Pub Date : 2026-01-10DOI: 10.1016/j.jsv.2025.119631
Ran Eckl, Hezi Y. Grisaro
This study investigates the dynamic response of linear-elastic and elastic-plastic Single Degree of Freedom (SDOF) systems subjected to two consecutive triangular pulse loads, a scenario relevant to blast-resistant design yet often neglected in conventional analysis. The concept of an amplification factor (AMF) is introduced to quantify the increase in maximum displacement relative to a single load. The response is analyzed across three classical regimes: impulsive, dynamic, and quasi-static, highlighting the dominant role of delay time between pulses in shaping the structural response. Closed-form expressions are derived for AMF in both impulsive and quasi-static limits, and analytical relationships are established between the amplification factor and the asymptotic bounds of Pressure-Impulse (P-I) diagrams. Parametric studies show that while the impulse and peak pressure ratios (η and κ) set the amplification bounds, the delay time (th) critically governs the maximum response. In the elastic-plastic case, three distinct regimes are identified based on the yielding state at the time of the second load, and closed-form expressions for the asymptotes are derived. The findings offer both fundamental insight and practical tools for constructing conservative failure envelopes without the need for extensive numerical simulations.
{"title":"Maximum response of SDOF systems under consecutive triangular pulses","authors":"Ran Eckl, Hezi Y. Grisaro","doi":"10.1016/j.jsv.2025.119631","DOIUrl":"10.1016/j.jsv.2025.119631","url":null,"abstract":"<div><div>This study investigates the dynamic response of linear-elastic and elastic-plastic Single Degree of Freedom (SDOF) systems subjected to two consecutive triangular pulse loads, a scenario relevant to blast-resistant design yet often neglected in conventional analysis. The concept of an amplification factor (AMF) is introduced to quantify the increase in maximum displacement relative to a single load. The response is analyzed across three classical regimes: impulsive, dynamic, and quasi-static, highlighting the dominant role of delay time between pulses in shaping the structural response. Closed-form expressions are derived for AMF in both impulsive and quasi-static limits, and analytical relationships are established between the amplification factor and the asymptotic bounds of Pressure-Impulse (P-I) diagrams. Parametric studies show that while the impulse and peak pressure ratios (<em>η</em> and <em>κ</em>) set the amplification bounds, the delay time (<em>t<sub>h</sub></em>) critically governs the maximum response. In the elastic-plastic case, three distinct regimes are identified based on the yielding state at the time of the second load, and closed-form expressions for the asymptotes are derived. The findings offer both fundamental insight and practical tools for constructing conservative failure envelopes without the need for extensive numerical simulations.</div></div>","PeriodicalId":17233,"journal":{"name":"Journal of Sound and Vibration","volume":"626 ","pages":"Article 119631"},"PeriodicalIF":4.9,"publicationDate":"2026-01-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145977915","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2026-01-09DOI: 10.1016/j.jsv.2026.119640
Gianfranco deM. Stieven , Carlos F.T. Matt , Liviu Nicu , Carolina P. Naveira-Cotta , Renato M. Cotta
A comprehensive hybrid analytical-numerical solution is presented for a viscoelastic cantilever Euler-Bernoulli beam with an eccentric damped tip mass, subjected to external excitation, viscous damping, and an arbitrary base motion that undergoes translation and small rotation. The solution is obtained using the Generalized Integral Transform Technique (GITT), based on the application of an implicit filter and an eigenfunction expansion supported by a biharmonic-type eigenvalue problem, yielding a fast and straightforward implementation. A numerically stabilized eigenproblem formulation is proposed, ensuring robust convergence and accurate eigenfunctions. This hybrid solution, presented in a state-space framework, is validated experimentally against damped and undamped natural frequencies, and verified numerically through time-varying free and forced transverse deflection. A physical analysis is presented through four studies: (i) parametric maps of the first two complex eigenvalues, highlighting the distinct modal roles of viscoelastic damping and viscous damping, tip mass magnitude, and eccentricity; (ii) the combined effect of tip-mass eccentricity and internal damping on free and forced vibration; (iii) the influence of tip-mass damping and viscoelastic damping on free and forced vibration; and (iv) a Frequency Response Function (FRF) evaluation considering viscoelastic damping and viscous damping. The resulting formulation delivers fast-convergent solutions, providing closed-form base actions and frequency-response characterizations. The accompanying time- and frequency-domain results, together with compact eigenvalue maps, supply benchmark-quality references that clarify damping and eccentricity effects and support design, identification, and model assessment in linear vibration.
{"title":"On the dynamics of viscoelastic cantilever beams under arbitrary base motion and eccentric damped tip mass via integral transform","authors":"Gianfranco deM. Stieven , Carlos F.T. Matt , Liviu Nicu , Carolina P. Naveira-Cotta , Renato M. Cotta","doi":"10.1016/j.jsv.2026.119640","DOIUrl":"10.1016/j.jsv.2026.119640","url":null,"abstract":"<div><div>A comprehensive hybrid analytical-numerical solution is presented for a viscoelastic cantilever Euler-Bernoulli beam with an eccentric damped tip mass, subjected to external excitation, viscous damping, and an arbitrary base motion that undergoes translation and small rotation. The solution is obtained using the Generalized Integral Transform Technique (GITT), based on the application of an implicit filter and an eigenfunction expansion supported by a biharmonic-type eigenvalue problem, yielding a fast and straightforward implementation. A numerically stabilized eigenproblem formulation is proposed, ensuring robust convergence and accurate eigenfunctions. This hybrid solution, presented in a state-space framework, is validated experimentally against damped and undamped natural frequencies, and verified numerically through time-varying free and forced transverse deflection. A physical analysis is presented through four studies: (i) parametric maps of the first two complex eigenvalues, highlighting the distinct modal roles of viscoelastic damping and viscous damping, tip mass magnitude, and eccentricity; (ii) the combined effect of tip-mass eccentricity and internal damping on free and forced vibration; (iii) the influence of tip-mass damping and viscoelastic damping on free and forced vibration; and (iv) a Frequency Response Function (FRF) evaluation considering viscoelastic damping and viscous damping. The resulting formulation delivers fast-convergent solutions, providing closed-form base actions and frequency-response characterizations. The accompanying time- and frequency-domain results, together with compact eigenvalue maps, supply benchmark-quality references that clarify damping and eccentricity effects and support design, identification, and model assessment in linear vibration.</div></div>","PeriodicalId":17233,"journal":{"name":"Journal of Sound and Vibration","volume":"626 ","pages":"Article 119640"},"PeriodicalIF":4.9,"publicationDate":"2026-01-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145977921","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2026-01-09DOI: 10.1016/j.jsv.2026.119646
Huachen Zhu , Ryan Mckay , Michael Kingan , Xianghao Kong , Jin Xuan Teh , Yusuke Hioka , Gian Schmid
A number of recent studies have shown that unsteady rotational motion of small unmanned aerial vehicle propellers can produce tonal noise. In this paper, time- and frequency-domain methods for calculating this noise are presented and validated against one-another. The unsteady loading on the propeller blades, required for the predictions, is calculated using both blade element momentum theory and computational fluid dynamics simulations. The noise prediction methods are validated against measurements. The propeller unsteady motion during these experiments was measured using a rotary encoder and this measured rotational motion was used as input to the noise prediction methods. The results presented in this paper focus on a case where the electric motor drives the propeller in unsteady rotational motion where the unsteady motion is almost sinusoidal with a frequency equal to 14 times the shaft rotation frequency. Predictions show that this unsteady rotational motion produces high amplitude tones at the frequency of the dominant fluctuation speed and adjacent harmonics of the blade passing frequency — confirming the findings of a previous study. These predictions are shown to be in generally good agreement with measurements. In addition, the polar and azimuthal directivity of this tonal noise is investigated.
{"title":"Tonal noise produced by a UAV propeller due to unsteady rotational motion","authors":"Huachen Zhu , Ryan Mckay , Michael Kingan , Xianghao Kong , Jin Xuan Teh , Yusuke Hioka , Gian Schmid","doi":"10.1016/j.jsv.2026.119646","DOIUrl":"10.1016/j.jsv.2026.119646","url":null,"abstract":"<div><div>A number of recent studies have shown that unsteady rotational motion of small unmanned aerial vehicle propellers can produce tonal noise. In this paper, time- and frequency-domain methods for calculating this noise are presented and validated against one-another. The unsteady loading on the propeller blades, required for the predictions, is calculated using both blade element momentum theory and computational fluid dynamics simulations. The noise prediction methods are validated against measurements. The propeller unsteady motion during these experiments was measured using a rotary encoder and this measured rotational motion was used as input to the noise prediction methods. The results presented in this paper focus on a case where the electric motor drives the propeller in unsteady rotational motion where the unsteady motion is almost sinusoidal with a frequency equal to 14 times the shaft rotation frequency. Predictions show that this unsteady rotational motion produces high amplitude tones at the frequency of the dominant fluctuation speed and adjacent harmonics of the blade passing frequency — confirming the findings of a previous study. These predictions are shown to be in generally good agreement with measurements. In addition, the polar and azimuthal directivity of this tonal noise is investigated.</div></div>","PeriodicalId":17233,"journal":{"name":"Journal of Sound and Vibration","volume":"626 ","pages":"Article 119646"},"PeriodicalIF":4.9,"publicationDate":"2026-01-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145977917","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2026-01-09DOI: 10.1016/j.jsv.2026.119643
Khaled F. Aljanaideh , Isam Al-Darabsah , Mohammad Al Janaideh
Sensor-to-sensor transmissibility operators are mathematical objects that relate two subsets of system outputs. A transmissibility operator can be used along with one subset of outputs to predict the other subset of outputs of the underlying system without knowledge of a model of the underlying system or the excitation signal acting on it. Transmissibility operators have been used in applications including fault detection, virtual sensing, state estimation, and system identification. Standard transmissibility formulations assume that the number of transmissibility inputs equals the dimension of the excitation signal acting on the underlying system. However, since transmissibilities operate in environments with unknown inputs, estimating the dimension of the excitation signal can be challenging. Moreover, numerical evidence from previous research shows that the predicted outputs obtained using transmissibility operators become more accurate as the number of transmissibility inputs increases. In this paper, we introduce a more general mathematical representation of transmissibility operators that allows the number of transmissibility inputs to exceed the excitation dimension, hence the term generalized transmissibility operators. We further show that the determinant of the difference between two generalized transmissibility operators constructed between the same outputs but under different input locations can be used to determine the poles of the underlying system, outperforming existing time- and frequency-domain transmissibility-based modal estimation techniques. The framework is validated through numerical pole estimation of a mechanical structure and experimental soft sensing of an acoustic system, demonstrating improved accuracy and robustness over existing approaches.
{"title":"Generalized sensor-to-sensor transmissibility operators: Theory, identification, and applications in soft sensing and modal estimation","authors":"Khaled F. Aljanaideh , Isam Al-Darabsah , Mohammad Al Janaideh","doi":"10.1016/j.jsv.2026.119643","DOIUrl":"10.1016/j.jsv.2026.119643","url":null,"abstract":"<div><div>Sensor-to-sensor transmissibility operators are mathematical objects that relate two subsets of system outputs. A transmissibility operator can be used along with one subset of outputs to predict the other subset of outputs of the underlying system without knowledge of a model of the underlying system or the excitation signal acting on it. Transmissibility operators have been used in applications including fault detection, virtual sensing, state estimation, and system identification. Standard transmissibility formulations assume that the number of transmissibility inputs equals the dimension of the excitation signal acting on the underlying system. However, since transmissibilities operate in environments with unknown inputs, estimating the dimension of the excitation signal can be challenging. Moreover, numerical evidence from previous research shows that the predicted outputs obtained using transmissibility operators become more accurate as the number of transmissibility inputs increases. In this paper, we introduce a more general mathematical representation of transmissibility operators that allows the number of transmissibility inputs to exceed the excitation dimension, hence the term <em>generalized</em> transmissibility operators. We further show that the determinant of the difference between two generalized transmissibility operators constructed between the same outputs but under different input locations can be used to determine the poles of the underlying system, outperforming existing time- and frequency-domain transmissibility-based modal estimation techniques. The framework is validated through numerical pole estimation of a mechanical structure and experimental soft sensing of an acoustic system, demonstrating improved accuracy and robustness over existing approaches.</div></div>","PeriodicalId":17233,"journal":{"name":"Journal of Sound and Vibration","volume":"628 ","pages":"Article 119643"},"PeriodicalIF":4.9,"publicationDate":"2026-01-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146036556","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2026-01-09DOI: 10.1016/j.jsv.2026.119654
Devavrit Maharshi , Michael I. Friswell , Barun Pratiher
The demand for lightweight, high-strength rotors with reliable vibration stability is rapidly increasing across aerospace, automotive, turbomachinery, and energy systems. Functionally graded graphene platelet-reinforced composites (FG-GPLRCs) offer a promising solution by enabling tailored stiffness and damping, achieving both weight reduction and enhanced dynamic performance. This study presents a novel analysis of the nonlinear dynamics of axially restrained FG-GPLRC multi-disk shafts under imbalance excitation, explicitly accounting for large-deflection behavior and multi-disk imbalance. The governing equations of the composite shaft-disk system are first derived and reduced using a fundamental-mode Galerkin approximation. The resulting reduced-order model is then analyzed via the method of multiple scales to obtain analytical expressions for the natural frequencies, which are subsequently validated through finite element simulations in ANSYS, confirming predictive accuracy. The investigation systematically examines how four reinforcement patterns, graphene platelet weight fraction, number of layers, and geometric ratios influence the vibration behavior and stability of the system. Results indicate that increasing the graphene platelet content from 0% to 2.5% substantially enhances performance, with natural frequencies rising by 170%-270% and critical damping by nearly 300%, while simultaneously reducing critical eccentricity and jump-down length by 80% and 8%, respectively. The reinforcement pattern and the number of graphene layers further shift frequencies by up to 37%, modify critical damping by 25%, affect jump-down length by 18%, and alter critical eccentricity by up to 30%. Overall, the findings highlight the potential of FG-GPLRC shafts for stable jump-free operation and the reliable design of high-speed rotor systems.
{"title":"Dynamic modeling and stability assessment of functionally graded graphene platelet-reinforced composite multi-Disk rotors","authors":"Devavrit Maharshi , Michael I. Friswell , Barun Pratiher","doi":"10.1016/j.jsv.2026.119654","DOIUrl":"10.1016/j.jsv.2026.119654","url":null,"abstract":"<div><div>The demand for lightweight, high-strength rotors with reliable vibration stability is rapidly increasing across aerospace, automotive, turbomachinery, and energy systems. Functionally graded graphene platelet-reinforced composites (FG-GPLRCs) offer a promising solution by enabling tailored stiffness and damping, achieving both weight reduction and enhanced dynamic performance. This study presents a novel analysis of the nonlinear dynamics of axially restrained FG-GPLRC multi-disk shafts under imbalance excitation, explicitly accounting for large-deflection behavior and multi-disk imbalance. The governing equations of the composite shaft-disk system are first derived and reduced using a fundamental-mode Galerkin approximation. The resulting reduced-order model is then analyzed via the method of multiple scales to obtain analytical expressions for the natural frequencies, which are subsequently validated through finite element simulations in ANSYS, confirming predictive accuracy. The investigation systematically examines how four reinforcement patterns, graphene platelet weight fraction, number of layers, and geometric ratios influence the vibration behavior and stability of the system. Results indicate that increasing the graphene platelet content from 0% to 2.5% substantially enhances performance, with natural frequencies rising by 170%-270% and critical damping by nearly 300%, while simultaneously reducing critical eccentricity and jump-down length by 80% and 8%, respectively. The reinforcement pattern and the number of graphene layers further shift frequencies by up to 37%, modify critical damping by 25%, affect jump-down length by 18%, and alter critical eccentricity by up to 30%. Overall, the findings highlight the potential of FG-GPLRC shafts for stable jump-free operation and the reliable design of high-speed rotor systems.</div></div>","PeriodicalId":17233,"journal":{"name":"Journal of Sound and Vibration","volume":"628 ","pages":"Article 119654"},"PeriodicalIF":4.9,"publicationDate":"2026-01-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146036557","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2026-01-08DOI: 10.1016/j.jsv.2026.119645
Lukas Bürger , Régis Boukadia , Frank Naets
Rolling contact is frequently modeled for simulating engineering systems (e.g. tires or bearings). When accounting for geometric and material nonlinearity, model order reduction (MOR) becomes essential to reduce the computational costs of dynamic simulations. Addressing nonlinear systems with distributed nonlinearities in combination with large areas of rough surface contact and a dynamically changing active set presents a challenge for state-of-the-art MOR methods. Therefore, a tailored a-priori MOR approach to address large deformation rolling contact for cyclically symmetric systems is presented.
We propose a novel two-step, projection-based nonlinear MOR for rolling contact. In the first step, the reduction basis based on the Multi Expansion Modal method is transformed to a Generalized Component Mode Synthesis framework to achieve rotational invariance of the basis. To capture the nonlinear variations due to rotation and the resulting change of the active contact area, an interpolation approach is employed to adjust the basis accordingly. In the second step, the Energy Conserving Sampling and Weighting hyper reduction parameters are also adapted through interpolation.
The proposed method is validated for the case of a Grosch wheel rotating on a smooth surface and a tire rotating on a rough road. In both cases, the reduced-order model accurately replicates the full-order model’s dynamic behavior. While the speedup is limited in the Grosch wheel case, significant speedup is achieved for a nonlinear tire model with a maximum speedup factor of 20.
{"title":"A reduced order modeling strategy for nonlinear elasto-dynamic systems with cyclic symmetry in rolling contact","authors":"Lukas Bürger , Régis Boukadia , Frank Naets","doi":"10.1016/j.jsv.2026.119645","DOIUrl":"10.1016/j.jsv.2026.119645","url":null,"abstract":"<div><div>Rolling contact is frequently modeled for simulating engineering systems (e.g. tires or bearings). When accounting for geometric and material nonlinearity, model order reduction (MOR) becomes essential to reduce the computational costs of dynamic simulations. Addressing nonlinear systems with distributed nonlinearities in combination with large areas of rough surface contact and a dynamically changing active set presents a challenge for state-of-the-art MOR methods. Therefore, a tailored a-priori MOR approach to address large deformation rolling contact for cyclically symmetric systems is presented.</div><div>We propose a novel two-step, projection-based nonlinear MOR for rolling contact. In the first step, the reduction basis based on the Multi Expansion Modal method is transformed to a Generalized Component Mode Synthesis framework to achieve rotational invariance of the basis. To capture the nonlinear variations due to rotation and the resulting change of the active contact area, an interpolation approach is employed to adjust the basis accordingly. In the second step, the Energy Conserving Sampling and Weighting hyper reduction parameters are also adapted through interpolation.</div><div>The proposed method is validated for the case of a Grosch wheel rotating on a smooth surface and a tire rotating on a rough road. In both cases, the reduced-order model accurately replicates the full-order model’s dynamic behavior. While the speedup is limited in the Grosch wheel case, significant speedup is achieved for a nonlinear tire model with a maximum speedup factor of 20.</div></div>","PeriodicalId":17233,"journal":{"name":"Journal of Sound and Vibration","volume":"626 ","pages":"Article 119645"},"PeriodicalIF":4.9,"publicationDate":"2026-01-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145977918","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2026-01-07DOI: 10.1016/j.jsv.2026.119641
Berkay Acar, Sedef Nisan Otlu, Zafer Gokay Tetik, Cetin Yilmaz
Size plays a crucial role in designing and realizing 3D phononic crystals and elastic metamaterials with ultrawide band gaps. Existing 3D designs with normalized bandwidth larger than 133.3% are typically fabricated from polymers by additive manufacturing in small sizes (lattice constant ≤ 50 mm). Achieving large bandwidths often requires thin ligaments (flexures), which can fail or deform significantly under self-weight when scaled up, affecting unit cell shape and normalized bandwidth. To mitigate stress and deformation problems at larger scales, a modular design is introduced, enabling separate production of high and low stress-bearing components for assembly. A 3D truss-like structure is formed using steel inertial amplification mechanisms as 600 mm truss elements. Optimization yields a wide stop band but results in thin flexures within these mechanisms. To minimize the stresses and deformations in the inertially amplified 3D truss structure, which weighs more than 100 kg, static weight compensation technique is proposed in which some of the flexures are prestressed to a targeted value before assembly. Consequently, very small static deflection is observed due to self-weight. The optimized 3D truss structure is manufactured and tested. It is revealed that the optimized design provides a complete ultrawide stop band for 3D excitations between 6.2 - 87.8 Hz. Despite the large size and weight, and the stress constraints, an ultrawide band gap (173.6%) is attained.
{"title":"Scaling Up 3D elastic metamaterials with ultrawide band gaps: A modular approach with weight compensation","authors":"Berkay Acar, Sedef Nisan Otlu, Zafer Gokay Tetik, Cetin Yilmaz","doi":"10.1016/j.jsv.2026.119641","DOIUrl":"10.1016/j.jsv.2026.119641","url":null,"abstract":"<div><div>Size plays a crucial role in designing and realizing 3D phononic crystals and elastic metamaterials with ultrawide band gaps. Existing 3D designs with normalized bandwidth larger than 133.3% are typically fabricated from polymers by additive manufacturing in small sizes (lattice constant ≤ 50 mm). Achieving large bandwidths often requires thin ligaments (flexures), which can fail or deform significantly under self-weight when scaled up, affecting unit cell shape and normalized bandwidth. To mitigate stress and deformation problems at larger scales, a modular design is introduced, enabling separate production of high and low stress-bearing components for assembly. A 3D truss-like structure is formed using steel inertial amplification mechanisms as 600 mm truss elements. Optimization yields a wide stop band but results in thin flexures within these mechanisms. To minimize the stresses and deformations in the inertially amplified 3D truss structure, which weighs more than 100 kg, static weight compensation technique is proposed in which some of the flexures are prestressed to a targeted value before assembly. Consequently, very small static deflection is observed due to self-weight. The optimized 3D truss structure is manufactured and tested. It is revealed that the optimized design provides a complete ultrawide stop band for 3D excitations between 6.2 - 87.8 Hz. Despite the large size and weight, and the stress constraints, an ultrawide band gap (173.6%) is attained.</div></div>","PeriodicalId":17233,"journal":{"name":"Journal of Sound and Vibration","volume":"626 ","pages":"Article 119641"},"PeriodicalIF":4.9,"publicationDate":"2026-01-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145977914","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2026-01-07DOI: 10.1016/j.jsv.2026.119642
Sylvain C. Humbert , Alessandro Orchini
The impacts of non-uniform flame response distributions on the stability of azimuthal thermoacoustic modes in annular combustors are investigated theoretically and illustrated in an experimental annular combustor test-rig with electroacoustic feedback. First, we exploit analytical results from an existing reduced-order model to establish and apply a general passive control strategy based on flame response staging to mitigate thermoacoustic instabilities stemming from both degenerate and non-degenerate eigenvalues. By means of a suitable pattern, an acoustics-flame response interaction that has a destabilising effect in the baseline symmetric configuration can be suppressed or turned into a stabilising interaction. For a mode pair whose degeneracy is lifted by the flame response staging pattern, our mitigation strategy exploits the presence of symmetry-breaking-induced exceptional points, which were recently identified in a previous study. The mitigation rules obtained when considering a degenerate or a non-degenerate mode in an isolated fashion are finally combined to establish a multi-mode strategy to prevent all azimuthal modes from being linearly unstable. The mitigation strategy is devised using a low-order model, and validated using an existing experimentally-determined state-space model and experiments in an electroacoustic feedback annular combustor test-rig. In addition, we show that if accurate estimates of the acoustic and thermoacoustic eigenvalues in the reference (symmetric) configuration are available, they can be exploited to calibrate the low-order model and then analytically predict the eigenvalues in the asymmetric configurations with good accuracy.
{"title":"Suppressing azimuthal thermoacoustic instabilities through symmetry-breaking flame response staging and exceptional points","authors":"Sylvain C. Humbert , Alessandro Orchini","doi":"10.1016/j.jsv.2026.119642","DOIUrl":"10.1016/j.jsv.2026.119642","url":null,"abstract":"<div><div>The impacts of non-uniform flame response distributions on the stability of azimuthal thermoacoustic modes in annular combustors are investigated theoretically and illustrated in an experimental annular combustor test-rig with electroacoustic feedback. First, we exploit analytical results from an existing reduced-order model to establish and apply a general passive control strategy based on flame response staging to mitigate thermoacoustic instabilities stemming from both degenerate and non-degenerate eigenvalues. By means of a suitable pattern, an acoustics-flame response interaction that has a destabilising effect in the baseline symmetric configuration can be suppressed or turned into a stabilising interaction. For a mode pair whose degeneracy is lifted by the flame response staging pattern, our mitigation strategy exploits the presence of symmetry-breaking-induced exceptional points, which were recently identified in a previous study. The mitigation rules obtained when considering a degenerate or a non-degenerate mode in an isolated fashion are finally combined to establish a multi-mode strategy to prevent all azimuthal modes from being linearly unstable. The mitigation strategy is devised using a low-order model, and validated using an existing experimentally-determined state-space model and experiments in an electroacoustic feedback annular combustor test-rig. In addition, we show that if accurate estimates of the acoustic and thermoacoustic eigenvalues in the reference (symmetric) configuration are available, they can be exploited to calibrate the low-order model and then analytically predict the eigenvalues in the asymmetric configurations with good accuracy.</div></div>","PeriodicalId":17233,"journal":{"name":"Journal of Sound and Vibration","volume":"628 ","pages":"Article 119642"},"PeriodicalIF":4.9,"publicationDate":"2026-01-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145986744","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2026-01-06DOI: 10.1016/j.jsv.2026.119644
Chunlin Jia , Zhanyu Li , Zixuan Yu , Hongkuan Zhang , Gengkai Hu
Accurately reconstructing scatterers within closed regions from sparse acoustic measurements presents a challenging inverse problem. Deep learning techniques are widely regarded as effective tools for solving such complex issues. However, conventional approaches often incur significant computational burdens by relying on massive training datasets to boost prediction accuracy. This paper presents an innovative approach that substantially improves network performance not by data augmentation, but by explicitly incorporating physical knowledge through adjoint-derived gradients. The method involves two synergistic stages: firstly, a physics-informed forward model is constructed by integrating gradient information via the adjoint method, which achieves 87 % higher accuracy in acoustic pressure prediction compared to standard data-driven counterparts on the test set; secondly, utilizing the trained forward network as a surrogate model to generate large-scale synthetic datasets for training a robust inverse estimation network. Results demonstrate superior performance: on independent test data, 99.94 % precision in determining scatterer count and high-precision reconstruction with localization resolution of 1/42 wavelength and radius resolution of 1/401 wavelength. Crucially, the method excels even in challenging acoustic shadow zones, surpassing traditional techniques. As the adjoint method is fundamental to sensitivity analysis across computational physics, this gradient-constrained framework can be readily extended to other inverse problems (including inverse electromagnetic scattering and elastic wave-based nondestructive testing) and gradient-based optimization applications like topology optimization, providing a pathway to enhanced accuracy with reduced data dependency.
{"title":"Enhancing acoustic scatterer inversion in closed domains with gradient-constrained deep learning","authors":"Chunlin Jia , Zhanyu Li , Zixuan Yu , Hongkuan Zhang , Gengkai Hu","doi":"10.1016/j.jsv.2026.119644","DOIUrl":"10.1016/j.jsv.2026.119644","url":null,"abstract":"<div><div>Accurately reconstructing scatterers within closed regions from sparse acoustic measurements presents a challenging inverse problem. Deep learning techniques are widely regarded as effective tools for solving such complex issues. However, conventional approaches often incur significant computational burdens by relying on massive training datasets to boost prediction accuracy. This paper presents an innovative approach that substantially improves network performance not by data augmentation, but by explicitly incorporating physical knowledge through adjoint-derived gradients. The method involves two synergistic stages: firstly, a physics-informed forward model is constructed by integrating gradient information via the adjoint method, which achieves 87 % higher accuracy in acoustic pressure prediction compared to standard data-driven counterparts on the test set; secondly, utilizing the trained forward network as a surrogate model to generate large-scale synthetic datasets for training a robust inverse estimation network. Results demonstrate superior performance: on independent test data, 99.94 % precision in determining scatterer count and high-precision reconstruction with localization resolution of 1/42 wavelength and radius resolution of 1/401 wavelength. Crucially, the method excels even in challenging acoustic shadow zones, surpassing traditional techniques. As the adjoint method is fundamental to sensitivity analysis across computational physics, this gradient-constrained framework can be readily extended to other inverse problems (including inverse electromagnetic scattering and elastic wave-based nondestructive testing) and gradient-based optimization applications like topology optimization, providing a pathway to enhanced accuracy with reduced data dependency.</div></div>","PeriodicalId":17233,"journal":{"name":"Journal of Sound and Vibration","volume":"626 ","pages":"Article 119644"},"PeriodicalIF":4.9,"publicationDate":"2026-01-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145977919","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2026-01-05DOI: 10.1016/j.jsv.2025.119635
Jinyue Yang , Thomas Humbert , Joachim Golliard , Gwénaël Gabard
Impedance eduction of acoustic liners with flow is usually performed under the assumption of a uniform mean flow and in the presence of an incident plane wave. However, recent studies have demonstrated that shear flow significantly influences the propagation of sound waves and their interaction with the liner. Consequently, it is crucial to characterize acoustic treatments in flow and acoustic conditions that closely resemble their target application, such as aircraft nacelles. This paper investigates and validates experimentally a direct method of impedance eduction in multimodal sound fields with shear flows on the MAINE Flow facility, which was validated only through simulations. Besides the double-liner configuration proposed to enhance the eduction robustness, additional developments are implemented, including a dominant mode selection algorithm to address the complexity introduced by multimodal fields and a 2-line microphone array design to avoid spurious mode effects. Different high-order incident modes (in the direction normal to the liner) are also considered. Finally, the recommended setup, with two types of liner samples, are used to investigate the effects of flow and incident acoustic field on liner impedance. It is also observed that using antisymmetric high-order modes as incident field significantly enhances the robustness of the eduction process.
{"title":"Direct impedance eduction of acoustic liners in multimodal ducts with shear flows","authors":"Jinyue Yang , Thomas Humbert , Joachim Golliard , Gwénaël Gabard","doi":"10.1016/j.jsv.2025.119635","DOIUrl":"10.1016/j.jsv.2025.119635","url":null,"abstract":"<div><div>Impedance eduction of acoustic liners with flow is usually performed under the assumption of a uniform mean flow and in the presence of an incident plane wave. However, recent studies have demonstrated that shear flow significantly influences the propagation of sound waves and their interaction with the liner. Consequently, it is crucial to characterize acoustic treatments in flow and acoustic conditions that closely resemble their target application, such as aircraft nacelles. This paper investigates and validates experimentally a direct method of impedance eduction in multimodal sound fields with shear flows on the MAINE Flow facility, which was validated only through simulations. Besides the double-liner configuration proposed to enhance the eduction robustness, additional developments are implemented, including a dominant mode selection algorithm to address the complexity introduced by multimodal fields and a 2-line microphone array design to avoid spurious mode effects. Different high-order incident modes (in the direction normal to the liner) are also considered. Finally, the recommended setup, with two types of liner samples, are used to investigate the effects of flow and incident acoustic field on liner impedance. It is also observed that using antisymmetric high-order modes as incident field significantly enhances the robustness of the eduction process.</div></div>","PeriodicalId":17233,"journal":{"name":"Journal of Sound and Vibration","volume":"626 ","pages":"Article 119635"},"PeriodicalIF":4.9,"publicationDate":"2026-01-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145927365","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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