Input Vibration Research Articles

Integrated Dynamic Modeling and Simulation of Wheeled Vehicle with Outer-Rotor In-Wheel Motors and Key Units

The purpose of this paper is to accurately establish a model of a special vehicle driven by in-wheel motors (IWMs) and investigate its dynamic characteristics. This study proposes a novel integrated vehicle modeling strategy, focusing on the IWM and other key subsystems. Based on this strategy, the vehicle model is developed and simulated in ADAMS. The natural frequencies of the vehicle and transmission characteristics of key components are compared with MATLAB simulation results to validate the accuracy of the model. In the time-domain analysis, the vehicle system’s time-domain characteristics are obtained by using random road spectra of different road grades as excitations. Our simulation results demonstrate that vibration input can be reduced by between 97% and 99% after multi-stage vibration reduction. This work will provide relevant parameters for the design of special vehicles driven by IWMs.

Feasibility of Using Somatosensory Input on Pediatric Patient Anxiety & Experience in the Dental Clinic

Abstract Date Presented 03/23/24 Dental anxiety can lead to avoidance of dental care, causing deterioration of dental health in the long run. This study explores the use of somatosensory input (deep pressure and vibration) to reduce dental anxiety in a pediatric dental clinic. Primary Author and Speaker: Mahira Ali Additional Authors and Speakers: Virginia W. Chu Contributing Authors: Liara Vinson, Jayakumar Jayaraman, Carol Caudill

Proposal and Evaluation of Vertical Vibration Theory of Air Caster

Urbanization and human development have increased the exposure of seismic risk. Therefore, engineers need to develop new and more efficient technologies to protect people and objects from the disastrous consequences of earthquakes. Air casters have gained attention and have been utilized in the past decade as effective seismic vibration control devices. Although such active isolation systems perform well in mitigating horizontal input vibrations, they might cause excessive rocking motions, if not designed properly. This fact emphasizes the importance of exploring the vertical dynamic properties of air isolation systems. To gain such an understanding, this research examines and proposes a formula for the vertical stiffness and damping of air caster systems. Theoretical solutions to the vertical stiffness and damping of such systems have been explored. Computer simulations considering fluid-structure interaction have also been performed to understand the dynamic behavior of the supporting air layer. Results have been compared to validate the proposed dynamic quantities within the considered simulation range. It is also concluded that the instantaneous air layer thickness, representing the air chamber pressure, and the bearing inlet flow rate are the key factors in determining the dynamic properties of the air layer. It is concluded that to evaluate the performance of the air caster seismic isolation device and increase the probability that the qualified seismic isolation performance will be exhibited, it is necessary to investigate which parameters are greatly involved in the viscous damping coefficient and the spring constant of amass-spring-damper system equivalent to the air caster isolation system.

A load impedance emulation active interface for piezoelectric vibration energy harvesters

A single stage active AC/DC electronic interface able to emulate the optimal load impedance of a Resonant Piezoelectric Vibration Energy Harvester (RPVEH) is proposed. As theoretically shown, unlike an electronic interface that emulates an optimal load generator, an interface that emulates an optimal load impedance does not require adaptation to the acceleration of input vibrations. This allows the use of a very simple control, avoiding the implementation of Maximum Power Point Tracking algorithms that require lossy microcontrollers. Thus, the proposed interface is equipped with a simple analog controller allowing the RPVEH to work in its Maximum Power Point in both steady-state and variable conditions of vibrations, without recurring to multivariable perturbative approaches, as it happens for the most of single stage AC/DC interfaces proposed in the literature. The absence of perturbative techniques allows a significant improvement of both stationary and dynamic performances. Experimental tests of a prototype of the proposed interface confirm the theoretical findings and the predicted behavior.

DEM analysis on diffuse failure of soil slope triggered by earthquakes

Earthquake-induced diffuse landslide can cause considerable harm. This study used discrete element modeling (DEM) to investigate the diffuse failure of soil slopes triggered by earthquakes. Initially, the DEM was validated through demonstrating satisfactory agreement with the experimental results of a shaking table test. Subsequently, the time and most realistic location of diffuse failure occurrence was quantified using discrete second-order work. Diffuse failure was associated with abrupt fluctuation of the second-order work and a local burst of kinetic energy. Within the context of second-order analysis, the frictional resistance of the slope was analyzed. Both the in-phase and the out-of-phase evolutions of frictional resistance and seismic loading were captured. The distinctive in-phase response was identified as an important feature of diffuse failure. Moreover, the predominant influence of particle rolling behavior on frictional resistance development during diffuse failure progression was highlighted. The magnitude and anisotropy of the contact force are profoundly influenced by the input vibration amplitude, resulting in variations in frictional resistance, which suggests that stress-induced anisotropy plays a crucial role in diffuse failure. The results of this study shed light on the grain-scale failure mechanisms of earthquake-induced landslides, and serve as the basis for elucidating the failure behavior of seismic-induced landslides.

Modal spectrum analysis for an imperfect beam model with random vibration

The cross-Spectral Density (SD) is a method of analyzing the relationship between randomly-input forces and their responses in the frequency domain in spectrum analysis. It is essential for analyzing antiresonant eigenfrequencies that are difficult to understand using only direct-SD. Additionally, the mass in a beam is often analyzed in modern engineering to control the vibration characteristics of a simple beam or as a major model for error. Especially, the scalability can be expected in various fields such as nanosensors as well as macroscopic scale by studying imperfect mass. Firstly, the correlation function and SD are defined for an arbitrary vibration input in a beam. Then, the response function is established according to a harmonic input of some unit force amplitude. Moreover, the direct- and cross-SDs for the response are calculated and mathematically compared with both results. Further analysis is performed by comparing the variation of the SD with response position, the standard deviation (StDev) of the mean of maximum responses, and the bandwidth. The developed cross-SD of the imperfect beam extends the previously developed SD models of the perfect beam and can provide ideas for new types of eigenfrequency analysis, vibration isolation, etc.

Droplet-based mechanical transducers modulated by the symmetry of wettability patterns

Asymmetric mechanical transducers have important applications in energy harvesting, signal transmission, and micro-mechanics. To achieve asymmetric transformation of mechanical motion or energy, active robotic metamaterials, as well as materials with asymmetric microstructures or internal orientation, are usually employed. However, these strategies usually require continuous energy supplement and laborious fabrication, and limited transformation modes are achieved. Herein, utilizing wettability patterned surfaces for precise control of the droplet contact line and inner flow, we demonstrate a droplet-based mechanical transducer system, and achieve multimodal responses to specific vibrations. By virtue of the synergistic effect of surface tension and solid-liquid adhesion on the liquid dynamics, the droplet on the patterned substrate can exhibit symmetric/asymmetric vibration transformation when the substrate vibrates horizontally. Based on this, we construct arrayed patterns with distinct arrangements on the substrate, and employ the swarm effect of the arrayed droplets to achieve three-dimensional and multimodal actuation of the target plate under a fixed input vibration. Further, we demonstrate the utilization of the mechanical transducers for vibration management, object transport, and laser modulation. These findings provide a simple yet efficient strategy to realize a multimodal mechanical transducer, which shows significant potential for aseismic design, optical molding, as well as micro-electromechanical systems (MEMS).

High-performance piezoelectric energy harvesting in amorphous perovskite thin films deposited directly on a plastic substrate

Most reported thin-film piezoelectric energy harvesters have been based on cantilever-type crystalline ferroelectric oxide thin films deposited on rigid substrates, which utilize vibrational input sources. Herein, we introduce flexible amorphous thin-film energy harvesters based on perovskite CaCu3Ti4O12 (CCTO) thin films on a plastic substrate for highly competitive electromechanical energy harvesting. The room-temperature sputtering of CCTO thin films enable the use of plastic substrates to secure reliable flexibility, which has not been available thus far. Surprisingly, the resultant amorphous nature of the films results in an output voltage and power density of ~38.7 V and ~2.8 × 106 μW cm−3, respectively, which break the previously reported record for typical polycrystalline ferroelectric oxide thin-film cantilevers. The origin of this excellent electromechanical energy conversion is systematically explored as being related to the localized permanent dipoles of TiO6 octahedra and lowered dielectric constant in the amorphous state, depending on the stoichiometry and defect states. This is the leading example of a high-performance flexible piezoelectric energy harvester based on perovskite oxides not requiring a complex process for transferring films onto a plastic substrate.

Improving and Predicting the Surface Roughness and the Machining Accuracy in Ultrasonic Vibration-Assisted Milling

The present research work amis to develop a controlled vibratory system for improving the performance of slotting process based on the vibration-assisted milling technique. In addition, the establishment of a statistical model for predicting the process efficiency was a key aim target.In the current investigation, an ultrasonic vibratory device was designed to provide vibration oscillations in the cutting feed direction to the 7075 aluminum alloy workpiece side at 34.7 kHz frequency and 10 μm amplitude. A LabView code has been developed to control the input vibration parameters. A full factorial design of experiments with 4 factors and 2 levels was conducted. An in-depth statistical analysis is then implemented to study the effect of machining and vibration parameters on the process performance. Then, a statistical model for predicting the process response in terms of cutting force, surface roughness, and machining accuracy has been established.Some experiments showed a significant reduction in cutting force up to 50% in the feed direction. Additionally, an improvement in workpiece surface roughness was recorded. Regarding the machined surface accuracy, introducing ultrasonic vibrations significantly reduces the produced slot width error compared to Conventional Milling (CM).The developed statistical model shows a very well agreement with the experimental results. Therefore, the developed VAM technique is suitable for manufacturing parts that require high geometrical and dimensional accuracy.

The Effect of Packaging Types on Fresh Peaches in the Direct‐To‐Consumer Environment: Distribution Testing, Life Cycle Assessment and Economic Impact

ABSTRACTThe direct‐to‐consumer (D2C) shipping mode presents new opportunity for fresh peach sales in North America where demand over the past four decades has steadily declined. The hazards in this distribution mode are severe, and fresh peaches are fragile emphasizing the need for proper protection. A full analysis that not only encompasses the effects of the D2C distribution environment but also incorporates analyses of the environmental and economic impact of the packages utilized for transit of peaches is necessary. In this study, we use the metrics of peach grade, firmness, soluble solids concentration and percent softness before and after the distribution simulation to compare the protective performance of six DTC packaging systems. All six packages consist of a single layer corrugated box with varying primary packaging. A life cycle analysis of each package system is performed as well as an economic analysis on the packaged materials and cost to ship. We conclude that peach damage in shock testing is related to the freedom of movement that peaches have within each package type and varies by package system. All the package types evaluated amplify input vibration in the frequency range commonly associated with the input from the tires of truck‐trailer systems. There are no statistical differences between package systems in the distribution simulation of the six package types except in peach softness and grade of melting flesh peaches. Finally, we found that a reduction in material use and change in format, that is, foam sheets to foam netting, provides for sufficient peach protection while reducing environmental and economic impact.

MelSPPNET—A self-explainable recognition model for emerald ash borer vibrational signals

IntroductionThis study aims to achieve early and reliable monitoring of wood-boring pests, which are often highly concealed, have long lag times, and cause significant damage to forests. Specifically, the research focuses on the larval feeding vibration signal of the emerald ash borer as a representative pest. Given the crucial importance of such pest monitoring for the protection of forestry resources, developing a method that can accurately identify and interpret their vibration signals is paramount.MethodsWe introduce MelSPPNET, a self-explaining model designed to extract prototypes from input vibration signals and obtain the most representative audio segments as the basis for model recognition. The study collected feeding vibration signals of emerald ash borer larvae using detectors, along with typical outdoor noises. The design of MelSPPNET considers both model accuracy and interpretability.ResultsExperimental results demonstrate that MelSPPNET compares favorably in accuracy with its similar non-interpretable counterparts, while providing interpretability that these networks lack. To evaluate the interpretability of the case-based self-explaining model, we designed an interpretability evaluation metric and proved that MelSPPNET exhibits good interpretability. This provides accurate and reliable technical support for the identification of emerald ash borer larvae.DiscussionWhile the work in this study is limited to one pest type, future experiments will focus on the applicability of this network in identifying other vibration signals. With further research and optimization, MelSPPNET has the potential to provide broader and deeper pest monitoring solutions for forestry resource protection. Additionally, this study demonstrates the potential of self-explaining models in the field of signal processing, offering new ideas and methods for addressing similar problems.

Roly-poly inspired tribo-electromagnetic energy harvester toward sustainable ocean energy harvesting

With the increasing global population, the demand for energy has also risen significantly. However, the utilization of fossil fuels for the purpose of energy production has resulted in the release of carbon emissions, accelerating the global warming. Therefore, the demand for carbon-free and renewable energy sources, which can replace the fossil fuels, is growing. In this study, a roly-poly-structure-inspired hybridized energy generator (RPHG) is demonstrated by combining a roly-poly triboelectric nanogenerator with an electromagnetic generator. By utilizing the RPHG, multiple vibrations can be induced from an external force due to the recovering force originated by the roly-poly structure of the RPHG. Consequently, the RPHG is capable of harvesting multiple vibrations from a single input vibration. To optimize the electrical performance of the RPHG, the effects of the substrate shape and the number of polytetrafluoroethylene balls into the electrical output is investigated. Also, the effect of the center of gravity on the electrical output generated from the RPHG is theoretically and experimentally confirmed. As a result, the average vibration number is increased from 2.6 to 25.1 with the 20 polytetrafluoroethylene balls when the tilted substrate with a tilted angle of 170° is applied to the RPHG, compared to the electrical output is generated from the RPHG with a flat substrate. The synergistic effect of the hybridization is demonstrated by comparing the charging speeds of a capacitor and the RPHG shows the fastest speed for charging the capacitor. Furthermore, our RPHG generates 2.45 and 19.29 times higher electrical output than the roly-poly triboelectric nanogenerator (RP-TENG) and electromagnetic generator, respectively. The proposed RPHG demonstrates the 195% higher conversion efficiency in terms of energy compared to the power owing to its unique structure. Also, although the RP-TENG and TENG without roly-poly structure (NRP-TENG) generate similar electrical power, the RP-TENG generates 242% higher electrical energy than NRP-TENG, showing the great potential to harvest the mechanical energy due to the roly-poly structure. As an application, a self-powered ocean wave monitoring system is implemented using the RPHG and it successfully detects strong, calm, and gentle waves. These results show the great potential of the RPHG to harvest vibration and ocean wave energy. Hence, we expect our RPHG to be a promising energy-harvesting solution for generating carbon-free energy.

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.

Field Testing and Numerical Simulation of the Dynamic Response of Loess Hill Site under High-Speed Train Load

In this study, the loess hill site of an elevated bridge section in Tongwei-Qin’an of the Baolan high-speed railroad was selected as the research object, and the vibration acceleration of the loess hill site under the elevated bridge was tested in the field under the train operating load. The results show that under the same intensity of train load, the time range of vibration acceleration observed by field test and numerical simulation decays linearly with increasing distance from the source, while the amplification effect appears in the loess hill site at a greater distance, and the vibration duration also appears to increase. The vibration acceleration waveforms at each observation point observed by field tests and numerical simulations are similar, and the peak vertical acceleration at each observation point obtained from numerical simulations is overall greater than the peak acceleration at each point obtained from field tests, with aSimulated− max/aObservated− max values ranging from 1.04 to 1.63. The Fourier spectrum frequencies recorded by numerical simulation and field test are mainly concentrated in the range of 1∼40 Hz, but the difference between the main frequencies recorded by the two is large. The main frequency of the energy spectrum recorded by the numerical simulation is around 15 Hz, which is the same as the main frequency of the energy spectrum vibration of the input vibration wave, and the main frequency of the energy spectrum vibration recorded by the field test is around 25 Hz.

Building Vibration Measurement and Prediction during Train Operations

Urban societies face the challenge of working and living in environments filled with vibration caused by transportation systems. This paper conducted field measurements to obtain the characteristics of vibration transmission from soil to building foundations and within building floors. Subsequently, a prediction method was developed to anticipate building vibrations by considering the soil and structure interaction. The rigid foundation model was simplified into a foundation–soil system connected via spring damping, and the building model is based on axial wave transmission within the columns and attached floors. Building vibrations were in response to measured input vibration levels at the ground and were validated through field measurements. The influence of different building heights on soil and structure vibration propagation was studied. The results showed that the predicted vibrations match well with the measured vibrations. The proposed prediction model can reasonably predict the building vibration caused by train operations. The closed-form method is an efficient tool for predicting floor vibrations prior to construction.

Proxy-Based Super-Twisting Algorithm for MEMS Mirror Control Under Input Saturation and Vibration

Proxy-Based Super-Twisting Algorithm for MEMS Mirror Control Under Input Saturation and Vibration

Ergonomic Comfort and Tolerance Trial Results for Digital Imaging Elasto Tomography (DIET) Breast Cancer Screening

Approximately 1 in 10 cancers diagnosed worldwide are female breast cancer. Mammography is currently the only approved large-scale breast screening modality. However, mammography exposes females to varying levels of radiation, and discomfort due to breast compression, which reduces compliance. Digital Imaging Elasto Tomography (DIET) is an emerging low-cost, radiation-free, compression-free breast cancer screening system. DIET delivers a low-amplitude, low-frequency mechanical vibration to a breast at the nipple and measures surface motion response, which is used to infer underlying tissue properties and diagnose cancers based on the large (400∼1000%) contrast in stiffness between healthy and cancerous tissue. However, female tolerance of these vibration inputs is unknown.An ergonomic trial was conducted on 40 female subjects to quantify comfort and tolerance to the input mechanical vibration by finding the largest tolerable vibration felt on the breast surface. The trial tested a range of frequencies [20 Hz, 25 Hz, 30 Hz] and amplitudes [1.0 mm, 1.5 mm], whereas prior DIET trials used only a 0.5 mm input. Results show little discomfort below 25 Hz, with some discomfort increasing above this value due to lack of isolation of the actuator in the DIET prototype. Ten (N=10, 25%) trial participants had prior mammography experience, and rated the overall discomfort of DIET 1.85 out of 5 on average, compared to a mammography discomfort rating of 4.5 out of 5 on average (p < 0.05, Mann-Whitney). Participants with no mammogram experience found the procedure more comfortable (average discomfort rating 1.4 out of 5). The results show the DIET technology using input vibration amplitudes up to 3x larger than previously is a comfortable and tolerable screening technology, and was a preferred screening method in those women who had experienced mammography previously, thus showing promising potential uptake of such a technology to increase equity of breast screening and improve outcomes for women.

Seismic Response Comparisons of Prefabricated and Cast In Situ Subway Station Structures in Liquefiable Site

Based on the engineering practice of the first prefabricated subway station (Shuangfeng Station) in Changchun, China, the applicability of prefabricated subway station structures (PSSSs) in liquefiable sites in seismically defended areas is investigated. In this paper, the finite difference software FLAC3D 5.0 is used to carry out the seismic response analysis of the PSSS in liquefiable ground, and the calculation results of the PSSS are compared with those of the same type of cast-in-place subway station condition. The results show that the trend of foundation excess pore pressure ratio (EPPR) in the PSSS condition is similar to that of the cast-in-place condition. For different ground vibration inputs, there is not much difference between the PSSS and the cast-in-place structure on the pore pressure (PP) of the surrounding liquefiable soil. The acceleration response of the PSSS is slightly smaller than that of the cast-in-place structure, and it has a better ability to adapt to ground deformation. The deformation of the upper part of the PSSS is slightly larger than that of the lower part, which is an important part of its deformation control, and the middle part is the key part of its strength control due to the presence of the center plate, which results in a significant increase in stiffness and stress. The flexible connection of the PSSS is easier to adapt to a larger vertical deformation than rigid connection, and its ability to resist overturning is better. Under the premise of ensuring static waterproofing, the PSSS can be constructed in liquefiable sites in earthquake-proof areas.

Biotransport in human phonation: Porous vocal fold tissue and fluid–structure interaction

Human phonation involves the flow-induced vibrations of the vocal folds (VFs) that result from the interaction with airflow through the larynx. Most voice dysfunctions correspond with the fluid–structure interaction (FSI) features as well as the local changes in perfusion within the VF tissue. This study aims to develop a multiphysics computational framework to simulate the interstitial fluid flow dynamics in vibrating VFs using a biphasic description of the tissue and FSI methodology. The integration of FSI and a permeable VF model presents a novel approach to capture phonation physics' complexity and investigate VF tissue's porous nature. The glottal airflow is modeled by the unsteady, incompressible Navier–Stokes equations, and the Brinkman equation is employed to simulate the flow through the saturated porous medium of the VFs. The computational model provides a prediction of tissue deformation metrics and pulsatile glottal flow, in addition to the interstitial fluid velocity and flow circulation within the porous structure. Furthermore, the model is used to characterize the effects of variation in subglottal lung pressure and VF permeability coefficient by conducting parametric studies. Subsequent investigations to quantify the relationships between these input variables, flow perfusion, pore pressure, and vibration amplitude are presented. A linear relationship is found between the vibration amplitude, pore pressure, and filtration flow with subglottal pressure, whereas a nonlinear dependence between the filtration velocity and VF permeability coefficient is detected. The outcomes highlight the importance of poroelasticity in phonation models.

Verification on prediction method of floor impact sound using vibro-acoustic coupling effect

The impact noise generated in concrete structures exhibits complex behavior due to the interaction between vibration and sound, making it difficult to predict. To achieve accurate predictions, it is important to consider the interaction between vibration and sound and input reliable data. In this study, a governing equation that considers the interaction between vibration and sound was proposed and validated using relatively reliable vibration data as input. Vibration and sound data were obtained from a mock-up house built with a structure similar to that of an actual residential building. The vibration data was analyzed using time history and modal decomposition to confirm the interaction between vibration and sound. Subsequently, the proposed governing equation was used to calculate the sound data by inputting the vibration data, which was then compared and analyzed against the measured data. In the time history analysis, it was observed that the calculated data after 0.8 seconds exhibited relatively less attenuation, suggesting a higher damping ratio in the mock-up house than anticipated. Furthermore, the modal decomposition comparison revealed a slight shift in the mode frequency from 43.0 Hz to 43.6 Hz, and the spectrum showed larger values in the calculated data, which can be attributed to the damping ratio. Further research on the damping ratio in residential buildings is planned to improve the accuracy of the prediction in the vibration-sound system.