Resonant Response Research Articles

Analyzing MEMS resonator static pull-in and dynamics under electric excitation via position feedback controller

Abstract The micro-electromechanical systems (MEMS) have efficacious and widespread use in several applications such as signal filtering, time referencing, sensing, and more. This paper's aim is to study the effect of a position feedback controller on a clamped-clamped MEMS resonator. The resonator's dynamics are modeled and studied to establish both the mode shape function and temporal function. Then, the method of multiple scales (MMS) is applied to generate analytical formulas for the resonator response, capturing nonlinearities and stability regions across various voltage levels. Several response plots are shown to clarify the controller's impact on the dynamical behavior of the resonator. The general behavior of the analyzed model is verified numerically using the fourth order Rung-Kutta technique. Incorporating the position feedback controller delayed static pull-in by increasing the DC pull-in voltage threshold. In addition, the analysis of the frequency and voltage response curves of different feedback settings indicates small vibration changes and reveals that the nonlinear behavior of the resonator changes from softening to hardening with the increase of the gap distance.

Multi-resonant TVA formed by a tree of deflated composite beams with core structured fabrics

Abstract This paper presents a study on a multi-resonant tuneable vibration absorber for the control of flexural vibrations of thin structures in a low frequency band where the response is characterized by distinct lightly damped resonances of low order flexural modes. The absorber is formed by a tree of deflated composite beams made by a core structured fabric wrapped on a plastic skin. The beams have increasingly smaller length and are fixed in the middle on a mast that works as a base-post and vacuum-junction too. The fabric in each beam is made by a lattice of interlocked truss-like rigid particles. The uniform pressure exerted by the deflated skin forces the particles to jam such that the fabric moves from its natural fluid-like state to a solid state whose rigidity depends on the confining pressure exerted by the skin. Hence, each beam is characterized by a fundamental flapping vibration mode whose response resembles that of a classical mass-spring-damper vibration absorber and can be suitably tuned by adjusting the level of vacuum. The paper first analyses the working principles of single-beam and three-beams absorbers with respect to their vibration transmissibility and base impedance frequency response functions. Then, it presents the vibration control generated by the single-beam and the three-beams absorbers tuned to minimise the resonant responses of a single or three low order flexural modes of a thin plate. The paper shows that the operational frequency of each beam-absorber can be suitably adapted in a band of 8 Hz by varying the vacuum pressure in a 5 – 80 kPa range. Also, it shows that the single-beam or multi-beams absorbers reduce the resonant response of the target flexural modes by 10 to 20 dB.

MULTI-AEROELASTIC PHENOMENA MODELLING PART I: THE DEVELOPMENT OF WHOLE LPC MODEL FOR CIVIL TURBOFAN ENGINE

Abstract Aeroelastic phenomena in the low pressure compression (LPC) system of civil turbofan engines can cause a significant high cycle fatigue (HCF) risk to LPC components. Currently, the mechanical integrity risk to the LPC components is assessed by performing multiple, discrete aeromechanical simulations, which require large resources and incur high time cost. Therefore, the development of a comprehensive modelling simulation approach is necessary to assess multiple phenomena and components simultaneously that can provide accurate results within design timescales. This paper presents the methodology for generating a common, system level model for investigating multiple aeroelastic phenomena in fan and outlet guide vanes (OGVs). The development of a high fidelity, full annulus CFD model of the whole low pressure compression system is described. Time accurate unsteady CFD simulations are then conducted at multiple flight conditions. These information-rich simulation models are interrogated to extract various parameters of interest to assess multiple aeroelastic phenomena such as, 1EO fan forced response, fan alternating passage divergence (APD) forced response, OGV buffet, and OGV resonant forced response etc. In the second part of this paper, the application of this modelling methodology is demonstrated to evaluate and to better understand the efficacy of OGV asymmetric cyclic patterns.

A novel horizontal self-tuning piezoelectric energy harvester based on a beam-slider system

Abstract With the rapid development of piezoelectric energy harvesting technologies, this approach is emerging as a promising power source for smart sensors. Despite this progress, a significant challenge remains in achieving a wider bandwidth while increasing the output power. In response to this challenge, this paper introduces a horizontal self-tuning beam-slider piezoelectric energy harvester (STBS-PEH). This innovative harvester employs a unilateral beam-slider mechanism to enable self-tuning of the energy harvesting by adjusting its resonant frequency to match the external excitation frequency. The electromechanical coupled dynamic model of this harvester has been established. Comprehensive simulations and experimental analysis have been conducted to demonstrate the wide bandwidth and high output power characteristics of the proposed harvester. Notably, the simulation results exhibit strong agreement with the experimental findings. The resonance response bandwidth of the STBS-PEH is particularly noteworthy, which is twice that of a conventional cantilever beam piezoelectric energy harvester. The root mean square (RMS) voltage and output power of the developed STBS-PEH can reach 23.54 V and 194.61 µW, respectively, at a frequency of 21 Hz, with an excitation amplitude of 0.5 g. These results demonstrate that the STBS-PEH is capable of powering low-power electronic devices in a broadband vibrational environment.

The effect of micro-vessel viscosity on the resonance response of a two-microbubble system

The effect of micro-vessel viscosity on the resonance response of a two-microbubble system

Complex dynamic behavioral transitions in auditory neurons induced by chaotic activity

Chaotic sequences are widely used in secure communication due to their high randomness. Chaotic resonance (CR) refers to the resonant response of a system to weak signals induced by chaotic activity, but its practical application remains limited. This study designs a simplified FitzHugh-Nagumo (FHN) auditory neuron model by simulating the physiological activities of auditory neurons and considering the combined stimulation of chaotic activity and sound signals. It is found that the neuron dynamics depend on both external sound stimuli and chaotic current intensity. Chaotic currents induce spikes in the neuron output sequence through CR, and the spikes become more frequent with increasing current intensity, eventually leading to a chaotic state regardless of the initial state. However, the sensitivity of the initial value of this chaotic sequence shifts to the chaotic current excitation system. The injection of chaotic currents can reduce the system's average Hamiltonian energy under certain conditions. By measuring the complexity of the generated sequences, we find that the addition of chaotic currents can enhance the complexity of the original sequences, and the enhancement ability increases with the intensity. This provides a new approach to enhance the complexity of original chaotic sequences. Moreover, different chaotic currents can induce different chaotic sequences with varying abilities to enhance the complexity of the original sequences. We hope our work can contribute to secure communication.

A rapid estimation method for the probability of wind-induced first plastic displacement of SDOF systems based on the Slepian model

The conventional method based on the Slepian model for estimating the probability distribution of the first plastic displacement of an ideal elastic-plastic oscillator (EPO) is only applicable for zero-mean white noise loads. This study proposes an improved method applicable to wind loads with non-zero mean and non-white noise characteristics for structures whose resonant response dominates the fluctuating wind-induced response. The original EPO's symmetric constitutive model under non-zero mean loads is modified to be equivalent to an asymmetric constitutive model under zero mean loads; thus, a SDOF system subjected to non-zero mean loads is transformed into a SDOF system under zero mean loads. When the resonant response dominates the fluctuating wind-induced response, the fluctuating wind-induced response can be approximated as a narrow-band stochastic process, the extreme values following a Rayleigh distribution, and the probability distribution of the local maximum displacement of the associated linear oscillator (ALO) can be directly obtained, making the Slepian model-based method applicable for non-white noise loads. A case study is performed to validate the accuracy of the proposed improved method, and the results demonstrate that the improved method proposed in this study can significantly enhance computational efficiency. The accuracy of the improved method is independent of the load characteristics but rather depends on the narrowband characteristics of the structural response. When the narrowband characteristics of the structural response are prominent, the improved method exhibits high accuracy.

Ferromagnetic resonance response in square artificial spin ice: Roles of geometry in vertex dynamics and magnetic configurations

Ferromagnetic resonance response in square artificial spin ice: Roles of geometry in vertex dynamics and magnetic configurations

Water wave interactions with surface-piercing vertical barriers in a rectangular tank: Connections with Bloch waves and quasimodes

Eigenmodes are studied for a fluid-filled rectangular tank containing one or more vertical barriers, and on which either Dirichlet or Neumann boundary conditions are prescribed on the lateral walls. In the case where the tank contains a single barrier, the geometry of the tank is equivalent to the unit cell of the cognate periodic array, and its eigenmodes are equivalent to standing Bloch waves. As the submergence depth of the barrier increases, it is shown that the passbands (i.e. frequency intervals in which the periodic array supports Bloch waves) become thinner, and that this effect becomes stronger at higher frequencies. The eigenmodes of a uniform array of vertical barriers in a rectangular tank are also considered. They are found to be a superposition of left- and right-propagating Bloch waves, which couple together at the lateral walls of the tank. A homotopy procedure is used to relate the eigenmodes to the quasimodes of the same uniform array in a fluid of infinite horizontal extent, and the quasimodes are shown to govern the response of the array to incident waves. Qualitative features of the mode shapes are typically preserved by the homotopy, which suggests that the resonant responses of the array in an infinite fluid can be understood in terms of modes of the array in a finite tank.

Electrochemically mutable soft metasurfaces.

Active optical metasurfaces, capable of dynamically manipulating light in ultrathin form factors, enable novel interfaces between humans and technology. In such interfaces, soft materials bring many advantages based on their flexibility, compliance and large stimulus-driven responses. Here, we create electrochemically mutable, soft metasurfaces that capitalize on the swelling of soft conducting polymers to alter the shape and associated resonant response of metasurface elements. Such geometric tuning overcomes the typical trade-off between achieving substantial tuning and low optical loss that is intrinsic to dynamic metasurfaces relying on index tuning of materials. Using the commercial polymer PEDOT:PSS, we demonstrate dynamic, high-resolution colour tuning and high-diffraction-efficiency (>19%) beam-steering devices that operate at CMOS-compatible voltages (~1.5 V). These results highlight how the deformability of soft materials can enable a class of high-performance metasurfaces that are suitable for body-worn technologies.

Fan Non-Synchronous Forced Vibration Under Crosswind

Abstract In this paper, a new aeroelastic phenomena for fans, referred to as non-synchronous forced vibration (NSFV), is presented. This type of aeroelastic instability can occur at high crosswind conditions when the flow at the intake lip separates and the disturbances caused by flow separation become unsteady. The results show that in the presence of unsteady separation in the intake, the fan can experience non-synchronous frequency excitations, which can result in resonant response in modes that are not identified by the Campbell diagram. The findings are corroborated by aeroacoustic theories. To the best of authors knowledge, this is the first time that fan forced response due to unsteady distortion is studied and the findings can unlock some of unexplained and unexpected vibrations experienced by engines.

Broadband surface enhanced infrared absorption with multiple Fano resonance by metallic oblique-wire-bundle metamaterial absorbers

Higher sensitivity with specific recognition of a sensor could ease the burden of sample purification or labelling procedure for specific testing and detection and there appear two methods including surface enhanced infrared absorption (SEIRA) and surface enhanced Raman scattering (SERS), promising better sensitivity and specificity, simultaneously, via detection of molecular footprints. Furthermore, researchers employ Fano resonance to further boost the detection limit of SEIRA by coupling between two absorption bands from molecules and metamaterials. Still, the current metamaterial absorbers are almost narrow band and require a specific design, only suitable for limited chemicals. Thus, in this work, we would like to design a broadband oblique-wire-bundle (OWB) metamaterial absorber (MA) which could interact with multiple functional groups’ absorption from a sample, thus easing the burden of custom-made resonators. In experiments, indeed, our designed OWB MA developed four Fano resonance responses with three PMMAs’ functional groups and one function group from carbon dioxide. The counterpart planar MA also performed SEIRA yet without occurrence of Fano resonance as a comparison. We believe this proposed OWB MA could facilitate the development of rapid detection in the field of food safety and chemical detection.

Nonlinear Dynamic Analysis of Riemann–Liouville Fractional-Order Damping Giant Magnetostrictive Actuator

Abstract In view of the large errors in the integer-order prediction model of the current giant magnetostrictive actuator (GMA), existing studies have shown that the fractional-order theory can improve the classical integer-order error situation. To this end, the Riemann–Liouville (R–L) fractional-order calculus theory is applied to the damping part of the GMA system; based on the averaging method and the power series method, the analytical and numerical solutions of the system are obtained, respectively, the motion of the GMA system is obtained through simulation, the parameters affecting the main resonance response of the system are analyzed as well as the motion characteristics of the system under the parameters, and the bifurcation and chaotic characteristics of the system are analyzed qualitatively and quantitatively. It is shown that the fractional-order model can improve the prediction accuracy of the system, the fractional order has a significant effect on the motion of the system, and the interval of the periodical motion parameter is less than an integer when the order of the damping term is (0,1), and the system can be induced to shift to periodic motion by changing the parameters.

Research on the nonlinear resonance response of the high-speed spindle system supported by preloaded ball bearings

Research on the nonlinear resonance response of the high-speed spindle system supported by preloaded ball bearings

Helicoid Grating-Coupled Surface Plasmon Resonance Sensor.

Ultrasensitive, rapid, and reliable biomolecular sensing is essential for biomedical diagnostics, requiring real-time monitoring and detection of trace samples. Optical sensing, particularly plasmonic biosensing, meets these demands through noninvasive, high-sensitivity detection based on the interaction between light and molecules. Here, we present novel plasmonic metamaterial-based sensing strategy, utilizing the circular dichroism (CD) response of grating-coupled surface plasmon resonance (SPR) from chiral nanoparticle grating structure (i.e., 2D helicoid crystal) on gold substrate. Strong chiroptic response of helicoids has been effectively expanded to produce a remarkable CD/greflection response in the SPR mode, achieved by spectral coupling of SPR with localized surface plasmon resonance (LSPR) in helicoids. This CD response, derived from the differential of left and right circularly polarized light, corrects optical fluctuations, enhancing sensitivity and reliability. Our SPR-CD-based approach achieves a sensitivity of 379.2 nm/RIU and detection limit of a few mM for d-glucose, offering a new paradigm for high-performance optical biosensors.

Internal Resonance and Nonlinear Dynamics of an Axially Moving FGM Sandwich Cylindrical Shell

This paper provides an in-depth study of the resonant responses and nonlinear dynamics of a novel axially moving functionally graded material (FGM) sandwich cylindrical shell structure, specifically designed for supersonic aircraft operating under various complex environments. We present the derivation of the mechanical parameters and the nonlinear dynamic equations associated with this FGM sandwich cylindrical shell. By analyzing the natural frequencies of the structure, which is clamped at both ends, we identify the necessary parametric conditions for the nonlinear system to exhibit 1:2 internal resonance and 1:1 principal parameter resonance. To further investigate the resonant responses, we utilize the pseudo-arc length continuation method. In addition, the fourth-order Runge-Kutta algorithm is employed to examine the nonlinear dynamic behaviors of this system. This research explores the impacts of different external conditions, such as external excitation and aerodynamic force, on the resonant response and nonlinear dynamics of the axially moving FGM sandwich cylindrical shell. The results indicate that both external excitation and aerodynamic force have a significant influence on the nonlinear vibrations of this structure. Understanding these factors is important for optimizing the flight performance of supersonic vehicles in adverse environmental conditions.

Highly selective filtering power divider using substrate integrated waveguide technique for radar applications

<p><span>This article exhibits a filtering power divider designed with substrate integrated waveguide (SIW) technique, having the power dividing as well as filtering functionalities. In the design band-pass performance is realized by merging SIW structure having high-pass response and complementary split ring resonator (CSRRs) with parallel tank LC resonant response and the dumbbells shape defected ground structure (DGS) with high out of band rejection characteristics. The anticipated structure serves as both a power divider and a filter, it reduces both the cost and the size of the system. Structure is constructed and tested to confirm the design functionality. The measurement result shows the return loss of -25.94 dB with 3-dB fractional bandwidth of 2.85% at 14 GHz.</span></p>

Nonlinear time-delay feedback control of a suspended cable under temperature effect

In engineering, controlling the vibration of suspended cables is crucial and urgent. Notably, prolonged exposure to varying temperatures alters the vibration characteristics of suspended cables, impacting the selection and effectiveness of control strategies. Given the advancements in temperature-sensitive materials and refined engineering needs, researching temperature effects on cable vibration control is essential. Consequently, this study explores the nonlinear vibration control of suspended cables under temperature variations using a time-delay velocity feedback strategy. A nonlinear dynamic model of time-delay vibration considering temperature effects is established based on Hamilton’s principle. Comparative analysis quantitatively characterizes how temperature variations affect the inherent properties, nonlinear dynamics, and control strategies of suspended cables. Using the method of multiple scales, this study obtains analytical solutions for the primary resonance response. Analysis of three critical variables, sag-to-span ratio, control gain, and time delay under temperatures of −40∘C, 0‘∘C and +40∘C led to an optimal control parameter design that achieves a vibration control efficiency of 93.6%, underscoring the effectiveness of the time-delay feedback strategy.

Passive wireless RFID strain sensor for directional-independent structural deformation monitoring

The advancement of Radio-frequency identification (RFID) sensor technology presents a novel approach to monitoring the health of structures. However, the traditional RFID antenna sensor encounters issues with limited sensitivity and strain measurement capabilities in a single direction. In this investigation, we propose, model, analyze, and test an enhanced wireless and passive RFID strain sensor that offers improved sensitivity to strains and quantifiable measurements in orthogonal directions. Theoretical analysis based on multiphysics elastodynamics and electromagnetics illustrating the resonant response and distribution of current field density between two sets of orthogonally installed sensors under applied stress. Our findings reveal that the RFID strain sensor exhibits characteristics to electromagnetically induced transparency like (EIT-like) effect, enabling independent and intensified measurement of strains both horizontally and vertically. Experimental data demonstrates a linear correlation between the shift in resonant frequency of the sensor antenna and transverse strains as well as longitudinal strains, with sensitivity coefficients measuring −1.76 kHz με−1 for transverse strain and 2.17 kHz με−1 for longitudinal strain respectively. Consequently, by accurately analyzing variations in resonant frequency it becomes possible to deduce both magnitude and direction of strains on the antenna effectively laying groundwork for future engineering applications.

Study on the response of a super high-rise guyed mast under synoptic winds based on aeroelastic wind tunnel test

The present study examines the aeroelastic properties and wind-induced displacement response of a super high-rise guyed mast, through a series of aeroelastic model wind tunnel tests. The simulated guyed mast with a prototype height of 356 m is a representative guyed mast in Asia and has not been reported in previous literature. The impact of wind speed on both the alongwind and crosswind displacement response and the Gaussianity along the heights of the aeroelastic model is then investigated using wind tunnel measurements. Furthermore, the characteristics of mode participation and the effect of wind velocity on this phenomenon, as well as the contributions of background and resonant dynamic response, are examined in both the alongwind and crosswind directions. The results indicate that the guyed mast displacement distributions along the heights are different from those observed in the conventional self-standing lattice towers. The characteristics of multi-mode participation are notable. As wind speeds increase, the alongwind resonant response peaks shift to lower frequencies and become less distinct. In contrast, the crosswind response peaks show no significant variation. The contributions of background and resonant response along the heights, respectively, exhibit a decreasing and an increasing tendency, and wind speed exerts an influence on these phenomena.