arXiv subjects

Bart Van Damme

Publications and source records attributed to Bart Van Damme.

12 recordsLinked to original sources

arXiv2026

Effect of introducing viscoelastic polyurethane on the dispersion and vibration isolation efficiency of chiral phononic crystals

Phononic crystals, a sequence of masses and (damped) springs, are being used more and more in practical applications, exploiting Bragg bandgaps to attenuate vibration transmission in a wide frequency range. In particular, chiral phononic crystals have demonstrated their ability to achieve low frequency bandgaps while maintaining a high static stiffness, and thus load bearing capacities. However, tuning of the bandgap frequencies is non-trivial because of their complex geometry. In this paper, viscoelastic inserts between the masses of the chain are introduced to improve the tunability of the crystal and take advantage of viscous damping. Modeling true viscoelasticity requires the implementation of frequency-dependent material properties, which is introduced in this work both for dispersion curve calculation and for harmonic force transmission simulations. As a real-world example, the intricate frequency-dependency of polyurethane is studied by examining the influence of four fractional derivative model parameters, which define the storage modulus and loss factor. The calculated dynamic force transmissibility of the phononic crystal is compared to classical, single-layer, isolation solutions. The results show that high viscous damping does not negatively affect the bandgap efficiency, which is a major advantage over resilient layer isolators where damping deteriorates the isolation properties. To validate the models, three crystals with different viscoelastic material properties in terms of stiffness and damping are manufactured and the measured force transmissibility is successfully compared to the numerical models.

physics.app-ph↗

arXiv2026

Pressure sensing by electro-mechanical coupling in compliant dielectric membranes polarized by a bias voltage

Among smart materials, piezoelectric materials occupy a very prominent position for sensing and actuation functions. Combined with simple or more advanced shunts, they are also proposed in various vibration mitigation schemes. However, the selection of available piezoelectric materials is mainly limited to ceramics (with an elastic modulus in the order of 10 Gpa (e.g. PZT ceramics) and a few polymer materials, with elastic modulus in the range of 1 Gpa (e.g. PVDF). In both cases, the high mechanical impedance and, consequently, the small dynamic strains limit the application of these materials to stiff structures. In this contribution, we discuss using a bias voltage to polarize dielectric materials and thereby compensate for the lack of spontaneous polarization observed in piezoelectrics. This enables access to materials with a wider range of elastic properties, such as soft elastomers, e.g. poly(dimethylsiloxane). As an example, we present a practical implementation of a silicone rubber membrane used as a highly compliant dynamic pressure sensor. For such nearly-incompressible materials, the capacitance change during dynamic deformation of the membranes is sufficiently large to generate a measurable dynamic voltage change over the membrane.

physics.app-ph↗

arXiv2026

A scalability benchmark study of model order reduction techniques for very large, strongly coupled vibroacoustic problems

Model Order Reduction (MOR) can significantly reduce the computational cost of vibroacoustic simulations. While most MOR research focuses on single-domain systems (e.g., structural dynamics or computational fluid mechanics), this work compares MOR techniques for large multi-domain problems to identify methods that remain efficient and accurate at very large scales. In particular, harmonic response simulations of vibroacoustic fluid-structure coupled systems used to compute transfer functions from an input force to either structural acceleration or pressure in the heavy fluid domain are of high interest. To achieve this, the most common MOR techniques based on modal methods and Krylov subspace methods are compared for multi-material systems. To assess the feasibility and accuracy of these techniques for different system sizes, a scalable benchmark model of a water-filled Plexiglass cylinder is developed, with mesh sizes from 10,000 to 1,000,000 Degrees of Freedom (DOF). The quality of the models is assured by validation against experimental data. The geometry, model data, and experimental results are made available so that they can be used as a benchmark for further studies. For systems larger than 100,000 DOF, the investigated modal methods become impractical due to memory limitations, even on powerful workstations. Among the tested techniques, a Krylov subspace two-level orthogonal Arnoldi reduction, combined with symmetrization and conditioning of the system matrices, provides the most accurate and efficient approximation of the target transfer functions - particularly for large-scale models up to 1,000,000 DOF. This approach achieves a speedup of up to 600 times compared to the full model.

physics.app-ph↗

arXiv2025

Matching frequency response measurements and reduced order models for the inverse identification of viscoelastic properties

3D-printed materials are used in many different industries (automotive, aviation, medicine, etc.). Most of these 3D-printed materials are based on ceramics or polymers whose mechanical properties vary with frequency. For numerical modeling, it is crucial to characterize this frequency dependency accurately to enable realistic finite-element simulations. At the same time, the damping behavior plays a key role in product development, since it governs a component's response at resonance and thus impacts both performance and longevity. In current research, inverse material characterization methods are getting more and more popular. However, their practical validation and applicability on real measurement data have not yet been discussed widely. In this work, we show the identification of two different materials, POM and additively manufactured sintered ceramics, and validate it with experimental data of a well-established measurement technique (dynamic mechanical analysis). The material identification process considers state-of-the-art reduced-order modeling and constrained particle swarm optimization, which are used to fit the frequency response functions of point measurements obtained by a laser Doppler vibrometer. This work shows the quality of the method in identifying the parameters defining the viscoelastic fractional derivative model, including their uncertainty. It also illustrates the applicability of this identification method in the presence of practical difficulties that come along with experimental data such as boundary conditions and noise.

physics.app-ph↗

arXiv2025

Practical implementation of a chiral phononic crystal demonstrator with ultra-low frequency bandgap

The use of phononic crystals for vibration attenuation and isolation has been widely studied, showing that the attenuation frequency range depends on their mass and stiffness. The concepts of chirality and tacticity have been introduced into classical phononic crystals to enrich the dynamics of the mass elements and thereby achieve lower frequency ranges with high vibration attenuation. Although these concepts have demonstrated their effectiveness on lab-scale crystals, their implementation in industrial applications is still rare. Chiral phononic crystals require a complex geometry that complicates their manufacturing. Existing examples require to be fabricated by 3D printing, making them expensive to build on a large scale for demonstration purposes or in-situ applications. In this study, we redefine a chiral phononic crystal design for translational-rotational coupling in order to enable its manufacturability using exclusively conventional processes. We then investigate the design space of these newly designed phononic crystals, using a simplified unit cell FEM model that minimizes computation time. A parametric study is conducted to investigate the crystal's tunability by modifying the dimensions of the chiral links between the masses. A large crystal with ultra-low frequency range attenuation -- starting at 60~Hz -- is then designed, with the aim to demonstrate the influence of the crystal's tacticity on the vibration isolation by hand sensing. A crystal composed of 2 unit cells is manufactured and its measured transfer function is compared with numerical predictions, thus highlighting the disparities between the behavior of the structure under real-life and ideal excitation conditions.

physics.app-ph↗

arXiv2024

Generative inverse design of multimodal resonant structures for locally resonant metamaterials

In the development of locally resonant metamaterials, the physical resonator design is often omitted and replaced by an idealized mass-spring system. This paper presents a novel approach for designing multimodal resonant structures, which give rise to multi-bandgap metamaterials with predefined band gaps. Our method uses a conditional variational autoencoder to identify nontrivial patterns between design variables of complex-shaped resonators and their modal effective parameters. After training, the cost of generating designs satisfying arbitrary criteria - frequency and mass of multiple modes - becomes negligible. An example of a resonator family with six geometric variables and two targeted modes is further elaborated. We find that the autoencoder performs well even when trained with a limited dataset, resulting from a few hundred numerical modal analyses. The method generates several designs that very closely approximate the desired modal characteristics. The accuracy of the best designs, proposed by the auto-encoder, is confirmed in tests of 3D-printed resonator prototypes. Further experiments demonstrate the close agreement between the measured and desired dispersion relation of a sample metamaterial beam.

physics.app-ph↗

arXiv2024

Enhancement of the sound absorption of closed-cell mineral foams by perforations: Manufacturing process and model-supported adaptation

Thin low-frequency acoustic absorbers that are economical to produce in large quantities are scarce, and their efficiency is often limited to a narrow frequency range. In this paper, we present opportunities to use highly porous mineral foams, in particular optimally designed gypsum foams, to achieve high absorption levels for layers of less than 1/10 of a wavelength thick. To reach this goal, we perforate a fraction of the initially closed pores using thin needles. Finite element simulations of the fluid flow in a representative volume element show how the combination of foam properties (cell size and wall thickness) and perforation pattern (hole diameter and perforation distance) can be chosen such that sub-wavelength absorption is obtained. In particular two transport parameters used in the approximate but robust Johnson-Champoux-Allard model for porous media have to be optimized: the flow resistivity and high-frequency tortuosity. The fluid flow modeling results are successfully compared with sound absorption measurements, showing indeed that the proposed material, once appropriately perforated, yields a remarkable low-frequency sound absorption peak. On a more fundamental level, this paper shows how the multiporosity, the presence of microcracks, and the material's surface roughness can be exploited to enhance its acoustic absorption at very low frequencies.

physics.flu-dyn↗

arXiv2024

Implementation of tunable frequency-dependent stiffness elements via integrated shunted piezoelectric stacks

Piezoelectric transducers applied on or integrated in structures, combined with appropriate circuits have been extensively investigated as a smart approach to the mitigation of resonant vibrations with high relative amplitudes. \cmt{A resonant shunt circuit consisting of the capacitive piezoelectric transducer and an inductance can be configured to target specific eigenmodes of a structure, if appropriately placed and tuned. Their effect is expressed in terms of mechanical impedance of the host structure, allowing for the exchange of energy between the mechanical and electrical domain, to dramatically affect the dynamic response of the structure. By re-framing the function of resonant shunted piezoelectric transducers as frequency dependent variable stiffness elements, this paper investigates their capability to realize a frequency dependent structural mechanical connectivity, where the load path within a lattice structure can be interrupted at will for specific frequencies by tunable null-stiffness components. Here, we offer the numerical and experimental verification of this idea, by demonstrating the ability to significantly affect the dynamic response of a unit cell of an adaptive lattice metamaterial, even away from a structural resonance. In the latter case, the null-stiffness shunt leads to an additional resonance peak in the truss' dynamic response.} Its realization as additively manufactured component points to the feasibility of such structures in real life.

physics.app-ph↗

arXiv2024

A Nonlinear Damped Metamaterial: Wideband Attenuation with Nonlinear Bandgap and Modal Dissipation

In this paper, we incorporate the effect of nonlinear damping with the concept of locally resonant metamaterials to enable vibration attenuation beyond the conventional bandgap range. The proposed design combines a linear host cantilever beam and periodically distributed inertia amplifiers as nonlinear local resonators. The geometric nonlinearity induced by the inertia amplifiers causes an amplitude-dependent nonlinear damping effect. Through the implementation of both modal superposition and numerical harmonic methods the finite nonlinear metamaterial is accurately modelled. The resulting nonlinear frequency response reveals the bandgap is both amplitude-dependent and broadened. Furthermore, the modal frequencies are also attenuated due to the nonlinear damping effect. The theoretical results are validated experimentally. By embedding the nonlinear damping effect into locally resonant metamaterials, wideband attenuation of the proposed metamaterial is achieved, which opens new possibilities for versatile metamaterials beyond the limit of their linear counterparts.

physics.app-ph↗

arXiv2022

A Graded Metamaterial for Broadband and High-capability Piezoelectric Energy Harvesting

This work studies a broadband graded metamaterial, which integrates the piezoelectric energy harvesting function targeting low-frequency structural vibrations, lying below 100 Hz. The device combines a graded metamaterial with beam-like resonators, piezoelectric patches and a self-powered piezoelectric interface circuit for energy harvesting. Based on the mechanical and electrical lumped parameters, an integrated model is proposed to investigate the power performance of the proposed design. Thorough numerical simulations were conducted to analyse the spatial frequency separation capacity and the slow-wave phenomenon of the graded metamaterial for broadband and high-capability piezoelectric energy harvesting. Experiments with realistic vibration sources show that the harvested power of the proposed design yields a five-fold increase with respect to conventional harvesting solutions based on single cantilever harvesters. Our results reveal the significant potential on exploitation of graded metamaterials for energy-efficient vibration-powered devices.

physics.app-ph↗

arXiv2022

Long-range order Bragg scattering and its effect on the dynamic response of a Penrose-like phononic crystal plate

In this article, we present scattering and localization phenomena in a thin elastic plate comprising an aperiodic arrangement of scatterers. By analysing the form factor of the scattering cluster, we sample the reciprocal space which shows strong scattering points associated with non trivial dispersion. Wide frequency regimes with very different dynamic responses are identified: isotropic wave dispersion at low frequency, and an attenuating regime with strong localization effects at higher frequencies. Illustrative comparisons are drawn with a periodic counterpart having the same density of scatterers. The novel findings are corroborated by analytical estimates, numerical finite-element simulations and vibrometric experiments. The results are relevant for the research community interested in extending phononic crystal phenomena to lower frequencies.

physics.class-ph↗

arXiv2021

Inherent Non-Linear Damping in Resonators with Inertia Amplification

Inertia amplification is a mechanism coupling degrees of freedom within a vibrating structure. Its goal is to achieve an apparent high dynamic mass and, accordingly, a low resonance frequency. Such structures have been described for use in locally resonant metamaterials and phononic crystals to lower the starting frequency of a band gap without adding mass to the system. This study shows that any non-linear kinematic coupling between translational or rotational vibrations leads to the appearance of amplitude-dependent damping. The analytical derivation of the equation of motion of a resonator with inertia amplification creates insight in the damping process, and shows that the vibration damping increases with its amplitude. The theoretical study is validated by experimental evidence from two types of inertia-amplification resonators. Finally, the importance of amplitude-dependent damping is illustrated when the structure is used as a tuned mass damper for a cantilever beam.

physics.app-ph↗