Low-amplitude Vibration Research Articles

Optimizing Contact-Less Magnetoelastic Sensor Design for Detecting Substances Accumulating in Constrained Environments

The optimization of a contact-less magnetoelastic sensing setup designed to detect substances/agents accumulating in its environment is presented. The setup is intended as a custom-built, low-cost yet effective magnetoelastic sensor for pest/bug detection in constrained places (small museums, labs, etc.). It involves a short, thin, and flexible polymer slab in a cantilever arrangement, with a short Metglas® 2826 MB magnetoelastic ribbon attached on part of its surface. A mobile phone both supports and supplies low-amplitude vibration to the slab’s free end. When vibrating, the magnetoelastic ribbon generates variable magnetic flux, thus inducing voltage in a contact-less manner into a pick-up coil suspended above the ribbon. This voltage carries specific characteristic frequencies of the slab’s vibration. If substances/agents accumulate on parts of the (suitably coated) slab surface, its mass distribution and, hence, characteristic frequencies change. Then, simply monitoring shifts of such frequencies in the recorded voltage enables the detection of accumulating substances/agents. The current work uses extensive testing via various vibration profiles and load positions on the slab, for statistically evaluating the sensitivity of the mass detection of the setup. It is shown that, although this custom-built substance/agent detector involves limited (low-cost) hardware and a simplified design, it achieves promising results with respect to its cost.

Composite metastructure with tunable ultra-wide low-frequency three-dimensional band gaps for vibration and noise control

Low-frequency vibration and noise control present enduring engineering challenges that garner extensive research attention. Despite numerous active and passive control solutions, achieving multiple ultra-wide attenuation regions remains elusive. Addressing vibration and noise control across a multidirectional broad low-frequency spectrum, three-dimensional metastructures have emerged as innovative solutions. This study introduces a novel three-dimensional composite metastructure featuring multiple ultra-wide three-dimensional complete band gaps. The research emphasizes the design strategy of elastic ligaments to achieve multiple ultra-wide attenuation regions spanning from 0.7 to 40 kHz. The band structures are elucidated through modal analysis and further substantiated by an analytical model based on a spring-mass chain with an additional resonator. The underlying physical mechanism for the formation of multiple ultra-wide band gaps is revealed through novel vibration modes from finite element analyses. Furthermore, we demonstrate that the distribution and the relative width of the ultra-wide band gaps can be tuned by modifying the geometric parameters of the metastructure. Utilizing additive manufacturing, prototypes are fabricated, and low-amplitude vibration tests are conducted to evaluate real-time vibration attenuation properties. Consistency is observed among theoretical, numerical, and experimental results. The proposed structure shows significant potential for high-performance meta-devices aimed at controlling noise and vibration across an extremely wide low-frequency spectrum.

Coding of self and environment by Pacinian neurons in freely moving animals

Pacinian corpuscle neurons are specialized low-threshold mechanoreceptors (LTMRs) that are tuned to detect high-frequency vibration (∼50-2,000Hz); however, it is unclear how Pacinians and other LTMRs encode mechanical forces encountered during naturalistic behavior. Here, we developed methods to record LTMRs in awake, freely moving mice. We find that Pacinians, but not other LTMRs, encode subtle vibrations of surfaces encountered by the animal, including low-amplitude vibrations initiated over 2m away. Strikingly, Pacinians are also highly active during a wide variety of natural behaviors, including walking, grooming, digging, and climbing. Pacinians in the hindlimb are sensitive enough to be activated by forelimb- or upper-body-dominant behaviors. Finally, we find that Pacinian LTMRs have diverse tuning and sensitivity. Our findings suggest a Pacinian population code for the representation of vibro-tactile features generated by self-initiated movements and low-amplitude environmental vibrations emanating from distant locations.

Wire rope isolator identification and dynamic modeling for small amplitude vibrations

Wire rope isolators are used in variety of applications to protect sensitive equipment from vibration. The nonlinear hysteretic behavior of steel wires provides advantages when compared to linear vibration isolators. This study proposes an amplitude dependent stiffness and damping model for low amplitude vibrations under axial loading, where the parameters can be determined with an experimental procedure. Comprehensive experimental results of forced vibration tests with varying loading, frequency and preload were considered in the model identification. Amplitude dependent stiffness and loss energy models were determined from the test data, and the effect of the preload and loading frequency on the model parameters were studied. It is shown, that the effect of preload and frequency is not evidently clear, while the effect of vibration amplitude is more significant. The mathematical model was further verified against measurements from base excitation loading. The proposed model can be used to study the effectiveness of the selected wire rope isolator configurations in chosen application, and to effectively perform dynamic design studies.

Performance of surge-induced synchronized switch harvesting on inductor as an efficient technique under strong electromechanical coupling and low amplitudes of vibration

The process of harvesting energy from ambient sources is key for various applications. This study examined the performance of two representative techniques from the surge-induced synchronized switch harvesting on inductor (S3HI) family under strong electromechanical coupling and compared this performance with that of some established techniques. S3HI techniques exploit the surge voltage to overcome the voltage barrier of diodes for rectifiers and storage capacitor voltages. One of their features, revealed in a previous study on weakly coupled systems, is that they can harvest substantial energy from low-level vibrations. This feature is desirable for certain use cases. This study aimed to clarify whether this feature is applicable even when the coupling is strong. The performance of various established techniques and two representatives from the S3HI group was studied by formulating an approximate analytical solution and performing numerical simulations and experiments. The theoretical results were confirmed to be consistent, and the discrepancy between experimental and theoretical results was minor. These results clearly demonstrate that the techniques from the S3HI family can effectively harvest substantial energy from small-amplitude vibrations, even when the coupling is strong. Moreover, the performance advantage of S3HI methods is even greater when the coupling is strong.

Contribution to micromechanical modeling of the shear wave propagation in a sand deposit

The object of study is the vertical wave propagation in a sand deposit. This paper is aimed at analyzing the vertical wave propagation in a sand deposit through micromechanical modeling that inherently takes account of intergranular slips during deformation. Such a problem, which is part of the general framework of wave propagation in the soil, has long been analyzed using continuum models based on approximate behavior laws. For this purpose, a 2D Discrete Element Method (DEM) model is developed. The DEM model is based on molecular dynamics with the use of circular shaped elements. The intergranular normal forces at contacts are calculated through a linear viscoelastic law while the tangential forces are calculated through a perfectly plastic viscoelastic model. A model of rolling friction is incorporated in order to account for the damping of the grains rolling motion. Different boundary conditions of the profile have been implemented; a bedrock at the base, a free surface at the top and periodic boundaries in the horizontal direction. The sand deposit is subjected to a harmonic excitation at the base. Using this model, the fundamental and resonance frequencies of the deposit are first determined. The former is determined from the low-amplitude free vibration and the latter by performing a variable-frequency excitation test. It is noted that there is a significant gap between the two frequencies, this gap could be attributed to the degradation of the soil shear modulus in the vicinity of the resonance. Such degradation is well proven in classical soil dynamics. The effects of deposit height and confinement on resonance frequency and free-surface dynamic amplification factor are then investigated. The obtained results highlighted that the resonance frequency is inversely proportional to the deposit’s thickness whereas the dynamic amplification factor Rd increases with the deposit’s thickness. In the other hand, when the confinement increases the deposit becomes stiffer, which results in reducing the amplification. Such result is in accordance with theoretical knowledge which states that the most rigid profiles such as rocks do not amplify seismic movement.

Tribological and corrosion behavior of hydrided zirconium alloy

Zirconium alloys (Zr-alloys) are used for the core components of nuclear reactors due to their exceptional properties, which make them suitable for the given applications such as low neutron absorption cross-section, good corrosion resistance, good wear resistance, good mechanical stability at high temperatures etc. The coolant water that flows inside the pressure tube contains LiOH to control the pH value of the coolant water, which can cause corrosion. The flow of coolant water produces low amplitude vibration, which can cause fretting wear of the components. Further, the coolant water at high temperature causes the hydride formation in the material, degrading the properties of zirconium alloys. The safe working of nuclear reactors is the prime objective, and the corrosion and wear behavior of the core components must be explored to prevent possible failure. Fretting wear or tribo-corrosion experiments were conducted on Zr‐2.5Nb alloy against SS-410 for varied fretting duration to understand the tribological response. Electrochemical corrosion experiments were performed under the aqueous solution of LiOH (10.4 pH) using Electrochemical Impedance Spectroscopy (EIS) and potentiodynamic polarization technique. The comparison was made between the tribological and corrosion response of unhydrided‐Zr‐2.5Nb alloy (Zr‐2.5Nb) and hydrided- Zr‐2.5Nb alloy (Zr‐2.5Nb‐H). The hydride formation causes the reduction in corrosion resistance of Zr‐2.5Nb alloy. The oxide layer is formed during the wear and corrosion process which protects the material from further wear and corrosion respectively.

Vibration displacement measurement method based on vision Gaussian fitting and edge optimisation for rotating shafts

The vibrations of rotating machinery contain crucial information for monitoring the operational status of machines and diagnosing potential faults. Measuring vibration displacement using machine vision is currently a promising approach for machine monitoring in industries. However, the existing vision-based vibration displacement measurement methods cannot satisfy the high-accuracy requirements for detecting micrometre-level displacements generated by low-amplitude vibrations of rotating machinery. Therefore, this study proposes an improved noncontact-type vibration displacement measurement method based on Gaussian fitting and edge optimisation for rotating shafts. The real number-type edge positions of the rotating shafts within the selected region of interest (ROI) are accurately extracted via Gaussian edge fitting. Subsequently, edge-linking schemes, double-threshold detection and edge fitting are preformed to optimise the real number-type position of the edges. Finally, continuous displacement extraction of rotating shafts is achieved by monitoring the edge positions in the ROI. The coefficient of determination is used to evaluate a series of simulated and actual experiments quantitatively. The experimental results verify the feasibility, effectiveness, and robustness of the proposed method. An eddy current sensor is used in the actual experiments to verify the accuracy of the proposed method. The result shows that the coefficient of determination reaches 0.9792 when the amplitude of the measured displacement signals is only 22.7 μm.

Grid-free touch recognition on arbitrary surface using triboelectric vibration sensor

Touch panels are extensively applied across various fields, serving as a critical platform for the future of human-machine interaction and the metaverse. However, touch panel development is impeded by complicated sensor systems, including electrode grids, stacked multilayers, and external power. Here, a highly sensitive self-powered vibration sensor based on the triboelectric nanogenerator (VS-TENG) is designed to realize grid-free touch recognition on arbitrary surfaces by detecting and locating an external vibration source. The VS-TENG adopts a sensing structure composed of a dual-layer copper electrode designed with a parametric surface and a fluorinated ethylene propylene (FEP) film, enabling the detection of vibrations within the frequency range of 1–4500 Hz and sub-micron low-amplitude vibrations. The dual-layer electrode structure is beneficial to resist the interference from external environment. The output performance of the VS-TENG under various vibration frequencies, amplitudes, and directions, as well as its sensing capabilities when installed on panels of different materials and shapes, are systematically analyzed. The touch panel based on the VS-TENG can easily rearrange the touch resolution according to given scenarios without any physical modification to the sensor, enabling game control and vivid handwriting. This highlights its significant potential for diverse applications in the future metaverse.

Effect of vehicle-induced vibration on the strength, nano-mechanical properties, and microstructural characteristics of ultra-high-performance concrete during hardening process

Ultra-high-performance concrete (UHPC) has been rapidly accepted in accelerating bridge construction attributed to its superior workability and mechanical performance. However, the unavoidable vehicle-induced vibration in construction site may cause the performance degradation of UHPC, and the influencing mechanisms have not been well-documented. In this study, the effects of various vibration parameters (amplitudes, frequencies, and phases) on the macroscopic properties, nano-mechanical properties and microstructure evolution of unhardened UHPC were investigated. Results demonstrated that the microstructural evolution and strength development of UHPC differed at different introduced vibration energy, although the vibration during the hardening process can disperse the unhydrated cement particles, decrease the Ca/Si values and form additional C–S–H gels. The low-energy vibration (low-amplitude vibration and vibration before initial setting) refined the pore structure and optimized the fiber orientation in UHPC, leading to a volume increase of gel nano-pores (<10 nm) and a higher fiber orientation coefficient (ηθ). This improvement results in an increase in its compressive and flexural strength by 0.6%–3.8% and 6.8%–24.5%, respectively. In contrast, however, the high-energy vibration (high-amplitude vibration and vibration after initial setting) coarsened the large capillary pores (100–5000 nm) and macro-pores macro-pores (>5000 nm). Furthermore, the interaction (adhesion and friction) between the aggregate and matrix in UHPC was also disrupted under this condition, as confirmed by SEM. This leads to the evolution of interfacial transition zone (ITZ) in UHPC from a dense framework to a framework with microcracks.

Self-powered piezoelectric energy harvesting with ultra-low power consumption for low-amplitude ambient vibrations

Self-powered piezoelectric energy harvesting with ultra-low power consumption for low-amplitude ambient vibrations

Study of nanoindentation behavior of NiCrCoAl medium entropy alloys under indentation process using molecular dynamics

Abstract The mechanical properties and deformation behavior of CoCrNiAl medium entropy alloy (MEA) subjected to indentation by an indenter tooltip on the substrate are explored using molecular dynamics (MD) simulation. The study investigates the effects of alloy compositions, temperature variations, and ultra vibration (UV) on parameters, such as total force, shear strain, shear stress, hardness, reduced modulus, substrate temperature, phase transformation, dislocation length, and elastic recovery. The findings indicate that higher alloy compositions result in increased total force, hardness, and reduced modulus, with Ni-rich compositions demonstrating superior mechanical strength. Conversely, increasing alloy compositions lead to reduced von Mises stress (VMS), phase transformation, dislocation distribution, and dislocation length due to the larger atomic size of Ni compared to other primary elements. At elevated substrate temperatures, atoms exhibit larger vibration amplitudes and interatomic separations, leading to weaker atomic bonding and decreased contact force, rendering the substrate softer at higher temperatures. Additionally, higher initial substrate temperatures enhance atom kinetic energy and thermal vibrations, leading to reduced material hardness and increased VMS levels. Increasing vibration frequency enlarges the indentation area on the substrate’s surface, concentrating shear strain and VMS with vibration frequency. Higher vibration amplitude and frequency amplify force, shear strain, VMS, substrate temperature, and dislocation distribution. Conversely, lower vibration amplitude and frequency result in a smaller average elastic recovery ratio. Moreover, increased amplitude and frequency values yield an amorphous-dominated indentation region and increased proportions of hexagonal close-packed and body-centered cubic structures. Furthermore, this study also takes into account the evaluation of a material’s ability to recover elastically during the indentation process, which is a fundamental material property.

A broadband hybrid energy harvester with displacement amplification decoupling structure for ultra-low vibration energy harvesting

Abnormal vibration of electrical equipment requires a large number of distributed sensors to monitor. However, there are issues that require maintenance and power supply. This work proposes a working mode for harvesting the low-grade vibration energy of electrical equipment, which can replace vibration sensors and achieve self-powered monitoring of equipment vibration. Additionally, we present a novel energy harvesting module that solves the issue of converting random vibration into linear vibration. The introduction of laminated hinges achieves large displacement output under small amplitude vibration and energy harvesting from random low amplitude vibration within a bandwidth of 2–23 Hz. The impact of geometric parameters on the proposed system is evaluated through parameter analysis. Experimental findings reveal that the device can achieve a maximum power output of 17.84 mW at an ultra-low 0.05 g acceleration., resulting in a peak power density of approximately 44.87 W/m3. Compared to traditional methods, peak power has increased by 266.2 %. Wireless vibration online monitoring systems for visualizing vibration status are created by combining the equipment with repeaters and phones. This research introduces a unique strategy for remote online vibration monitoring that may be used in distributed sensor systems to identify malfunctioning machinery.

Influence of magnetically-induced nonlinear added stiffness on the lift galloping of square cylinders at low Reynolds number

A square cylinder may gallop if subjected to fluid flow, experiencing a self-excited vibration mode that can harvest energy for low-power applications. The harvested power is typically low and depends on the upstream flow velocity and system dynamic parameters. In this study, the influence of nonlinear stiffness induced by two repulsive magnetic poles on the galloping response of square rods is investigated at a mass ratio of 10 and a Reynolds number of 200. The vibration response of two identical coaxial square rods with magnetic poles attached to their opposite ends is analyzed. Two simplified configurations are selected to model the magnetic forces: a pair of identical monopoles and a pair of identical dipoles. Results show that the magnet configuration and strength significantly affect the vibration amplitude and the onset flow velocity. A weak magnetic force can enhance vibration and reduce onset flow velocity, while a stronger pair of dipoles may push the bistable system to a state of low-amplitude vibration with a mean displacement. The influence of magnets in this configuration has potential as a control technique for energy harvesting applications.

Converting energy from overhead transmission line vibrations using a low-frequency and low-amplitude harvester in a smart grid

Introduction: Overhead transmission line vibration is detrimental to the normal operation of the power grid. It is necessary to remotely monitor overhead transmission lines with sensors in normal operation, and sensors require a constant source of energy. Harvesting energy from transmission line vibrations is an excellent solution to power these sensors.Methods: A low-frequency and low-amplitude vibration energy harvester is proposed, analyzed, produced and experimented in this study. A main constituent of the energy harvester is an outer support, an inner support, four one-way bearings, a bevel gear system and a DC generator. The harvester converts the linear reciprocating motion of the line into reciprocating swing at first and then converts it into fixed-direction rotation. Theoretical analyses are conducted to determine the harvester performance factors. Finally, the harvester is fabricated and tested.Results: The test results are in good accordance with the simulation results. At the vibrating speed as 0.48 m/s, the maximum output power and output voltage are 4.2 W and 24.7 V, respectively. The weather sensor and video recorder installed on the transmission line are powered by the harvester.Discussion: The energy harvester also effectively suppresses the vibration of transmission lines and has great potential in the constructions of smart grids. The harvester provides a feasible solution for harvesting line vibration energy and suppressing line breeze vibration simultaneously.

Magnetic Modulation of the Piezoelectric Polyvinylidene Fluoride Film Energy Harvester for Noncontact Dynamic Characteristics Control

This paper aims to improve the performance of the piezoelectric buckled beam under low vibration environment using the noncontact magnetic modulation method. Based on the bi-stable buckling beam structure, the magnetic force is introduced to capture more energy. In order to investigate the influence of magnetic force in the process of vibration, the dynamic response of the harvester is analyzed under different magnetic force through numerical simulation and experiment. It is found that the magnetic force has a softening effect on the structure, namely, it could reduce the stiffness of the buckled beam. Therefore, the energy harvester could realize large-amplitude vibration under low-amplitude or low-frequency vibration with the help of magnetic force. The experimental results show that the harvester can realize inter-well vibration only when the vibration acceleration is 3.5[Formula: see text]g and the frequency is 15[Formula: see text]Hz without the magnetic force. The harvester only needs 2.5[Formula: see text]g acceleration or 10[Formula: see text]Hz vibration frequency to realize the large-amplitude vibration. While in the case of 12[Formula: see text]mm magnetic gap. After the magnetic force is introduced in the harvester, the voltage output under 2.5[Formula: see text]g acceleration is increased from 1 to 4[Formula: see text]V, and the voltage output at 10[Formula: see text]Hz vibration frequency is increased from 0.2 to 2[Formula: see text]V. Therefore, the proposed magnetically tuned bi-stable energy harvester can better operate in low frequency and low amplitude environments.

Noninvasive identification of directionally-dependent elastic properties of soft tissues using full-field optical data

This paper introduces an innovative approach for elastic property characterization of soft tissues, having directional-dependent material behavior, via their vibration response measurement and interpretation. The full-field time-dependent surface displacements as a result of externally excited soft tissues are collected through digital image correlation (DIC). A developed analytical model, capturing the low-amplitude vibration behavior of anisotropic layered human skin with the incorporation of the influence of subcutaneous elasticity and inertia, is employed to accurately predict its resonant frequencies and pertaining displacement field images. An efficient solution approach for the model is implemented into an inverse algorithm to rapidly characterize the anisotropic elastic properties based on importing the vibration characteristics. To show the merit of the approach, a 3-D finite element (FE) simulation model was used to generate full-field data, detected and matched with a set of specific vibration modes via modal assurance criterion (MAC). The validity of the model implemented into the inverse characterization algorithm is demonstrated through a comparison of predicted vibration frequencies and mode-shapes simulated via the 3-D FE model for different cases with anisotropic elastic properties in different layers of the skin. It is shown that modes are influenced differently when anisotropic properties are introduced to the model. Thus, the established inverse characterization algorithm is capable of rapidly predicting the elastic material properties of anisotropic soft sheets with adequate accuracy.

Nonlinear Dynamic Mechanical Characteristics of Air Springs Based on a Fluid–Solid Coupling Simulation Method

The use of air springs has become widespread in various industries due to their exceptional superelastic properties; however, their strong nonlinear characteristics have become a hindrance to numerical simulations of air springs and have garnered increasing attention. This paper examined the nonlinear dynamic mechanical characteristics of air springs from a fluid–structure interaction perspective and verified the accuracy of the simulation analysis model through quasistatic tension and compression experiments. The average relative errors for air spring load and gas pressure were found to be 8.1% and 7.7%, respectively, which supports the validity of the model. The impact of frequency and amplitude excitations on the axial load characteristics of air springs was investigated through tension and torsion testing. The results showed that increasing the excitation frequency improves the stability of the axial load, while increasing the excitation amplitude enhances the axial load value. The change in axial compression was found to be more significant than that in axial tension, as it was affected not only by the axial load but also by the radial load, which is a key factor affecting the dynamic characteristics of air springs. A radial load analysis model was established to study the influence of frequency and amplitude excitations on the axial load characteristics of air springs. The simulation results indicated that under different amplitudes, the radial load of air springs goes through four stages: a steady period, rising period, steady period, and falling period. Additionally, under the same amplitude, the radial load value increases with an increase in frequency. This research on the dynamic load characteristics of air springs under amplitude and frequency excitations is important for their application in low-frequency and low-amplitude vibration environments, and its findings can be utilized to improve the technical parameters of air springs for suspension damping.

Bond-pad damage in ultrasonic wedge bonding

Utilizing SEM/EDX analysis, microscale fracture at the bond-pad is detected when Cu wire is wedge bonded to a Cu or Al substrate. It is found that when a bond is fractured by pulling the wire similar to a pull test, a bulge on the wire and a cavity in the substrate are formed and fracture occurs in the original substrate. Using a 3D optical profiler, it is revealed that for a constant bond force and bond power, cavity's depth, radius, and surface area increase with bond time. These metrics are proposed as new factors for optimizing the wedge bonding process. A suitable combination of bonding parameters should maximize the cavity's surface area (as it pertains to bond's pull force) while minimizing the cavity's depth relative to the substrate's thickness to prevent damage in the substrate. Furthermore, employing Molecular Dynamics simulations, a possible plastic deformation mechanism for bond-pad damage is proposed. The mechanism points to the potential benefits of using a small-grain-sized substrate, a low transducer's vibration amplitude, and a high transducer's frequency for minimizing the cavity's depth.

Design and characterization of non-linear electromagnetic energy harvester with enhanced energy output

This paper presents design, analysis, and characterization of a compliant non-linear electromagnetic energy harvester operating on the principle of bi-stability incorporated with a displacement amplification mechanism. The energy harvester engenders energy from ambient vibrations at multiple modes and with frequencies ranging from 80 to 120 Hz. The energy harvester is analytically modeled using the mechanic’s elastic beam theory. Finite Element Analysis (FEA) has been carried out using commercial Finite Element Method (FEM) based software to perform static, fatigue, dynamic and electromagnetic analysis. Bi-stable mechanism has been used to harness energy at a wider frequency bandwidth while lever mechanism is acting as a displacement amplifier for enhancing low frequency vibration amplitude with the amplification factor of 6.24. With such amplification factor, the energy harvester can be deployed to extract vibrations of diminutive level and recast them into electrical energy in the form of generated voltage. Spring steel material, owing to its structural sensitivity, stiffness and higher value of ultimate stress, was used for its fabrication. The use of Neodymium (N52) magnets, copper coils and shaker were put into practice for testing of this device. The coil resistance is 2.5 Ω with number of turns kept at 350. The maximum output voltage of 1.86 V was generated at 106 Hz with root mean square value of 548 mV. Testing results are in accordance with the results obtained through simulations and thus useful electrical power of 11.1 mW can be generated from ambient vibrations at a wider bandwidth of 18 Hz with operating frequency ranging from 99 to 117 Hz.