzed in the paper at hand. The squeal model consists of the first modal forms of an elastic wheel and is equipped with a three-dimensional hard Coulomb contact. Based on this model, a linear stability analysis of the stationary run through a curve is performed for the four wheels of the investigated bogie. The results show that in particular the front inner wheel tends to squeal. A numerical simulation of the system's differential inclusions performed on the unstable states shows the existence of a self-excited stick-slip oscillation. The computed frequency of the limit cycle agrees well with the measurements. The design of the squeal model, the steps necessary to perform the stability analysis on systems with non-ideal constraints, as well as the non-smooth dynamics code used to perform the simulations are explained in detail.
Adjoint computation of Berry phase gradients
Bösch, Cyrill; Serra-García, Marc; Böhm, Christian; et al. (2025)
Journal of Sound and Vibration
Berry phases offer a geometric perspective on wave propagation and are key to designing materials with topological wave transport. However, controlling Berry phases is challenging due to their dependence on global integrals over the Brillouin zone, making differentiation difficult. We present an adjoint-based method for efficiently computing the gradient of the Berry phase with respect to system parameters. We introduce an adjoint-based algorithm that computes Berry-phase gradients via only one forward and one adjoint solve. Under reasonable assumptions the algorithm’s time complexity is O(N¹⁺¹/ᴰ), where N is number of grid points in a numerical discretization scheme and D is the space dimension. Thereby it outperforms numerical differentiation and perturbation theory for problems with a large number of design variables. This approach enables the use of advanced, gradient-based optimization techniques to design new continuously parameterized materials with tailored topological wave properties. Furthermore, via multi-objective optimizations this method allows to co-design the topological characteristics in tandem with other objectives. We apply the method to an elastic metamaterial rod.
Model reduction to spectral submanifolds and forced-response calculation in high-dimensional mechanical systems
Ponsioen, Sten; Jain, Shobhit; Haller, George (2020)
Journal of Sound and Vibration
We show how spectral submanifold (SSM) theory can be used to extract forced-response curves without any numerical simulation in high-degree-of-freedom, periodically forced mechanical systems. We use multivariate recurrence relations to construct the SSMs, achieving a major speed-up relative to earlier autonomous SSM algorithms. The increase in computational efficiency promises to close the current gap between studying lower-dimensional academic examples and analyzing larger systems obtained from finite-element modeling, as we illustrate on two different discretized damped-forced beam models. Using the exact reduction procedure via SSMs for obtaining forced response curves, we further demonstrate speed gains of several orders in magnitude relative to the available state-of-the-art continuation packages, while retaining accuracy. © 2020 Elsevier Ltd.
Failure of thermoacoustic instability control due to periodic hot gas ingestion in Helmholtz dampers
Miniero, Luigi; Mensah, Georg A.; Bourquard, Claire; et al. (2023)
Journal of Sound and Vibration
Passive damping devices such as Helmholtz dampers are often employed in gas turbines to mitigate thermoacoustic instabilities. The periodic ingestion of the combustion chamber hot gas in the resonant cavity of Helmholtz dampers can be a serious issue, if not considered in the design phase of these devices. The periodic hot gas ingestion modulates the density in the damper neck and thereby the damper’s resonance frequency. This effect, combined with the nonlinearities in the acoustic damping caused by the periodical reversal of the flow direction in the neck, can prevent the intended control of the thermoacoustic feedback. Despite its relevance for gas turbine design, this topic has not received significant attention in literature. This study presents experimental and theoretical investigations of that problem. A physics-based model is derived with a few empirical parameters, calibrated with data which were collected from an experimental setup comprising a tunable Helmholtz damper connected to a combustor operated at atmospheric pressure. This model of noise-driven coupled oscillators with nonlinear damping and stiffness is capable of reproducing the bistable dynamics observed in the experiments for specific ranges of equivalence ratios. The model is then used to draw general conclusions about the robustness of dampers with respect to this unwanted phenomenon. In particular, the influence of the geometry and flow conditions on the damping and stiffness nonlinearities, which both participate to possible failure of the passive control, is described. We show that in the case of broadband dampers, the effect of the nonlinear stiffness is weaker than the one of damping nonlinearity, and that it can become significant for more narrow-band dampers. The results can be used for designing acoustic dampers that are robust with regard to the risk of spontaneous loss of thermoacoustic stability due to periodic hot gas ingestion.
Simultaneous broadband vibration isolation and energy harvesting at low frequencies with quasi-zero stiffness and nonlinear monostability
Fang, Shitong; Chen, Keyu; Zhao, Bao; et al. (2023)
Journal of Sound and Vibration
Vibration, as one of the most ubiquitous phenomena, would be a sustainable energy harvesting source to power wireless sensor nodes. However, vibration may be undesirable with detrimental effects such as damage to buildings, discomfort to passengers, etc. So far, the simultaneous broadband energy harvesting and vibration isolation at low frequencies between 0 and 15 Hz is still an open issue. Motivated by this, we propose a novel device with a quasi-zero-stiffness (QZS) support through cam–roller–spring mechanism (CRSM) and multiple nonlinear monostable piezoelectric energy harvesters. A semi-analytical electromechanical model considering AC/DC circuits is developed and validated. Simulation results show that when the high-energy branches of the proposed device with six nonlinear monostable harvesters are triggered, the peak power and energy harvesting frequency bandwidths are respectively increased by up to 69.29% and 1.22 times compared with those of its counterpart with linear harvesters. Furthermore, these are achieved at frequencies lower than 15 Hz without the sacrifice of low force transmissibility and isolation frequencies. Parametric studies indicate that except for the harvester damping, no matter how other parameters change, the superiority of the proposed device exists compared with its linear counterpart. It can be potentially used in building a smart floor tile with dual functions of energy harvesting to power wireless sensor nodes for footfall tracking or light-emitting diodes, and vibration isolation to enhance pedestrian comfort and safety.

Publications 1 - 10 of 36

Journal: Journal of Sound and Vibration

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