Vibration Output Research Articles

Vortex-induced vibration triboelectric nanogenerator for low speed wind energy harvesting

We propose a novel vortex-induced vibration (VIV) based triboelectric nanogenerator (TENG) that makes it possible for efficient energy harvesting from wind at low speed. A theoretical model for VIV-TENG is constructed to investigate the vibration response and output voltage varying with wind speed, which is compared with and validated by experiments. Results show that there is a lock-in region where the vibration amplitude and output voltage are large. When the wind speed is 2.78 m/s, the average power is achieved to be 392.72 μW and the average power density is 96.79 mW/m2, which are much higher than those reported in previous studies. In order to broaden the lock-in region, we further design a new model of tandem vortex-induced vibration triboelectric nanogenerators. The resonance wind speed region is remarkably widened due to interactions between two cylinders subjected to VIV. The demonstration of continuously powering wireless sensors is performed to show the practicability of the designed VIV-TENG. Overall, the present study enables applications of TENG for realizing self-powered wireless sensing under low wind speed environments.

Effect of mechanical compliance of mounting clamp on electrical properties and vibration response of high-frequency piezoelectric ultrasonic transducer for microelectronic packaging and interconnection

To figure out how the mechanical compliance of the mounting clamp impacts the performance of the high-frequency piezoelectric ultrasonic transducer, several flexible hinge-based mounting clamps with different compliance were designed, then a series of experiments and analyses were performed. The electrical characteristic analysis results show both the electromechanical coupling coefficient and the quality factor of the transducer increase with the increment in the mechanical compliance of the clamp, in the meanwhile, the frequency shift between the actual and nominal resonance frequencies of the transducer is greatly reduced. Under the same excitation condition, with the mechanical compliance of the clamp increasing by 2.2 times, the longitudinal and lateral vibration outputs of the transducer have increased by 39.8% and 44.4%, respectively, indicating more ultrasonic energy is transferred to the output tip of the transducer, which also enlarges the action area of the ultrasonic energy. The power spectrum of the longitudinal vibration signal reveals that the energy distributed at the fundamental has increased by 3.96 times, while that of the second- or third-harmonics exhibits a significant decline, manifesting the promotion of the compliance can improve the purity of the fundamental vibration, and lower the modal coupling level.

Microcontroller-based supporting tool for socializing in physical distancing during Covid-19 pandemic

Physical distancing is one of the procedures to avoid the spread of Covid-19. Several researchers have created tools to support physical distancing and the detection focus is on the front or back side with sound alert. However, this kind of sound alert can disturb other people activities. Moreover, people have a blind spot in their right and left side vision which is more than 400 on the horizontal plane. The study aims to design two bracelets for socializing in physical distancing during Covid-19 pandemic. It works at a distance of 1 meter within a radius of 1200 on eye blind spot and provide the option of a vibration or sound alert or both with the push button. The main components of this tool are Arduino nano as the system controller, HC-SR 04 ultrasonic sensor as the distance measure, PIR HC-SR 501 sensor as the people movement detection, continuous rotation servo motor MG90S as the sensors driver of 1200, vibrating DC motor type 310-101 as the vibration output and buzzer as the sound output. The result of this study is two bracelets that available to detect distance and movement on the 1200 rotation angle. When both of bracelets on the 1-meter distance, they will make vibration, sound, or both.

Comparative analysis of the VPR-4M vibrating feeder dynamics for the reflected ore output from the outlets and its modernized analog with a vibro-impact adaptive drive

A study has been conducted on the developed mathematical model of the VPR-4M vibrating feeder oscillations, which is used for the output and loading of reflected ore from the outlets at underground mining and its modernized analog with a vibro-impact adaptive drive. It is shown that at the same excitation parameters the intensity of the feeder tray oscillations with vibro-impact drive exceeds the intensity of the VPR-4M feeder tray oscillations, which leads to an increase in the transportation speed and ore leakage. With increasing load from the ore on the trays there is an increase in the oscillation parameters of the vibro-impact drive, which leads to more intense oscillations of the feeder tray with vibro-impact drive in comparison with the oscillations of the VPR-4M feeder. The vibrating system of the feeder with vibro-impact adaptive drive performs polyfrequency oscillations, which leads to increased intensity and distance of oscillation spreading in the ore. The identified advantages increase the efficiency and productivity of vibration output by increasing the speed of ore transportation through the tray, intensifying its leakage from the outlet and reducing the probability of ore hangs due to increasing intensity and oscillation distance through the ore in the outlet.

Experimental and numerical study of underwater piezoelectric generator based on Vortex-induced Vibration

Efficient energy use to be transformed into electricity for small power devices has drawn increasing attention. A piezoelectric energy harvester is proposed to convert flow energy underwater to electrical energy. The harvester consists of the connecting device, springs, base, bluff body, piezoelectric cantilever beam and displacement sensor. The output voltage is derived from the flow-solid-electric coupling equations, including a nonlinear van der Pol equation, a linear equation of structural vibration and a piezoelectric equivalent circuit. Vibration response and output performance are obtained based on the finite central difference method. The theoretical results show that the vibration frequency, amplitude and average power increase with the limited water velocity. Furthermore, it is demonstrated that a proper selection of structure mass and load resistance can improve average harvested power for the available water velocity. Finally, the experimental prototype is fabricated to test piezoelectric generator performance at different water speeds, which shows good agreement with the theoretical results. This work provides a significant guide for the underwater use of piezoelectric energy harvesters.

Feedback-driven error-corrected single-sensor analytics for real-time condition monitoring

In this paper, a single-sensor based output-only algorithm is proposed for real-time condition monitoring of mechanical vibrating systems. Four key aspects of real-time condition monitoring and maintenance are presented through Recursive singular spectrum analysis (RSSA): (a) Filtering, (b) Enhancification, (c) Fault detection, and (d) Modal identification. Recent prominence of eigen perturbation (EP) solutions for condition monitoring has led to the development of RSSA as the go-to real-time algorithm for single-sensor diagnosis. As single-sensor econometrics has been long sought as a viable option for cases involving instrumentation redundancies, non-optimal sensor placement, and cost considerations, RSSA provides replication, scalability, and transferability for real-time fault detection studies. With the output vibration signals streaming in real-time, the Hankel covariance matrix is formed which filters out the noise subspace in the grouping stage. Online enhancification becomes particularly useful when the signal statistics are masked by time-varying non-stationary excitation. Application examples involving AM–FM signals and operational noise in structural systems demonstrates the versatility of RSSA towards spatio-temporal fault detection in real-time. The efficacy of the proposed algorithm is further validated by experimental investigations of real-time complete modal identification from partial sensor information. With applications extending to real-time passive control and aligned to current infrastructure monitoring demands worldwide, RSSA demonstrates potential to establish as a benchmark algorithm for online condition monitoring.

VISTATM: Visual Impairment Subtle Touch AidTM – a range detection and feedback system for sightless navigation

We devised a low-tech, low-cost, robust, and minimally obtrusive navigational travelling aid to be paired with and bolster standard white cane use for people with visual impairments. The device combines ultrasonic range detection with proportional vibrational output. The navigational aid was devised using a sensing belt equipped with independent ultrasonic sensors for distance measurements. Sensors were mounted using adjustable mobile clips to allow for user variability. The sensing belt was connected to a stimulation belt affixed to the ribcage. The stimulation belt used vibrating motors with vibration proportional to the distance between the belt wearer and surrounding obstacles sensed by corresponding ultrasonic sensors. The device was validated through preliminary testing on blindfolded, but fully sighted, persons and one blind person (all authors) in navigating a novel environment without supplemental aid. Testing sessions varied from 45 to 90 min. In preliminary tests, the devised ultrasonic-sensor-belt and vibration-actuator-equipped belt combination was capable of informing users of surrounding obstacles in real-time while navigating a hallway with several turns.

Usefulness of inclined circular cylinders for designing ultra-wide bandwidth piezoelectric energy harvesters: Experiments and computational investigations

This study proposes to change the inclination angle (α) of a circular cylinder with respect to oncoming flow in order to broaden the effective wind speed bandwidth of the piezoelectric energy harvester. Comprehensive wind tunnel experiments are conducted to investigate the energy harvesting characteristics of the system under different inclination angles. The experimental results demonstrate that compared to the conventional vortex-induced vibration piezoelectric energy harvester (VIVPEH), an appropriate inclined cylinder can broaden the effective wind speed range for the VIVPEH. It is experimentally shown that the inclined cylinder at α = 60° can reduce the threshold wind speed and broaden the effective wind speed bandwidth by more than 229%. In addition, inclined circular cylinders at α = 25°, 30°, 35°, 40°, and 45° can produce torsional vibration and high voltage output under high wind speed. Through frequency analysis and computational fluid dynamics (CFD) simulations, the influence mechanism and causes of torsional vibration are explored in detail. The results show that the axial flow will prevent the free shear layer from falling off and cause the force imbalance at the top and bottom of the inclined cylinder, resulting in a torsional vibration and a series of other phenomena. The appearance of the torsional vibration rapidly reduces the frequency of the conventional transverse vortex-induced vibration (VIV). The superposition of the transverse bending vibration and the torsional vibration within a certain wind speed range results in a high voltage output.

Electromechanical coupling analysis of three-dimensional braided piezoelectric composites energy harvester

In this article, three-dimensional (3-D) braided composite material is used to design the piezoelectric energy harvester in view of its excellent mechanical properties. The energy harvesting model of 3-D braided piezoelectric beam composed of two piezoelectric layers and a 3-D braided composites elastic layer is established. The material properties of 3-D braided composites designed according to the four-step braiding process are obtained by performing finite element analyses on its representative unit. Vibration characteristics and output responses of this energy harvester are investigated in detail and the comparison trend between theoretical and simulated results shows good consistency.

Selection criteria of piezoelectric materials for double-parabolic-reflectors ultrasonic transducers (DPLUS) for high-power ultrasound

To suit double parabolic reflectors wave-guided ultrasonic transducer (DPLUS) for high-power ultrasound applications, we investigated the selection criteria of piezoelectric materials for DPLUS. Four piezoelectric materials were prepared: two lead–zirconate–titanate (PZT) types and two lead-free types. For non-resonant excitation of the DPLUS waveguide, the piezoelectric constant e and the thickness of piezoelectric materials are two important evaluation indexes. PZT 5H was found as the best candidate. For resonant excitation of the DPLUS waveguide, two situations should be distinguished. For low-frequency modes excitation, the discussed modes matching issue is essential. For high-frequency modes excitation, high-power properties of the piezoelectric material are important for improving the vibration output of DPLUS; LFP 0202 was found as the best candidate. Low-frequency modes can achieve 8 m s−1 of maximum peak vibration velocity, but high-frequency modes were smaller than 2 m s−1. Results are important to design the DPLUS for various high-power ultrasound applications.

An underwater flag-like triboelectric nanogenerator for harvesting ocean current energy under extremely low velocity condition

Ocean current energy harvester is a promising infrastructure to achieve self-powered marine wireless sensing system. This study proposes and investigates an underwater flag-like Triboelectric Nanogenerator (UF-TENG) based on the flow-induced vibration. The UF-TENG consists of two conductive ink-coated polyethylene terephthalate membranes and one strip of poly tetra fluoroethylene membrane with their edges sealed up by a waterproof PTFE tape. In this way, the triboelectric layers are prevented from contacting water. It is verified that the vortex street induced by a cylinder enhances the vibration of the UF-TENG. The low velocity startup enables the UF-TENG to harvest extremely low-velocity ocean current energy, e.g., presently achieving 0.133 m/s as the critical startup velocity. The proposed UF-TENG has a simpler structure and better low velocity performance when comparing with electromagnetic generators and piezoelectric generators. Parametric studies are conducted to evaluate the influence of geometrical parameters of the UF-TENG on the vibration behavior and output performance. It is demonstrated that the underwater electrical appliance can be powered by parallel UF-TENG units. The present UF-TENG is a more cost-effective and more accessible hydroelectric technology to utilize the renewable ocean current for powering sensors or micro electric appliances in Internet of Things.

Dynamic modeling and vibration analysis of a cracked 3K-II planetary gear set for fault detection

Abstract. The 3K planetary gear system is a basic planetary transmission structure with many advantages over the 2K-H planetary gear system. However, the vibration characteristics will be more complicated due to the increase of central gears meshing with each planet gear simultaneously. In this paper, a lumped-parameter model for a 3K-II planetary gear set was developed to simulate the dynamic response. The time-varying stiffness of each meshing pair for different gear tooth root crack faults is calculated via the finite element method. By considering the effect of time-varying transmission paths, the transverse synthetic vibrations are obtained. Subsequently, the feasibilities of transverse synthetic vibration signals and output torsional vibration signals as reference for fault diagnosis are analyzed by studying the time-domain and frequency-domain characteristics of these two vibration signals. The results indicate that both the transverse synthetic vibration signals and output torsional vibration signals can be used for fault identification and localization of the 3K-II planetary gear train, and yet they both have their limitations. Some results of this paper are available as references for the fault diagnosis of 3K planetary gear trains.

Degradation of rhodamine B in water by ultrasound-assisted TiO2 photocatalysis

Rhodamine B is widely used in the dyeing of paints, acrylic and other fabrics as well as biological products. It is highly toxic to organisms when directly discharged into water. To this end, in this paper, degradation of Rhodamine B in water by ultrasound-assisted TiO2 photocatalysis was investigated. The effects of various factors, such as the amount of catalyst, the speed of mechanical stirring, the frequency of ultrasonic vibration, the ultrasonic output power, the initial pH value of the reaction solution, the initial concentration of Rhodamine B, the introduced air, and physical adsorption, etc., on the degradation of Rhodamine B in wastewater were studied, and the optimal degradation conditions were obtained: rotational speed, pH value, initial rhodamine B concentration, ultrasonic vibration frequency, output power and TiO2 nanoparticles dosage were 500 r/min, 7, 20 mg/L, 40 kHz, 300 W and 500 mg/L respectively. Finally, degradation mechanism was discussed. The results indicate that ultrasound-assisted TiO2 photocatalysis method is of great potential application value in removal of organic pollution and environmental purification.

NONLINEAR SYSTEM IDENTIFICATION OF WPC TERRACE WALL WITH HAMMERSTEIN-WIENER MODEL USING AMBIENT VIBRATION

Today, many advances in engineering field have been and are being made. Especially the predictions of the strengths and behavior of the models designed against external factors are of great importance. Elimination of negative effects and necessary updates on the model or in other words, strengthening works play the biggest role in the design stages. In addition to all these, the dynamically influenced situations of existing structures should be revealed. New methods have been developed for this and similar reasons. System identification is one of these methods. System identification is simply the estimation of the mathematical model of the building from the input and output vibration data obtained through the structures. Thanks to the predicted mathematical model, the reactions of the building to dynamic effects can be predicted. The aim of this study is to reveal the mathematical model of the WPC terrace wall with the nonlinear system identification method. Finally, nonlinear system identification of the WPC terrace wall results demonstrated that fit to estimation data was nearly 100 % and it can be concluded that Hammerstein–Wiener system identification method is efficient and accurate in identifying mathematical model of the WPC terrace wall.

Unsupervised Damage Detection for Offshore Jacket Wind Turbine Foundations Based on an Autoencoder Neural Network.

Structural health monitoring for offshore wind turbine foundations is paramount to the further development of offshore fixed wind farms. At present time there are a limited number of foundation designs, the jacket type being the preferred one in large water depths. In this work, a jacket-type foundation damage diagnosis strategy is stated. Normally, most or all the available data are of regular operation, thus methods that focus on the data leading to failures end up using only a small subset of the available data. Furthermore, when there is no historical precedent of a type of fault, those methods cannot be used. In addition, offshore wind turbines work under a wide variety of environmental conditions and regions of operation involving unknown input excitation given by the wind and waves. Taking into account the aforementioned difficulties, the stated strategy in this work is based on an autoencoder neural network model and its contribution is two-fold: (i) the proposed strategy is based only on healthy data, and (ii) it works under different operating and environmental conditions based only on the output vibration data gathered by accelerometer sensors. The proposed strategy has been tested through experimental laboratory tests on a scaled model.

High-speed giant magnetostrictive actuator using laminated silicon steel core.

The high-frequency eddy current loss limits the output speed of the giant magnetostrictive actuator (GMA). This paper investigates a GMA using a laminated silicon steel core. Compared with the integral silicon steel core, the laminated silicon steel core can reduce the equivalent conductivity and eddy currents. The laminated structure reduces the magnetic reluctance of the core and increases the magnetic field intensity in the giant magnetostrictive material rod. Therefore, the actuator can output large vibration amplitude under high-frequency magnetic field. At the sinusoidal excitation current of 35A (rms) @ 2 kHz, the output vibration amplitude of the actuator using the laminated silicon steel core is 11.1 µm @ 4 kHz, which is 44.2% higher than that of the actuator with the integral silicon steel core. This indicates that the laminated structure of the magnetic core is beneficial to improve the output speed of GMA.

Operational modal parameter identification with correlated colored noise excitation

Operational modal analysis refers to the modal analysis of a structure in its operating state. The advantage of operational modal analysis is that only the output vibration signal of a system is used. The classical operational modal analysis algorithm is based on the white noise excitation assumption, and it is considered that there is no correlation between the excitations; several identification methods have been developed in time and frequency domains. But excitations are not completely independent with each other and not pure white. In this article, the matrix theory is used to prove that the operational modal analysis algorithm can still be used to identify modal parameters when the excitation is correlated. In the simulation, five kinds of colored noise excitations are applied to the cantilever beam with correlated excitations, which shows that the idea proposed in this article is rational. In the experiment, the foundation excitation of colored noise is added to the cantilever beam, which can be regarded as applying several related excitations. It also shows the rationality of this idea.

A self-tuning adaptive-passive lever-type vibration isolation system

In this study, a novel self-tuning adaptive-passive lever-type vibration isolation system for base excitations is described. Due to inertial coupling within the vibration isolation system, an antiresonance frequency is generated, which depends on the amplification ratio of the lever. At this frequency, the instantaneous center of zero velocity of the lever coincides with the hinge that is under the payload. As a result, the payload experiences minimum amount of vibration. When the excitation frequency changes, the system changes the lever ratio so as to bring the antiresonance frequency to coincide with the excitation frequency to suppress the output vibration. The designed mechanical system does not require any electronic sensors or actuators. The self-tuning operation is enabled by an elastic fin type actuator powered by the input vibration rendering the system self-powered. The installation of the actuator enables it to act also as a sensor, so no additional vibration sensor is required. The equations of motion of the system are derived and the location of the instantaneous center is obtained analytically. Then, multi-body dynamic simulations are carried out to verify the self-tuning response of the system. A prototype incorporating a variable ratio lever, a softly suspended ground mass and an elastic fin type actuator is manufactured. Experimental results validate that the system always goes to antiresonance condition in the working frequency range. Statement of author contributionCetin Yilmaz proposed the idea of this paper and dealt with most of the theoretical formulation with the help of Onur Ozyar. Onur Ozyar did all the numerical simulations. Together, they analyzed the results. Onur Ozyar did most of the manufacturing with some help from Cetin Yilmaz. Together they did the experiments. Finally, they wrote the manuscript together.

Modelling the railway induced ground vibrations in soft soil areas of Western Finland

The vibrations induced by railway are a major problem in Western Finland’s soft soil areas, where the residential areas are located near railway. FTIA started to investigate the problem and together with VR-Transpoint, they organized extensive test drives in the Kokemäki-Pori railway. The rolling stock was brought to test drives from Russia. The test drives were monitored and the measured data is used in this study for the 2D modelling of the vibration phenomena. The main goal of this study was to investigate the resulting vibrations at various train speeds at particular site in 2D FE model. The study focuses on the frequency of the input load and the output vibration. The track-embankment-ground system has a frequency response to the input load, which can be assumed to be the natural frequency of the subsoil. The natural frequencies can be calculated with response analyses. With good assumption of the natural frequencies of the ground, the model can be used to discover which frequencies of the input load causes harmful vibration in the railroad environment. The train speed affects to the frequencies of the input load. The model can also be used to find the certain speed of a certain rolling stock, which will cause the certain frequency that will propagate and cause harmful vibrations in a certain soft soil areas.

Age Effects of Bone Conduction Vibration Vestibular-evoked Myogenic Potentials (VEMPs) Using B81 and Impulse Hammer Stimuli.

Recently developed, the Radioear B81 bone oscillator allows for higher bone conduction vibration output; however, normative data are lacking regarding its use in vestibular-evoked myogenic potential (VEMP) testing. The purpose of this study was to examine the effect of age on cervical and ocular VEMP (c- and oVEMP) responses using the B81 and to compare with air conduction stimuli (ACS) and impulse hammer (IH) VEMP response characteristics. c- and oVEMP were completed with ACS, B81, and IH stimuli in healthy participants (age range = 10 to 87 years, n = 85). Regardless of stimulus type, c- and oVEMP amplitudes and response rates decreased with age. For cVEMP response rates, ACS performed better or equal to B81, which was superior to the IH. For cVEMP corrected amplitude, ACS had significantly higher amplitudes compared with B81 and IH. There was no difference in cVEMP corrected amplitude between B81 and IH. For oVEMP, response rates were comparable between stimuli with the largest disparity in response rates occurring in the oldest groups where IH outperformed both ACS and B81. For oVEMP amplitude, IH had significantly higher amplitudes compared with B81 and ACS. There was no difference in oVEMP amplitude between B81 and ACS. Age significantly affected c- and oVEMP amplitudes regardless of stimulus type (ACS, B81, IH). All stimuli are appropriate for eliciting c- and oVEMP in the young individuals. While ACS resulted in higher cVEMP corrected amplitudes, either ACS or B81 are appropriate for older individuals. However, for oVEMPs, higher response rates and larger amplitudes were noted for IH followed by B81 and ACS. Overall, the B81 performed well across the lifespan for c- and oVEMPs and may be a reasonable bone conduction vibration option for patients with absent ACS VEMPs, but at this time is not recommended as a replacement to ACS.