Pub Date : 2025-12-05DOI: 10.1016/j.jsv.2025.119598
Jens D. Richardt , Boris Lossouarn , Jan Høgsberg , Jean-François Deü
Effective vibration reduction of mechanical structures by piezoelectric shunt damping requires a precise design of the electrical shunt circuit. In this context, the influence of dielectric losses on the accuracy of shunt calibration is analyzed. Numerical analysis of an SDOF structure shows that dielectric losses can result in a significantly increased vibration amplitude when not accounted for in the calibration of a resonant shunt. To address this, a new correction method based on impedance matching is proposed, enabling the use of existing tuning expressions not accounting for dielectric losses. It is demonstrated numerically and experimentally that the influence of dielectric losses is more pronounced for low electromechanical coupling factors. The proposed correction method is shown to provide an accurate correction for the influence of dielectric losses on the shunt tuning.
{"title":"Accounting for dielectric losses in piezoelectric shunt tuning","authors":"Jens D. Richardt , Boris Lossouarn , Jan Høgsberg , Jean-François Deü","doi":"10.1016/j.jsv.2025.119598","DOIUrl":"10.1016/j.jsv.2025.119598","url":null,"abstract":"<div><div>Effective vibration reduction of mechanical structures by piezoelectric shunt damping requires a precise design of the electrical shunt circuit. In this context, the influence of dielectric losses on the accuracy of shunt calibration is analyzed. Numerical analysis of an SDOF structure shows that dielectric losses can result in a significantly increased vibration amplitude when not accounted for in the calibration of a resonant shunt. To address this, a new correction method based on impedance matching is proposed, enabling the use of existing tuning expressions not accounting for dielectric losses. It is demonstrated numerically and experimentally that the influence of dielectric losses is more pronounced for low electromechanical coupling factors. The proposed correction method is shown to provide an accurate correction for the influence of dielectric losses on the shunt tuning.</div></div>","PeriodicalId":17233,"journal":{"name":"Journal of Sound and Vibration","volume":"625 ","pages":"Article 119598"},"PeriodicalIF":4.9,"publicationDate":"2025-12-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145787935","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 : 2025-12-05DOI: 10.1016/j.jsv.2025.119573
Xiaozhe Chen , Baitong Zhou , Vladislav Sorokin
In this paper, the Sommerfeld effect in a non-ideal vibrational system with two degrees of freedom driven by an AC motor is investigated. The interaction between the AC motor and the vibration system is explored, leading to the development of a dynamical model and the establishment of the governing differential equations of motion. Subsequently, the motion coupling is considered by the analysis of the electromagnetic torque of the AC motor. The first-order approximate solution of the equations is then obtained by using the averaging method, and the torque balance equation is derived. Based on this torque balance condition, the characteristics of the Sommerfeld effect in the system are analyzed. The existence of multiple steady-state motions in the system is confirmed by experimental results for both sweep and fixed-frequency excitations, which are supported by the theoretical analysis. Furthermore, the occurrence of the Sommerfeld effect is identified through the parameters of the AC motor, which are monitored by the programmable logic controller. It is noted that in engineering applications, the electrical input and unbalanced mass of the AC motor can be utilized for the suppression of the Sommerfeld effect in vibrating systems.
{"title":"Sommerfeld effect of non-ideal double-body vibration system driven by AC motor","authors":"Xiaozhe Chen , Baitong Zhou , Vladislav Sorokin","doi":"10.1016/j.jsv.2025.119573","DOIUrl":"10.1016/j.jsv.2025.119573","url":null,"abstract":"<div><div>In this paper, the Sommerfeld effect in a non-ideal vibrational system with two degrees of freedom driven by an AC motor is investigated. The interaction between the AC motor and the vibration system is explored, leading to the development of a dynamical model and the establishment of the governing differential equations of motion. Subsequently, the motion coupling is considered by the analysis of the electromagnetic torque of the AC motor. The first-order approximate solution of the equations is then obtained by using the averaging method, and the torque balance equation is derived. Based on this torque balance condition, the characteristics of the Sommerfeld effect in the system are analyzed. The existence of multiple steady-state motions in the system is confirmed by experimental results for both sweep and fixed-frequency excitations, which are supported by the theoretical analysis. Furthermore, the occurrence of the Sommerfeld effect is identified through the parameters of the AC motor, which are monitored by the programmable logic controller. It is noted that in engineering applications, the electrical input and unbalanced mass of the AC motor can be utilized for the suppression of the Sommerfeld effect in vibrating systems.</div></div>","PeriodicalId":17233,"journal":{"name":"Journal of Sound and Vibration","volume":"625 ","pages":"Article 119573"},"PeriodicalIF":4.9,"publicationDate":"2025-12-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145787936","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 : 2025-12-04DOI: 10.1016/j.jsv.2025.119599
Jianqiang Pan , Leyan Yang , Fei Qi , Pengfei Zou , Liangliang Xu , Weikang Jiang
Identification of azimuthal and radial modes in non-uniform cylindrical ducts with varying diameters is crucial for investigating noise reduction and combustion instability in aero-engines or gas turbines. However, conventional mode identification techniques face difficulties in establishing the observation matrix coefficients that arise from variations in the duct diameter. To address this issue, a methodology based on the Wentzel–Kramers–Brillouin approximation is proposed to accomplish the mode identification and reconstruction of the sound field in the cylindrical duct with varying diameters. It provides the amplitude and phase variation rules of its observation coefficients in the axial direction while preserving the orthogonality of the mode basis functions. The effects of turning points and mode scattering are considered, and guidelines for applying the new method are established. It is verified by simulation using inputs of dominant higher-order radial modes. The results demonstrate a high signal-to-noise ratio while effectively analyzing the impacts of microphone array configuration, cut-on modes selection, and the setting of observation matrix coefficients. Experimental results show that the reconstructed sound field matches the sound field measured by microphones. This validates the effectiveness of the proposed method and highlights its promising potential in engineering applications.
{"title":"Identification of acoustic modes in non-uniform cylindrical ducts with slowly varying diameters","authors":"Jianqiang Pan , Leyan Yang , Fei Qi , Pengfei Zou , Liangliang Xu , Weikang Jiang","doi":"10.1016/j.jsv.2025.119599","DOIUrl":"10.1016/j.jsv.2025.119599","url":null,"abstract":"<div><div>Identification of azimuthal and radial modes in non-uniform cylindrical ducts with varying diameters is crucial for investigating noise reduction and combustion instability in aero-engines or gas turbines. However, conventional mode identification techniques face difficulties in establishing the observation matrix coefficients that arise from variations in the duct diameter. To address this issue, a methodology based on the Wentzel–Kramers–Brillouin approximation is proposed to accomplish the mode identification and reconstruction of the sound field in the cylindrical duct with varying diameters. It provides the amplitude and phase variation rules of its observation coefficients in the axial direction while preserving the orthogonality of the mode basis functions. The effects of turning points and mode scattering are considered, and guidelines for applying the new method are established. It is verified by simulation using inputs of dominant higher-order radial modes. The results demonstrate a high signal-to-noise ratio while effectively analyzing the impacts of microphone array configuration, cut-on modes selection, and the setting of observation matrix coefficients. Experimental results show that the reconstructed sound field matches the sound field measured by microphones. This validates the effectiveness of the proposed method and highlights its promising potential in engineering applications.</div></div>","PeriodicalId":17233,"journal":{"name":"Journal of Sound and Vibration","volume":"625 ","pages":"Article 119599"},"PeriodicalIF":4.9,"publicationDate":"2025-12-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145734764","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 : 2025-12-03DOI: 10.1016/j.jsv.2025.119600
Alok Sinha
This paper deals with the stability and forced response of a bladed disk under fluctuating rotor speed which leads to time varying blades’ stiffnesses. Inevitable small variations in blades’ stiffnesses due to manufacturing tolerances result in time-varying mistuning. Using the method of slowly varying parameters, stability conditions are obtained analytically and verified by numerical solution of governing differential equations. The stabilizing effects of random and alternate mistuning are investigated in the presence of time varying blades’ stiffnesses. For stable bladed disks with time-varying random mistuning and with constant random mistuning, statistical distributions of the peak maximum amplitude are generated via Monte Carlo simulations at 0.1% and 1% damping ratios.
{"title":"Vibration of a mistuned bladed disk under fluctuating rotor speed","authors":"Alok Sinha","doi":"10.1016/j.jsv.2025.119600","DOIUrl":"10.1016/j.jsv.2025.119600","url":null,"abstract":"<div><div>This paper deals with the stability and forced response of a bladed disk under fluctuating rotor speed which leads to time varying blades’ stiffnesses. Inevitable small variations in blades’ stiffnesses due to manufacturing tolerances result in time-varying mistuning. Using the method of slowly varying parameters, stability conditions are obtained analytically and verified by numerical solution of governing differential equations. The stabilizing effects of random and alternate mistuning are investigated in the presence of time varying blades’ stiffnesses. For stable bladed disks with time-varying random mistuning and with constant random mistuning, statistical distributions of the peak maximum amplitude are generated via Monte Carlo simulations at 0.1% and 1% damping ratios.</div></div>","PeriodicalId":17233,"journal":{"name":"Journal of Sound and Vibration","volume":"625 ","pages":"Article 119600"},"PeriodicalIF":4.9,"publicationDate":"2025-12-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145734763","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 : 2025-12-01DOI: 10.1016/j.jsv.2025.119587
Gyan Setu, A K Darpe, B Premachandran
An assembly of a disc shrink-fitted on a shaft are widely used in industry to provide a tight mounting enabling a positive drive. Although this kind of mounting alleviates the need for keyways and keys, the contact pressure from the interference fit generates localized stress and deformation in the shaft and the mounted disc. The increased stress may influence the natural frequencies and the dynamics of the shaft depending on the disc/hub dimensions. Earlier, the effect of such a disc mounting was accounted for in the model by raising the diameter of the shaft at the mounting location, without systematically studying the effect of the varying degree of the interference fit. The present work introduces a novel analytical approach to account for the shrink-fit of the mounted disc on the shaft for different interference fit levels and shaft-disc configurations (disc diameter and thickness). The contact pressure due to shrink fit is modelled as a uniform axisymmetric pressure band in the shrink fit region. The stress and deformation in the shaft and disc are evaluated using the Fourier-Bessel formulation. The proposed method utilizes mathematical formulation to evaluate the fit-induced axial stress and the corresponding increase in the stiffness. The method then estimates the required diameter of the step at the shrink-fit region more precisely than predicted by a previous approach. The objective is also to investigate the extent of the influence of the induced local stress due to the shrink fit on the bending natural frequency of the shaft-disc assembly. To validate the proposed approach, an experimental modal analysis is performed on the test specimen with shrink fit and the measured natural frequencies are compared with the calculated ones. The experimental natural frequencies for off-center shaft-disc configurations and overhung shaft-hub configurations are within 5 % of those obtained theoretically, signifying the capability of the proposed mathematical approach to model the shrink-fit assembly accurately. In contrast to the empirical approach of modeling the shrink fit, the novel modelling approach presented in the paper offers a systematic and better way of modeling and of accurately predicting the associated bending natural frequencies.
{"title":"A new modeling approach for an eigenvalue analysis of a shrink-fitted shaft-disc assembly","authors":"Gyan Setu, A K Darpe, B Premachandran","doi":"10.1016/j.jsv.2025.119587","DOIUrl":"10.1016/j.jsv.2025.119587","url":null,"abstract":"<div><div>An assembly of a disc shrink-fitted on a shaft are widely used in industry to provide a tight mounting enabling a positive drive. Although this kind of mounting alleviates the need for keyways and keys, the contact pressure from the interference fit generates localized stress and deformation in the shaft and the mounted disc. The increased stress may influence the natural frequencies and the dynamics of the shaft depending on the disc/hub dimensions. Earlier, the effect of such a disc mounting was accounted for in the model by raising the diameter of the shaft at the mounting location, without systematically studying the effect of the varying degree of the interference fit. The present work introduces a novel analytical approach to account for the shrink-fit of the mounted disc on the shaft for different interference fit levels and shaft-disc configurations (disc diameter and thickness). The contact pressure due to shrink fit is modelled as a uniform axisymmetric pressure band in the shrink fit region. The stress and deformation in the shaft and disc are evaluated using the Fourier-Bessel formulation. The proposed method utilizes mathematical formulation to evaluate the fit-induced axial stress and the corresponding increase in the stiffness. The method then estimates the required diameter of the step at the shrink-fit region more precisely than predicted by a previous approach. The objective is also to investigate the extent of the influence of the induced local stress due to the shrink fit on the bending natural frequency of the shaft-disc assembly. To validate the proposed approach, an experimental modal analysis is performed on the test specimen with shrink fit and the measured natural frequencies are compared with the calculated ones. The experimental natural frequencies for off-center shaft-disc configurations and overhung shaft-hub configurations are within 5 % of those obtained theoretically, signifying the capability of the proposed mathematical approach to model the shrink-fit assembly accurately. In contrast to the empirical approach of modeling the shrink fit, the novel modelling approach presented in the paper offers a systematic and better way of modeling and of accurately predicting the associated bending natural frequencies.</div></div>","PeriodicalId":17233,"journal":{"name":"Journal of Sound and Vibration","volume":"625 ","pages":"Article 119587"},"PeriodicalIF":4.9,"publicationDate":"2025-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145683818","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 : 2025-12-01DOI: 10.1016/j.jsv.2025.119559
Yin Zhang , Han Wu
Four types of springs, which are widely used to model the beam defects and stiffening effects, induce the discontinuities of the beam displacement and its first, second and third derivatives. These discontinuities can either increase or decrease the beam stiffness. The variations of beam stiffness change its natural frequencies and mode shapes. The four types of springs are modeled as the concentrated ones, which are characterized by the generalized functions of the Dirac delta function and its derivatives. The new analytical solutions to the free vibration of the Euler–Bernoulli beam with these four discontinuities are derived. By constructing the proper solution forms and using the distributional derivative rule of the generalized functions, the new analytical solutions are derived, which are the direct solutions to the fourth order differential equation of the Euler–Bernoulli beam governing equation with the presence of the generalized functions. The analytical solutions are with the advantage of satisfying all the transition conditions. With the analytical solutions, the eigenvalue problem formulation only involves the beam boundary conditions, which is a 4 × 4 matrix computation and significantly simplifies the problem formulation procedure. This new eigenvalue problem formulation provides an efficient method of computing the natural frequencies and mode shapes of the beam with the discontinuities caused by the springs. Besides the defects and stiffening effects, the beam boundaries can also be modeled by these four types of springs. With the different combinations of the four types of springs, various and general beam boundary conditions are formed. With the models of these four types of springs, the analytical solution to the free vibration of a beam with more general defects, stiffening effects and boundary conditions is presented.
{"title":"Analytical solutions to free vibration of beam with discontinuities caused by springs","authors":"Yin Zhang , Han Wu","doi":"10.1016/j.jsv.2025.119559","DOIUrl":"10.1016/j.jsv.2025.119559","url":null,"abstract":"<div><div>Four types of springs, which are widely used to model the beam defects and stiffening effects, induce the discontinuities of the beam displacement and its first, second and third derivatives. These discontinuities can either increase or decrease the beam stiffness. The variations of beam stiffness change its natural frequencies and mode shapes. The four types of springs are modeled as the concentrated ones, which are characterized by the generalized functions of the Dirac delta function and its derivatives. The new analytical solutions to the free vibration of the Euler–Bernoulli beam with these four discontinuities are derived. By constructing the proper solution forms and using the distributional derivative rule of the generalized functions, the new analytical solutions are derived, which are the direct solutions to the fourth order differential equation of the Euler–Bernoulli beam governing equation with the presence of the generalized functions. The analytical solutions are with the advantage of satisfying all the transition conditions. With the analytical solutions, the eigenvalue problem formulation only involves the beam boundary conditions, which is a 4 × 4 matrix computation and significantly simplifies the problem formulation procedure. This new eigenvalue problem formulation provides an efficient method of computing the natural frequencies and mode shapes of the beam with the discontinuities caused by the springs. Besides the defects and stiffening effects, the beam boundaries can also be modeled by these four types of springs. With the different combinations of the four types of springs, various and general beam boundary conditions are formed. With the models of these four types of springs, the analytical solution to the free vibration of a beam with more general defects, stiffening effects and boundary conditions is presented.</div></div>","PeriodicalId":17233,"journal":{"name":"Journal of Sound and Vibration","volume":"625 ","pages":"Article 119559"},"PeriodicalIF":4.9,"publicationDate":"2025-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145683921","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 : 2025-12-01DOI: 10.1016/j.jsv.2025.119571
Nidish Narayanaa Balaji , Erhan Ferhatoglu
Dynamic responses of friction-damped structures often exhibit significant variability due to uncertainties inherent in both contact parameters and residual tractions. While the former are closely related to the epistemic description of the interfacial contact, the latter reflects the loading history. Although previous studies have individually examined the impact of these uncertainties on the response variability, their simultaneous consideration with a comparative quantification remains unexplored. To address this gap, we present a parametric analysis in the context of uncertainty propagation and sensitivity analysis using Polynomial Chaos Expansion. In this study, the variability of the amplitude-dependent nonlinear modal properties due to the above uncertainties are examined as a metric to assess the influence of such parameters on the overall dynamics. We use a planar 3-mass frictional oscillator representing a simplified model of two adjacent blades with an underplatform damper as the numerical benchmark for the investigations. The influence of different probability distributions is investigated and it is shown that frequency variability is predominantly governed by the uncertainty in tangential contact stiffness. On the other hand, the damping behavior in the partial slip regime is highly sensitive to the non-unique nature of residual tractions. While contact parameter uncertainty is widely recognized as a primary source of vibration response variability within the joint mechanics community, the findings of this study underline the critical importance of accounting for the non-unique nature of residual tractions.
{"title":"Vibration response variability in friction-damped systems: Quantification of the influence of contact and traction uncertainties","authors":"Nidish Narayanaa Balaji , Erhan Ferhatoglu","doi":"10.1016/j.jsv.2025.119571","DOIUrl":"10.1016/j.jsv.2025.119571","url":null,"abstract":"<div><div>Dynamic responses of friction-damped structures often exhibit significant variability due to uncertainties inherent in both contact parameters and residual tractions. While the former are closely related to the epistemic description of the interfacial contact, the latter reflects the loading history. Although previous studies have individually examined the impact of these uncertainties on the response variability, their simultaneous consideration with a comparative quantification remains unexplored. To address this gap, we present a parametric analysis in the context of uncertainty propagation and sensitivity analysis using Polynomial Chaos Expansion. In this study, the variability of the amplitude-dependent nonlinear modal properties due to the above uncertainties are examined as a metric to assess the influence of such parameters on the overall dynamics. We use a planar 3-mass frictional oscillator representing a simplified model of two adjacent blades with an underplatform damper as the numerical benchmark for the investigations. The influence of different probability distributions is investigated and it is shown that frequency variability is predominantly governed by the uncertainty in tangential contact stiffness. On the other hand, the damping behavior in the partial slip regime is highly sensitive to the non-unique nature of residual tractions. While contact parameter uncertainty is widely recognized as a primary source of vibration response variability within the joint mechanics community, the findings of this study underline the critical importance of accounting for the non-unique nature of residual tractions.</div></div>","PeriodicalId":17233,"journal":{"name":"Journal of Sound and Vibration","volume":"625 ","pages":"Article 119571"},"PeriodicalIF":4.9,"publicationDate":"2025-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145734778","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 : 2025-12-01DOI: 10.1016/j.jsv.2025.119588
Tian Ruilan , Wang Minghao , Zhang Xiaolong , Wang wei , Feng Wenjie
Stiffness hardening restricts the advancement of quasi-zero-stiffness vibration isolators (QZSVIs), due to inadequate matching degree of positive and negatives stiffness. To overcome this barrier, inspired by the deformation behavior of the spring wire in variable-pitch nonlinear springs (VPNSs), an engagement model (EM) is proposed to accurately tailor the nonlinear positive stiffness characteristics of the VPNS to match the targeted negative stiffness. And the mechanical levitation (ML) phenomenon is discovered, which inhibits the energy conversion from potential to kinetic energy in a conservative system, making it highly suitable for constructing ultra-low-frequency vibration isolators. Due to the sensitivity of the ML phenomenon to stiffness fluctuations, a friction lock-up (FLU) regulation function is established to reduce this sensitivity and suppress the amplification of response amplitude. Then, a mechanical levitation system (MLS) is constructed to suppress ultra-low-frequency vibrations. The results demonstrate that the EM reduces the maximum absolute stiffness error of the VPNS by approximately 90 % and successfully eliminates stiffness hardening. Based on the FLU, the vibration isolation performance of the MLS achieves a 75 % improvement in implementing a natural frequency close to 0 Hz. The transmissibility is about -8 dB at 1 Hz and -20 dB at 5 Hz. The results provide a new method for stiffness hardening inhibition and a new direction for the advancement of ultra-low-frequency vibration isolation technologies.
{"title":"Mechanical levitation system for ultra-low-frequency vibration isolation","authors":"Tian Ruilan , Wang Minghao , Zhang Xiaolong , Wang wei , Feng Wenjie","doi":"10.1016/j.jsv.2025.119588","DOIUrl":"10.1016/j.jsv.2025.119588","url":null,"abstract":"<div><div>Stiffness hardening restricts the advancement of quasi-zero-stiffness vibration isolators (QZSVIs), due to inadequate matching degree of positive and negatives stiffness. To overcome this barrier, inspired by the deformation behavior of the spring wire in variable-pitch nonlinear springs (VPNSs), an engagement model (EM) is proposed to accurately tailor the nonlinear positive stiffness characteristics of the VPNS to match the targeted negative stiffness. And the mechanical levitation (ML) phenomenon is discovered, which inhibits the energy conversion from potential to kinetic energy in a conservative system, making it highly suitable for constructing ultra-low-frequency vibration isolators. Due to the sensitivity of the ML phenomenon to stiffness fluctuations, a friction lock-up (FLU) regulation function is established to reduce this sensitivity and suppress the amplification of response amplitude. Then, a mechanical levitation system (MLS) is constructed to suppress ultra-low-frequency vibrations. The results demonstrate that the EM reduces the maximum absolute stiffness error of the VPNS by approximately 90 % and successfully eliminates stiffness hardening. Based on the FLU, the vibration isolation performance of the MLS achieves a 75 % improvement in implementing a natural frequency close to 0 Hz. The transmissibility is about -8 dB at 1 Hz and -20 dB at 5 Hz. The results provide a new method for stiffness hardening inhibition and a new direction for the advancement of ultra-low-frequency vibration isolation technologies.</div></div>","PeriodicalId":17233,"journal":{"name":"Journal of Sound and Vibration","volume":"625 ","pages":"Article 119588"},"PeriodicalIF":4.9,"publicationDate":"2025-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145734766","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 : 2025-11-30DOI: 10.1016/j.jsv.2025.119572
Thomas J. White, Raphaël C. Assier, William J. Parnell
This paper analyses the propagation of acoustic waves through slowly varying lined ducts via a Wentzel-Kramers-Brillouin (WKB) approach. It is assumed that the curvature of the duct boundary can be related to a small parameter, ϵ, and slowly varying modes can be defined as solutions to the Helmholtz equation. The duct lining is approximated by a surface impedance boundary condition applied at the fluid-duct interface. It is assumed that slowly varying modes exist in the duct and do not reflect or change eigenstate as they propagate. Posing a WKB ansatz, the known leading order asymptotic solution is recovered and corrected to first order, more accurately representing the normal boundary condition, and addressing errors in the pressure field. It is found that, when compared with numerical simulations performed using COMSOL, this solution is unsatisfactory when there are multiple highly cut-on modes for a given frequency. This is due to modal coupling, which is especially prevalent at low frequencies. It is possible to account for the coupling whilst retaining a WKB approach, by defining a coupled mode solution, where the acoustic field is projected over a set of propagating modes which satisfy the true boundary condition. This approach is implemented to and validated against full numerical simulations performed in COMSOL.
{"title":"Sound propagation in slowly varying ducts","authors":"Thomas J. White, Raphaël C. Assier, William J. Parnell","doi":"10.1016/j.jsv.2025.119572","DOIUrl":"10.1016/j.jsv.2025.119572","url":null,"abstract":"<div><div>This paper analyses the propagation of acoustic waves through slowly varying lined ducts via a Wentzel-Kramers-Brillouin (WKB) approach. It is assumed that the curvature of the duct boundary can be related to a small parameter, ϵ, and slowly varying modes can be defined as solutions to the Helmholtz equation. The duct lining is approximated by a surface impedance boundary condition applied at the fluid-duct interface. It is assumed that slowly varying modes exist in the duct and do not reflect or change eigenstate as they propagate. Posing a WKB ansatz, the known leading order asymptotic solution is recovered and corrected to first order, more accurately representing the normal boundary condition, and addressing errors in the pressure field. It is found that, when compared with numerical simulations performed using COMSOL, this solution is unsatisfactory when there are multiple highly cut-on modes for a given frequency. This is due to modal coupling, which is especially prevalent at low frequencies. It is possible to account for the coupling whilst retaining a WKB approach, by defining a coupled mode solution, where the acoustic field is projected over a set of propagating modes which satisfy the true boundary condition. This approach is implemented to <span><math><mrow><mi>O</mi><mo>(</mo><mi>ϵ</mi><mo>)</mo></mrow></math></span> and validated against full numerical simulations performed in COMSOL.</div></div>","PeriodicalId":17233,"journal":{"name":"Journal of Sound and Vibration","volume":"625 ","pages":"Article 119572"},"PeriodicalIF":4.9,"publicationDate":"2025-11-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145837273","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 : 2025-11-30DOI: 10.1016/j.jsv.2025.119575
Harry A. Simpson , Eleni N. Chatzi , Manolis N. Chatzis
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.
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