Sinusoidal Vibration Research Articles

Heat Transfer and Entropy Generation in Vibrational Flow: Newtonian vs. Inelastic Non-Newtonian Fluid

A computational method is employed to solve heat transfer and entropy generation within a circular pipe. The thermal boundary condition assumes a constant wall temperature, while viscosity is taken to be dependent on temperature. A power-law type shear-thinning fluid is utilized in the analysis, with sinusoidal vibration applied horizontally perpendicular to the flow direction. Temperature distributions across the pipe are illustrated. Additionally, the entropy generation rate over the entire fluid volume under vibration was examined, comparing the results between steady flow and vibrational flow for both types of fluids. It was found that radial mixing is more pronounced in non-Newtonian fluids as vibration increases the strain rate, which is higher for low Reynolds numbers. The research provides a quantitative analysis of heat transfer and entropy generation for both Newtonian and shear-thinning fluids at different Reynolds numbers. It was observed that the effectiveness of superimposed vibrational flow is limited, especially for low Reynolds numbers and flow behavior index characteristic of shear-thinning fluids.

System Integration Design of High-Performance Piezo-Actuated Fast-Steering Mirror for Laser Beam Steering System

This paper presents an innovative piezo-actuated fast-steering mirror (FSM) that integrates control design and system operation to improve the tracking performance of laser beam steering (LBS) systems. The proposed piezoelectric FSM is centered on two pairs of stacked actuators functioning in the tip-tilt direction via novel flexible hinges with strain-gauge sensors for position measurement. The suggested flexible hinge scheme allows the first fundamental resonance mode with the optical mirror to exceed 400 Hz while achieving an actuation range of ±5 mrad. Thus, the design offers a wider mechanical actuation range than conventional piezoelectric FSMs. Moreover, LBS systems that use fast-steering motion controllers should be robust against dynamic disturbances, such as periodic external vibrations. Such disturbances, inherently associated with the operating conditions for LBS systems, typically reduce the stability of the tip-tilt motion. To attenuate the effects of such disturbances, a high-precision control system is necessary for the tip-tilt motion. Therefore, a control method integrating a proportional–integral controller with an adaptive feedforward control (AFC) algorithm is outlined to enhance tip-tilt tracking performance during high-speed scanning, compared with conventional LBS systems. Based on experimental findings, the AFC algorithm boosted control performance under dynamic disturbances, such as sinusoidal vibrations with multiple frequencies.

Processing the fine-grained features of tactile textures involves the primary somatosensory cortex

Abstract Dynamic tactile perception and discrimination of textures require the ability to encode and differentiate complex vibration patterns elicited at the level of the skin when sliding against a surface. Whether the primary somatosensory cortex (S1) can encode the fine-grained spectrotemporal features distinguishing textures remains debated. To address this question, EEG frequency-tagging was used to characterize responses to vibrotactile oddball contrasts between two textures. In a first session designed to identify the topographical distribution of responses originating from the hand and foot representations in S1, standard and deviant stimuli were pure sinusoidal vibrations differing in frequency and intensity. In a second session, standard and deviant stimuli were two different snippets of bandpass-filtered white noise matched in terms of intensity and average frequency content, but differing in terms of their complex spectrotemporal content. Using the S1 functional localizer, we showed that oddball responses to a spectrotemporal contrast follow the somatotopical organization of S1. Our results suggest that the encoding of fine-grained spectrotemporal features associated with different vibration patterns involves S1.

The importance of different body parts for the (un-)pleasantness of whole-body vibration on an aircraft seat bench

Noise and vibration are two physical factors that can reduce the perceived comfort of passengers during a flight. To reduce the detrimental impact of seat transmitted vibration, it is necessary to understand which body parts and, thus, which corresponding seat parts are relevant for the pleasantness assessment. In this study, 40 participants (19 female, 21 male) rated the pleasantness of sinusoidal whole-body vibrations in the vertical direction while seated on a typical aircraft seat bench and listening to a synthetic broadband aircraft cabin noise over headphones. The vibration signals covered seven frequencies and four vibration levels, and pleasantness ratings were made on a verbally anchored scale. In addition, the participants separately marked those body parts that contributed significantly to their rating and those where they felt a vibration for each of the vibroacoustic stimuli. The results showed that not all body parts at which vibration were felt were also classified by the participants to reduce the ratings significantly, especially at higher vibration levels. A median split of the participants into groups of lighter and heavier participants indicates which body properties might be underlying factors for certain judgments.

Effect evaluation of fluid movement and rock properties for artificial seismic activity on hydrocarbons

Despite the effectiveness of seismic stimulation in enhancing oil production from reservoirs, the impact of high-frequency vibrations on oil droplets confined within pore throats has not been adequately investigated. This laboratory-scale experimental study examines the impact of low and high-frequency sinusoidal vibrations in dislodging oil droplets trapped in a specific pore-throat region. Sinusoidal vibrations ranging from 10 to 80 Hz and with maximum displacement amplitudes of 1.2–0.06 mm are applied. By comparing the images captured prior to and after the application of seismic vibrations, the amount of oil recovered is determined. Commercial gasoline and diesel are used as trapped oil samples, and water is used as the injection fluid to bring out the effect of fluid viscosities in seismic dislodgment. While applying vibrations to trapped oil in the pore throat, three different recovery modes are observed: continuous, snap-off, and emulsified. The continuous oil recovery mode is observed in cases with minimal flow resistance through the pore throat, whereas a snap-off or intermittent recovery mode is observed when the flow resistance is high, and the vibration frequencies fall within the midrange of 40-60 Hz. An emulsified oil recovery mode is observed at high vibration frequencies. The amount of recovered oil increases as geometrical restrictions and trapped oil viscosity decrease. Seismic mobilization is observed to be directly proportional to the mobilization velocity and inversely proportional to the entrapped oil viscosity and geometrical restriction factors.

Mechanical simulation and electrical performance analysis of high current connectors

Abstract Automotive high-current connectors are one of the key components in new energy vehicles, used for transmitting high currents within the vehicle. However, vibration is unavoidable during the actual operation of connectors. This vibration directly affects the contact pressure between the connector’s contact points, thereby influencing the electrical contact performance of the connector. This paper simplifies the contact components of the electrical connector using a cantilever beam model and conducts theoretical calculations of the contact pressure. Utilizing Ansys Workbench simulation software, the study investigates the contact pressure of the electrical connector under static and various sinusoidal vibration conditions, followed by sinusoidal frequency sweep vibration experiments. The research findings indicate that under vibration conditions, the contact pressure is lower than that under static conditions, and the electrical resistance fluctuates during the vibration process.

Development of a space-compatible packaging system for an integrated monolithic ultra-stable optical reference.

We report the development of a space-compatible packaging system for an integrated monolithic ultra-stable optical reference toward China's next-generation geodesy mission with low orbit satellite-to-satellite tracking. Building on our previous work, we optimized the mounting structure and thermal insulation mechanism using the finite element method. The comprehensive simulation results demonstrated the robustness of the entire packaging system with enough margins to withstand severe launch loads and maintain an ultra-high geometric cavity length stability. A long-term prediction of the vacuum maintenance around the cavity during in-orbit operation was conducted. An engineering prototype, within which an integrated monolithic optical reference has been mounted, was built based on our optimized design, and it has successfully passed typical aerospace environmental tests, including sinusoidal vibration (∼10g, 10-100Hz), random vibration (∼0.045g2/Hz, 10-2000Hz), and thermal cycling (0-45, 3 °C/min, lasting for 90h). The experimental thermal time constant of the prototype exceeded 9.5 × 104 s, enabling a temperature stability of 1.1 × 10-6K/Hz1/2 at 10 mHz on the optical cavity, with external active temperature control. The design is also suitable and useful for laboratory and terrestrial applications.

Modulating Wetting States of Molten Aluminum Droplets on SiO2 Surfaces via Vertical Sinusoidal Vibrations.

Vibration affects the wetting behavior of droplets, and it is feasible to use vibration to modulate the adhesion characteristics of droplets. In this paper, the effect of vertical sinusoidal vibrations on the wettability of molten aluminum droplets on the substrate surfaces of smooth and with nanopillars is investigated. The increase in the frequency or amplitude of the vibration leads to a rise in the interfacial potential energy between the molten droplets and the substrate, which in turn leads to the occurrence of the Wenzel-Cassie transition. Once the vibration frequency reaches the threshold values, the molten droplets leave from the substrate, that is, dewetting occurs. The molten droplets in the Wenzel state undergo a Wenzel-Cassie transition before dewetting occurs. A phase diagram describing the frequency thresholds at which the molten aluminum droplets undergo dewetting and the Wenzel-Cassie transition at different amplitudes is plotted. For a specific amplitude, the frequency of vibration required for dewetting to occur in molten aluminum droplets in the Young state is lower than that in the Wenzel state. The needed vibrational frequency for dewetting or the Wenzel-Cassie transition decreases with increasing amplitude.

Mechanical simulation analysis of an electric scroll compressor

Abstract As a precision automotive component, electric scroll compressors have high requirements for reliability. In order to save the cost of environmental testing and shorten the market cycle of new products, the modal parameters of a compressor are measured, and the first six modal parameters are obtained. Secondly, the simplified finite element model of the compressor is established, modal analysis is carried out, and the modal frequency error obtained by the two methods is controlled within a reasonable range to ensure the accuracy of the modeling. Finally, based on the established simulation model, the structural response and stress of the compressor under various working conditions, such as sinusoidal vibration and random vibration, are analyzed, and the extreme values of displacement and stress are obtained. The results show that the structural design of the compressor meets the requirements of the environmental test of on-board equipment. The test and simulation methods used in this paper also have certain reference significance for other mechanical equipment.

Multi-condition adaptive detail characterization model of magnetorheological dampers and experimental verification

The theoretical model for predicting the damping characteristics of magnetorheological dampers (MRDs) is significant for enhancing the design efficiency of the control algorithm. However, some existing theoretical models face limitations in characterizing MRD damping characteristics simultaneously in terms of nonlinear detail characterization and adaptability to variable working conditions. Therefore, this paper proposed the Composite Double-Boltzmann (CDB) model combining the Double-Boltzmann (DB) function widely used in the field of biology and chemistry for its strong nonlinear characterization capability. Utilizing this model to fit the sinusoidal vibration testing data of the MRD prototype under variable combination working conditions, obtaining quantitative relationships between the undetermined parameters in the CDB model and the excitation current, vibration frequency, and amplitude to enable the model to address both the nonlinear details characterization of MRDs and adaptability to variable working conditions. Subsequently, the validity of the quantitative relationships were verified by comparing the calculated parameter values using the quantitative relationships with the original accurate parameter values. In order to verify the validity of the CDB model, extensive unknown working condition vibration tests were conducted on the MRD prototype under variable excitation currents, vibration frequencies, amplitudes and random excitation working conditions, employing the CDB and Tanh models to predict the damping characteristics, to compare to demonstrate the CDB model’s capability of adapting to variable working conditions while accurately characterizing the nonlinear details of MRD damping characteristics.

Effect of rotating shaft vibration on lip seal performance

Rotary lip seals are important components in various rotating machinery and are inevitably affected by vibration. This paper introduces the first simulation model for rotary lip seals under radial sinusoidal vibration conditions based on the mixed lubrication theory. Using the proposed model, the effects of varying vibration amplitudes and frequencies on the tracking performance, leakage rate, and friction torque of lip seals were analyzed. The simulation results indicate that, the leakage rate exhibits an initial increase followed by decrease as the vibration amplitude increases, while the friction torque exhibits a decrease followed by increase. Excessively high vibration frequencies may induce separation between the lip and shaft surface, resulting in severe leakage.

Adaptive compound control of laser beam jitter in deep-space optical communication systems

In deep-space optical communication systems, precise pointing and aiming of the laser beam is essential to ensure the stability of the laser link. In this paper, an adaptive compound control system based on adaptive feedforward and Proportional-Integral-Differentiation (PID) feedback is proposed. The feedforward controller is stabilized using Youla-Kucera (YK) parameterization. In the YK parameterized structure, the free parameter Q(z) consists of an adaptive filter. The proposed method constitutes an adaptive feedforward control algorithm through the adaptive filter Q(z). The problem of suppressing laser jitter is transformed into a problem of minimizing a sensitivity function containing the adaptive filter. The stability of the compound control system is ensured by configuring the individual parameters of the YK parameterized feedforward controller and the PID controller, and the adaptive regulation of the controller is realized on the premise of system stability. To verify the effectiveness of the compound control system, we established an experimental platform for laser beam stabilization control. We experimentally compare the effectiveness of the proposed control method with the classical method. The experimental results show that the method proposed in this paper can effectively suppress the complex laser beam jitter consisting of narrow-band sinusoidal and broad-band continuous vibrations.

Complete description of effects on reconstruction of dynamic objects from time-averaged digital holography to high-speed digital holography

Time-averaged holography (TAH) is a specialized technique for studying objects subjected to sinusoidal vibration, characterized by presenting a Bessel J0 envelope in the object’s reconstruction, a condition that occurs when the vibration period is much shorter than the hologram exposure time. In this work, we present an analytical expression that describes the reconstruction effects when both the exposure time and the period can take arbitrary values, allowing the application of the TAH technique for exposure times as fractions of the period. We observe that the presented function contains higher-order Bessel functions. Additionally, we found that the envelope not only depends on the relationship between the exposure time and the vibration period but is also directly related to the vibration amplitude. The expression we introduce applies to conditions where exposure times are very short, possible with pulsed lasers, called high-speed holography (HSH), where the object reconstructs as if it were static. This mathematical expression serves as a bridge that continuously connects the techniques of HSH and TAH, enabling a smooth transition between both techniques.

On the use of sinusoidal vibrations for disaggregating clusters of non-settling inertial particles immersed in yield-stress fluids

The effect of sinusoidal vibration is numerically investigated on the dynamical behavior of a cluster of 50 identical non-Brownian circular solid particles randomly distributed in a circular envelope. The cluster is immersed in a finite vessel filled with an inelastic viscoplastic fluid obeying the Casson model. The solid particles are modeled using the improved smoothed-profile method (iSPM) whereas the flow of the continuous phase is modeled using the lattice Boltzmann method (LBM). An in-house LBM-iSPM code, modified for Casson fluid, is used to study the effect of sinusoidal vibration on disaggregating the cluster. We have deliberately ignored the gravitational term in the equations of motion so that the sole effect of vibration on the cluster response can better be investigated. Numerical results suggest that vibration can disaggregate the cluster with its efficiency depending on the fluid's yield stress. For any given yield stress, vibration can disperse the cluster provided the frequency and/or amplitude of the forced oscillation are larger than a threshold. The secondary flow formed in the channel during the transient phase is shown to be the main cause of the cluster's fluid-mediated dispersion. It is shown that the system reaches equilibrium when the secondary flow is vanished through dissipation. Vibration is predicted to become more effective in disaggregating clusters the larger the size of the particles or the smaller their number density.

NaV1.1 and NaV1.6 Play Unique and Essential Roles in Muscle Spindle Afferent Function in Adult Mice

Voltage gated sodium channels (NaVs) are crucial for the generation and propagation of action potentials. There are 9 different isoforms found in mammals (NaV1.1-1.9), and NaV1.1, NaV1.6, and NaV1.7 are found in the muscle proprioceptors that sense muscle stretch, the muscle spindle afferents. This sensory information is critical for motor reflexes and the sense of body and limb position in space. We previously found that mice lacking one or both copies of NaV1.1 in peripheral sensory neurons displayed motor deficits, including intention tremors. Muscle spindle afferents in these mice also had unstable static stretch sensitivity but normal dynamic sensitivity, suggesting a specific deficit in the maintenance of proprioceptor excitability when the Piezo2 channel was likely to be closed (Espino, et al., 2022). We hypothesized that NaV1.6 would also be necessary for normal motor behavior and muscle spindle afferent function. We generated sensory neuron specific deletions of NaV1.6 by crossing NaV1.6fl/fl mice with mice expressing PirtCre (NaV1.6cko) and observed severe motor deficits on the open field and rotarod test only in NaV1.6cko (n=15) and not NaV1.6Het (n=12) mice compared to NaV1.6fl/fl controls (n=8). In contrast to mice lacking NaV1.1, we did not observe intention tremors. We used an ex vivo muscle nerve preparation consisting of the extensor digitorum longus muscle and peroneal branch of the sciatic nerve. The muscle was maintained at the length of maximal twitch contraction (Lo) and given a battery of 9 ramp-and-hold stretches (2.5, 5, and 7.5% Lo repeated 3 times each) and 16 sinusoidal vibrations (5-100 μm amplitude; 10-100 Hz frequency). Preliminary results include recordings from 18 adult mice of both sexes (NaV1.6fl/fl n=8; NaV1.6cko n=10). We were only able to find stretch sensitive responses in 3 of 10 NaV1.6cko mice, and those were severely impaired with firing rates less than 5 Hz. In contrast, we found robust slowly adapting responses to stretch in all 8 NaV1.6fl/fl mice. Only 1 of 10 NaV1.6cko mice had any firing in response to vibration, in contrast to the normal dynamic sensitivity observed in NaV1.6fl/fl and NaV1.1cko afferents. This suggests that NaV1.6 plays a critical role in initiating muscle spindle afferent transmission, whereas NaV1.1 is essential for maintaining proprioceptor excitability during static stretch. Future studies will determine whether loss of NaV1.7, which does not result in motor deficits, alters muscle spindle afferent function. This work was supported by NIH Grant 5SC3GM127195 (KAW) a RISE Fellowship 5R25GM71381 (SO), NIH 5T32GM099608-10 and 1T32GM1144303-01A1 (CE). This is the full abstract presented at the American Physiology Summit 2024 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.

Granular vibration pumping system for handling and characterizing particulate materials.

A unique setup for a granular vibration pumping system was developed to ease the installation into a wide variety of granular handling processes and provide flexible options for granular physics research. Although the granular vibration pumping system can notably lift granular materials with an oscillating pipe, the climbing mechanism and related granular physics are yet to be clarified thoroughly. The new setup employs an eccentric cam mechanism as the excitation source, a linear system with dust tolerance, and a recording system, making it simple, compact, and adaptable for extending experiments. The excitation mechanism generated a clear sinusoidal vibration in the pipe, realizing better reproducibility of the climbing motions of glass beads. Moreover, the compact design facilitates the close placement of multiple pipes vibrating individually, which affects the transport performance. In addition, various types of sample cells that store particles and the imaging system allow for the detailed observation of particle motions in the pipes and even the sample cells. This developed system provides easy and accurate tuning of the existing parameters of the granular vibration pumping system, as well as new options for a further understanding of granular physics.

Seat-to-hand vibration transmissibility influence on cognitive performance via tablet evaluation

Exposure to Whole Body Vibration can affect the individual’s cognition, and different frequencies and magnitude of vibration cause different effects, which can have either an improvement or deteriorate the individual’s cognitive abilities. The present work aims to correlate seat-to-hand vibration transmissibility with the cognitive performance, simulating the working condition of a bus fare collectors. For this purpose, tests with 20 volunteers on a vibrating platform with sinusoidal vibration applied in the vertical direction were performed. The vibration amplitudes of 0.2 and 0.7 m/s2, and frequencies of 5 and 30 Hz were used. A daily routine of a bus fare collectors was simulated, based on data from the public transport system in the Belo Horizonte city. Vibration signals were collected on the platform chair and on the volunteer’s hands, and were post-processed. Cognitive performance was assessed using a Brain Training App, and three indicators were considered: score, accuracy and reaction time to respond. The results showed that the frequencies adopted were beneficial to the score and accuracy, with the frequency of 5 Hz having better results, and the reaction was negatively affected for both frequencies. The vibration transmissibility showed that both frequencies presented the characteristic of attenuation, that is, the vibration amplitudes decreases from the platform chair to the volunteer’s hands. Furthermore, there was a correlation (direct or inverse correlation) between the transmissibility with the reaction, accuracy and score when exposed to whole body vibration, and the type of correlation varied for each frequency and amplitude tested.

Method for measuring time waveforms of minute sinusoidal displacements using continuous waves with a network analyzer

This study proposes a method for precise measurement of time waveforms of minute sinusoidal displacements using continuous waves. The technique involves measuring the S-parameter of ultrasonic waves reflected from an object undergoing sinusoidal vibration with a network analyzer. When the sinusoidal displacement is not sufficiently small, second-order side peaks emerge in its inverse Fourier transform, alongside the main and first-order side peaks. This method, which incorporates second-order side peaks previously overlooked, enhances the accuracy of measurements. It facilitates precise measurement of sinusoidal displacements ranging from 0.3 to 50 μm at frequencies between 10 and 300 Hz.

Dual-stage theoretical model of magnetorheological dampers and experimental verification

The theoretical model for predicting the damping characteristics of magnetorheological dampers (MRDs) not only facilitates the optimization of MRD parameters, but also provides assistance for the theoretical design of MRDs. However, some existing models have limitations in fully characterizing the damping characteristics of MRDs. In this paper, the working stage of MRDs was categorized into yield and pre-yield stages based on whether the internal magnetorheological fluid attains the dynamic shear yield state or not, and the Herschel–Bulkley model with pre-yield viscosity (HBPV) and improved polynomial model (IPOL) were employed to respectively characterize the yield and pre-yield stages of MRDs. Subsequently, the HBPV-IPOL model was proposed to characterize the complete damping characteristics of MRDs in low-frequency vibration conditions, with considering the local loss effect of the fluid in the model. To accurately characterize the magnetic induction intensity in the MRD damping channel, employing the steady-state finite element method for magnetic field analysis; on this basis, dividing the damping channel to investigate the variation trends of the magnetic induction intensity in different regions. Simultaneously, the zero-field region hypothesis was proposed to quantitatively consider the influence of minute magnetic induction intensity in the traditional zero-field regions on the damping characteristics of MRDs. Finally, integrating the impact trends of currents in different regions, and employing the HBPV model to determine the impact magnitude of each region within the damping channel on the damping characteristics of the MRD in the yield stage. In the pre-yield stage, polynomial curves were fitted to experimental damping force–velocity curves, and the obtained polynomials were employed to predict the damping characteristics. Extensive experiments have been conducted on MRD samples to assess the predictive performance of the model on MRD damping characteristics under sinusoidal displacement excitation vibration conditions with different excitation currents, vibration frequencies and vibration amplitudes.

Evaluation of viscous damper on the vibration transmission to the piping system and the support structure exposed to sinusoidal vibration in vertical, horizontal, and lateral directions.

Viscous dampers have been shown to be a potential solution to addressing piping vibration problems. The primary objective of this study is to confirm the ability of viscous dampers in addressing piping vibration problem in a piping system at different supporting structural stiffness. The piping systems were fabricated and arranged horizontally, vertically, and axially with respect to the direction of the input vibration force. Input force was applied to the piping system using an electromagnetic shaker. A sinusoidal vertical vibration at a 5 Hz frequency (21 mm/s RMS) was applied at one end of the piping system. The use of viscous damper was varied from no viscous damper to one, two and three dampers. Results showed that having three viscous dampers installed caused the piping vibration at point P2 showed the maximum reduction in vibration of up to 80% for three axes, respectively. For the case of structural vibration, the measurement results showed that point S1 experienced the highest vibration exposure before the installation of the viscous dampers, in all axes. With the three viscous dampers installed, the maximum vibration reduction for the sinusoidal vibration test case at point S1 were 86% and 91% for the x- and z-axes, respectively. In conclusion, viscous dampers able to reduce both the piping and structural vibration in multiple axes. This study also highlights the importance of positioning dampers in reducing piping vibration and vibration transmitted to the structure, with reduction up to 90% amplitude for sinusoidal input and 80% for random input.