Vibration Environment Research Articles

Electromechanical characteristics analysis of L-shaped pipelines with enhanced active constrained damping treatment

Abstract Fluid-conveying pipelines are widely employed in various engineering fields, such as aerospace, nuclear, and marine fields. These pipelines work in serious vibration environments, which can quickly damage the pipeline system. The vibration control of pipelines is a prominent challenge in the engineering field. This paper is aimed to investigate the electromechanical analysis characteristics of L-shaped pipelines with the Enhanced Active Constrained Layer Damping (EACLD) structure. A finite element model of the L-shaped pipeline with EACLD is established. The dynamic behaviour of an L-shaped pipeline with an EACLD structure was analysed in both the time and frequency domains. The influence of the voltage and the position, the length and the elastic modulus, the thickness and the edge element parameters are all considered. Additionally, the influence of the EACLD patch orientation on static displacement and stress are considered. Simulation results indicate that reasonable selection of the parameters for the EACLD patch and edge element can enhance vibration damping effectiveness, which can provide effective design guidance for active vibration control of the pipeline system. 

Laser speckle interferometry approach for measuring the first wall surface micro-morphology in fusion devices with only single interferogram based on Hilbert transform

During the operation of the EAST device, the surface morphology of the first wall in will change due to the erosion and redeposition from plasma-wall interaction (PWI). In this paper, a novel phase extraction approach using only single interferogram based on twice Hilbert transform (THT) has been proposed and implemented. The current approach has a significant advance for eliminating the phase-shifting errors in principle, but the problems of phase flipping and loss due to ignoring non-physical negative frequency spectrum must to be overcome. To address these problems a judgement method is proposed in current investigation to distinguish the regions of the negative spatial frequency. Then a binary matrix was developed to modify the wrapped phase of the measured interferogram. The validation of the proposed THT approach has been demonstrated by the micro-morphology reconstruction of laser ablation craters on molybdenum (Mo) and tungsten (W) tiles, which are commonly used as the first wall in EAST device. Results indicate that the THT approach has a reasonable measurement accuracy with relative errors around 10%. Also, the current THT approach presents an enhanced robust under the EAST-like vibrational environments.

Comparison and analysis of denoising method in TBM key tunnelling data

ABSTRACT Environmental vibrations and other factors cause significant random errors in raw data collected during TBM tunnelling. Such errors can reach up to 25% and will severely reduce the performance of data mining and machine learning model. To improve the data quality and find a suitable denoising method for TBM data, this study first proposed two assurance indicators to evaluate the effectiveness of data denoising, such as distortion degree (θ) and denoising magnitude (λ). Then, the effects of the data denoising schemes were compared. The results demonstrate that: (1) The Convlove19 scheme has better performance and is recommended for the denoising processing for TBM data. It can preserve the statistical characteristics of the raw data to the maximum extent possible and can improve the performance of the machine learning model by 15∼25%. (2) “Boring cycle segmentation after denoising strategy” (SAD) has better performance than “Boring cycle segmentation before denoising strategy” (SBD) and is recommended. The findings in this study can help with TBM data cleaning and quality improvement, as well as provide a reference for noise reduction of other data with similar features.

Effects of train speed and passenger capacity on the environmental vibration of viaduct and surrounding soil of suburban railways

Compared with the general urban rail transit, some of the current rapid urban rail transit can reach a maximum speed of 140 km/h when the train is running, which exceeds the speed level of the general urban rail transit. To consider the influence of different speeds and loads on the vibration of viaducts and the surrounding soil environment, this paper establishes a three-dimensional finite element model of rail-viaduct soil. The results show that: the frequency domain acceleration of each measurement point increases with the increase of train speed; except for the measurement point which is 20 m away from the centerline of the track, the frequency domain speed of each measurement point increases with the increase of train speed; the frequency domain speed under the low-frequency component of the viaduct measurement point increases with the increase of train loading, and the growth rate is obviously larger than that of the middle and high frequency bands, and the frequency domain speed of the measurement points in the site also increases with the increase of train loading, and the growth rate of the low-frequency band is obviously larger than that of the middle and high frequency bands. The frequency domain velocity at each measurement point of the site also increases with the increase of train load, and the growth rate of the low-frequency band is obviously larger than that of the middle and high-frequency bands.

A flexural-beam-type wide-frequency piezoelectric energy harvester for vertical shaft lifting system vibration monitoring

Abstract The coal mine lifting system may experience serious safety accidents due to severe problems with the bucket guides and rolling guide shoes. A piezoelectric energy harvesting (PEH) device for vibration sensor monitoring of shaft lifting system is proposed for the first time to monitor health of shaft lifting system. However, there are differences in the vibration frequencies, the working conditions are complex, leading to issues such as low energy recovery efficiency of the PEH and difficulty in achieving self-powered. To enhance PEH adaptability and reliability, a specifically designed flexural-beam-type wide-frequency piezoelectric energy harvester(FBT-WF-PEH) and a method of achieving real-time vibration monitoring through auxiliary power supply have been proposed. The results indicate when the excited frequency is 17Hz, the highest external output voltage is 11.2V, and under an external load of 17.5kΩ, the maximum output power is 7.168mW, demonstrating a good performance in terms of output power, and energy harvest bandwidth. The captive power supply test verified the PEH can utilize the vibration environment to achieve auxiliary power supply for monitoring systems under working conditions, which is of great significance for conducting research on health monitoring systems for lifting equipment. On the other hand, the new structure proposed in this study matches the operating frequency in the shaft lifting system, and the energy harvest efficiency is higher.

Influence of different vibration directions on the solder layer fatigue in IGBT modules

Insulated-gate bipolar transistor (IGBT) modules are extensively utilized in high-speed trains, ships, and electric vehicles. Compared to those used in power systems, IGBT modules in these applications are more susceptible to vibration effects on their reliability. This paper proposes a multi-physics field simulation method and a lifetime model for IGBT modules to assess the impact of different vibration directions on solder layer fatigue. Initially, a multi-physics field model of the IGBT module is developed, incorporating electrical, thermal, mechanical, and vibration coupling. The effectiveness of this multi-physics simulation model is verified by an experimental platform. Subsequently, the influence of different vibration directions on solder layer fatigue in the IGBT module is analysed, and a life model of the IGBT is proposed through simulation. Finally, a power cycling with a vibration environment experimental platform is established to validate the effect of vibration on solder layer fatigue in the IGBT module. The simulation and experimental results indicate that vertical vibration accelerates the solder layer fatigue of IGBT modules, and the lifetime of an IGBT module operating under vertical vibration at 30 Hz is about 15 % shorter than that of an IGBT module operating under power cycling alone. The error between the calculated results of the solder layer failure and the experimental result is <5 %.

Whale Optimization Algorithm for structural damage detection, localization, and quantification

This paper introduces an approach for vibration-based damage detection based on matrix updating aided by the Whale Optimization Algorithm (WOA). The methodology uses the Data-driven Stochastic Subspace Identification (SSI-DATA) technique to determine the modal parameters, which are compared with those obtained from both healthy and damaged conditions of the structure. The methodology’s efficacy is assessed through three distinct steps: numerical simulations, experimental data, and real-world data from a bridge. Initially, numerical analyses are conducted on a cantilever beam, a 10-bar truss, and a Warren truss subjected to environmental vibrations with varying damage cases and noise levels. Subsequently, experimental validations are performed on a test system and in the Z24 Bridge. Results from the computational simulations demonstrate the method’s promise to identify, locate, and quantify single and multiple damage cases, even amidst signal noise, variations in the first vibration mode as minimal as 0.015%, and complex structures with 54 elements. Moreover, the matrix updating method utilizing WOA showcased superior accuracy compared to existing techniques in the literature. In addition, the Z24 Bridge example validated the capability of the presented damage detection method to localize structural damage solely based on natural frequencies.

Nonlinear normal modes and response to random inputs of systems with bilinear stiffness

This work seeks to provide a comprehensive review of the effects that stiffness bilinearity can have on the nonlinear modes of a system, its response in a random vibration environment, and the connection between the two. Stiffness bilinearity here refers to a continuous piecewise linear force vs displacement function that is composed of two linear regions. This work focuses on a bilinear stiffness function that is regularized so there is a smooth transition at the point where the two linear regions meet. A single-degree-of-freedom system (SDOF) and a two-degree-of-freedom (2DOF) system are explored and several interesting behaviors are shown. The SDOF bilinear spring model is characterized by four parameters: the low amplitude frequency, the ratio of the linear stiffnesses on either side of the transition, the displacement at which the transition occurs, and the rate or sharpness of the transition. The effect of each parameter on the shape of the NNM is described. In a 2DOF system, these parameters have similar effects, but modal coupling is found to play a significant role. When a bilinear system is subjected to random excitation, many harmonics appear in the response for both the SDOF and 2DOF cases. The root-mean-square (RMS) response of the bilinear system can be larger or smaller than the corresponding linear case depending on the values of the parameters and the type of forcing (broadband, bandlimited, in the shape of a vibration mode, etc.). However, many cases were observed in which the RMS response of the bilinear system was almost the same as that of a linear system, and hence the response could be predicted well using linear analysis. It is hoped that the results presented herein can assist engineers in helping to determine when linear analysis would be adequate to predict the failure of a system, when a rigorous nonlinear analysis is required, and what phenomena are likely to be observed in the latter case.

Method for Predicting Environmental Vibration Impact of Existing Subway Lines and Its Practical Application

To predict accurately the impact of track vibrations caused by subway trains on adjacent buildings and address the problem of their excessive dynamic response, a method for predicting the environmental vibration impact of existing subway lines is proposed in this paper. A coupled numerical dynamical model of the train/track/tunnel system is established using the multi-scale method. Using field-measured soil vibration data, empirical formulas for soil frequency and material damping coefficient are calibrated. By combining the numerical model and the empirical formulas, buildings’ indoor vibrations and noise level can be assessed. At the same time, a solution to the problem of excessive vibration of buildings along a subway line is also proposed that optimizes the track fastener parameters. Field tests verified the accuracy of the prediction method and the effectiveness of the optimized track parameters. These research results provide a reference for predicting the vibration of buildings along subway lines and using the proposed preventive solutions.

Vacancy defect and piezoelectric field assisted photocatalytic performance of BiO(Cl1/3Br1/3I1/3)x for the degradation of organic pollutants

Semiconductor photocatalysts have been widely researched in wastewater treatment of organic dyes, among which bismuth halide semiconductors have shown great application prospects due to their unique layered structure and diverse micromorphology. As for photocatalysis, high concentration of photo-generated carriers and their effective separation are considered to be the key to obtain excellent photocatalytic performance. In view of the common issues of high bandgap energy and low carrier separation rate in bismuth halide, in this paper, the BiO(Cl1/3Br1/3I1/3)x catalysts with different proportions of Bi3+ and (Cl1/3Br1/3I1/3)- were designed and synthesized by hydrothermal method, through constructing hybrid energy levels and thus accomplishing by multi-halogen doping to widen the light absorption range. For another, the efficient separation of electrons and holes was achieved in BiO(Cl1/3Br1/3I1/3)x in virtue of a built-in field stemmed from the intrinsic piezoelectric effect, and band tilting. Meanwhile, more active sites were induced by Vo•• and VBiʹʹʹ due to the directional impact of the built-in field. Ultimately, BiO(Cl1/3Br1/3I1/3)5/7 demonstrated the optimum catalytic performance under the combined light irradiation and ultrasonic vibration, with the degradation efficiency of MB reaching 91.28% in 60 min and the k of 0.0360 min-1, and 97.44% degradation efficiency of Rh B within 18 min and the k of 0.1565 min-1 together with excellent cycling stability. The prepared BiO(Cl1/3Br1/3I1/3)5/7 catalyst has a huge application potential for the degradation of wastewater, taking full advantage of environmental vibration energy and light energy.

Dynamic Monitoring of Steel Beam Stress Based on PMN-PT Sensor

Steel beams are widely used load-bearing components in bridge construction. They are prone to internal stress concentration under low-frequency vibrations caused by natural disasters and adverse loads, leading to microcracks and fractures, thereby accelerating the instability of steel components. Therefore, dynamic stress monitoring of steel beams under low-frequency vibrations is crucial to ensure structural safety. This study proposed an external stress sensor based on PMN-PT material. The sensor has the advantages of high sensitivity, comprehensive frequency response, and fast response speed. To verify the accuracy and feasibility of the sensor in actual engineering, the LETRY universal testing machine and drop hammer impact system were used to carry out stress monitoring tests and finite element simulations on scaled I-shaped steel beams with PMN-PT sensors attached. The results show that: (1) The PMN-PT sensor has exceptionally high sensitivity, maintained at 1.716~1.726 V/MPa in the frequency range of 0~1000 Hz. The sensor performance is much higher than that of PVDF sensors with the same adhesive layer thickness. (2) Under low-frequency random vibration, the sensor’s time domain and frequency domain output voltages are always consistent with the waveform of the applied load, which can reflect the changes in the structural stress state in real time. (3) Under the impact of a drop hammer, the sensor signal response delay is only 0.001 s, and the sensitivity linear fitting degree is above 0.9. (4) The simulation and experimental results are highly consistent, confirming the superior performance of the PMN-PT sensor, which can be effectively used for stress monitoring of steel structures in low-frequency vibration environments.

Surface wave isolation by variable depth infilled trenches

Excessive environmental vibrations generated by urban traffic pose adverse effects on nearby structures and residents. These vibrations are predominantly carried by surface waves, which are localized within the surface layer of soil. The isolation of surface waves through the embedding of periodic wave barriers in soils between the source and the receiver has gained significant attention in recent years. In this paper, a novel approach is proposed for isolating surface waves induced by urban traffic through the use of variable depth infilled trenches. This innovative design not only achieves efficient surface wave isolation but also minimizes the consumption of structural materials. Based on the measured dominant frequency range of rail transit and the available soil parameters, variable depth infilled trenches are designed with suitable dimensions. The eigenvalue equation is solved using the finite element method to derive the dispersion relations and bandgap of identical regularly spaced trenches. To study the efficacy of the proposed structure, a finite element model of the soil-infilled trench system is developed using COMSOL. The mechanism underlying the isolation of surface wave is elucidated, and the effect of variable angle α on the isolation efficiency within 40–50 Hz η40−50Hz of surface waves is studied. The results of this study reveal that for variable angle α of 15°, the surface wave isolation efficiency within 40–50 Hz η40−50Hz is 90.9 % and 92.5 % for uniformly increasing depth infilled trenches and uniformly decreasing depth infilled trenches, respectively. Although the surface wave isolation efficiencies predicted for the variable depth infilled trench arrangements are only 93.8 % and 95.5 % of those predicted for the regularly spaced identical infilled trenches, the variable depth arrangements result in a remarkable 34 % reduction in material usage. These findings highlight the potential of the proposed variable depth infilled trenches as a cost-effective and efficient solution for surface wave isolation.

Reliability sensitivity analysis for set pressure tolerance of the direct-operated relief valve in a vibration environment

Reliability sensitivity analysis for set pressure tolerance of the direct-operated relief valve in a vibration environment

A magnetic plucking frequency up-conversion piezoelectric energy harvester with nonlinear energy sink structure

In low and wide frequency vibration environments, the efficiency of vibration energy harvesters is relatively low. This paper presents a magnetic plucking frequency-up-conversion bistable Piezoelectric Energy Harvester (PEH) that features a Nonlinear Energy Sink (NES) structure for low and wide frequency vibration absorption. Based on the Euler-Bernoulli stepped beam theory, a theoretical model was derived from the Lagrange equation. The system's bandwidth and power generation capability were analyzed through frequency sweeping. This study thoroughly investigated the up-conversion working mechanism of the NES magnetically plucked PEH super-harmonic vibration. The results reveal that the system encompasses two power generation frequency bands: interwell periodic vibration and chaotic vibration. Under an excitation acceleration of 0.25 g, the interwell periodic vibration range during forward frequency sweep is from 3.30 to 4.31 Hz with an average power of 4.71 mW, and during reverse sweep, it is from 2.02 to 4.05 Hz with 2.43 mW. The coordination between NES and PEH is one of the crucial factors affecting power generation. Frequency mismatch can lead to asymmetrical displacement and alternating strong-weak voltage outputs.

Ergonomic assessment of mid-air interaction and device-assisted interactions under vibration environments based on task performance, muscle activity and user perceptions

Mid-air interaction has been increasingly introduced for human-computer interaction (HCI) tasks in vibration environments, but it has seldom been assessed from ergonomic aspects, especially in comparison with device-assisted interactions. This study aimed to provide a comprehensive ergonomic assessment of mid-air interaction and device-assisted interactions under vibration environments based on task performance, muscle activity in the upper limb and shoulder, and user perceptions. A within-subjects design was implemented in this study, where participants were required to perform basic pointing and dragging tasks with four interaction modes (i.e., one mid-air interaction and three device-assisted interactions) under static, low and high vibration environments, respectively. Both small and large target sizes were examined. Muscle activity was recorded with surface electromyography for five muscles from participants’ dominant arm. Results showed that mid-air interaction yielded longer task completion time, more errors, higher perceived workload, lower usability ratings, and larger muscle activities in the forearm, upper arm and shoulder compared with device-assisted interactions. There were significant interaction effects between vibration and interaction mode. Specifically, compared with device-assisted interactions, mid-air interaction was associated with greater susceptibility to the detrimental effects of vibration (poorer task performance and larger muscle activities). Target size significantly affected task performance, but the effects varied by tasks. Overall, our results suggest that mid-air interaction presents a higher ergonomic risk compared with device-assisted interactions, especially in vibration environments. These findings provide implications for better use, configuration and ergonomic assessment of interaction tools in vibration environments, and are useful in developing evidence-based interventions to control ergonomic risk in HCI tasks in vibration environments.

High-Speed Train-Induced Vibration of Bridge–Soft Soil Systems: Observation and MTF-Based ANSYS Simulation

In this paper, a multi-transmitting formula (MTF) was integrated into ANSYS software through secondary development, enabling dynamic finite element simulation of wave propagation in infinite domains. The numerical reliability and accuracy of the MTF were verified through a plane wave problem involving a homogeneous elastic half-space, as well as 3D scattering and source problems in a three-layered soil site. Additionally, a comparative analysis of various artificial boundaries was conducted to highlight the advantages of the MTF. Field observations of environmental vibrations caused by high-speed railway operations revealed localized amplification of vibrations along the depth direction at the Kunshan segment of the Beijing–Shanghai high-speed railway. Based on these observations, a series of numerical analyses were conducted using the customized ANSYS integrated with the MTF to investigate the underlying causes and mechanisms of this phenomenon, as well as the spatial variation characteristics of foundation vibrations induced by bridge vibrations during high-speed train operations. This study reveals the mechanism by which the combined effect of bridge piles and soft soil layers influences the depth variation in peak ground accelerations during site vibrations. It also demonstrates that the presence of bridge piers and pile foundations effectively reduces vibration intensity in the vicinity of the railway, playing a crucial role in mitigating vibrations induced by high-speed train operations.

Experimental investigation on heat transfer enhancement of supercritical pressure aviation kerosene in tubular laminar flow by vibration

In advanced aero-engine thermal management systems, aviation kerosene serving as a coolant unavoidably works in a vibration environment. In this article, the laminar heat transfer performance of Chinese aviation kerosene RP-3 flowing through a horizontal micro-tube under various vibration conditions at supercritical pressures was investigated experimentally. The effects of several impact factors such as system pressure, heat flux, mass flux, inlet temperature, vibration acceleration, and vibration frequency on the heat transfer enhancement were explored in a systematic manner. Experimental results indicate that: (i) the vibration could lead to intense thermal and momentum mixing among different boundary layers of tubular laminar flow and significantly strengthens the heat transfer, and the higher Re can lead to a stronger enhancement effect. The maximum observed HTER across all experimental data is 2.8, occurring at x/d = 224.1 with the inlet temperature of 373 K; (ii) HTER hardly changes with system pressures, exhibiting a maximum relative deviation of 3.9 % at different pressures. Heat transfer enhancement has a strong dependency on heat flux, as the heat flux increases from 36 kW/m2 to 108 kW/m2, the average HTC increased by up to 36.4 %; (iii) the HTC and HTER monotonically rise with increasing vibration acceleration. Peak values in HTC and HTER are observed at vibration frequencies of 625 Hz, 191 Hz, and 242 Hz; (iv) vibration has little impact on the thermal acceleration but noticeably weakens the buoyancy close to the outlet area at high heat flux. Two well-predicted correlations for the Nu in tubular laminar flow, one with vibration and one without, are proposed.

Noncontact magnetically coupled piezo-electromagnetic rotary energy harvester

Aiming at the problems of high environmental vibration frequency, low output power and short life of the energy harvesters, a noncontact magnetically coupled piezo-electromagnetic rotary energy harvester is proposed in this paper. It consists of a base, a top cover, a rotating body, a cantilever beam, a permanent magnet, a coil, a hollow tube and a clamp. The novel hybrid harvester can produce both piezoelectric and electromagnetic energy at the same time, and in addition, it can efficiently generate electricity at low ambient vibration. Moreover, the piezoelectric material is protected from direct collision by noncontact magnetic coupling excitation. In order to conduct a comprehensive study on the performance of the piezoelectric-electromagnetic rotary energy harvester, we set up a rotating test platform to carry out systematic test verification, and to determine the distance between the permanent magnet and the rotating body and the number of permanent magnets on the rotating body. The test results show that when four permanent magnets are uniformly pasted on the rotating body and the rotating speed is 775 r/min, the piezoelectric and electromagnetic output power are 3.4 mW and 2.69 mW, respectively, and the total hybrid output power is 6.09 mW.

Dynamic modelling and experimental validation of a dynamic track stabiliser vehicle–track spatially coupling dynamics system

A dynamic track stabiliser vehicle is an unconventional vehicle for maintaining the quality of ballasted tracks, and its dynamic performance has a significant impact on its working efficiency. For the first time, this paper proposes a comprehensive dynamic track stabiliser vehicle–track coupled vertical and lateral multi-body dynamics model based on classical vehicle–track coupling dynamics theory. In this model, detailed attention is given to the vertical, lateral, roll, yaw, and pitch motions of the components, including the vehicle body, bogies, wheelsets and stabilisers. The Shen–Hedrick–Elkins theory is employed to describe non-linear wheel–rail contact relationships between the bogie wheelsets and the rails, and three various methodologies are adopted to address complicated wheel–rail interaction problems between the stabiliser wheelsets and the rails. This comprehensive multi-body dynamics model enables a detailed investigation of the dynamic performance of the system under complex excitations, such as the lateral excitation of the stabilisers and vertical downward pressure exerted by hydraulic cylinders, especially the dynamic response of the stabilisers in the vibration environment of the complete vehicle. The dynamics model was fully validated by comparing its results with time- and frequency-domain data obtained from field tests. The results indicate that the model is capable of being used for analysis of the dynamic performance of dynamic track stabiliser vehicles.

Courtship performance, not ornamentation, predicts mating success in two sister-species of wolf spider with divergent phenotypes

Mate choice is posited to explain the evolution and maintenance of numerous secondary sexual traits, including ornamentation. This study explores the role of ornamentation in the mating success of two sister-species of wolf spider with divergent ornamentation. Mature male Schizocosa crassipalpata lack ornamentation while males of its closest living relative, S. bilineata, express both dark pigmentation and foreleg brushes. Following phenotypic manipulations of foreleg ornamentation – i.e. adding ornamentation in the form of dark pigment to non-ornamented males (S. crassipalpata, Aim 1) and removing ornamentation in varying degrees from highly ornamented males (S. bilineata, Aim 2 – shaving brushes; Aim 3 – shaving brushes and painting over dark pigment in vibration present/absent environments) – we found no evidence that ornamentation alone improves male mating success in either species, regardless of the vibratory signaling environment. In both S. bilineata experiments, however, higher courtship rates resulted in higher mating success, suggesting selection for courtship performance. Furthermore, females were more likely to turn, a presumed receptivity display, in response to males that courted at a higher rate. Also, similar to findings in another relative (S. stridulans), we found indications that ornamentation may function to ease a male’s reliance on courtship performance – i.e., at low courtship rates, only ornamented males can secure a mating. Our phenotypic manipulations also influenced courtship behavior in S. bilineata. Shaved males began courting earlier and courted more often over a longer time than intact males, yet ultimately acquired similar matings. This increased courtship effort likely compensated for reduced ornamentation. Finally, the vibratory environment appears crucial for female–male dialogue in S. bilineata, as vibratory absent environments resulted in increased female attacks and decreased male courtship rates. Together, our data suggest that S. crassipalpata females do not possess a preference for ornamentation and that S. bilineata females do not use ornamentation alone in mating decisions. Instead, our results are consistent with a hypothesis that ornamentation in Schizocosa evolved, and is likely maintained, due to its interactions with dynamic movement displays (i.e. leg movements), which can themselves be plastically altered based on the signaler’s phenotype as well as the signaling environment.