Mechanical Vibration Research Articles

Research progress of piezoelectric materials in protecting oral health and treating oral diseases: a mini-review.

Piezoelectric materials, as a class of materials capable of generating electrical charges under mechanical vibration, have special piezoelectric effects and have been widely applied in various disease treatment fields. People generate vibrations in the oral cavity during daily activities such as brushing teeth, using electric toothbrushes, chewing, and speaking. These natural vibrations (or external ultrasound) provide ideal conditions for activating piezoelectric materials, leading to their high potential applications in protecting oral health and treating oral diseases. Based on this, this review reports on the research progress and trends of piezoelectric materials in the protection of oral health and the treatment of oral diseases in the past 5years, and discusses its treatment mechanism, challenges and shortcomings, aiming to provide theoretical basis and new ideas for the future application of piezoelectric materials in the field of oral cavity. Finally, a brief outlook is provided, suggesting that the potential of piezoelectric materials may enable them to quickly move towards real clinical applications.

Ultrasonic-induced amorphization and strengthening mechanisms of ultrasonic vibrations assisted friction stir Al/Ti welds

Integration of aluminum (Al) and titanium (Ti) alloys offers an effective approach to sustainable and high-quality development of the automotive and aviation industries. However, challenges arise when welding Al alloys to Ti alloys due to the formation of detrimental intermetallic compounds at the interface. With the implementation of ultrasonic vibrations, the temperature and strain rate were both increased during Al/Ti friction stir welding (FSW), leading to the formation of an amorphous interlayer, instead of intermetallic compound (IMC), at the interface. The interfacial microcracks were eliminated in the ultrasonic vibrations assisted friction stir welding (UVFSW). There were Ti particles separated from the Ti substrate and dispersed in the Al alloy, thereby resulting in a more gradual and moderate evolution of the interfacial microstructure. Due to the improved interfacial microstructure with ultrasonic vibrations, the lap shear strength was almost twice that of the conventional FSW welds within same welding conditions. Meanwhile, ultrasonic vibrations also improved the fabrication efficiency with a higher optimal traversing speed. The failure mode shifted from interface separation of FSW welds to a shear dimple fracture of the UVFSW welds, demonstrating the better plasticity and reliability of the UVFSW Al/Ti dissimilar joints.

Multifunctional Magnetic Muscles for Soft Robotics

Despite recent advancements, artificial muscles have not yet been able to strike the right balance between exceptional mechanical properties and dexterous actuation abilities that are found in biological systems. Here, we present an artificial magnetic muscle that exhibits multiple remarkable mechanical properties and demonstrates comprehensive actuating performance, surpassing those of biological muscles. This artificial muscle utilizes a composite configuration, integrating a phase-change polymer and ferromagnetic particles, enabling active control over mechanical properties and complex actuating motions through remote laser heating and magnetic field manipulation. Consequently, the magnetic composite muscle can dynamically adjust its stiffness as needed, achieving a switching ratio exceeding 2.7 × 10³. This remarkable adaptability facilitates substantial load-bearing capacity, with specific load capacities of up to 1000 and 3690 for tensile and compressive stresses, respectively. Moreover, it demonstrates reversible extension, contraction, bending, and twisting, with stretchability exceeding 800%. We leverage these distinctive attributes to showcase the versatility of this composite muscle as a soft continuum robotic manipulator. It adeptly executes various programmable responses and performs complex tasks while minimizing mechanical vibrations. Furthermore, we demonstrate that this composite muscle excels across multiple mechanical and actuation aspects compared to existing actuators.

Crack-Based Composite Flexible Sensor with Superhydrophobicity to Detect Strain and Vibration.

Vibration sensors are widely applied in the detection of faults and analysis of operational states in engineering machinery and equipment. However, commercial vibration sensors with a feature of high hardness hinder their usage in some practical applications where the measured objects have irregular surfaces that are difficult to install. Moreover, as the operating environments of machinery become increasingly complex, there is a growing demand for sensors capable of working in wet and humid conditions. Here, we present a flexible, superhydrophobic vibration sensor with parallel microcracks. The sensor is fabricated using a femtosecond laser direct writing ablation strategy to create the parallel cracks on a PDMS film, followed by spray-coating with a conductive ink composed of MWCNTs, CB, and PDMS. The results demonstrate that the developed flexible sensor exhibits a high-frequency response of up to 2000 Hz, a high acceleration response of up to 100 m/s2, a water contact angle as high as 159.61°, and a linearity of 0.9812 between the voltage signal and acceleration. The results indicate that the sensor can be employed for underwater vibration, sound recognition, and vibration monitoring in fields such as shield cutters, holding significant potential for mechanical equipment vibration monitoring and speech-based human-machine interaction.

Development of a liquid-helium free cryogenic sample holder with mK temperature control for autonomous electron microscopy

The automated and autonomous cryogenic transmission electron microscopy (Cryo-EM) demands a sample holder capable of maintaining temperatures below 10 K with precise control, long holding times, and minimal helium use. Rising to this challenge, we initiated an ambitious project to develop a novel closed-cycle cryocooler-based cryogenic sample holder that operates without the use of liquid helium and the consumption of gaseous helium. This article presents the design, construction, and experimental testing of the initial prototype, which achieves an ultimate temperature of 5.6 K with exceptional stability close to 1mK, while providing a wide temperature control range from 295 K to 5.6 K, marking a clear advancement in cryo-EM holder development. While the prototype was not designed for atomic resolution imaging and thus lacks a sturdy support system to mitigate mechanical vibrations from the cryocooler's pulsed tube, this innovative approach successfully demonstrates proof of concept. It offers unprecedented capabilities for state-of-the-art cryogenic microscopy and microanalysis in materials and biological sciences.

Sludge carbon promotes barium titanate piezoelectric property to activate persulfate degradation of enrofloxacin

AbstractBACKGROUNDPiezoelectric catalysis using perovskite‐type barium titanate (BaTiO3) has been applied to the decomposition of refractory organic pollutants through piezoelectric catalytic persulfate (PS). Nevertheless, challenges such as a limited specific surface area, poor electrical conductivity and a tendency towards agglomeration in BaTiO3 necessitate the exploration of novel methods to enhance its piezoelectric efficiency.RESULTSSludge carbon (SC) from sewage treatment and BaTiO3 was utilized to develop a novel piezoelectric catalytic material (BaTiO3/SC). The specific surface area of BaTiO3/SC reached 67.92 m2 g−1, which is nine times larger than that of BaTiO3 alone. The inclusion of SC in the composite enhanced the number of active sites and contributed to a higher degree of graphitization, improved electrical conductivity, and provided a more stable structure for BaTiO3/SC. This material was capable of harvesting mechanical vibration energy from ultrasound, thereby generating piezoelectric catalytic properties and activating PS to achieve a 93% decomposition ratio of enrofloxacin (ENR) in water within 80 min. The activation of PS by BaTiO3/SC piezocatalysis led to the production of reactive oxygen species (ROS), such as •OH and SO4−•. These ROS attack the quinolone ring of ENR, which is susceptible to cleavage, resulting in the decomposition of ENR into intermediates of lower toxicity.CONCLUSIONThe incorporation of SC has enhanced the piezoelectric performance of BaTiO3, rendering BaTiO3/SC a novel perovskite‐type piezoelectric catalytic material that improves piezoelectric efficiency. The BaTiO3/SC system, through its piezoelectric catalytic activation of PS, demonstrates potential for decomposition of refractory organic pollutants in water treatment. © 2024 Society of Chemical Industry (SCI).

The Clinical Utility of Whole Body Vibration: A Review of the Different Types and Dosing for Application in Metabolic Diseases.

Whole body vibration (WBV) is an innovative exercise mimetic that utilizes a vibrating platform to transmit mechanical vibrations throughout the body. WBV has been a popular area of research in recent years due to its potential physiological and therapeutic benefits in both health and disease. The utility of WBV is rooted in the various parameters (i.e., frequency, amplitude, duration) that affect the overall dose of vibration delivered to the body. Each type of WBV, coupled with these aforementioned parameters, should be considered when evaluating the use of WBV in the clinical setting. Thus, the purpose of this review is to provide an overview of recent literature detailing the different types of WBV, the various parameters that contribute to WBV efficacy, and the evidence of WBV in metabolic disease. A systematic search was conducted using Medline, Embase, Cochrane, CINAHL, and PubMed. All types of study designs were considered, with exclusions made for animal studies, duplicates, and study protocols without data. Thirty-four studies were included. In conclusion, as a modern exercise mimetic with therapeutic potential for metabolic diseases, understanding the interplay between the types and dosing of WBV is critical for determining its utility and efficacy. Further studies are certainly needed to elucidate the full therapeutic potential of WBV in metabolic diseases.

Ultracoherent Gigahertz Diamond Spin-Mechanical Lamb Wave Resonators.

We report the development of an all-optical approach that excites the fundamental compression mode in a diamond Lamb wave resonator with an optical gradient force and detects the induced vibrations via strain coupling to a silicon vacancy center, specifically, via phonon sidebands in the optical excitation spectrum of the silicon vacancy. Sideband optical interferometry has also been used for the detection of in-plane mechanical vibrations, for which conventional optical interferometry is not effective. These experiments demonstrate a gigahertz fundamental compression mode with a Q factor of >107 at temperatures near 7 K, providing a promising platform for reaching the quantum regime of spin mechanics, especially phononic cavity quantum electrodynamics of electron spins.

Fuzzy Modelling Algorithms and Parallel Distributed Compensation for Coupled Electromechanical Systems

Modelling and controlling an electrical Power Generation System (PGS), which consists of an Internal Combustion Engine (ICE) linked to an electric generator, poses a significant challenge due to various factors. These include the non-linear characteristics of the system’s components, thermal effects, mechanical vibrations, electrical noise, and the dynamic and transient impacts of electrical loads. In this study, we introduce a fuzzy modelling identification approach utilizing the Takagi–Sugeno (T–S) structure, wherein model and control parameters are optimized. This methodology circumvents the need for deriving a mathematical model through energy balance considerations involving thermodynamics and the non-linear representation of the electric generator. Initially, a non-linear mathematical model for the electrical power system is obtained through the fuzzy c-means algorithm, which handles both premises and consequents in state space, utilizing input–output experimental data. Subsequently, the Particle Swarm Algorithm (PSO) is employed for optimizing the fuzzy parameter m of the c-means algorithm during the modelling phase. Additionally, in the design of the Parallel Distributed Compensation Controller (PDC), the optimization of parameters pertaining to the poles of the closed-loop response is conducted also by using the PSO method. Ultimately, numerical simulations are conducted, adjusting the power consumption of an inductive load.

Force Element Analysis in Vortex-Induced Vibrations of Side-by-Side Dual Cylinders: A Numerical Study

A numerical investigation was conducted in this study utilizing Force Element Analysis to explore the vortex-induced vibration (VIV) mechanism of side-by-side dual cylinders under the conditions of Reynolds number Re = 100, mass ratio m* = 10, and spacing ratios L/D ranging from 3 to 6. The hydrodynamic forces by force element formulas were incorporated into the vibration response calculations of elastically supported rigid cylinders using a User-Defined Function (UDF) and the fourth-order Runge–Kutta method. A comprehensive analysis was performed to elucidate the combined effects of the spacing ratio L/D and reduced velocity Ur on the vibration responses, quantifying the hydrodynamic forces involved in the mutual interaction during VIV for side-by-side dual cylinders. The influence mechanisms of inter-cylinder interaction and their effects on the resultant hydrodynamic phenomena were discussed. It was revealed that for side-by-side arranged dual cylinders outside the “lock-in region”, the lift and drag forces are predominantly supplied by the volume vorticity forces in conjunction with surface vortices (including frictional) forces. However, within the “lock-in region”, the surface acceleration lift forces provide greater force contributions, and the volume vorticity lift force contributes significantly to negative values. Notably, alterations to the spacing ratio do not change the proportion of force element components. The amplitudes of the cylinders’ mutual interaction forces are identical in magnitude but opposite in phase. Additionally, the “slapping” phenomenon near the “lock-in region” leads to “bounded” trajectories of cylinders.

Coupling vibration mechanism of rotating shaft–disc–blade system with blade crack—A systematical investigation on the effect of crack, condition, and structure parameters

Rotating shaft–disc–blade (RSDB) system is one of the most important parts of turbomachinery, such as aero-engine, gas turbine, and power plant. Understating and revealing the coupling vibration mechanism of RSDB system is significant for blade health monitoring and blade crack detection. However, the multi-structure, multi-vibration source, and multi-stress coupling makes it a very tough task. This study aims to reveal the coupling vibration mechanism of RSDB system by systematically investigating the steady-state vibration responses under the influences of different blade crack, operation condition, and structure parameters. First and foremost, a coupling vibration model of RSDB system that comprehensively considers the multi-structure, multi-vibration source, and multi-stress coupling effects is presented. And then, a novel condition indicator for blade health monitoring, called blade–blade distance, is proposed to better characterize and analyse the coupling vibration of RSDB system with blade crack. At last, the comprehensive effects of blade crack, operating condition, and structure parameters on the coupling vibration mechanism of the RSDB system with blade crack are systematically studied. The comparative results demonstrate the effectiveness of blade–blade distance and super-harmonic components of shaft torsional vibration and blade bending vibration for indicating the presence of blade crack and tracking the crack severity. Another observation should be noted is that the vibration behaviour including the blade–blade distance, super-harmonic components of shaft torsional vibration and blade bending vibration, the combination frequency components of shaft bending vibration are co-affected by blade crack, operating condition, and structure parameters. It is indicated that the blade health monitoring and crack detection of rotating blade should comprehensively consider different indicators to obtain a more robust and accurate results.

Nacreous Glass Composites with Superior Performance Engineered through Mechanical Vibration and Silanization (Adv. Funct. Mater. 36/2024)

Nacreous Glass Composites with Superior Performance Engineered through Mechanical Vibration and Silanization (Adv. Funct. Mater. 36/2024)

Numerical study on bifurcation characteristics of wind-induced vibration for an H-shaped section

In order to reveal the influence of initial excitation on the bifurcation phenomenon of bridge decks, a new perspective of flow characteristics is developed based on the computational fluid dynamics numerical simulation method. Then, the bifurcation mechanism of vortex-induced vibration (VIV) response and nonlinear flutter response of the H-shaped section is investigated. The results show that when the wind speed is 2 m/s, under a small torsional excitation of 0.5°, the flow field of the H-shaped section will develop into the vortex shedding mode of the vertical vibration, resulting in vertical VIV. However, while under a large excitation of 6°, the flow field will directly transform into the vortex shedding mode of the torsional vibration, resulting in torsional VIV. Therefore, the bifurcation phenomenon of the VIV response is observed. When the wind speed is 4 m/s, the H-shaped section exhibits a nonlinear flutter limit cycle oscillation under a large excitation of 8°, but its response can be ignored under a small excitation of 0.5°. This phenomenon is attributed to the significant change in the transition of the vortex shedding mode from a small amplitude to a stable large amplitude, and the flow field lacks enough energy to complete the transition of the vortex shedding mode, resulting in the bifurcation phenomenon of the nonlinear flutter response. When the wind speed is 3.0 m/s, the large excitation will change the vortex shedding frequency of the new H-shaped section, resulting in the torsional VIV.

Vibration compensation control strategy of composite cage rotor bearingless induction motor based on fuzzy coefficient adaptive-linear-neuron method

To address the vibration problem induced by rotor eccentricity in a composite cage rotor bearingless induction motor(CCR-BIM), a vibration compensation control approach based on the fuzzy coefficient adaptive-linear-neuron is proposed. Firstly, the CCR-BIM mathematical model and the mechanism of unbalanced vibration are investigated, obtaining the expression of rotor displacement when the rotor is unbalanced. Afterwards, the displacement is decomposed by the fuzzy coefficient adaptive-linear-neuron algorithm to obtain the harmonic component related to vibration, and the value range of the weight coefficient is determined using stability analysis. Furthermore, through analyzing the shortcomings of the traditional PID vibration compensation method, a rotor vibration compensation method based on the fuzzy coefficient adaptive-linear-neuron is put forward to achieve high-performance vibration compensation control. Finally, the PID method and the proposed fuzzy coefficient adaptive-linear-neuron algorithm are simulated and verified by experiments. The findings demonstrate that the proposed algorithm successfully not only suppresses rotor unbalanced vibration but also exhibiting great dynamic performance.

The population growth model of electrostatic charges: A novel concept for engineering optimal performance triboelectric nanogenerators

Lateral sliding triboelectric nanogenerators LS-TENGs promise to combine low cost and high-efficiency mechanical energy harvesting at low frequency with the advantages of light weight and simple device architecture. To date, device power generation optimization has only been addressed on the framework of the optimal load resistance through the maximum power transfer theorem (MPTT). However, MPTT is a concept to optimize the power transferred from TENGs to loads, but not for optimizing the power generated by the TENG itself. In response, this work reports a concept that resembles the population growth model of species for designing enhanced performance LS-TENGs with optimal charge-generating rate. In this way, devices designed under the proposed concept possess a significantly enhanced optimal charge and power generation rate up to 3-fold and 8-fold respectively superior to those found for conventional rectangular TENGs with similar capacity, which allows us power up sustainably for hours low power consumption devices with a few minutes of mechanical energy harvesting. Thereby, this model aids in the development of enhanced performance LS-TENGs capable of collecting mechanical vibrations and optimally converting them into electrical energy by breaking the limits set by the MPTT, as well as opening a route towards batteryless power autonomy.

A kind of single-phase full bandgaps phononic crystals and experimental evidence

The exceptional performance of locally resonant phononic crystals (PCs) in vibration attenuation and noise reduction within nuclear power plants has garnered widespread attention in scholarly circles. To address the need for improved predictive accuracy in substrate structures characterized by significant flexibility, a one-dimensional mechanical model rooted in the mass-spring chain paradigm has been established. This model offers a straightforward and accurate means of predicting the lower and upper frequencies of the initial bandgap within locally resonant phononic crystals. Moreover, the dynamic model elucidates modal characteristics and vibrational responses inherent to locally resonant phononic crystals. Utilizing the proposed model, a singular-phase phononic crystal structure boasting full bandgaps has been devised. This structure facilitates the omnidirectional acquisition of locally resonant bandgaps across an exceedingly low-frequency spectrum through the incorporation of cantilever beam elements. Such a design holds immense promise within the realm of large-scale mechanical vibration isolation. As a means of validation, steel samples embodying this phononic crystal model were fabricated. Experimental results demonstrated an insertion loss of approximately 18.67 dB, affirming the vibration isolation efficacy of the singular-phase phononic crystal configuration.

Study on intelligent tyre force estimation algorithm based on strain analysis

The objective of this paper is to propose a novel approach to develop an algorithm for estimating the grounding force between a tyre and the road surface. First, a finite element model of a heavy-duty tyre is developed in this paper, and the validity of the model is verified by load application tests and mechanical vibration tests. When the tyres are operated under various operating conditions, that is, load, side deflection, side tilt and longitudinal slip conditions, the sensitivity analysis is performed by combining the three-directional forces based on the strain curves measured when the tyres are rolling, respectively. In order to achieve accurate estimation of the three-directional forces, this paper establishes a three-directional force estimation model using the support vector machine (SVM) technique, with the tyre force-sensitive eigenvalues as inputs and the tyre forces as outputs, so as to achieve the three-directional force estimation of the tyre-grounded three-directional forces. joint estimation of tyre-road contact force. The results show that the estimation error of vertical force is 1.79%, the estimation error of lateral force is 3%, the estimation error of longitudinal force is 4.65% and in general, the estimation error of grounding force is kept within 5%, and the estimation effect is good.

The Physiology of Vocal Damping: Historical Overview and Descriptive Insights in Professional Singers

Summary/ObjectiveVocal damping has been historically described as a distinctive phonatory glottic behavior where the posterior part of the vocal folds is strongly adducted and vibration occurs in the anterior part. The aim of the present descriptive study is to analyze anterior glottis phonation patterns in professional singers through a multidimensional approach, in order to better understand the physiological underpinnings of vocal damping and their relation to glottic vibratory mechanisms. MethodsTen professional singers (five males and five females) with no vocal complaints were recruited. Each subject was asked to produce ascending and descending glissandos in a spontaneous way; sustained vowels and little sung fragments in vocal fry, chest voice, falsetto, and whistle register. Each singer was asked to produce – where possible – damping sounds.A multidimensional investigation including acoustic analysis, electroglottography and videolaryngostroboscopy was carried out. ResultsAmong the enrolled singers, nine out of ten successfully produced vocalizations with a typical anterior-vibrating glottic pattern indicative of damping. All nine singers achieved a damping glottic configuration when vocalizing in the falsetto register and five were consciously able to switch between a full-glottic falsetto and a damping falsetto upon request. Three male and two female singers were able to produce a damping glottic configuration while emitting whistle notes. Three male singers demonstrated damping glottic configurations when producing chest notes in a belting style. ConclusionsIn conclusion, it is possible to state that damping is an existing and documentable glottic behavior, with a wide range of manifestations across vocal registers. The present preliminary study describes damping in the domains of chest voice, falsetto and whistle register. A proper damping phenomenon, defined as the modification of the glottic vibratory boundaries according to pitch variations, is described for M2 emissions, both in male and female larynx. The analysis of passaggio patterns allows to describe damping-M2 as a possible vibratory sub-mechanism.

Fast computation of the spectral correlation via frequency-averaging

Spectral Correlation (SC) has become a critical analytical instrument for assessing the second-order cyclostationarity (CS) in signals, especially for mechanical vibration signals. Nonetheless, the computational demand for computing SC is considerable. Built upon the Smoothed Cyclic Periodogram (SCP), a consistent estimator named Fast Smoothed Cyclic Periodogram (FastSCP) is proposed to address this issue. FastSCP represents the computational process of SCP through the convolution of spectral components and incorporates the Overlap-Save algorithm for accelerating. Comparison results with other fast SC estimators, including Fast Spectral Correlation (FastSC) and Faster Spectral Correlation (FasterSC), indicate that the proposed method is competitive in terms of both computational cost and memory usage, particularly when dealing with wide cyclic frequency ranges.

Dual-loss nonlinear independent component estimation for augmenting explainable vibration samples of rotating machinery faults

Obtaining fault samples for diagnosing faults in rotating machinery for engineering applications can be costly. To address this challenge, fault sample augmentation methods are used to train fault diagnosis models. However, existing techniques mainly focus on comparing augmented signal loss with real ones, overlooking the underlying vibration mechanism of rotating machinery faults. Addressing this limitation, a novel approach, called dual-loss nonlinear independent component estimation (DLNICE), is proposed to enhance understanding of fault features in vibration signals. This integrates augmentation losses in both time and frequency domains to enrich fault vibration samples. DLNICE effectively utilizes limited fault samples for augmentation by estimating nonlinear independent components, capturing key fault characteristics like impulsiveness and cyclo-stationarity. Therefore, augmented fault samples become more explainable for analyzing rotating machinery faults. Experimental evaluations on bearing and gearbox vibration samples confirm the effectiveness of DLNICE. Utilizing the augmented samples leads to an average accuracy of 86.27 % in bearing fault diagnosis, and that of 81.60 % in gearbox fault diagnosis. The results demonstrate that DLNICE excels in augmenting high-quality vibration samples of rotating machinery faults.