Journal of Sound and Vibration最新文献

{"title":"Optimal damping adapted to a set of initial conditions","authors":"K. Lelas","doi":"10.1016/j.jsv.2025.119076","DOIUrl":"10.1016/j.jsv.2025.119076","url":null,"abstract":"<div><div>Vibrating systems can respond to an infinite number of initial conditions and the overall dynamics of the system can be strongly affected by them. Therefore, it is of practical importance to have methods by which we can determine the damping that is in some sense optimal for all initial conditions, or for a given set of initial conditions. For a single and multi degree of freedom systems, we determine the optimal damping coefficients adapted to different sets of initial conditions using the known method of minimizing the (zero to infinity) time integral of the energy of the system, averaged over a set of initial conditions, and using two new methods that we introduce. One method is based on determining the damping for which the energy of the system, averaged over a set of initial conditions, drops the fastest to a given threshold value. The other method is based on determining the damping that gives minimal average settling time of the system, where we take that the system settled when its energy dropped to a given threshold value. We show that the two new methods give results for optimal damping that are in excellent agreement with each other, but are significantly different from the results given by the minimization of the average energy integral. More precisely, for considered multi degree of freedom systems and sets of initial conditions, the two new methods give optimal damping coefficients that converge to the critical damping of the first mode as the target energy threshold decreases. On the other hand, for these same systems and sets of initial conditions, the method of minimizing the average energy integral gives optimal damping coefficients which are deep in the overdamped regime with respect to the first mode.</div></div>","PeriodicalId":17233,"journal":{"name":"Journal of Sound and Vibration","volume":"609 ","pages":"Article 119076"},"PeriodicalIF":4.3,"publicationDate":"2025-04-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143776780","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}

{"title":"Dynamic and stability analysis of high-speed maglev train–guideway coupled system under crosswind","authors":"Zun-Di Huang ,&nbsp;Wei-Kai Kong ,&nbsp;Su-Mei Wang ,&nbsp;Zhen-Bin Zhou ,&nbsp;Yi-Qing Ni ,&nbsp;Ning Chang","doi":"10.1016/j.jsv.2025.119092","DOIUrl":"10.1016/j.jsv.2025.119092","url":null,"abstract":"<div><div>Strong crosswinds in coastal areas present significant risks to the safety and performance of high-speed maglev train operations. These winds can lead to deteriorated aerodynamic performance and increased instability, which in turn greatly affect both operational safety and passenger comfort. To address these challenges, this study aimed to develop a comprehensive numerical simulation model that integrates aerodynamic loads, allowing for an in-depth investigation of the dynamic response and characteristics of the high-speed maglev train–guideway system under crosswind conditions. A sophisticated three-dimensional model of the high-speed maglev train–guideway system with 442 degrees of freedom was established, taking into account the levitation and guidance forces exerted by electromagnets, managed through feedback controllers. This model was designed to accurately reflect the interactions between the train and guideway, considering both the aerodynamic and mechanical dynamics involved. To obtain the necessary wind load data, an aerodynamic model of the high-speed maglev train–guideway system was developed and validated against experimental data. The efficiency and accuracy of the established numerical model were rigorously validated by comparing its results with experimental data and other numerical findings. Subsequent analyses focused on the dynamic response and ride comfort of the maglev train, both without and with crosswinds. The impact of varying wind speeds on the dynamic characteristics of the train was also examined. The results indicate that as wind speed increases, the stability of the train system deteriorates significantly, underscoring the critical need for enhanced design and operational strategies to ensure safety and comfort.</div></div>","PeriodicalId":17233,"journal":{"name":"Journal of Sound and Vibration","volume":"609 ","pages":"Article 119092"},"PeriodicalIF":4.3,"publicationDate":"2025-04-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143824095","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}

{"title":"Theoretical analysis and one-step balancing solutions of four types of density harmonic defects in hemispherical resonators","authors":"Lei Meng,&nbsp;Ping Zhou,&nbsp;Dongming Guo","doi":"10.1016/j.jsv.2025.119087","DOIUrl":"10.1016/j.jsv.2025.119087","url":null,"abstract":"<div><div>The performance of hemispherical resonators is highly sensitive to circumferential density harmonic defects. Due to a limited understanding of the imbalances induced by the first three harmonic defects and their corresponding balancing theory, typical resonators operating in the second bending mode often balance only the 4th harmonic defect iteratively. This paper studies unbalanced effects caused by density harmonic defects in the <em>n</em>-th bending mode using elastic thin shell theory. It demonstrates that imbalances are related solely to the (<em>n</em> − 1)-th, <em>n</em>-th, (<em>n</em> + 1)-th, and 2<em>n</em>-th density harmonic defects. Furthermore, identification and balancing equations for the four types of harmonic defects are presented. The existence of one-step balancing solutions is examined, and the one-step balancing solutions are investigated. Fixed balancing orientation can linearize the balancing equations, and balancing the four types of harmonic defects requires a minimum of eight positions. Using the commonly employed hemispherical resonator in the second bending mode as an example, this study offers a complete solution with “arbitrary constant” properties. Numerical calculations indicate that the proposed complete solution achieves an accuracy of 10 ng, and uncertainties in the magnitude of corrections do not lead to divergence. The new theory and method eliminate coupling issues inherent in traditional <em>n</em>-symmetry removal algorithms, reduce the number of balancing iterations, and facilitate quick, efficient, and accurate balancing of high-precision hemispherical resonators.</div></div>","PeriodicalId":17233,"journal":{"name":"Journal of Sound and Vibration","volume":"610 ","pages":"Article 119087"},"PeriodicalIF":4.3,"publicationDate":"2025-04-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143820530","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}

{"title":"Generalized difference mode decomposition for adaptively extracting fault components of rotating machinery under non-stationary conditions","authors":"Sha Wei ,&nbsp;Bingchang Hou ,&nbsp;Dong Wang ,&nbsp;Shulin Liu ,&nbsp;Zhike Peng","doi":"10.1016/j.jsv.2025.119089","DOIUrl":"10.1016/j.jsv.2025.119089","url":null,"abstract":"<div><div>Compared with existing adaptive signal decomposition methods, difference mode decomposition can effectively extract repeated transient signal components caused by rotating machinery faults. It assumes that signal components are separable in the frequency domain while there is a frequency aliasing phenomenon among signal components under non-stationary conditions in practice. Therefore, adaptive extraction of fault components from original vibration signals under non-stationary conditions is still a challenging topic in signal decomposition fields. In this paper, a novel adaptive signal decomposition method called generalized difference mode decomposition (GDMD) is proposed as an extended version of difference mode decomposition. Firstly, the proposed GDMD method transforms non-stationary signals in the time domain into stationary signals in the angular domain by using the resampling technique. Secondly, a physically explainable optimal difference spectrum is obtained to make a distinction between health signals and fault signals based on convex optimization. Besides, positive and negative thresholds of the optimal difference spectrum are automatically determined through change-point analysis. Finally, signal components are reconstructed by utilizing the inverse fast Fourier transform according to the two thresholds. The experimental research on the inner and outer race faults of rolling bearings has demonstrated the effectiveness of the proposed GDMD method in feature extraction and fault diagnosis under non-stationary conditions.</div></div>","PeriodicalId":17233,"journal":{"name":"Journal of Sound and Vibration","volume":"609 ","pages":"Article 119089"},"PeriodicalIF":4.3,"publicationDate":"2025-04-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143815900","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}

{"title":"Simplified equivalent SDOF system for predicting complex dynamic response of 1D and 2D elements under nonuniform dynamic load","authors":"Hezi Y. Grisaro","doi":"10.1016/j.jsv.2025.119090","DOIUrl":"10.1016/j.jsv.2025.119090","url":null,"abstract":"<div><div>The dynamic response of blast-loaded structural elements includes multiple modes of vibrations. An equivalent Single Degree of Freedom (SDOF) system is a popular fast-running engineering tool for design to capture the global behavior of the structural element, assuming a single and dominant Mode of Vibration (MOV). Typical models include a nonuniform load or a concentrated load at the midspan. In a close-in detonation scenario, the dominant mode of vibration differs from uniform loading. This paper develops an equivalent SDOF system to account for a nonuniform dynamic load. A literature review on the characteristics of the dynamic load from close-in detonation is provided. The non-uniform load is used to develop transformation factors based on the uniformity of the load. Next, a simplified approach is analytically developed, where the load is assumed to be uniform, allowing for a simpler system to be solved (similar to common practices in design manuals and commercial software). An equivalent uniform load is applied to achieve the same peak displacement. The method has also been developed for the noncentral detonation of 1D members. The method presented in the paper is validated with detailed Multi-Degree-of-Freedom (MDOF) models of one and 2D elements.</div></div>","PeriodicalId":17233,"journal":{"name":"Journal of Sound and Vibration","volume":"609 ","pages":"Article 119090"},"PeriodicalIF":4.3,"publicationDate":"2025-04-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143824096","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}

{"title":"Measurement, scaling and optimal dimensions of airfoil leading-edge serrations in isotropic turbulence","authors":"Angus Wills,&nbsp;Danielle Moreau,&nbsp;Charitha de Silva,&nbsp;Con Doolan","doi":"10.1016/j.jsv.2025.119079","DOIUrl":"10.1016/j.jsv.2025.119079","url":null,"abstract":"&lt;div&gt;&lt;div&gt;Noise reduction results are presented for a set of leading edge serrations on a flat plate airfoil in isotropic turbulence, obtained from integrated beamforming results. Triangular, sinusoidal, and tangent serration profiles have been investigated, as well as a modified sinusoid which consists of a sinusoid at the tip and a tangent curve at the root. The serrations have a non-dimensional amplitude and wavelength of &lt;span&gt;&lt;math&gt;&lt;mrow&gt;&lt;mi&gt;h&lt;/mi&gt;&lt;mo&gt;/&lt;/mo&gt;&lt;mi&gt;c&lt;/mi&gt;&lt;mo&gt;=&lt;/mo&gt;&lt;mn&gt;0&lt;/mn&gt;&lt;mo&gt;.&lt;/mo&gt;&lt;mn&gt;065&lt;/mn&gt;&lt;/mrow&gt;&lt;/math&gt;&lt;/span&gt; and &lt;span&gt;&lt;math&gt;&lt;mrow&gt;&lt;mi&gt;λ&lt;/mi&gt;&lt;mo&gt;/&lt;/mo&gt;&lt;msub&gt;&lt;mrow&gt;&lt;mi&gt;Λ&lt;/mi&gt;&lt;/mrow&gt;&lt;mrow&gt;&lt;mi&gt;t&lt;/mi&gt;&lt;/mrow&gt;&lt;/msub&gt;&lt;/mrow&gt;&lt;/math&gt;&lt;/span&gt; between 0.7 and 15 respectively, where &lt;span&gt;&lt;math&gt;&lt;mi&gt;h&lt;/mi&gt;&lt;/math&gt;&lt;/span&gt; is the serration amplitude, &lt;span&gt;&lt;math&gt;&lt;mi&gt;c&lt;/mi&gt;&lt;/math&gt;&lt;/span&gt; is the chord length, &lt;span&gt;&lt;math&gt;&lt;mi&gt;λ&lt;/mi&gt;&lt;/math&gt;&lt;/span&gt; is the serration wavelength and &lt;span&gt;&lt;math&gt;&lt;msub&gt;&lt;mrow&gt;&lt;mi&gt;Λ&lt;/mi&gt;&lt;/mrow&gt;&lt;mrow&gt;&lt;mi&gt;t&lt;/mi&gt;&lt;/mrow&gt;&lt;/msub&gt;&lt;/math&gt;&lt;/span&gt; is the spanwise integral length scale of the incoming flow. All serrations show a reduction in noise level compared to the straight leading edge reference case. Between 2 and &lt;span&gt;&lt;math&gt;&lt;mrow&gt;&lt;mn&gt;3&lt;/mn&gt;&lt;mspace&gt;&lt;/mspace&gt;&lt;mi&gt;dB&lt;/mi&gt;&lt;/mrow&gt;&lt;/math&gt;&lt;/span&gt; noise reduction was observed for all cases at a Strouhal number based on &lt;span&gt;&lt;math&gt;&lt;mi&gt;h&lt;/mi&gt;&lt;/math&gt;&lt;/span&gt;, &lt;span&gt;&lt;math&gt;&lt;mrow&gt;&lt;mi&gt;S&lt;/mi&gt;&lt;msub&gt;&lt;mrow&gt;&lt;mi&gt;t&lt;/mi&gt;&lt;/mrow&gt;&lt;mrow&gt;&lt;mi&gt;h&lt;/mi&gt;&lt;/mrow&gt;&lt;/msub&gt;&lt;/mrow&gt;&lt;/math&gt;&lt;/span&gt;, with value 0.1. Above &lt;span&gt;&lt;math&gt;&lt;mrow&gt;&lt;mi&gt;S&lt;/mi&gt;&lt;msub&gt;&lt;mrow&gt;&lt;mi&gt;t&lt;/mi&gt;&lt;/mrow&gt;&lt;mrow&gt;&lt;mi&gt;h&lt;/mi&gt;&lt;/mrow&gt;&lt;/msub&gt;&lt;mo&gt;=&lt;/mo&gt;&lt;mn&gt;0&lt;/mn&gt;&lt;mo&gt;.&lt;/mo&gt;&lt;mn&gt;3&lt;/mn&gt;&lt;/mrow&gt;&lt;/math&gt;&lt;/span&gt;, leading edge noise reduction increases with frequency and peaks at a serration wavelength of &lt;span&gt;&lt;math&gt;&lt;mrow&gt;&lt;mi&gt;λ&lt;/mi&gt;&lt;mo&gt;/&lt;/mo&gt;&lt;msub&gt;&lt;mrow&gt;&lt;mi&gt;Λ&lt;/mi&gt;&lt;/mrow&gt;&lt;mrow&gt;&lt;mi&gt;t&lt;/mi&gt;&lt;/mrow&gt;&lt;/msub&gt;&lt;mo&gt;=&lt;/mo&gt;&lt;mn&gt;1&lt;/mn&gt;&lt;/mrow&gt;&lt;/math&gt;&lt;/span&gt;, a trend that holds for all shape profiles investigated. In this higher frequency range, subtle variations in shape profile significantly vary the noise reduction qualities. The modified sinusoidal profile outperforms all others up to &lt;span&gt;&lt;math&gt;&lt;mrow&gt;&lt;mi&gt;S&lt;/mi&gt;&lt;msub&gt;&lt;mrow&gt;&lt;mi&gt;t&lt;/mi&gt;&lt;/mrow&gt;&lt;mrow&gt;&lt;mi&gt;h&lt;/mi&gt;&lt;/mrow&gt;&lt;/msub&gt;&lt;mo&gt;=&lt;/mo&gt;&lt;mn&gt;1&lt;/mn&gt;&lt;/mrow&gt;&lt;/math&gt;&lt;/span&gt;, as long as the serration wavelength is shorter than &lt;span&gt;&lt;math&gt;&lt;mrow&gt;&lt;mi&gt;λ&lt;/mi&gt;&lt;mo&gt;/&lt;/mo&gt;&lt;msub&gt;&lt;mrow&gt;&lt;mi&gt;Λ&lt;/mi&gt;&lt;/mrow&gt;&lt;mrow&gt;&lt;mi&gt;t&lt;/mi&gt;&lt;/mrow&gt;&lt;/msub&gt;&lt;mo&gt;=&lt;/mo&gt;&lt;mn&gt;4&lt;/mn&gt;&lt;/mrow&gt;&lt;/math&gt;&lt;/span&gt;. At higher frequencies, the modified sinusoidal serrations have a similar noise reduction to the triangular and tangent curve serrations, which reaches a maximum of &lt;span&gt;&lt;math&gt;&lt;mrow&gt;&lt;mn&gt;9&lt;/mn&gt;&lt;mspace&gt;&lt;/mspace&gt;&lt;mi&gt;dB&lt;/mi&gt;&lt;/mrow&gt;&lt;/math&gt;&lt;/span&gt; for serrations with &lt;span&gt;&lt;math&gt;&lt;mrow&gt;&lt;mi&gt;λ&lt;/mi&gt;&lt;mo&gt;/&lt;/mo&gt;&lt;msub&gt;&lt;mrow&gt;&lt;mi&gt;Λ&lt;/mi&gt;&lt;/mrow&gt;&lt;mrow&gt;&lt;mi&gt;t&lt;/mi&gt;&lt;/mrow&gt;&lt;/msub&gt;&lt;mo&gt;=&lt;/mo&gt;&lt;mn&gt;4&lt;/mn&gt;&lt;/mrow&gt;&lt;/math&gt;&lt;/span&gt;. Overall sound pressure level results show the noise reduction in this high-frequency regime is independent of the Reynolds number. Fluctuating pressure measurements at the roots of t","PeriodicalId":17233,"journal":{"name":"Journal of Sound and Vibration","volume":"608 ","pages":"Article 119079"},"PeriodicalIF":4.3,"publicationDate":"2025-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143747125","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Notched Hysteretic Damping Model and Device for Simultaneous Control of Structural Displacement and Acceleration Responses","authors":"Ruhan Zhang ,&nbsp;Huating Chen ,&nbsp;Luwei Shi ,&nbsp;Lingyun Peng","doi":"10.1016/j.jsv.2025.119085","DOIUrl":"10.1016/j.jsv.2025.119085","url":null,"abstract":"<div><div>The traditional ideal elasto-plastic hysteresis model performs well in controlling structural displacement, yet its effectiveness in controlling acceleration is often suboptimal. The force equilibrium relationship of a single-degree-of-freedom (SDOF) system reveals that the structural acceleration response is closely related to the damping force at peak displacement. Based on this, a notched bilinear hysteretic model was proposed to make the damping force zero at peak displacement. The displacement and acceleration responses were compared with those of a traditional ideal elasto-plastic model by slowly varying the SDOF parameters to obtain steady-state results. An algorithm for the proposed hysteretic model was established using MATLAB, its integrated control effect on the displacement and acceleration responses of the SDOF was verified by a nonlinear time history analysis, and its optimal control interval and parameters were obtained. A damping device was subsequently developed based on the characteristics of the notched bilinear hysteretic model and its feasibility and mechanical properties were verified through experimental studies. The results showed that a well-designed notched bilinear hysteretic model can effectively control structural displacement while achieving effective control of the acceleration response, thus enabling dual control of both structural displacement and acceleration.</div></div>","PeriodicalId":17233,"journal":{"name":"Journal of Sound and Vibration","volume":"608 ","pages":"Article 119085"},"PeriodicalIF":4.3,"publicationDate":"2025-03-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143783598","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}

{"title":"Mitigation of negative damping effects in deep drilling operations through active control","authors":"Hélio J. Cruz Neto,&nbsp;Marcelo A. Trindade","doi":"10.1016/j.jsv.2025.119078","DOIUrl":"10.1016/j.jsv.2025.119078","url":null,"abstract":"<div><div>Rotary drilling systems face harmful interactions between the drill-bit and rock formation, resulting in torsional stick–slip vibrations that reduce efficacy and damage drilling components. To mitigate these issues, designing an active controller that effectively reduces vibrations using the limited real-time data available during field operations is crucial. In this context, this paper examines the apparent negative damping effects leading to instability in the drilling system and introduces a novel control technique, based on the concept of a negative damping coefficient developed within this study, to counterbalance them. Given the critical importance of measured signals for the proposed technique’s efficiency, this paper also identifies relevant feedback signals to ensure asymptotic stability. To evaluate the effectiveness of the proposed controller, representative models of bit-rock interaction and drill-string torsional dynamics are developed, employing non-regularized dry friction and the finite element method. The model also addresses specific aspects required by the controller, including the addition of the error integral as a state variable and the reformulation of the equations of motion as a stabilization problem. The performance and stability of the proposed controller are compared with proportional–integral (PI) and optimal static output feedback (OSOF) controllers. Simulations show that it outperforms the PI controller, both for the nominal model and under parameter uncertainties. Robustness analyses further confirm its superiority over PI and OSOF, in addition to indicating a seeming global stability of the closed-loop system equipped with the proposed controller. Results encourage further investigations into the apparent global stability provided by the proposed controller and its implementation in laboratory setups or full-scale drilling rigs.</div></div>","PeriodicalId":17233,"journal":{"name":"Journal of Sound and Vibration","volume":"610 ","pages":"Article 119078"},"PeriodicalIF":4.3,"publicationDate":"2025-03-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143786238","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}

{"title":"Controlling instability of high-speed magnetically suspended vehicles: The interaction of the electromagnetic and wave-induced instability mechanisms","authors":"Andrei B. Fărăgău,&nbsp;Andrei V. Metrikine,&nbsp;Jithu Paul,&nbsp;Rens van Leijden,&nbsp;Karel N. van Dalen","doi":"10.1016/j.jsv.2025.119077","DOIUrl":"10.1016/j.jsv.2025.119077","url":null,"abstract":"<div><div>Maglev and the newer Hyperloop technologies are advanced transportation systems that eliminate wheel–rail friction using electromagnetic suspension/levitation. The electromagnetic suspension is inherently unstable and requires a control strategy for safe operation, which has been previously studied in the context of Maglev. However, the interaction between electromagnetic instability and another instability mechanism, known as wave-induced instability, occurring at high vehicle velocities, has not been explored. This interaction between two distinct instability mechanisms is the focus of this study. From a practical perspective, this study examines the stability of magnetically suspended vehicles (e.g., Maglev or Hyperloop) in relation to vehicle velocity and control gains. To account for this, this study properly includes the infinite guideway, thus allowing vehicle velocity to influence system stability. The results show that at sub-critical velocities, the guideway’s reaction force helps suppress perturbations and stabilize the system, with instability driven solely by improper electromagnetic control. However, at super-critical velocities, wave-induced instability drastically reduces the stable parameter space. This study further proposes a methodology to distinguish the contribution of each instability mechanism to the overall system stability, which is important for efficient mitigation measures. The findings reveal that beyond a certain super-critical velocity, wave-induced instability dominates much of the control-gain plane, with the control strategy effective in only limited regions. In conclusion, the study recommends revising control design strategies, as solely focusing on maximizing energy dissipation through control can trigger wave-induced instability. A more effective approach balances energy dissipation with avoiding the activation of wave-induced instability by steering clear of problematic vibration frequencies. These insights provide guidance for improving control strategies.</div></div>","PeriodicalId":17233,"journal":{"name":"Journal of Sound and Vibration","volume":"608 ","pages":"Article 119077"},"PeriodicalIF":4.3,"publicationDate":"2025-03-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143747124","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}

{"title":"A self-tuned rotative nonlinear vibration absorber and energy harvester: A conceptual case study","authors":"Breno A.P. Mendes,&nbsp;Eduardo A.R. Ribeiro,&nbsp;Carlos E.N. Mazzilli","doi":"10.1016/j.jsv.2025.119081","DOIUrl":"10.1016/j.jsv.2025.119081","url":null,"abstract":"<div><div>In this work, we address the conceptual model of an innovative rotative non-linear vibration absorber (RNVA) with an inner oscillator in series with a piezoelectric element, which can simultaneously control a rigid cylinder's motion under parametric excitation, and harvest energy. The study is grounded on results obtained in previous publications, according to which the controlling features of the RNVA are enhanced after the standard constant rotation radius model is replaced by the self-tuned radius provided by the inner oscillator. Scenarios are numerically investigated for a range of relevant system parameters, considering the possibility of impact between the inner oscillator's mass and the cylinder internal wall. Qualitative analysis is also pursued using techniques such as the complexification/averaging and multiple scales methods, followed by stability analysis using, whenever possible, Lyapunov's first method, Poincaré map and Floquet theory, for impact-free cases.</div></div>","PeriodicalId":17233,"journal":{"name":"Journal of Sound and Vibration","volume":"608 ","pages":"Article 119081"},"PeriodicalIF":4.3,"publicationDate":"2025-03-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143783599","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}