Range Of Excitation Frequencies Research Articles

Modeling dynamics of a planetary variator applied in the adaptive TMDVI

A planetary variator, which is a type of the continuously variable transmission (CVT), is described in terms of dynamical modeling and assessment of its efficacy in the tuned mass damper with a variable inerter (TMDVI). An off-the-shelf planetary variator is used and modified for this application. Then, kinematic and dynamic models of the device are developed and its parameter values are determined. In the next step, the model is validated experimentally. In the second, theoretical part of the paper, an implementation of the modified device as a part of the TMDVI is considered. The variator enables tuning of the natural frequency of the TMDVI to the current frequency of excitation and allows the resonance frequency to be crossed via an optimal path with a low oscillation amplitude of the main body. Additionally, the previously proposed method to control the TMDVI to obtain efficient mitigation of vibrations in a wide range of excitation frequencies is extended. • The paper presents experimental examination of a planetary variator. • We derive validated mathematical model of a planetary variator. • We show possible application of a variator as a part of a tuned mass damper with variable inertance. • We propose an optimization method that allows efficient mitigation of vibrations. • We show response of a damped system with optimized damper.

Oscillation Control of Two-Wheeled Robot using a Gyrostabilizer

Two-wheeled robots are popular in transportation applications because of their high maneuverability. In this research, the oscillation attenuation performance of the control moment gyroscope (CMG) for the two-wheeled robot was studied. The stored kinetic energy of a CMG can offer a weight and volume saving compared to conventional vibration absorbers. This CMG is also more reactionless than other conventional absorbers by transforming the impact of angular momentum to unidirectional thrust along the center of gravity. The gimbals can precess while providing the angular momentum under the gravitational force. This study indicated that the CMG can operate in a wide range of excitation frequencies to balance the robot in a stable period. Because the flywheel speed is much easier changed to thrust against the unwanted oscillations disturbing the robot stability. There is a relation between the gimbal amplitude and the flywheel speed of CMG, in which the required flywheel speed can be reduced if the higher gimbal amplitude is chosen. It can be also concluded from the study that the oscillation amplitudes at the target frequency can decrease as much as flywheel speed increases. There was also a mathematical model using ANSYS software. The simulation results using ANSYS matched well with the theoretical results of the Lagrangian model.

Energy Harvesting in a System with a Two-Stage Flexible Cantilever Beam.

The subject of the research contained in this paper is a new design solution for an energy harvesting system resulting from the combination of a quasi-zero-stiffness energy harvester and a two-stage flexible cantilever beam. Numerical tests were divided into two main parts-analysis of the dynamics of the system due to periodic, quasiperiodic, and chaotic solutions and the efficiency of energy generation. The results of numerical simulations were limited to zero initial conditions as they are the natural position of the static equilibrium. The article compares the energy efficiency for the selected range of the dimensionless excitation frequency. For this purpose, three cases of piezoelectric mounting were analyzed-only on the first stage of the beam, on the second and both stages. The analysis has been carried out with the use of diagrams showing difference of the effective values of the voltage induced on the piezoelectric electrodes. The results indicate that for effective energy harvesting, it is advisable to attach piezoelectric energy transducers to each step of the beam despite possible asynchronous vibrations.

Dynamic instability analysis of perforated stiffened laminated composite panels subjected to non-uniform in-plane edge load under hygrothermal condition

A robust and computationally efficient finite element (FE) formulation has been developed in an effort to understand the parametric instability behaviour of a perforated stiffened composite panel subjected to a pulsating non-uniform edge load under a hygrothermal environment. The panel is modelled using a 9-noded heterosis element to avoid shear locking, whereas the stringer uses a 3-noded isoparametric beam element with a displacement compatibility condition employed at the skin–stringer​ interface. Due to the non-uniform distribution of stress in the perforated panel as a result of exposure to environmental and mechanical loading conditions, a unique dynamic technique has been implemented to account for the instability performance by employing two types of boundary conditions. In the current investigation, an unstiffened panel is initially obtained based on the highest value of the dynamic instability opening (DIO) and the unstable excitation frequency of the panel for different lamina schemes, cutout shapes, and loading conditions. The obtained unstiffened panel is further investigated for various stiffener configurations to determine a highly unstable perforated stiffened panel based on the DIO value and instability zone frequency range. Detailed parametric studies are then carried out considering the cutout sizes, cutout orientation, panel’s aspect ratio, and stiffener depth to understand the parametric instability behaviour of the panel in a hygrothermal environment. It is found that moisture significantly influences the dynamic instability behaviour of the perforated stiffened panel compared to the temperature exposure by shifting the instability zone towards the lower frequency. The width of the instability region of the stiffened panel broadens abruptly as the magnitude of the applied static in-plane edge load enhances. Also, for certain combinations of the dynamic and static load factors, the lower bound of the instability region reduces to zero, resulting in fluttering. In general, it is observed that stiffer the panel, wider is the instability zone with a higher unstable excitation frequency range.

Resonance in the flow past a highly confined circular cylinder

A three-dimensional direct numerical simulation is carried out to investigate the response of the flow past a highly confined circular cylinder to single-mode sinusoidal perturbations. The Reynolds number is fixed at 1000, and the blockage ratio (the ratio of the cylinder diameter to the distance between two lateral walls) is fixed at 0.6. Local perturbations are introduced upstream of the cylinder at normalized excitation frequencies (fe/f0) from 0.2 to 3.4, where f0 is the vortex shedding frequency in an unperturbed flow. It is observed that the vortex shedding frequency of the perturbed flows (fs) and the excitation frequency (fe) are locked-on in four distinct modes including fs = 2.0fe, fs = 1.5fe, fs = 1.0fe, and fs = 0.5fe, respectively. Among them, the fundamental lock-on with fs = 0.5fe appears over a wide range of excitation frequencies (fe/f0 = 1.4–2.8). By contrast, only the fundamental lock-on regime of fs = 0.5fe is observed when perturbing an unconfined flow at the same Reynolds number, highlighting the significant impact of confinement on the lock-on behavior. It is further revealed that the lock-on behavior is controlled by the responses of separated shear layers in the near wake, which switch from higher modes to lower modes with increasing excitation frequency in the confined flow.

Modeling and analysis of dynamic characteristics of rubber isolators for electric vehicles under high-frequency excitation

The rubber isolator is a key component connecting the vehicle body and the powertrain, which plays a significant role in reducing the vibration transmission from the engine to the vehicle body. With the development of electric vehicles, the excitation frequency generated by the powertrain can exceed 2 kHz. The conventional dynamic models are usually used to simulate the low-frequency dynamic characteristics of rubber isolators, in the range of 0–200 Hz, which is the main excitation frequency range of the traditional internal combustion engine vehicle. However, they cannot simulate the high-frequency dynamic characteristics accurately since the inertial force caused by the mass of rubber isolators increases greatly under high frequencies. And the high-frequency dynamic characteristics of rubber isolators is of great significance for isolator fatigue life prediction, powertrain system vibration isolation design and noise control caused by the high-frequency resonance of the isolator. In this paper, a general model with mass elements is proposed to describe the effect of the inertial force on high-frequency dynamic stiffness. Based on the proposed model and considering the different expressions of the viscoelastic properties of rubber isolators, three improved dynamic models of rubber isolators are established, and used to analyze the high-frequency dynamic characteristics of rubber isolators. It has been demonstrated that the inertial force plays a non-negligible role in the dynamic characteristics of rubber isolators under high-frequency excitation. The proposed model can be used to analyze the effect of the inertial force on the dynamic characteristics at high frequencies accurately. The high-frequency dynamic characteristic modeling method of rubber isolators presented in this paper is helpful to the vibration and noise analysis of electric vehicle powertrain systems under high-frequency excitation.

Analytical solutions for flexible circular spiral eddy current array coils inside a conductive tube under different operation modes

The eddy current induction of flexible eddy current array probe composed of thin curved circular spiral coils is studied using the second-order vector potential formalism. The analytical expressions of self-and mutual impedance change of coil array element inside a conductive tube under three standard eddy current array operation modes are derived. They are self-transmitting and receiving, absolute and differential transmit-receive, respectively. Further derivation shows that the coefficient matrices of characteristic equations in these modes are the same regardless of whether the element is placed inside or outside a tube, but the non-homogeneous terms are different. Therefore, the solution to another case can be obtained quickly through the transformation relationship. The experimental results show that the theoretical predictions are consistent with the experiment over the 5 kHz–1 MHz excitation frequency range. At the same time, the real and imaginary part errors of impedance change are analyzed, and the application of small inductance flexible coil in three operation modes is discussed. Finally, these expressions provide academic support for the eddy current testing of pipeline defects and their significance in the inversion of tube electromagnetic properties.

High-Frequency Self-Focusing Ultrasonic Transducer With Piezoelectric Metamaterial

Focused ultrasonic waves are widely used in medical imaging, fibroids ablation and acoustic tweezers due to its high sensitivity and large energy at the focal spot. Although, acoustic metamaterials have emerged for acoustic focusing, they have limited to low frequency, narrowband and less acoustic transmission. Herein, an active gradient metamaterial (AGM) based on composite structure on traditional piezoelectric materials is proposed to achieve the acoustic impedance matching and underwater acoustic focusing. Based on the principle that the acoustic wave emitted from the piezoelectric plate reaches the focal spot at the same time, an aperiodic axisymmetric composite with gradient depth is established. A <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$200 ~\mu \text{m}$ </tex-math></inline-formula> kerf is selected, and the depth ranges from <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$44 ~\mu \text{m}$ </tex-math></inline-formula> to <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$146 ~\mu \text{m}$ </tex-math></inline-formula> . The acoustic field pressure intensity is simulated with finite element software, and measured by a needle hydrophone with fabricated transducer. Based on the good agreement between the simulation and experimental results with the excitation frequency range of 4 MHz-20 MHz, the active self-focusing and broadband focusing behaviors of the AGM are demonstrated. It is expected to apply the proposed acoustic metamaterial in biomedical and industrial applications.

Synchronous detection of bolts looseness position and degree based on fusing electro-mechanical impedance

Looseness is the most common form of failure in bolt connections, which can cause safety accidents by reducing the rigidity of the structural connection, and the detection of bolt looseness is vital to maintain the health of the structure. However, due to the limitations of existing methods, it is difficult to detect the position of loose bolt and degree of looseness synchronously. In this study, an Electro-mechanical impedance (EMI) detection method based on fusing multi-frequency ranges was proposed. Firstly, the feasibility of bolt looseness detection based on EMI technology was analyzed through theoretical deduction; secondly, the qualitative relationship between excitation frequency and detection range was explored through finite element simulation, which provides a basis for the proposed fusing multi-frequency ranges method, and the conclusion was verified in four-bolted flange structure; finally, a detection method for bolt looseness was proposed, which uses the impedance shift as the damage index, and detect the position of loose bolt and degree of looseness synchronously by fusing EMI in multiple frequency ranges. The verification results show that the proposed method can identify the loosening status of bolts in the flange structure with high accuracy.

Pipeline Vibration Control Using Magnetorheological Damping Clamps under Fuzzy-PID Control Algorithm.

Aiming at the problem of low-frequency vibration of the hydraulic pipeline, a new type of semi-active damping magnetorheological (MR) damping clamp structure is designed. The structure size and material of the MR damping clamp were determined. The control model of the vibration damping system was established, and the control method combining fuzzy control and Proportional-Integral-Derivative (PID) control was used to carry out the numerical simulation, which proved that the fuzzy–PID control algorithm is effective and stable. The results show that the MR damping clamp proposed in this paper can effectively suppress the axial displacement and acceleration of the hydraulic pipeline in the excitation frequency range of 1 Hz~10 Hz. This research provides a new technical approach for low-frequency vibration control of hydraulic pipelines.

Nonlinear Dynamics of a Star-Shaped Structure and Variable Configuration of Elastic Elements for Energy Harvesting Applications.

The subject of the model research contained in this paper is a new design solution of the energy harvesting system with a star-shaped structure of elastic elements and variable configuration. Numerical experiments focused mainly on the assessment of the configuration of elastic elements in the context of energy harvesting efficiency. The results of computer simulations were limited to zero initial conditions as it is the natural position of the static equilibrium. The article compares the energy efficiency for the selected range of the dimensionless excitation frequency. For this purpose, four cases of elastic element configurations were compared. The results are visualized based on the diagram of RMS voltage induced on piezoelectric electrodes, bifurcation diagrams, Lyapunov exponents, and Poincaré maps, showing the impact of individual solutions on the efficiency of energy harvesting. The results of the simulations show that the harvester’s efficiency ranges from 4 V to 20 V depending on the configuration and the frequency range of the excitation, but the design allows for a smooth adjustment to the given conditions.

Enhanced Seismic Protection System for an Emergency Diesel Generator Unit

Nuclear power plants are required to maintain operation after an earthquake, leading to a safe shutdown if necessary. In the case of a loss of offsite power, the onsite emergency diesel generator is critical to ensure procedural operations of the nuclear power plant. As a means to reduce the overall seismic risk, a three-dimensional seismic protection system is proposed to enhance the seismic performance of the emergency diesel generator. The proposed seismic isolation system decouples the horizontal and vertical components of shaking and considers available hardware to achieve an effective isolation solution over the range of excitation frequencies considered. Numerical analysis of the proposed system demonstrates a reduction in seismic demands on the emergency diesel generator and provides a higher safety margin than conventional base installation procedures. Umbilical lines that cross the isolation plane are considered and impose additional constraints on the displacement capacity of the isolation system. However, increasing the displacement capacity of these components can significantly increase the safety margin against failure. The seismic protection system can be customized depending on the seismic hazard and application to different seismic regions.

Performance enhancement of Hall Effect Thrusters using radiofrequency excitation

Radiofrequency excitation in single-stage Hall Effect Thrusters is proposed as a method to increase the performance of these devices. The topology of the magnetic and electric field within Hall Effect Thrusters makes it possible to excite quasistatic waves which travel longitudinally through the channel across a magnetostatic field, whose resonances are found at the electron cyclotron gyrofrequency and its upper harmonics. An in-house pseudo 2-dimensional axial–radial Particle-In-Cell software developed at the Imperial Plasma Propulsion Laboratory called PlasmaSim is verified and validated against the Russian thruster SPT-100 and adapted to be used as a computational tool to analyze plasma-wave interactions. A benchmark case study for 2-dimensional axial–radial plasma simulation codes is proposed, and PlasmaSim plasma in-channel properties are evaluated in this analysis. In terms of performance, comparison between simulated and experimental measurements shows average values in agreement with thrust, specific impulse and anode efficiency, over the full range of discharge power conditions of the SPT-100. The proposed method of radiofrequency excitation is to vary the ground reference potential of the neutralizing hollow cathode at high frequency. A range of potential excitation frequencies is established on the basis of hot plasmas’ theory, with candidate frequencies varying between 0.1 GHz to 2 GHz for the plasma conditions within a SPT-100 device. Simulation’s results give a deeper insight into the nature of these waves and their propagation in the plasma. Quantitative analyses as a function of power and excitation frequency are reported, showing the impact on thruster performance and in-channel plasma properties. The thruster’s total power is taken as the sum of the DC discharge power and AC radiofrequency power, which is calculated numerically from the simulation results based on the time varying discharge current and voltage. Taking an average over the experimental discharge power of the SPT-100, an improvement of 30% in anode efficiency, 15% in thrust and 13% in specific impulse is obtained for the most optimum configuration of frequency and voltage (fRF=450 MHz, VRF=10 V).

Novel contactless Hybrid Static Magnetostrictive Force-Torque (CHSMFT) sensor using Galfenol

This paper presents a novel Contactless Hybrid Static Magnetostrictive Force-Torque (CHSMFT) sensor using Galfenol. Initially, the sensor's design principles for measuring axial force and torque are outlined. The magneto-mechanical properties of the materials used, such as B-H curves and magnetic permeability, are determined and used in the finite element method when various mechanical preloads and magnetic fields are applied. The CHSMFT sensor is evaluated analytically using the equivalent circuit method and numerically using COMSOL Multiphysics® software based on the obtained experimental results. Afterward, the sensor is fabricated based on the results of the analytical and finite element method and experimentally validated for a range of electrical currents and excitation frequencies. The analytical and finite element method results are then compared to the experimental results. In force and torque measurements, sensitivity, precision, and linearity error are presented separately. Finally, the CHSMFT sensor's performance characteristics under optimal conditions are presented. Sensitivity is found to increase with rising electrical current (or magnetic field) and frequency. Maximum sensitivities are obtained at 0.7349 mV/kgf and 2.24 mV/Nm for axial load and torque measurements, respectively.

Slosh Suppression Blocks - A concept for mitigating fluid motions in floating closed containment fish pen in high energy environments

This paper introduces a new concept to mitigate sloshing, tailored to floating closed containment aquaculture systems, termed slosh suppression blocks. Slosh suppression blocks reduce the natural sloshing periods by contracting the free surface area without any significant reduction of the operational volume in the tank, and can be retrofitted to existing systems. Sloshing energy is dissipated on top of the suppression blocks, out of the fluid domain to reduce the spread of turbulent eddies in the main body of the fluid in the tank. The fundamental idea and working principles of the slosh suppression blocks are illustrated with an experimental setup representing a 2D section of a closed-containment system under forced horizontal excitations. Maximum sloshing amplitudes are compared for 25 different test configurations for a range of excitation frequencies, using cubic slosh suppression blocks of different sizes. For selected configurations, the fluid's internal state is assessed by visualising the fluid motions both experimentally and by numerical simulations. The results show that slosh suppression blocks reduce the total sloshing volume and turbulent motions within the main body of the tank, providing a much calmer, controlled low energy living environment which is regarded essential for fish wellbeing. It is found that positioning the top of the slosh suppression blocks flush with the still water level mitigates and damps internal sloshing most effectively. To quantify and characterise the degree of slosh suppression, three slosh indices are introduced; the slosh reduction index, the slosh overtopping index and the slosh free surface index. The novel concept of slosh suppression blocks provides an important step forward in the design of floating closed containment aquaculture tanks that minimises sloshing and internal fluid motions in energetic environments.

Design of Piezoelectric Energy Harvester Generating Power over a Range of Excitation Frequencies Using

Today, there is a real desire to develop the piezoelectric ‎power harvester to enhance the performance of Wi-Fi sensors ‎and low-power devices to use them in heavy weather for longer times. In this study, the harvester model built from piezoelectric bimorphs called; “Piezo Bending ‎Actuators 427.0085.11Z” from Johnson Matthey, N42 ‎magnets, and some electrical parts such as; accelerometer, ‎shaker, HP 54601B oscilloscope used ‎in the ‏experimental setup‎. ‎&#x0D; The results show, that the system frequency has ‎an inverse relationship with a gap between magnets, where the ‎frequency increases 100% as the distance decreases from 4.6mm ‎to 0.7 mm‏.‏‎ In addition, the amplitude of increases by 104% as ‎the gap decreases from 4.6mm to 0.7 mm. Also, the ‎production power and amplitude have an inverse relation ‎with the magnet distance. ‎Keywords: power harvester, magnetic gap, tuned magnetic force, piezoelectric, resonances.

Finite element modal analysis and experiment of rice transplanter chassis

The vibration problem during the operation of rice transplanters is the most common phenomenon. In order that the static and dynamic characteristics of the rice transplanter chassis can meet the requirements of more stable operation, the research took the 2ZG-6DK rice transplanter as the research object to carry out a vibration reduction optimization study. In the research, the Pro/Engineer 5.0 software was first used to model the chassis of the rice transplanter. The constructed finite element model was revised by using the structural parameter revision method and the mixed penalty function method. The model was imported into ANSYS Workbench to solve the modal frequency and vibration shape of the rice transplanter chassis. Based on the MAC (modal assurance criterion) criterion, modal tests were carried out to verify the accuracy of the finite element theoretical analysis. Through the analysis of the characteristics of the external excitation frequency, the chassis is structurally optimized to avoid resonance caused by the natural frequency of the chassis falling within the road excitation frequency range. The final optimization results showed that the first four orders of modal frequencies of the chassis were adjusted to 32.083 Hz, 33.751 Hz, 42.517 Hz, and 50.362 Hz, respectively, in the case that the chassis mass was increased by 6.714 kg (8.8%). They all avoid the range of road excitation frequency (10-30 Hz) so that the rice transplanter can effectively avoid the resonance phenomenon during operation. This study can provide a reference for the design and optimization of the chassis structure of transplanter. Keywords: transplanter chassis, vibration, finite element analysis, modal experiment, MAC criterion, optimization design DOI: 10.25165/j.ijabe.20221505.6230 Citation: Chen K K, Yuan Y W, Zhao B, Jin X, Lin Y, Zheng Y J. Finite element modal analysis and experiment of rice transplanter chassis. Int J Agric & Biol Eng, 2022; 15(5): 91–100.

Modal Analysis for Localization Phenomena in Two-Pendulum Arrays Subjected to Vertical Excitation

When an array of two identical pendula connected by a linear, torsion spring is subjected to vertical excitation, the two pendula may oscillate with different amplitudes. This is referred to as a localization phenomenon. In this paper, modal analysis is performed to investigate the cause of the phenomenon. The equations of motion for the two pendula are derived in the physical coordinate. First, in the linearized equations of motion, the natural frequencies and the corresponding modal vectors are determined. Then, the equations of motion in the physical coordinates are transformed to those in the modal coordinates. Van der Pol’s method is employed to obtain the frequency response curves for the principal parametric resonance in the modal coordinates, and the response curves for the physical coordinates are determined using the coordinate transformation. These theoretical response curves are validated by being compared to the time histories and their FFT results. The numerical results show that as the excitation frequency decreases, a branch of the response curves for the first mode undergoes a pitchfork bifurcation, which induces the second mode owing to the nonlinear coupling with the first mode, and the two modes appear simultaneously at a specific excitation frequency range. This is the reason why localization phenomena are observed in the physical coordinates.

Plantar Soft Tissue Characterization Using Reverberant Shear Wave Elastography: A Proof-of-Concept Study

Plantar soft tissue stiffness provides relevant information on biomechanical characteristics of the foot. Therefore, appropriate monitoring of foot elasticity could be useful for diagnosis, treatment or health care of people with complex pathologies such as a diabetic foot. In this work, the reliability of reverberant shear wave elastography (RSWE) applied to plantar soft tissue was investigated. Shear wave speed (SWS) measurements were estimated at the plantar soft tissue at the first metatarsal head, the third metatarsal head and the heel from both feet in five healthy volunteers. Experiments were repeated for a test-retest analysis with and without the use of gel pad using a mechanical excitation frequency range between 400 and 600 Hz. Statistical analysis was performed to evaluate the reliability of the SWS estimations. In addition, the results were compared against those obtained with a commercially available shear wave-based elastography technique, supersonic imaging (SSI). The results indicate a low coefficient of variation for test-retest experiments with gel pad (median: 5.59%) and without gel pad (median: 5.83%). Additionally, the values of the SWS measurements increase at higher frequencies (median values: 2.11 m/s at 400 Hz, 2.16 m/s at 450 Hz, 2.24 m/s at 500 Hz, 2.21 m/s at 550 Hz and 2.31 m/s at 600 Hz), consistent with previous reports at lower frequencies. The SWSs at the plantar soft tissue at the first metatarsal head, third metatarsal head and heel were found be significantly (p<0.05) different, with median values of 2.42, 2.16 and 2.03 m/s, respectively which indicates the ability of the method to differentiate between shear wave speeds at different anatomical locations. The results indicated better elastographic signal-to-noise ratios with RSWE compared to SSI because of the artifacts presented in the SWS generation. These preliminary results indicate that the RSWE approach can be used to estimate the plantar soft tissue elasticity, which may have great potential to better evaluate changes in biomechanical characteristics of the foot.

Vibration and stability analysis on the water entry process of a thin plate

In this study, the stability and vibration characteristics of a thin plate in the water entry process are investigated. In the water entry process, the mass, damping and stiffness of the system change continuously with time to make the stability of the fluid-structure system exhibit the time-varying characteristics. Based on the nonlinear plate theory and the linear potential flow theory, the equation of motion of the plate interacting with external airflow and water flow is established. For the linear equation, the changes of the natural frequencies of the plate entering the water are researched by applying the generalized eigenvalue method, from which the stability of the system is analyzed. For the nonlinear equation, the displacement time responses and phase portraits of the plate subjected to harmonic excitation are discussed by numerical simulations. When the plate enters the water, the stability of the plate becomes worse. The range of the external excitation frequency makes significant effects on the vibration characteristics of the plate. The plate falls into instability with the entry velocity increasing. Finally, the effects of the fluid density, the aspect ratios and the length-to-thickness ratios of the plate on the stability and vibration characteristics of the plate are discussed.