Bending Vibration Research Articles

An analytical method for the vibration characteristics of double panel structures with uniform elastic boundary supports

ABSTRACT In this paper, the methods for solving the free vibration and forced vibration of double panel structures under arbitrary boundaries are studied. Based on the Mindlin plate theory, the natural boundary between plates and plates is constrained by artificial springs, and the theoretical model of the structure is derived. The displacement function of in-plane vibration and bending vibration is expressed by a modified Fourier series expansion. The effectiveness and reliability of this method are verified by a series of numerical calculations and comparison with those of the finite element method. Through the parameter analysis, it can be seen that the vibration isolation effect can be increased by properly increasing the coupling height or making the connecting plate closer to the boundary of the bottom plate. The method presented in this paper can be used in vibration absorption and structural design of such structures.

Effects of Wheel Flats on Vibration and Stress Response of the Wheel-Rail System in High-Speed Trains

With the advancement of high-speed and lightweight vehicles, the occurrence of wheel tread wear, including wheel flats, has escalated. The resulting impact loads on axle-end components and the dynamic response of the axle cannot be overlooked. On-track tests were conducted on wheel flats to obtain wheel-rail forces, axle box vibration accelerations, and axle stresses during service. Time–frequency analysis was employed to uncover patterns of variation with speed. Additionally, a dynamic model of the high-speed train–track system was developed to replicate test conditions, investigating the characteristics of wheel–rail loads and structural elastic vibrations under high-frequency excitation for various flat sizes and higher operating speeds. The findings reveal that under wheel flats, the time-domain response of the wheel–rail system exhibits periodic impacts, while the frequency-domain shows high-frequency energy comprising multiple harmonics of the wheel rotation frequency. Wheel–rail forces, axle box vibration accelerations, and axle stresses exhibit inflection points with increasing speed, particularly within the 120–160 km/h range. In the high-frequency domain, axle stresses display characteristic frequencies that remain unchanged with speed, attributed to the coupled vertical bending vibration modes of the wheel–rail system. These research results offer foundational support for predicting fatigue damage to axle-end components, assessing axle stress, and establishing tolerances for tread defect limits.

Exploring the influence of yttrium on the structural, physical, and optical properties of sol-gel synthesized silicophosphate glasses for photonics applications

Yttrium-incorporated silicophosphate glasses hold significant appeal in key sectors such as photonics, optoelectronics, lasers, biomedical applications, and light-emitting diodes (LEDs). In this study, the sol-gel method has been used to prepare the pure and yttrium-doped silicophosphate glasses. The aim of this study is to discover the effect of yttrium doping on the structural, physical, and optical properties of silicophosphate glasses. Various techniques such as X-ray diffraction (XRD), FTIR spectroscopy, and UV–visible analysis have been employed to examine the structural and optical properties of the prepared samples. The XRD analysis confirmed that all the prepared samples exhibited an amorphous nature. Optical measurements conducted indicated that the incorporation of trivalent yttrium ions led to an increase in the refractive index of the prepared samples. Furthermore, a decrease in the energy band-gap values of the samples was observed. The FTIR spectral analysis unveiled the presence of diverse vibration modes in the synthesized samples. These encompassed symmetrical and asymmetrical stretching vibrations of P-O-P linkages, bending vibrations of P-O in PO4 groups, elongation and flexure vibrations of OH groups, and water absorption vibrations of P-O-H in the glasses. The acquired spectra robustly substantiate the function of yttrium oxide as a network modifier within the silicophosphate glass system. The theoretical values of optical basicity (Λth) demonstrated an increase from 0.465 to 0.472, while the values of the interaction parameter (A) exhibited a decrease from 0.218 Å−3 to 0.215 Å−3. Silicophosphate glasses doped with trivalent yttrium ions exhibit significant potential as materials for optoelectronic devices and optical filter systems.

Bending and free vibration of piezomagnetic Timoshenko beams with the flexomagnetic and surface effects

Bending and free vibration of piezomagnetic Timoshenko beams with the flexomagnetic and surface effects

Acetylacetone – 2-methoxyethanol solutions: Fourier transform infrared spectral studies

The H-bond interactions in the solutions of acetylacetone (AcAc) with 2-methoxyethanol (2-MOE) have been investigated using FTIR spectroscopy. Theoretical calculations on monomers (eight enol isomers and one keto form) and dimers of AcAc have been carried out. The results confirm that both the keto and enol forms of AcAc exist as monomers in liquid AcAc. The analysis of the carbonyl and hydroxyl bands indicates the existence of both the AcAc conformers in the solutions. The intensity of the bands due to the hydroxyl stretching and in-plane bending vibrations decreases rapidly with a decrease in 2-MOE concentration.

Flexural and vibration behaviour of co-cured CFRP composite joints with MWCNT-modified adhesive

Among the diverse adhesive-bonded joining methods, the co-curing technique offers several advantages for fusing structural components. Co-curing technique effectively enhances specific strengths and ensures more equitable stress distribution. This research investigated the multi-walled carbon nanotubes (MWCNTs) incorporated with varying wt.% in carbon fibre-reinforced polymeric (CFRP) composite joints through co-cure bonding techniques. The effects of flexural and vibration behaviour in CFRP composite joints were evaluated using the three-point bending and free vibration tests. Experimental results revealed that the epoxy adhesive containing 0.5 wt.% nanofiller demonstrated the highest flexural strength and modulus. These values were significantly superior to pure epoxy adhesive, exhibiting increases of 270 and 120%, respectively. However, the 1.0 wt.% of nanofiller exhibited the maximum natural frequency under three vibration modes, which is 29, 17, and 14% higher than the pure epoxy adhesive. The statistical analysis of the results was examined using an ANOVA, ensuring the reliability of the findings. Optimisation and prediction were done with the Levenberg-Marquardt artificial neural network, further reinforcing the confidence in the outcomes. The overall coefficient (R) mean square error of 0.99844 is within the acceptable range, indicating that both outcomes are reliable and in agreement.

Ultrasonic-assisted ultra-precision turning of zinc-selenide with straight-nosed diamond tools

This study proposes a novel ultra-precision machining technology that uses ultrasonic vibration and a straight-nosed diamond tool to improve the processing of the brittle optical material zinc selenide (ZnSe). This research addresses the challenges posed by Poisson's effect in ultrasonic vibration-assisted single-point diamond turning, which causes bending vibration along the depth of cut, resulting in lower machining efficiency and surface quality. This study analyses the relationship between one-dimensional ultrasonic vibrations at the diamond tool edge and induced bending vibrations using both theoretical and experimental methods. By investigating ultrasonic vibration dynamics in the feed direction and at the straight cutting edge, the results showed that ultrasonic vibration helps to improve the ductile-brittle transition ratio of the cutting area and surface quality. These improvements are accomplished by regulating the cutting position at the tool cutting edge, adjusting cutting parameters, and optimizing ultrasonic parameters. The machined surface roughness of ZnSe is reduced by approximately 30-46% at higher feed rates under ultrasonic vibration with straight-nosed diamond tools. The findings demonstrate the potential of this novel technology to reduce tool wear and brittle fractures, resolving the challenge of ultra-precision machining for optical materials.

Wind-induced response and control criterion of the double-layer cable support photovoltaic module system

The cable support photovoltaic module system has obvious characteristics of wind-induced vibration. In order to study the wind-induced vibration response characteristics and mechanism of the double-cable support photovoltaic module systems, and further discuss the stiffness control criterion. The wind-induced vibration response of a new type of cable-truss support photovoltaic module system with a span of 35m is studied through the aeroelastic wind tunnel test. Firstly, the scaled aeroelastic test model was established to meet the aeroelastic test requirements. Then, the effects of wind direction, PV module inclination angle, and stability cable initial prestress on the wind-induced vibration response characteristics under uniform flow and turbulent field are studied. Finally, the wind-induced vibration response mechanism and stiffness control criterion are discussed. The results show that the increase of inclination angle will lead to a decrease in critical wind speed, the 0° wind direction is the most unfavorable, and the increase of initial prestress can increase the critical wind speed but is inefficient. The critical wind speed under the turbulent flow field is about 30% higher than that of the uniform flow field. The instability vibration is the result of multi-mode coupled vibration of vertical bending and torsion. It is suggested that the stiffness control criterion is more appropriate as 1/100. The research results are of great significance for the design and application of the cable support photovoltaic module system.

A multimodal rotational acoustic manipulation device for hydrophilic/hydrophobic floating and submerged particles

Rotational acoustic manipulation technology offers precise control of particle motion, making it advantageous for applications in microfluidics, biomedicine, materials research, and so on. Current advanced techniques that use acoustic waves to rotate particles include microstructure vibration, microbubble oscillation, and acoustic holography. Although these methods have achieved some success in rotational acoustic manipulation, they face challenges such as limited types of particles, complex device fabrication, and single-mode manipulation. To address these issues, this study proposes a novel rotational acoustic manipulation device based on traveling wave acoustic fields. The traveling wave acoustic field is achieved by planning the vibration modes of the vibrational source. In this study, a ring-shaped piezoelectric ceramic with four-quadrant dual polarization is designed to excite two orthogonal B11 bending vibration modes of the vibrator. By adjusting the phase difference of the excitation signals, these two B11 bending vibration modes can be coupled into either clockwise or counterclockwise traveling wave vibration modes, thereby establishing unidirectional rotating traveling waves in the water within the PDMS ring. The PDMS ring features an open structure, meeting the requirements for manipulating both floating and submerged particles. The performance of the proposed acoustic manipulation device is validated and analyzed through experiments with hollow glass particles, hollow polystyrene particles, and solid polystyrene particles. The results demonstrate that the proposed acoustic manipulation device can achieve precise fixed-point self-rotation and regional revolution manipulation of particles, regardless of their floating, submerged, hydrophilic, or hydrophobic properties. This indicates the high universality and robustness of the device, making it applicable for the manipulation of various types of particles. Overall, this study introduces a novel acoustic manipulation method for particle rotation, providing strong support for the development and application of acoustic manipulation devices in diverse fields.

Melting, viscosity and structure of lithium-free CaO-SiO2 based melt: Substituting Li2O with Na2O and B2O3

Lithiation-free mold fluxes with excellent performances are urgently needed to be developed, due to the desire for Li2CO3 (Li2O) from the lithium battery industry. So, in this study, the melting, viscosity and structure of the CaO-SiO2 based flux melt, with the aim to replace Li2O by Na2O and B2O3, were investigated. Results show that the melting temperature decreased from 1258.1-1651.9 K to 1245.3–1632.5 K, and the viscosity at 1573 K decreased from 0.310 to 0.098 Pa s, when the ratio of Li2O/(Na2O + B2O3) decreased from 0.38 to 0.00. Meanwhile, the break temperature reduced from 1475.3 to 1451.4 K, and the activation energy of viscous flow also decreased from 181.44 to 55.39 kJ/mol, with the decease of Li2O/(Na2O + B2O3) ratio. Melt structure analyses indicate that the simpler structural units, such as Q0(Si), Q1(Si), [AlO4]5- tetrahedral and B-O- in [BO3] increased, while the more complex structural units, like Q2(Si), Q3(Si), bending vibration of Si-O-Al and boron ring in borate reduced, when Li2O was replaced by Na2O and B2O3. These changes suggest that the DOP of the flux melt was reduced and the melt structure was simplified during the lithiation-free process.

A Stacked Neural Network Model for Damage Localization.

Traditional vibration-based damage detection methods often involve human intervention in decision-making, therefore being time-consuming and error-prone. In this study, we propose using Artificial Neural Networks (ANNs) to detect patterns in the structural response and create accurate predictions. The features extracted from the response signal are the Relative Frequency Shifts (RFSs) of the first eight weak-axis bending vibration modes, and the predictions refer to the damage location. To increase the accuracy of the predictions, we propose a novel stacked neural network approach, capable of detecting damage locations with high accuracy. The dataset used for training involves, as input data, the RFSs calculated with an original method for numerous damage locations and severities. The following models were used as building blocks for our stacked approach: Multilayer Perceptron, Recurrent Neural Network, Long Short-term Memory, and Gated Recurrent Units. The entire beam was thus split into segments and each network was trained in this stacked model on one beam segment. All results obtained with the models are also compared to a standard neural network trained on the entire beam. The results obtained show that the model that performs the best contains 14 stacked two-layer feedforward networks.

Meshfree method for bending and free vibration analysis of laminated plates using the Reissner’s mixed variational theorem

Free vibration and bending behavior of laminated plates are investigated using a combination of Reissner’s mixed variational theorem and the meshless radial point interpolation method. By introducing Reissner’s mixed variational theorem, a refined transverse shear stress field is derived based on three-dimensional (3D) elasticity equations. The efficiency and accuracy of this model are demonstrated through numerical examples. It is found that accurate prediction of shear stresses significantly improves the prediction of natural frequency for composite laminated plates. The difference between shear stresses derived from 3D equilibrium equations and that from constitutive equations is significant.

Phase and microstructural characterization of swat soapstone (Mg3Si4O10(OH)2)

Abstract This study focuses on the comprehensive exploration of Swat soapstone, employing a range of analytical techniques, including X-ray diffraction (XRD), scanning electron microscopy (SEM), energy-dispersive X-ray (EDX) spectroscopy, Fourier-transform infrared (FTIR) spectroscopy, and X-ray fluorescence (XRF) spectroscopy. XRD was used to identify the phase and lattice parameters of the soapstone. SEM further scrutinizes the dispersed soapstone particles, revealing different structural characteristics such as a slightly elongated, cubic-like structure, a straight rod-like formation, and a rough, textured surface. EDX spectroscopy was utilized for studying the elemental composition of the soapstone. The analysis identifies talc as the primary mineral in Swat soapstone, with iron, an element, also contributing notably to its composition. This underscores the complexity of Swat soapstone’s internal structure. XRF analysis further contributes to the elemental characterization, revealing a dominant composition of silicon (Si) at 48.567 wt% and a notable contribution from iron (Fe) at 16.108 wt%. FTIR analysis confirmed the absorption of infrared radiation at the non-bridging oxygen (Si–O–) within the silicate network and the Si–O–Si bending vibration. This work investigates the chemical and morphological details of the Swat soapstone.

Tunable Imaging Distance Focusing Module Directly Driven by a Thin‐plate Piezoelectric Actuator

AbstractWith the advancement of imaging technology, the performance of optical focusing modules becomes crucial for determining imaging quality. Conventional focusing modules frequently face challenges of excessive bulk and weight, complicating the integrated design and limiting application fields. Herein, this study presents a piezo‐actuated optical focusing module (POFM) and the construction strategy to alleviate these issues. A novel radial‐bending resonant‐type piezoelectric actuator (RB‐RPA) is developed to directly drive the POFM. The RB‐RPA, which features a hollow structure (27 × 27 × 7 mm3), utilizes both radial and bending vibration modes of a thin metal plate. It achieves a speed of 122.93 mm s−1, a thrust force of 0.14 N, and a displacement resolution of 0.52 µm. Employing the proposed construction strategy, RB‐RPA is integrated with imaging components to fabricate a POFM prototype. Furthermore, the micrometer‐level displacement resolution of POFM facilitates optical focusing on imaging targets, allowing the acquisition of sharp images within 70 ms. It achieves an image resolution of 119.57 lp mm−1 within a 42 mm segment of the captured image. Finally, a QT‐based interface for the POFM, enables real‐time image capture and sharpness evaluation, thereby enhancing imaging efficiency and integration. This work provides a potential candidate for next‐generation imaging devices.

Analysis of vibration characteristics of ship propeller spindle

In order to obtain the vibration response characteristics of the propeller spindle system effectively and accurately, and provide the basis for the subsequent fault diagnosis, the modal simulation and test of the spindle model were carried out. With the propeller set as eccentric mass, the amplitude and torsion angle of the spindle model were simulated under the condition of excited vibration and unexcited vibration respectively, and the frequency response of bending and torsion under the coupled condition was obtained. The newmark-β method was used to solve the transient response of the bent-torsional coupling model. The results shows that when the propeller spindle system undergoes rotation at a specific frequency and experiences bending vibration excitation force, the latter will induce torsional vibration response. Moreover, the amplitude of the torsional vibration response varies with changes in the frequency of the bending vibration excitation force.

Biofabrication of highly effective and easily regenerated CuO nanoparticles as adsorbents for Congo red and malachite green removal

An effective and easily regenerated adsorbent is the one for which scientists are making an effort to explore. In this study, copper oxide nanoparticles (CuO NPs) were synthesized in a green manner from a leaf extract of Moringa stenopetala and used for dye adsorption. XRD, FTIR, and SEM were employed for the characterization of CuO NPs. The crystallite size of the CuO NPs was calculated via Debye–Scherrer equation from the XRD data and was found to be 8.33 nm. The Cu–O bonding bending vibration at 1116 cm− 1 and stretching vibration at 1649 cm− 1 observed from the FTIR data strongly confirmed the formation of CuO NPs. SEM morphology analysis confirmed the formation of nanoparticles with a plate-like morphology and a spherically random orientation. The zero-point charge of CuO NPs was investigated and reported to be at pH 7. The adsorption of dyes on the greenly produced CuO NPs was studied by optimizing different adsorption parameters. The removal efficiencies of the green CuO NPs adsorbent were 99.54% at the optimum conditions (pH, 4; dye concentration, 30 mg/L; amount of adsorbent, 0.25 g; and contact time, 80 min) and 98.33% at the optimum conditions (pH, 11; dye concentration, 20 mg/L; amount of adsorbent, 0.4 g; and contact time, 80 min) for congo red and malachite green, respectively. The adsorption efficiency of the biosynthesized CuO NPs for the mixture of the two dyes was 92.3%. The green synthesized adsorbent was regenerated and able to work effectively for four cycles for the two dyes. The results of the kinetics-type investigation indicate that the adsorption of both dyes by the CuO NPs adsorbent best fits a pseudo-second-order model. The isotherm model-type investigation resulted in the fitting of the Langmuir adsorption isotherm for both the congo red and malachite green dyes.

On the bending, buckling and free vibration analysis of bio-inspired helicoidal laminated composite shear and normal deformable beams

The mechanical behaviours of bio-inspired helicoidal symmetric laminated composite (BIHLC) beams are investigated via the Ritz method. By exploiting the variational formulation, equations of motion along with element stiffness, geometrical stiffness, and mass matrices are derived. The study conducts a thorough examination, covering bending, buckling stability, and free vibration analyses of BIHLC beams with various lamination schemes. The developed model is verified against existing literature on conventional composite laminated and BIHLC beams. The study also examines the mechanical response of BIHLCs, considering boundary conditions, lamination schemes, orthotropy ratios, and aspect ratios. Notably, deflections, critical buckling loads, and fundamental frequencies demonstrate variations dependent on the specific lamination scheme, boundary condition, and aspect ratio. Novel findings, presented for the first time, offer valuable insights for future studies in this area.

Symmetry Breaking and Modal Localization in a System of Parametrically Excited Microbeam Resonators

In this work, we study the nonlinear dynamics of parametrically excited bending vibrations of two weakly coupled beam microresonators under electrothermal excitation. A steady-state harmonic temperature distribution in the volume of the resonators in the frequency domain was obtained. A system of equations for mechanically coupled beam resonators is derived, considering the deposited particle on one of them. Using asymptotic methods of nonlinear dynamics, equations in slow variables were obtained, which were studied by methods of the theory of bifurcations. It is shown that in a perfectly symmetrical system in a certain frequency range, the effect of symmetry breaking is observed – the emergence of a mode with different amplitudes of oscillations of two beam resonators, which can be the basis for a new principle of high-precision measurements of weak disturbances of various physical natures, in particular – measurements of ultra-low masses of deposited particles.

Synthesis and Characterization of CL-PA Ionic Liquid

Caprolactam is most commonly used in the production of Nylon 6 in industry and is generally produced from cyclohexanone by the Beckmann rearrangement. Orthophosphoric acid is generally used in fertilizer production and is produced through two processes: wet and dry. In this study, detailed characterization of CL-PA was carried out by synthesizing CL-PA ionic liquid from orthophosphoric acid (PA) and caprolactam (CL). FTIR, Raman and UV-Vis spectroscopic analyses reveal that a bond is formed between CL and PA. The thermal behavior of CL-PA ionic liquid was inspected by TGA and DSC. It has been observed that the decomposition temperature of CL-PA ionic liquid is different from that of the starting materials (CL and PA). It was disclosed by DSC analysis that CL-PA ionic liquid only has a glass transition temperature. The room-temperature CL-PA ionic liquid synthesized from solid CL with melting point of 70.34 ℃ and 85 wt.% PA did not show any melting or freezing point and the glass transition temperature was found to be −27 ℃. It was revealed that CL-PA ionic liquid was more thermally stable than CL which alone almost completely evaporated at about 197 ℃. As a result of FTIR analysis of CL-PA ionic liquid and its constituents, it was demonstrated that –NH peaks of CL disappeared in the CL-PA spectrum and the peak of C=O group shifted to a lower frequency (i.e., 1604 cm⁻1). In the Raman analysis of CL-PA and its constituents, it was observed that the asymmetric C=O bending vibration and C=O stretching vibration of CL disappeared in the CL-PA spectrum. In the UV spectrum, it was observed that the maximum absorbance of CL-PA ionic liquid varied with respect to that of CL.

Estimation of mass and moisture content of flat square lumber in a stack during air-drying process by the vibration method with additional mass

A vibration test to measure the mass of a specimen without weighing it using the difference between the resonance frequency with an additional mass and that without it (vibration method with additional mass, VAM) was applied to Japanese cedar flat square lumber with dimensions of 210 mm × 135 mm × 3000 mm both with and without a pith in the process of air-drying. The longitudinal and bending vibration tests were performed on the specimens with and without an additional mass. The accuracy of VAM that was expressed by the estimated mass by VAM to the measured mass (MVAM/M0) was sufficiently high throughout the air-drying process. The accuracy of VAM for the longitudinal vibration was higher than that for the bending vibration. The moisture content based on the estimated mass by VAM was in the expected range.