Vibration Output Research Articles

Influence of simulated adverse events of the floating mass transducer in a mechanical middle ear model

Background The Vibrant Soundbridge Implant provides multiple options for coupling the Floating Mass Transducer (FMT) to the ossicles. A parametric evaluation in clinical trials is difficult. Aims/Objectives We studied the vibratory output of the FMT with three couplers—short process, former long process, and current long process—in an acoustic-mechanical middle ear model (AMEM) under simulated impaired coupling conditions. Materials and Methods The AMEM, with life-sized ossicles, was tested via acoustic and electrical (FMT-) stimulation. Simulated impairments included accidental bone-contact, cable tension, and insufficient connection. Stapedial footplate vibrations were measured using Laser Doppler. Results Acoustic stimulation generally fulfilled the ASTM standard. With normal coupling, SP- and LP-couplers performed comparable to temporal bone data. Impaired coupling led to various effects: bone-contact reduced the transmission up to 20 dB, cable tension minimally affected SP and current LP couplers but reduced the sound transmission for the former LP coupler. Connecting the SP-coupler with only two of four titanium legs caused a single frequency dip without affecting overall magnitude, whereas off-axis LP fixation reduced the output by 15-20 dB around 1000 Hz. Conclusions and Significance The AMEM generated reproducible, ASTM-compliant measurements. SP and current LP couplers showed resilience to potential FMT implantation impairments in most frequencies.

Wearable Electrohydraulic Actuation For Salient Full‐Fingertip Haptic Feedback

AbstractAlthough essential for an immersive experience in extended reality (XR), providing salient and versatile touch feedback remains a technical challenge. Existing solutions restrict hand movements with bulky rigid structures, require a tethered energy source to power actuators worn on the hand, or output vibrations that lack expressiveness. This study introduces a design strategy for compact, lightweight, untethered haptic feedback centering on a 30‐µm‐thick inflatable chamber that naturally conforms to the fingertip; to minimize fluidic losses and enable high bandwidth, a soft electrohydraulic pump mounted on the hand actuates the chamber via a mechanically transparent fluidic channel. A 15.2‐mm‐diameter prototypical actuation chamber achieves 8 N peak force, 3 N steady‐state force, stroke up to 5 mm, and bandwidth from 0 to 500 Hz. In contrast to these salient fingertip cues, the entire hydraulic system has a weight less than 8 g and a thickness less than 2 mm. Additionally, this study presents a validation approach that uses a commercial fingertip sensor to confirm that the haptic feedback created by the device imitates the touch signals generated during typical hand interactions. Together, this design strategy and validation method can enable a broad spectrum of haptic activities in diverse XR applications, including medical training, online shopping, and social interactions.

Design and characteristic analysis of a high-performance deformable piezoelectric wind energy harvester based on coupled vibrations

Design and characteristic analysis of a high-performance deformable piezoelectric wind energy harvester based on coupled vibrations

Dynamic modelling and mechanical analysis of an inertial linear piezoelectric actuator with double stators

Abstract To achieve higher output performance in precision applications, and in order to gain deeper insight into operation principle, a dynamic model is established including the transmission relationship between the stators, the driving shaft, and the mover based on a slip-slip type inertial linear piezoelectric actuator with double stators. The influence of stator material and symmetry ratio of the excitation signal on the vibration characteristics of the stator and the output performance are investigated. This study reveals the relationship between these factors through a combination of simulations and experiments. Prototypes using several materials are machined and assembled, and the vibration characteristics and output performance are rigorously tested. The results obtained from the experimental measurements are consistent with the simulation results, confirming the validity and rationality of the dynamic model. The experimental results of the stator, as well as the actuator, are analyzed. It can be concluded that the actuator is able to output a larger effective displacement in one motion period with the increased symmetry ratio of the triangular wave signal, applied with a higher operating frequency, resulting in a higher output velocity of 42 mm/s and a larger load of 300 g with the steel stator, and a higher displacement resolution of 18 nm can be achieved using the AL alloy stator. This research not only provides an effective method for enhancing and selecting the desired output performance for the researched actuator but also can be extended to other slip-slip type inertial linear piezoelectric actuators.

Performing Magnetic Boundary Modulation to Broaden the Operational Wind Speed Range of a Piezoelectric Cantilever-Type Wind Energy Harvester.

Small piezoelectric wind-induced vibration energy harvesting systems have been widely studied to provide long-term sustainable green energy for a large number of wireless sensor network nodes. Piezoelectric materials are commonly utilized as transducers because of their ability to produce high output power density and their simple structure, but they are prone to material fracture under large deformation conditions. This paper proposes a magnetic boundary modulated stepped beam wind energy harvesting system. On the one hand, the design incorporates a composite stepped beam with both high- and low-stiffness components, allowing for efficient vibration and electrical energy output at low wind speeds. On the other hand, a magnetic boundary constraint mechanism is constructed to prevent the piezoelectric sheet from breaking due to excessive deformation. Experiments have confirmed that the effective operational wind speed range of the harvester with magnetic boundary constraints is doubled compared to that of the harvester without magnetic boundary constraints. Furthermore, by adjusting the magnetic pole spacing of the boundary, the harvesting system can generate sufficiently high output power under high-wind-speed conditions without damaging the piezoelectric sheet.

Vibrational coupling-based multilayer flexible triboelectric nanogenerator for wide-amplitude omnidirectional wave energy harvesting

Vibrational coupling-based multilayer flexible triboelectric nanogenerator for wide-amplitude omnidirectional wave energy harvesting

Quality control on vibrator ground force in land vibroseis acquisition

Many quality control (QC) methods are used to monitor the output force from seismic vibrators. These QC tools usually provide the vibrator output force in three aspects — fundamental force, phase, and harmonic distortion — to measure the quality of the ground force compared with the predetermined sweep. As the vibrator works on challenging earth surfaces, such as unconsolidated ground surfaces, the peak harmonic distortion, a key vibrator QC parameter, always exceeds its QC threshold. This necessitates a vibrator reshoot and thereby a degradation of productivity. The purpose of this paper is to demonstrate that in unconsolidated ground surface areas a new setting of the harmonic cutoff frequency on a vibrator controller is recommended. This new setting reduces the unnecessary harmonics around 200 Hz so that the peak harmonic distortion is controlled in the required QC range. Therefore, unnecessary vibrator reshoots can be avoided, leading to improved productivity.

Chromaticity Recognition Technology of Colored Noise and Operational Modal Analysis

Operational Modal Analysis (OMA) refers to the modal analysis with only output vibration signals of a structure in its operating state. Classic OMA has developed multiple recognition methods in both the time and frequency domains, where when the random excitation is unknown, the excitation chromaticity is usually treated as white color, which can often cause errors and affect the accuracy of identifying frequencies or damping ratios. In this article, the chromaticity recognition function is defined and a method Chromaticity Recognition Technology (CRT) for identifying noise chromaticity based on system response is proposed. Then, a simulation example is presented. The noise chromaticity is identified for the response of the system under four types of colored noise excitation, and the results of the identification of operational mode parameters with and without CRT are compared. Furthermore, the sensitivity of traditional OMA to different colored noise has been investigated. An experiment with a cantilever under base excitation of pink noise has been undertaken and the results demonstrate the feasibility of the proposed CRT in this paper.

Rapid Estimation Model for Wake Disturbances in Offshore Floating Wind Turbines

The precise wake model is crucial for accurately estimating wind farm loads and power, playing a key role in wake control within wind farms. This study proposes a segmented dual-Gaussian wake model, which is built upon existing dual-Gaussian wake models but places greater emphasis on the influence of initial wake generation and evolution processes on the wind speed profile in the near-wake region. The enhanced model optimizes the wake speed profile in the near-wake region and improves the accuracy of wake diffusion throughout the entire flow field. Furthermore, the optimized dual-Gaussian wake model is utilized to estimate the power output and blade root vibration loads in offshore wind farms. Through comparative analysis of high-fidelity simulation results and actual measurement data, the accuracy of the optimized dual-Gaussian wake model is validated. This approach offers high computational efficiency and provides valuable insights for load fluctuations and power estimation, thereby advancing the development of wake control strategies rapidly.

Research on piezoelectric simulation characteristics based on ALN piezoelectric thin film structure

AlN piezoelectric thin films possess exceptional performance and find extensive applications in the fields of underwater acoustic communication and hydroacoustic sensing. To enhance the output voltage values of AlN piezoelectric thin films and optimize their structure, comprehensive simulations and analyses were carried out by using COMSOL on both circular and square film configurations. These investigations specifically focused on examining the impact of dimensional variations on resonance frequency and output voltage, as well as exploring the relationship between vibration frequency and output voltage. The findings revealed that by employing an appropriate cavity radius, increasing the thickness of the thin film can effectively enhance the output voltage. However, if the thickness surpasses 1.5 μm, the output voltage will gradually decline. Notably, the square film exhibited a significantly higher output voltage measurement of 2158 pm compared to the circular film.

Nonlinear vibration and amplitude ratio output performance of a resonant micro-gyroscope based on bifurcation detection

In this paper, we design a 3-degree-of-freedom (3-DOF) nonlinear resonant micro-gyroscope, which innovatively utilizes the bifurcation phenomenon of the nonlinear resonant beam as a detection method and uses the amplitude ratio before and after bifurcation as the sensitivity output of the system. The steady-state response of the driving equation is first solved by the complex exponential method. Coriolis force is amplified by the lever mechanism and transmitted to the axial direction of the resonant beam. The dimensions of the resonant beam are designed so that the frequency of Coriolis force is in a 2:1 relationship with the natural frequency of the resonant beam to enhance the parametric excitation effect. Subsequently, Hamilton principle and Galerkin method are used to derive and discretize the dynamical equations of the resonant beam containing axial force, respectively. The multi-scale method is used to perturbation analysis of discrete equations. Finally, the bifurcation characteristics and the amplitude-frequency response with different input angular velocities are studied. The results show that the comprehensive performance of the micro-gyroscope system using backward frequency sweep (BFS) is better than forward frequency sweep (FFS). Furthermore, by using the BFS, the relative sensitivity of the nonlinear resonant micro-gyroscope based on the amplitude ratio variation rises by about 168 times compared with that based on the frequency variation in the linear case. In addition, when considering the input angular velocity with the same magnitude but different directions, the bifurcation frequency of resonant beam is closely related to the direction of the input angular velocity, and the direction of the input angular velocity can be further identified by utilizing this phenomenon.

Dynamic response of Camellia oleifera fruit-branch based on mathematical model and high-speed photography

Dynamic response of Camellia oleifera fruit-branch based on mathematical model and high-speed photography

Design and performance analysis of 3-D braided piezoelectric composite vibration energy harvester

In this article, an innovative three-dimensional (3-D) braided piezoelectric composite vibration energy harvester (BPCVEH) is designed. The geometry and representative volume unit (RVU) models of the 3-D braided piezoelectric composites (BPCs) are established based on the braided process. The effective elastic, piezoelectric, and dielectric constants of the 3-D BPCs are also predicted. The electro-mechanical coupling vibration equation of the 3-D BPCVEH under forced vibration is derived, and its output response and vibration mode are analyzed. The effects of environment frequency, load resistance, and external excitation acceleration on the voltage and power response of 3-D BPCVEH with different volume fractions are studied.

A real time digital vibration acceleration fiber sensing system based on a multi-carrier modulation/demodulation technique

A multi-longitudinal mode fiber laser sensor (MLMFLS) system based on digital modulation/demodulation technique for vibration acceleration detection is proposed. To the best of the authors’ knowledge, this is the first digital vibration acceleration demodulation system ever reported by a MLMFLS system. A few beat frequency signals (BFS) generated by the MLMFLS are used as signal carriers of applied vibration signals. Based on multi-channel digital down-conversion technique, the weak vibration signals modulated on the BFS are superposed by utilizing the digital universal software radio peripheral (USRP). The signal-to-noise ratio (SNR) of the output vibration signal is greatly enhanced. A spectral subtraction method is also utilized to improve the SNR of the demodulated vibration signal. The acceleration of the vibration signal is obtained after second order differential of the time domain vibration signal. By simply changing the position of window function of short-time Fourier transform, a real-time vibration frequency and acceleration sensing system is achieved. The measurement results demonstrated a minimum detectable acceleration of 0.03 g at vibration frequency of 1.0 Hz by the designed sensing system. It also has a simple structure, high signal-to-noise ratio and stability.

Design and experiment of a double-sided staggered conical teeth traveling wave ultrasonic motor

This paper proposed a double-sided staggered conical teeth traveling wave rotating ultrasonic motor based on in-plane bending mode, which reduces the difficulty of rotor preload application and improves the output characteristics of in-plane bending mode traveling wave rotating ultrasonic motor. The motor has four sets of drive teeth alternately distributed on both the inner and outer sides of the vibrator, with the drive teeth gap dedicated to accommodate the piezoelectric ceramic piece, and the staggered drive teeth on both sides of the vibrator are used to drive the rotor rotation. The motor operates in two in-plane third-order bending modes with the same frequency and orthogonal to each other, and is excited by four sets of piezoelectric ceramic disks spaced 90 degrees apart from the inner and outer sides. After the prototype was completed, its vibration characteristics and output performance were experimentally tested, and the actual effects of the three excitation schemes were compared. The experimental results show that the motor can provide a maximum output torque of 1.82 N·mm and a maximum no-load speed of 96.4 rpm when the excitation voltage is 300 V and the excitation frequency is 20.60 kHz.

A Hand-Held Device Presenting Haptic Directional Cues for the Visually Impaired.

Haptic information is essential in everyday activities, especially for visually impaired people in terms of real-world navigation. Since human haptic sensory processing is nonlinear, asymmetric vibrations have been widely studied to create a pulling sensation for the delivery of directional haptic cues. However, the design of an input control signal that generates asymmetric vibrations has not yet been parameterised. In particular, it is unclear how to quantify the asymmetry of the output vibrations to create a better pulling sensation. To better understand the design of an input control signal that generates haptic directional cues, we evaluated the effect of the pulling sensations corresponding to the three adjustable parameters (i.e., delay time, ramp-down step length, and cut-off voltage) in a commonly applied step-ramp input signal. The results of a displacement measurement and a psychophysical experiment demonstrate that when the quantified asymmetry ratio is in a range of 0.3430-0.3508 with an optimised cut-off voltage for our hand-held device, the haptic directional cues are better perceived by participants. Additionally, the results also showed a superior performance in haptic delivery by shear forces than normal forces.

A harmonic suppression method for low-frequency electromagnetic vibrators

Due to various nonlinear factors in an ordinary electromagnetic vibrator, the distortion of its output vibration waveform will always happen, especially at low frequencies (≤20 Hz), which blocks its application in a lot of area. To improve the acceleration waveform precision and reduce distortions at low frequencies, a waveform harmonic suppression method for low-frequency electromagnetic vibrators is proposed. After extracting the harmonic components in the output acceleration waveforms, a digital composite signal with harmonic compensation components is prospected according to the frequency response characteristic of the vibrator, and then sent back to drive the vibrator, which results in that the harmonic components in the formal waveform is suppressed. The proposed method was verified by simulations and experiments, and results show that the total harmonic distortions (THDs) of accelerations are reduced effectively at low frequencies, typically from 23% to less than 2% at the frequency as low as 0.1 Hz. The method is stable and robust because there is no real-time feedback loop in the system.

Feasibility study on a full‐scale wind turbine blade monitoring campaign: Comparing performance and robustness of features extracted from medium‐frequency active vibrations

AbstractThe present work investigates the performance of different features, extracted from vibration‐based data, for structural health monitoring of a 52‐meter wind turbine blade during fatigue testing. An active vibration monitoring system was used during the test campaign, providing periodic excitation of single frequencies in the medium‐frequency range, and using accelerometers to measure the vibration output on different parts of the blade. Based on previous work from the authors, data is available for the wind turbine blade in healthy state, with a manually induced damage, and with progressively increasing damage severity. Using the vibration data, different signal processing methods are used to extract damage‐sensitive features. Time series methods and time‐frequency domain methods are used to quantify the applied active vibration signal. Using outlier analysis, the health state of the blade is classified, and the classification accuracy through use of the different features is compared. Highest performance is generally obtained by auto‐regressive modeling of the vibration outputs, using the auto‐regressive parameters as features. Finally, suggestions for future improvements of the present method toward practical implementation are given.

Enhanced piezoelectric energy harvesting performance using trailing-edge flap

Enhanced piezoelectric energy harvesting performance using trailing-edge flap

Relative importance and interactions of parameters of finite-element models of human middle ear.

In the last decades, finite-element models of the middle ear have been widely used to predict the middle-ear vibration outputs. Even with the simplest linear assumption for material properties of the structures in the middle ear, these models need tens of parameters. Due to the complexities of measurements of material properties of these structures, accurate estimations of the values of most of these parameters are not possible. In this study, we benefited from the stochastic finite-element model of the middle ear we had developed in the past, to perform global sensitivity analysis. For this aim, we implemented Sobol' sensitivity analysis which ranks the importance of all uncertain parameters and interactions among them at different frequencies. To decrease the computational costs, we found Sobol' indices from surrogate models that we created using stochastic finite-element results and the polynomial chaos expansion method. Based on the results, the Young's modulus and thickness of the tympanic membrane, Young's modulus and damping of the stapedial annular ligaments, and the Young's modulus of ossicles are among the parameters with the greatest impacts on vibrations of the umbo and stapes footplate. Furthermore, the most significant interactions happen between the Young's modulus and thickness of the tympanic membrane.