Surface Vibrations Research Articles

Far-end delamination characterization of CFRP laminates using nonlinear ultrasonic spectra of scaling subtracted vibration response

The application of nonlinear ultrasonic techniques for the near-end damage characterization of carbon fiber reinforced polymers (CFRP) has proven to be successful and extensive. However, the nonlinear ultrasonic response is weak and may be overwhelmed by the linear component of signals if the damage is located at the far-end. In this paper, the scaling subtraction method (SSM) is adopted to filter out the nonlinear ultrasonic signature aimed at the better characterization of far-end delaminations in CFRP laminates. A three-dimensional finite element model is constructed first to validate the feasibility of separation effect of SSM. Then the experimental study is conducted for a delaminated CFRP plate using laser scanning Doppler vibrometer (LSDV) response measurements. Results show that the far-end delamination can be detected and localized clearly since the nonlinear features can be accurately separated from the surface vibration response by using SSM. Moreover, the far-end delamination size is qualitatively analyzed by using the maximum response amplitude (MRA) of the higher harmonics of SSM signals, and a positively correlated trend is shown as the delamination size increases. This work demonstrates the applicability and potential of SSM technique for the comparative assessment of far-end defect information in composites.

Dynamic analysis of MSE wall subjected to surface vibration loading

Abstract Extensively used Mechanically Stabilized Earth (MSE) walls in Rail Transportation System (RTS) are vulnerable to surface vibrations generated by moving vehicles. Hence, it is necessary to consider the effects of surface vibrations during the design of MSE walls for RTS. Steel-reinforced panel-type MSE walls are shown to perform well during vibration loading, but costly steel materials have led to greater reliance on affordable and readily available geosynthetics for reinforcement. Limited research exists on the behavior of panel-type MSE walls with geosynthetics considering RTS-induced vibrations frequencies. Thus, this study employs Finite Element software PLAXIS 3D to simulate the impact of surface vibration frequencies on panel-type MSE walls. The qualitative study encompasses two reinforcement cases (geogrids and steel strips) of 4 m MSE wall height and four harmonic loading frequencies representing RTS-induced surface vibrations for simulation. The dynamic responses of MSE wall are presented in terms of lateral wall displacements and lateral earth pressure distributions. Furthermore, the distributions of tensile strain and the identification of potential slip surface locations are presented. The findings indicated that MSE wall and reinforcement responses are governed by RTS-induced vibrations and fundamental frequency of backfill soil. This highlights the need for consideration of both the fundamental frequency of the backfill soil and RTS-induced vibrations in the design of MSE walls.

The effect of the vibratory surface finishing process on surface integrity and dimensional deviation of selective laser melted parts

Selective laser melting (SLM) is an additive manufacturing method used in aerospace and biomedical industries due to its ability to fabricate complex geometries with excellent mechanical properties. However, achieving the desired surface quality can be challenging. Vibratory surface finishing (VSF) is a widely used post-processing technique in engineering industries to improve surface quality. In this study, SLM-produced stainless steel 316L samples with different geometries, including samples with flat surfaces (SFS), samples with bulged surfaces (SBS), and samples with concave surfaces (SCS), were processed using triangular, spherical, and cylindrical media shapes for different processing times. The research aimed to analyze the surface integrity and dimensional deviation of each sample type after VSF. Our study employed a full factorial design of experiments (DoE) to assess the influences on the surface integrity, dimensional deviations, surface morphology, and surface hardness of 316L stainless steel parts produced via SLM. After VSF, the average Ra value was reduced by 75% after 9 h of operation, achieving the lowest Ra value (1.68 μm) using spherical media. Spherical media also reduced Ra values on concave surfaces by approximately 71%, with a reduction from 14.55 to 4.15 μm. The study found that VSF helps improve surface roughness while affecting the components’ average dimensional deviation and subsurface microhardness. The microhardness measurement showed a value of 220 HV, which was approximately 6.4% higher than the bulk hardness.

Modelling the dynamic magnetic actuation of isotropic soft magnetorheological elastomers

Soft magnetorheological elastomers (s-MRE) are a kind of smart material with soft magnetic particles embedded in an elastomer matrix. Under a magnetic field, there is pronounced magnetostriction and magnetically controllable mechanical properties for s-MRE, offering broad application prospects in soft robotics, surface pattern control and vibration control. While most existing literature on s-MRE focuses on the quasi-static behaviour, neglecting inertia effect, the dynamic behaviour and potential nonlinear oscillation phenomenon in certain scenarios of s-MRE-based actuators remain underexplored. In order to addressing this gap, a novel dynamic model which incorporates the magnetization, nonlinear viscoelasticity and inertia effects of isotropic s-MRE is proposed to explore the interplay among magnetic field, inertia and viscoelasticity on its dynamic behaviour. After developing the corresponding two-dimensional finite element implementation platform, this study examines the magnetic-induced dynamic behaviour of an isotropic s-MRE-based bilayer beam through numerical simulation. The influence of inertia and viscoelasticity on the magnetic-induced deformation as well as the unique nonlinear vibration characteristics of isotropic s-MRE-based system, such as superharmonic and resonance jump, are explored. Furthermore, to further enhance practical applications, novel magnetic field control algorithms aimed at mitigating harmonic distortion and tuning the vibration frequency of isotropic s-MRE-based magnetic actuation systems are introduced. These findings significantly advance the understanding the dynamic behaviour of s-MRE, paving the way for practical applications of s-MRE in magnetic field-driven loudspeakers and active noise control devices.

INVESTIGATION OF CORRELATION BETWEEN PROCESS PARAMETERS AND VIBRATION WITH USE OF WASTE CBN INSERTS IN DEEP ROLLING

Vibration is a mechanical phenomenon in which oscillations occur around an equilibrium point. In addition, the used and waste-cutting inserts create a great problem for the industry; therefore, these inserts constitute a problem to be solved in terms of both recycling and waste costs. The aim of this study is to analyze the correlation between vibration process parameters, formed during deep rolling, and surface roughness, micro-hardness with the using of the waste CBN inserts. For this, in total, 27 experiments in total were conducted with the help of a specially designed tool holder after parameters had been selected. The surface roughness, micro-hardness and vibration values of the specimens that were applied deep rolling were measured and the correlation between these values was investigated. When deep rolling was applied to the workpieces with used and waste CBN inserts, it was seen that the waste CBN inserts could be used in deep rolling and that the surface roughness improved and the surface hardness increased. In addition, it was seen that with the increase of the number of passes and rolling forces, the micro-hardness increased, and that feed rate, the number of passes and rolling forces had the biggest effect on vibration, respectively.

Chatter failure comparison for high-speed milling of aerospace GH4099 with silicon nitride ceramic end mills: A laboratory scale investigation

Chatter generated in the high-speed cutting process can seriously limit the machining efficiency and affect the surface machining quality, which urgently needs to be controlled. Aiming at brittle ceramic end mills that are very sensitive to vibration, a strategy based on the modal experimental method is proposed to construct effective and accurate stability lobe diagram (SLD) for chatter prediction and failure analysis in this work. Firstly, the tool tip frequency response function (FRF) of four kinds of self-developed ceramic end mills and commercial cemented carbide end mills with the same structure are established by means of hammering modal experiments, and the modal parameters are solved and identified. Then, based on our established high-speed milling chatter prediction model, the milling force coefficients are obtained by linear regression analysis and calculation, thereby the milling SLDs of five end milling tools are developed. Finally, a series of high-speed side milling experiments are carried out using consistent cutting conditions. The results show that the constructed SLDs can effectively predict the chatter failure region and milling stability for five kinds of end mills, and four ceramic milling tools exhibit more excellent chatter suppression performance according to frequency domain analysis of vibration signals and the observation of workpiece surface vibration marks, in which the S4 ceramic milling tool presents the most significant high-speed milling stability.

Investigation of field scenarios using a 4n degrees of freedom transient torque and drag model

A coupled drill string dynamics model presents an opportunity to understand, replicate and potentially control the vibrations occurring along a drill string in a deep well. This paper describes a 4n degrees of freedom (4nDOF) model of the axial, torsional and lateral dynamics, consisting of coupled wave equations and lumped elements, which include modeling of the contact between the drill string and wellbore with a stiff string assumption. The model accounts for the bit-rock interaction, structural damping, and hydraulic forces acting on the lumped elements. The 4nDOF model is compared with three field scenarios from a drilling operation in the North Sea: a three-stage top drive start-up procedure, a drilling sequence starting from off-bottom conditions, and a backreaming operation at low rotational speed. The selected cases include instances of stick–slip and higher modes of torsional vibrations, which persist despite the use of a surface vibration mitigation system. High-frequency data recorded by a downhole measurement sub placed near the drill bit are used to verify the simulated downhole rotational speed and triaxial accelerations. The model is useful for analyzing torsional stick–slip events, which are replicated with a similar period and amplitude as in the downhole measurements. Furthermore, the model accurately reproduces the transition between first and second mode torsional oscillations upon the activation of a tuned top drive vibration mitigation system. The model can also be used to analyze lateral deformations and whirling of the drill string at various depths. The field case simulations show that the lateral dynamics can undergo significant changes at certain points in the drill string during torsional stick–slip and higher-mode torsional oscillations. The proposed model can be used to run simulations in close to real-time on a standard personal workstation, thus making it a valuable tool for devising and testing new drill string vibration mitigation solutions.

Interaction between droplet impact and surface roughness considering the effect of vibration

Droplet impingement is pivotal in several fields, such as agricultural spraying, ink printing and firefighting. Although droplet impact studies have received much attention, the combined effects of roughness and vibration on droplet dynamics still need to be explored. In this study, an in-depth analysis is carried out to address this issue, and high-speed photography is utilised to explore the droplet impact process under different roughness and vibration conditions. The results show that higher surface roughness dissipates the kinetic energy of droplet spreading, thus inhibiting droplet spreading. Conversely, vibration imparts additional inertial effects to the droplet, leading to sustained oscillations once the droplet stabilises, which in turn results in a more pronounced variation in the droplet's dynamic contact angle. Therefore, in this paper, the vibrational Weber number (Wev) is employed to characterise the interaction between the vibration-induced extra inertia force and the droplet's surface tension. Moreover, as the Wev increases, the relative velocity of the droplet impact also rises, further intensifying the droplet's spreading behaviour. At a Wev of 8.72 and a surface roughness of 0.4 μm, droplet spreading is enhanced by 33%. While at a surface roughness of 6.3 μm, droplet spreading was suppressed by 32% relative to a surface roughness of 0.4 μm. Ultimately, an empirical model was proposed to predict the droplets' maximum dimensionless spreading coefficient (βmax) under vibration conditions, with an error of ±9.5% in the model prediction. This study delves into the dynamic characteristics of droplets under the combined influence of surface roughness and vibration, offering crucial theoretical foundations and profound insights for engineering applications in the field.

Modeling of Sound Radiation from a Loaded Rolling Tire

In recent work it has been possible to model the surface vibration of a loaded rolling tire, including the influence of the acoustic mode that forms within the tire cavity. For example, it has been found that the acoustic cavity mode splits owing to the deformation of the tire when it is loaded, and that the split widens owing to Doppler effects when the tire is rolling. It has also been demonstrated that the force at the hub that results from the acoustic cavity mode is strongly dependent on interaction with circumferential structural modes of the treadband. The finite element models developed to-date, thus allow a prediction of the tire's surface vibration. To predict the sound radiation from the deformed, rolling tire, the surface vibration data has been used as the input to boundary element calculations; the effect of the ground surface is modeled by creating an "image" tire. The calculations have been used to illustrate the nature of the exterior sound radiation that results from the acoustic cavity mode, which can be relatively efficient due to the sonic phase speed of the mode within the tire cavity, as opposed to the subsonic structural wave propagation along the treadband.

Numerical analysis of the effect of trench on indoor vibration adjacent to railway ground line

By establishing a 3D finite element numerical simulation analysis model of railway-soil-trench-building, the accuracy of the simulation analysis model is verified using on-site measured data of surface vibration attenuation law. Install vibration isolation trenches with different depths at different locations between the building and the railway, and analyze and compare the impact of indoor vibration in different situations. The results indicate that; The surface vibration caused by railways attenuates rapidly around 30m~76m from the line, and then shows a slight amplification trend around 120m. The surface vibration near the railway is mainly concentrated in the range of 15-90Hz; The vibration reduction effect of trench on different indoor rooms in buildings varies greatly. By optimizing the parameters of trench, the average indoor vibration reduction effect can be close to 5dB, and the vibration reduction effect of trench at different positions varies greatly. The increase in trench from 6m to 12m increases the indoor vibration isolation effect.

Estimation of wave velocity and analysis of dispersion characteristics based on wavelet decomposition

Due to the complexity of the crustal medium and stratigraphic boundaries, seismic waves typically exhibit attenuation and dispersion after propagation through the medium. By studying the regularity of seismic wave dispersion, soil layer information can be extracted. Current spectral decomposition techniques take less account of signal filtering processing of seismic waves, and the complexity of the stratigraphy tends to reduce the accuracy of dispersion analysis. Based on the above, a new method for calculating the dispersion characteristics of a site from surface and downhole ground vibration recordings is proposed, which is simpler than the spectra analysis of surface waves (SASW) method and eliminates the need for multiple pickups and additional equipment. This method is based on wavelet decomposition and seismic wave filtering, and a numerical simulation example is established to verify the effectiveness of the method. Then, the records of the Tohoku earthquake on March 11, 2011 are used as actual strong earthquake examples for filtering and dispersion analysis. Finally, it is concluded that the seismic wave dispersion analysis method based on wavelet decomposition can effectively filter and analyze seismic waves in specific frequency bands.

An experimental investigation on machining-induced surface/subsurface characteristics of nickel based Inc-718 alloy: A novel hybrid approach in milling process

Nickel-based superalloy Inc-718 has become an indispensable alloy in critical sectors, especially in the aerospace industry, thanks to its unique characteristics. However, some properties of the alloy (especially low thermal conductivity and hot hardness) cause difficulties in its machinability. For this reason, comprehensive studies to improve the machinability of Inc-718 alloy by considering the microstructural properties are guiding. In this context, the present study uses various methods to increase the machinability efficiency of Inc-718, while also investigating their effect on microstructural properties. Firstly, the effect of the pre-heating process (hot), pure-MQL (PMQL), nanofluid-MQL (NMQL), and hybrid methods (hot+PMQL and hot-NMQL) on the surface roughness, cutting forces, tool wear, vibration, and temperature was investigated while milling Inc-718 surfaces. Then the utilization of Electron Backscatter Diffraction (EBSD) facilitated a comprehensive examination of microstructural behavior, with a specific focus on Euler-colored maps and phase distribution maps, providing valuable insights into the material's behavior under distinct milling conditions. As a result, hot+PMQL, hot+SiC-NMQL, and hot+Al2O3-NMQL provided an important contribution to the improvement of machinability characteristics. Also, it was seen that in EBSD analysis, a limited area is affected by heat in the hot machining environment. The crystal orientations of the pre-heated and hybrid machined Inc-718 alloy are highly similar to that of the dry-machined alloy. This similarity indicates that the removal of the heated layer from the workpiece during the milling process contributes to the preservation of the microstructure.

Atmospheric Wave Radiation by Vibrations of an Ice Shelf

AbstractLidar and radar observations of persistent atmospheric wave activity in the Antarctic atmosphere motivate investigation of generation of acoustic‐gravity waves (AGWs) by vibrations of ice shelves and exploiting their possible ionospheric manifestations as a source of information about the ice shelves' conditions and stability. A mathematical model of the waves radiated by vibrations of a finite area of the lower boundary of the atmosphere is developed in this paper by extending to AGWs an efficient, numerically exact approach that was originally developed in seismology and underwater acoustics. The model represents three‐dimensional wave fields as Fourier integrals of numerical or analytical solutions of a one‐dimensional wave equation and accounts for the source directionality, AGW refraction and diffraction, and the wind‐induced anisotropy of wave dissipation. Application of the model to the generation of atmospheric waves in Antarctica by free vibrations of the Ross Ice Shelf reveals a complex three‐dimensional structure of the AGW field and elucidates the impact of various environmental factors on the wave field. The intricate variation of the wave amplitude with altitude and in the horizontal plane is shaped by the spatial spectrum of the ice surface vibrations and the temperature and wind velocity stratification from the troposphere to the mesosphere. It is found that the waves due to the low‐order modes of the free oscillations of the Ross Ice Shelf, which have periods of the order of several hours, can transport energy to the middle and upper atmosphere in a wide range of directions from near‐horizontal to near‐vertical.

Spreading Widths of Giant Monopole Resonance in the Lead Region: Random Matrix Approach

The microscopic calculation of the decay width of giant monopole resonance (GMR) anticipates the mixing of one-phonon states with configurations of increasing complexity. To this aim we develop the effective approach for description of monopole excited states that are obtained in the quasiparticle random phase approximation (QRPA), with regard of the coupling between one- and two-phonon states. Based on the QRPA one-phonon states, we generate the coupling and two-phonon states by means of the Gaussian orthogonal ensemble (GOE) distribution. Within our approach the spreading width of the GMRs in 204,206,208Pb are described by means of a random matrix approach on two energy scales. It is demonstrated that the main contribution into the decay of the GMR is determined by a small number of two-phonon states strongly coupled to low-energy surface vibrations. While a vast majority of the coupling matrix elements (that are small in value and following the GOE distribution) are responsible for the fine structure of the GMR spreading width. A remarkable agreement between the results of the full microscopic calculations (based on QRPA phonons coupled by means of the microscopic coupling matrix elements with calculated two-phonon states) with those of the developed approach confirms the vitality of the proposed ideas.

Synthesis of an electromechanical system of body tilt and recuperation of vibration energy for a high-speed electric train

This paper considers issues related to the undercarriage system of a high-speed electric train with body inclination and a vibration recovery system. The main suspension systems of the electric train body, which are currently used, were investigated. The existing shock absorption systems and alternative approaches and solutions for increasing the speed characteristics of electric rolling stock have been highlighted. A basic problem of these suspension systems was put forward, which is the lack of the possibility of recovery of oscillations, as well as the complexity of systems for tilting the body. The main dimensional and power parameters of the proposed promising shock absorber are presented. The characteristics of basic parameters of the electromechanical shock absorber were compared with those of a pneumatic spring shock absorber. A simulation model of a high-speed electric train with an electromechanical shock absorber was built in the MATLAB Simulink environment. The main units of the simulation model were defined and described, owing to which it is possible to simulate the inclination of the body to a given angle and the simulation of vibration energy recovery. Based on the results of simulating the operation of an electromechanical shock absorber as part of the undercarriage of the electric locomotive, it was determined that the synthesis of this system makes it possible to tilt the body by 5 degrees in 2 seconds. It is also stated that the proposed system makes it possible to reduce the vibrations of the electric train body by 2 times, and to recover 84 W/h of vibration energy. The body tilt results are predetermined by the speed of the mechanism due to the absence of a compressor set used in the pneumatic system. The scope of application of the vibration damper also includes the automotive field, subject to additional research into the form, amplitude of road surface vibrations and changes in overall parameters in accordance with the requirements

Investigation on the Damping Effect of FST System under Moving Load Using the Track–Tunnel-Layered Saturated Ground Model

In this paper, a single-tier beam-spring-damping system and a two-tier beam-spring-damping system are adopted to simulate the FT (fixed track) and FST (floating slab track) system, respectively. The tunnel is modeled as an infinitely long Euler—Bernoulli beam embedded in the layered saturated soil. By solving the governing equations of the saturated soil and employing the TRM (transmission and reflection matrices) method, the frequency response function of the tunnel-layered saturated soil model is obtained. Making use of the interaction between the tunnel and track systems, the track system is coupled with the tunnel-layered saturated ground model. The solutions for the dynamic response of the track system–tunnel-layered saturated ground model under moving loads in the time–space domain are obtained using the inverse Fourier integral transform. To evaluate the damping effect of the FST system on the vibration of tunnel and soil, four damping coefficients are defined and the vibration results of the FT system–tunnel-layered saturated soil model are compared with those of the FST system–tunnel-layered saturated soil under different moving loads and soil conditions. The numerical results show that both the vibration displacement and acceleration amplitude are attenuated after using the FST system, and the damping coefficient of acceleration is about 30% greater than that of the displacement. In addition, the damping effect of the FST system on the ground surface vibration is associated with the embedded depth of the tunnel and the soil stiffness.

The quality improvement method of vibroseis records

Vibroseis seismic acquisition technology is a method of acquiring seismic data utilizing correlation technology. Specifically, the seismic single shot record is obtained through correlation between the reference signal and the mother record. Specifically, the seismic single shot record is obtained through correlation between the reference signal and the mother record. Specifically, the seismic single shot record is obtained through correlation between the reference signal and the mother record. In line with pertinent technical regulations, greater correlation between the two signals equates to superior correlation outcomes. The reference signal is transmitted to the surface via the vibration of the vibrating plate. This is achieved using the vibroseis machine. However, due to the coupling relationship between the vibrating plate and the surface, the vibration signal output by the former is not equivalent to the vibration signal received by the latter. Consequently, the correlation between the reference signal and parent record fails to procure the best correlation result. In this paper, a technique is presented for establishing a correlation between the surface vibration signals captured by the geophone in proximity to the vibroseis and the reference record. This approach improves the quality of the correlated single shot, and holds significant potential for broad dissemination.

Fully optic characterization of acoustic impedance implementable in conventional optical microscope

The intrinsic acoustic impedance (Z) changes with inflammation and canceration. This paper proposes an optically Z measurement method using a common optical microscope for simultaneous measurement of optical-acoustical observation. Photoacoustic (PA) waves were generated by the PA effect of the pulsed laser (a 527 nm nanosecond laser light) at the black ink and resin pasted area on the outside of the bottom of the petri dish (surface A). The generated PA waves propagated to the inner boundary of the petri dish and reflected, with a reflection coefficient of R. The reflected waves propagated to surface A and vibrated it. The surface vibration was measured with a self-built Sagnac interferometer using a contentious light laser and a 10x objective lens. Measurements were made air-filled and water-filled petri dishes. The observed times of echo signal corresponded to the sound speed of longitudinal and transverse propagation. The reflected wave amplitude of air was larger than in a water-filled petri dish. They related that R water and R air are 0.24 and 1.00, respectively. There corresponds to the Z ratio of the polystyrene petri dish and the water or air inside. Thus, this result showed that sample Z was measured optically.

Correction of scanning laser Doppler vibrometer measurements when subjected to six degree-of-freedom base motion

Scanning laser Doppler vibrometer (SLDV) measurements are affected by sensor head vibrations as though they are vibrations of the target surface itself. Previous work has established a fully general theoretical analysis which shows that the only measurement required for measurement correction is of the vibration velocity at the incident point on the final steering mirror in the direction of the outgoing laser beam. Two practical—but not quite perfect—options for measurement correction were presented (one more suitable to manufacturer implementation, one more applicable to the vibration engineer end user). In both cases, placement of the correction transducer is critical with correction working for totally arbitrary instrument vibration and scan angle. Experimental validation, employing frequency-domain based processing, has been completed for one degree-of-freedom, on-axis vibration. Simultaneously, advancements in the data processing approach have realised improved correction in practice, especially for lower frequencies and for transient, as opposed to statistically stationary, vibration. In this paper, extension of the experimental validation to six degree-of-freedom instrument vibration is presented for the first time. In combination with the latest data processing approaches, reductions in the measurement error of 29.4 and 28.2 dB for the frequency- and time-domain processing techniques, respectively, are realised.

Computer Vision-Based Bridge Inspection and Monitoring: A Review.

Bridge inspection and monitoring are usually used to evaluate the status and integrity of bridge structures to ensure their safety and reliability. Computer vision (CV)-based methods have the advantages of being low cost, simple to operate, remote, and non-contact, and have been widely used in bridge inspection and monitoring in recent years. Therefore, this paper reviews three significant aspects of CV-based methods, including surface defect detection, vibration measurement, and vehicle parameter identification. Firstly, the general procedure for CV-based surface defect detection is introduced, and its application for the detection of cracks, concrete spalling, steel corrosion, and multi-defects is reviewed, followed by the robot platforms for surface defect detection. Secondly, the basic principle of CV-based vibration measurement is introduced, followed by the application of displacement measurement, modal identification, and damage identification. Finally, the CV-based vehicle parameter identification methods are introduced and their application for the identification of temporal and spatial parameters, weight parameters, and multi-parameters are summarized. This comprehensive literature review aims to provide guidance for selecting appropriate CV-based methods for bridge inspection and monitoring.