Data on the flexural vibration of thin plate with elastically restrained edges: Finite element method and wave based method simulations.
ABSTRACT: The data here reported refer to the numerical examples shown in the research article “Wave based method for flexural vibration of thin plate with general elastically restrained edges” (Liu et al., 2020 ). Within the examples, only the datasets regarding the plates with elastic or elastic-damping supports are provided. The datasets contain the raw data directly obtained from the forced vibration simulations. The simulations are carried out using two methods: the finite element method realized in ANSYS Mechanical APDL and the proposed wave based method (Liu et al., 2020 ), implemented in a MATLAB code. The data obtained from ANSYS serves as reference for the response of the plate under different boundary conditions. For each frequency, the transverse displacements of the plate at two pre-selected points are listed in the spreadsheet (e.g. MS Excel). When damping is present, they are separated into real part and imaginary part. This part of data can be used as reference when other novel methods are developed. The datasets obtained from MATLAB include the contribution factors as well as the wave functions. Based on them, one can obtain the displacement as a complex number at any point of the plate after a simple postprocessing. Postprocessing codes to obtain the frequency response function for a user-given point and the displacement field at a user-given frequency are also provided. This part of data presents much more information than the previous part as well as the corresponding results in the related research article. It makes it possible to see the responses at other points or other frequencies that are not considered in the research article, without repeating the time-consuming simulations. Moreover, if someone wants to further improve the wave based method, this part of data will be helpful, either for analysing the limitations of the proposed method or for more direct comparisons. Any research related to the flexural vibration of plate can also consider the data provided in this article.
Project description:We investigate the effects of structural damping on the interaction of a turbulent eddy with flexible plates with respect to the efficiency of aerodynamic noise generation. Potential benefits are studied using a model based on a point-reacting compliant semi-infinite plate on a spring-damper foundation. This scattering problem is solved using the Wiener-Hopf technique. We compare results for semi-infinite compliant plates with finite ones. In both cases, plate vibration lead to reductions of sound radiation, especially at resonance; damping tends to reduce such acoustic benefits. We also present a formulation that considers the effect of structural damping on the acoustic properties of finite elastic plates. Numerical results are obtained by applying a boundary element method to solve the Helmholtz equation subject to the boundary conditions imposed by the plate vibration. Under specific conditions, such as high fluid loading factor and low bending-wave Mach number, the acoustic power scattered by an edge tends to be smaller than that which propagates over the plate as bending waves. Results show that structural damping attenuates these waves and may modify the far-field acoustic pressure, mostly by reducing the scattered sound at structural resonances. All models show that large damping coefficients lead to locally over-damped responses. There is thus an ideal range of structural damping to reduce both plate vibration and acoustic scattering.
Project description:In regenerative medicine, techniques which control stem cell lineage commitment are a rapidly expanding field of interest. Recently, nanoscale mechanical stimulation of mesenchymal stem cells (MSCs) has been shown to activate mechanotransduction pathways stimulating osteogenesis in 2D and 3D culture. This has the potential to revolutionise bone graft procedures by creating cellular graft material from autologous or allogeneic sources of MSCs without using chemical induction. With the increased interest in mechanical stimulation of cells and huge potential for clinical use, it is apparent that researchers and clinicians require a scalable bioreactor system that provides consistently reproducible results with a simple turnkey approach. A novel bioreactor system is presented that consists of: a bioreactor vibration plate, calibrated and optimised for nanometre vibrations at 1 kHz, a power supply unit, which supplies a 1 kHz sine wave signal necessary to generate approximately 30 nm of vibration amplitude, and custom 6-well cultureware with toroidal shaped magnets incorporated in the base of each well for conformal attachment to the bioreactor's magnetic vibration plate. The cultureware and vibration plate were designed using finite element analysis to determine the modal and harmonic responses, and validated by interferometric measurement. This helps ensure that the vibration plate and cultureware, and thus collagen and MSCs, all move as a rigid body, avoiding large deformations close to the resonant frequency of the vibration plate and vibration damping beyond the resonance. Assessment of osteogenic protein expression was performed to confirm differentiation of MSCs after initial biological experiments with the system, as well as atomic force microscopy of the 3D gel constructs during vibrational stimulation to verify that strain hardening of the gel did not occur. This shows that cell differentiation was the result of the nanovibrational stimulation provided by the bioreactor alone, and that other cell differentiating factors, such as stiffening of the collagen gel, did not contribute.
Project description:Polyvinyl alcohol fiber reinforced engineering cementitious composites (PVA-ECCs) exhibit excellent tight-cracking and super-high toughness behaviors and have been widely used in bridge repair projects. In reality, the conventional method in bridge repair is that a portion of the bridge is closed and repaired while the other portion is left open to traffic. Consequently, newly placed PVA-ECC bridge repairs (NP-ECC-BRs) are exposed to continuous traffic vibrations (TRVs), even during the setting periods. However, whether or not TRVs affect the expected flexural properties of NP-ECC-BRs remains unknown. The purpose of this investigation was to determine the effects of TRVs on the attainable flexural properties of NP-ECC-BRs. For this purpose, a total of 324 newly fabricated thin-plate specimens were exposed to different vibration variables using self-designed vibration equipment. After vibration, a four-point flexural test was conducted to determine the flexural properties of the specimens. The results indicate that the effects of TRVs on the strengths of NP-ECC-BRs was significantly negative, but insignificantly positive for flexural deformation. We concluded that in the design of PVA-ECC bridge repairs, effects of TRVs on the flexural deformation capacity of NP-ECC-BRs are not a cause for concern, but serious consideration should be given to the associated reduction of flexural load-bearing capacity.
Project description:The topology concept in the condensed physics and acoustics is introduced into the elastic wave metamaterial plate, which can show the topological property of the flexural wave. The elastic wave metamaterial plate consists of the hexagonal array which is connected by the piezoelectric shunting circuits. The Dirac point is found by adjusting the size of the unit cell and numerical simulations are illustrated to show the topological immunity. Then the closing and breaking of the Dirac point can be generated by the negative capacitance circuits. These investigations denote that the topological immunity can be achieved for flexural wave in mechanical metamaterial plate. The experiments with the active control action are finally carried out to support the numerical design.
Project description:The use of wave-based locomotion mechanisms is already well established in the field of robotics, using either standing waves (SW) or traveling waves (TW). The motivation of this work was to compare both the SW- and the TW-based motion of a 20-mm long sub-gram glass plate, with attached 3D printed legs, and piezoelectric patches for the actuation. The fabrication of the robot did not require sophisticated techniques and the speed of motion was measured under different loading conditions. In the case of the TW mechanism, the influence of using different pairs of modes to generate the TW on the locomotion speed has been studied, as well as the effect of the coupling of the TW motion and the first flexural vibration mode of the legs. This analysis resulted in a maximum unloaded speed of 6 bodylengths/s (BL/s) at 65 V peak-to-peak (Vpp). The SW approach also examined different modes of vibration and a speed of locomotion as high as 14 BL/s was achieved, requiring, unlike the TW case, a highly precise location of the legs on the glass supporting platform and a precise tuning of the excitation frequency.
Project description:This paper investigates abnormal stop band behavior of resonance-based flexural elastic metamaterials under the rotational resonance motion. Due to the unique physics of flexural waves, we found that the stop band generated by the rotational resonance motion exhibits peculiar behavior which are quite different from general belief - it is shown that the negativity due to the rotational resonance does not provide any stop bands and the stop band generation due to the rotational resonance is governed by totally different band gap condition. To explain the peculiar behavior, a discrete Timoshenko beam model with both effective mass and rotational inertia as independent variables is introduced, and the wave behaviors of resonance-based flexural elastic metamaterial are precisely and fully described. The unique band gap condition, including the peculiar behavior, is derived with numerical validations. We expect our new model can provide a strong background for various flexural elastic metamaterials which can be effectively applied in various vibration devices.
Project description:The paper presents new results on the localization and transmission of flexural waves in a structured plate containing a semi-infinite two-dimensional array of rigid pins. In particular, localized waves are identified and studied at the interface boundary between the homogeneous part of the flexural plate and the part occupied by rigid pins. A formal connection has been made with the dispersion properties of flexural Bloch waves in an infinite doubly periodic array of rigid pins. Special attention is given to regimes corresponding to standing waves of different types as well as Dirac-like points that may occur on the dispersion surfaces. A single half-grating problem, hitherto unreported in the literature, is also shown to bring interesting solutions.
Project description:This paper describes two methods for vibration damping in a broad band frequency range using a piezoelectric patch. The first method, applied to an adaptive device, uses a bias (static voltage control), which applies stresses or releases stresses in a piezoelectric component to modify its mechanical characteristics and thereby its resonance frequency. The second method is based on a semipassive approach [synchronized switch damping (SSD)], developed to control structural vibration damping using a piezoelectric component. Attenuations of 10 and 4.8 dB in vibration velocity have been obtained using the adaptive frequency and SSD methods.
Project description:This paper is devoted to investigating numerically, by finite element analysis (FEA), and analytically the influences and effects of laser processing of the surface of thin-plate, low-carbon structural steel. The plate mechanical properties-axial and flexural stiffnesses, force-deflection behavior and cross-section force-strain behavior-are investigated after different laser treatments. An analytical methodology of the estimation of the cross-section area of the laser-processed metal is also proposed in the present article, that can be applied to choosing the reasonable distance between the centers of the laser-processed tracks. The methodology takes into account the width of the laser-processed tracks and the distances between these tracks. The experimental, finite element numerical and analytical analyses showed that the laser treatments of the surface of the steel plate increase the yield point of the laser-processed metal and the axial and flexural stiffnesses of the plate.
Project description:Simulation data are presented for identifying and analysing the dynamic properties of the rainbow metamaterials as presented in the articles "Rainbow metamaterials for broadband multi-frequency vibration attenuation: numerical analysis and experimental validation" (Meng et al., 2019 ) and "Optimal design of rainbow elastic metamaterials" (Meng et al., 2019 ). In this data article, the frequency response functions and mode shapes of the rainbow metamaterials are numerically calculated by Finite Element models set up in Ansys Mechanical APDL. Harmonic analysis was performed to figure out the receptance function values of the rainbow metamaterials within the frequency regime 0-500 Hz. Modal analysis was applied to estimate the mode shapes, which could be used to explain the critical peaks and dips in the receptance function curve. Source files of Finite Element models are provided in the data. The Finite Element simulation is not only an effective alternative way to estimate the dynamic properties of the rainbow metamaterials, the mode shape analysis, which is unlikely to be achieved with the analytical model, provides direct insights into the underlying vibration mechanism of the rainbow metamaterials.