Wind-induced Vibration Research Articles

A novel elastic strip suspension-based bi-directional electromagnetic wind energy harvester designed specifically for wind energy factories

In this study, we propose a novel parallel elastic strips suspended electromagnetic wind energy harvester (ESWEH) based on wind-induced vibration. Profiting galloping phenomena caused by wind flow, the hollow square tube is conceived to generate a significant transverse vibration, and two magnets are equipped on the hollow square tube to generate electrical energy utilizing the electromagnetic induction principle. The symmetrical design of the ESWEH enables it to harvest bi-directional wind energy, while this structure is easy to be assembled into an integrated energy harvesting factory to meet various power supply requirement. A theoretical model is developed to explain the operational mechanism of the proposed electromechanical coupling system. Further, a series of experiments are conducted in a wind tunnel to examine its power generation characteristics (including power-resistance, voltage-resistance) under a closed-circuit condition. The results of the experiments indicate that, when the wind velocity exceeds 2 m/s, the ESWEH equipped with both front and back attached fins produces a continuous and stable current output, with a voltage value exceeding 2.0 V and power exceeding 2.0 mW. Moreover, at an incoming wind velocity of 4 m/s, anaverage power of 7.8 mW is obtained, accompanied by a Root Mean Square (RMS) voltage of 3.2 V when connected to a resistance of 1.2 kΩ. In conclusion, the proposed ESWEH shows good performances in various aspects such as a simplified structure, efficiency-cost, low critical wind velocity and a high-power capacity. The experimental results further indicate that the proposed structure has potential application in construction of a stable power supplying system and wind energy factory for wireless sensors.

Wind Load Effects and Gust Loading Factor for Cable-Suspended Photovoltaic Structures

The cable-suspended PV system has gained increasing popularity due to its large span and good site adaptability. However, this structure is quite sensitive to wind actions, and wind-induced module damage and structure failure have been frequently reported. Therefore, in this study, we carried out wind tunnel tests to study wind load effects on PV arrays with different lengths and widths. Considering the wind sheltering effects of upstream modules, reduction factors for the wind load were proposed in different array zones. Numerical simulations of wind-induced vibration and equivalent static analysis were conducted to yield gust loading factors for the PV array. This study showed that the maximum wind suction and pressure for the middle zone occurred at 0° and 180°, respectively, while those for the outermost zone appeared under oblique flows (e.g., 30° and 150°). For the PV modules beyond the windward fourth row, the reduction factors of the wind loads were 0.4 (maximum suction) and 0.2 (maximum pressure) for the middle zone and 0.5 (maximum suction) and 0.75 (maximum pressure) for the outermost zone. The gust loading factors for the typical wind directions of 0° and 180° varied from 2.2 to 2.7 for the middle zone and from 1.3 to 1.5 for the outermost zone.

Wind-induced torsional vibration in a ponderosa pine tree

The overall response of above-ground tree parts to wind loading consists of torsional and bending vibrations. While bending vibrations have been frequently measured in previous studies, measurements of torsional vibrations are scarce. Therefore, three-dimensional tree response measurements were conducted along the stem and on several branches of a ponderosa pine (Pinus ponderosa) tree. The measurements reveal that tree parts respond to external forces with torsional and bending vibrations even at low wind loads. As wind loading intensifies, the contribution of torsional vibration to the overall tree response rapidly diminishes, stabilizing at a lower level Concurrently, the share of bending vibrations becomes more prominent, accounting for nearly the entire tree response. Torsional vibrations are most pronounced in the crown space and more localized than bending vibrations. Under the wind loading conditions during the study period, they were hardly measurable in the lower stem parts. If one aims to quantify torsion in above-ground tree parts, multiple measurements are necessary depending on the research objectives. The results also indicate that depending on the wind load, one- and two-dimensional measurements of the wind-induced tree response made in lower stem parts are only sometimes suitable to capture the overall tree response to wind loads.

Periodic solutions and bifurcations of a tristable flutter-based energy harvester

This paper designs a tristable flutter-based energy harvester that can harvest large amplitude interwell wind-induced vibration energy. To explore its periodic responses and bifurcation characteristics, the harmonic balance method and the incremental harmonic balance method are employed to solve its approximate solutions by combining the two-point tracing algorithm. By analyzing the incremental harmonic balance solutions, three different response regions and five vibration types are found. The wind tunnel experiment verifies the existence of these vibration types and the correctness of incremental harmonic balance solutions. Five bifurcation points are analyzed using the Floquet theory, and two evolution paths of its periodic solutions are studied. Finally, the influences of the potential well depths on the stable periodic solutions are studied. The shallow potential energy well is beneficial to improving the response stability. This study aims to fill the gap in the semi-analytical and analytical solution of nonlinear flutter-based energy harvesters, contribute to the theoretical analysis of wind-induced vibration energy harvesting, and provide more possibilities for the design of high-performance wind-induced vibration energy harvesters.

Fluid–structure interaction on vibrating square prisms considering interference effects

Existing research on interference effects predominantly focuses on rigid structures. However, studies based on rigid models tend to overlook the feedback of structural motions on the flow field, thus failing to capture the intrinsic dynamics of the interference effect induced by wind-induced structural vibrations. This paper provides a comprehensive analysis of the fluid–structure interaction mechanisms considering interference effects involving two parallel square prisms, employing large-eddy simulation (LES). Various factors, including wind speed, arrangement, and vibration amplitude, are meticulously considered in the analysis. The study utilized three-dimensional LES simulations, incorporating the narrowband synthesis random flow generator method for inlet turbulence generation and adjusted through the “feedback” approach to ensure accuracy and efficiency. The research highlighted different structural arrangements exhibited distinct interference effects, and the end effect of the structure could substantially modify the flow pattern at various heights. In the tandem arrangements, the study observed several flow phenomena, including early reattachment, attenuation of the end effect, premature formation of roll structures, increased turbulence in the flow field due to vibration, resulting in wider second leading-edge separation, and a fragmented wake flow on the downstream structure. For side-by-side arrangements, the “acceleration effect” was identified and found to be further intensified by structural vibrations. The vibration of the interfering structure was noted to cause changes in vortex shedding frequencies and alterations in the wake flow pattern. In addition, vibration would enhance the interference effect but increasing amplitude and wind speed might diminish the interference effect. Overall, this study offers valuable insight into the intricate interplay of factors influencing the aerodynamics of parallel structures across diverse arrangements and under varying conditions.

Electromagnetic Wind-induced Vibration Energy Harvester with a Resonant Cavity

Wind energy, as the most widely distributed form of renewable energy, holds great significance in addressing the energy supply issue for micro-power electronic equipment. Therefore, this paper proposes an electromagnetic wind-induced vibration energy harvester with a resonant cavity (EWVEH). When the wind blows through the resonant cavity, the pressure inside the cavity increases, causing a change in the pressure distribution. The pressure on the lower surface of the elastic beam exceeds the pressure on the upper surface, leading to a pressure difference. When the pressure difference exceeds the damping force of the elastic beam, it will cause the beam to move, and then the vibration energy will be converted into electrical energy through electromagnetic conversion. The installation angle of the elastic beam and the size and position of the resonant cavity outlet will affect the fluid distribution in the resonant cavity and the vibration characteristics of the elastic beam. This, in turn, will change the output characteristics of the EWVEH. The simulation analysis and experimental research demonstrate that a smaller installation angle for the cantilever and a smaller outlet for the resonant cavity is advantageous for the EWVEH to obtain higher output power. Furthermore, the position of the air outlet also impacts the efficiency of the EWVEH. At a wind velocity of 14 m/s, the load voltage and power of the EWVEH are 39 mV and 101.4 μW, respectively.

Nonlinear Finite Element Analysis and Fatigue Damage Assessment of Wind-Induced Vibration for the Tension Cable-Supported Power Transmission Structure

Nonlinear Finite Element Analysis and Fatigue Damage Assessment of Wind-Induced Vibration for the Tension Cable-Supported Power Transmission Structure

Investigation of Effect of Wind-Induced Vibration on Typical Frame Structures on the Open Decks of Large Cruise Ships Based on the Subdomain Method

Due to the tall and large superstructures of cruise ships, the wind-induced vibration of frame structure on open decks cannot be neglected. This study investigated the wind-induced vibration of a typical frame structure on a cruise ship by using wind tunnel tests and numerical simulations. Wind tunnel tests were conducted to explore the simulation methods of the fluid–structure interaction (FSI). CFD simulations were performed to obtain the wind field data of the entire ship, which was utilized as an input for the open deck through the subdomain method. Subsequently, wind-induced vibration simulations of the guide rail frame structure on the open deck was carried out under various wind conditions. The results revealed that employing the turbulence model SST k-ω had a good agreement with the experimental data. The entire ship’s CFD results have a significant impact on the subdomain’s wind-induced vibration results. The vibration frequency of the guide rail frame structure was mainly concentrated between 0.8–10.1 Hz. The most unfavorable conditions appear at the wind attack angles of 0° and 120°. This study can provide some instructive insights for the prediction of wind-induced vibration and control of typical structures on the open decks of large cruise ships.

Inerter location effect on the generalized tuned mass damper inerter control

This paper investigates the inerter location effect on the generalized tuned mass damper inerter (TMDI) control, in which the end of the inerter is located at any position of the primary structure. A good understanding of the inerter location effect can help us achieve an optimal generalized TMDI control. Two mass ratios weighting the mass amplification effect and negative stiffness effect are defined to understand the inerter location effect. Based on the two mass ratios, the relationship between the TMD and generalized TMDI is established, the analytical solution of the optimal tuning frequency is derived, and a high-accuracy prediction equation judging whether the generalized TMDI performs better than the TMD is proposed. Finally, numerical analyses on a 76-story high building equipped with TMD and generalized TMDI are performed. The results show that the the generalized TMDI in fact is a large mass ratio TMD with a frequency-dependent stiffness, the generalized TMDI with larger inertance and smaller physical mass has more inerter location choices, and the damping ratio of the primary structure has no influence on the critical inerter location. The generalized TMDI considering the inerter location effect has better control effect than the TMD in suppressing both the wind-induced vibration and earthquake-induced vibration. The mean reduction ratios of peak floor accelerations for the TMD and TMDI controls are 60.53% and 54.5% under the wind-induced force excitation, and those of maximum floor drift ratios for the TMD and TMDI controls are 94.32%, 87.56% under the earthquake excitation.

Wind-induced vibration control of tall buildings by designing the overhead fire water tanks as compliant deep tank dampers-inerter

Building codes often mandate the installation of overhead fire water tanks (OFWTs) on multi-storeyed buildings. The present study proposes a cost-effective solution by utilizing these OFWTs as tuned liquid dampers (TLDs) in tall buildings to improve serviceability under wind-induced excitation. However, designing OFWTs as TLDs is often hindered by the deep nature of the OFWTs and practical constraints in dimensioning the tank as per the tuning requirement. To alleviate these hindrances, the OFWT is designed as a compliant deep tank damper-inerter (CDTDI). A compliant damper system is achieved by connecting the tank with the building through spring and dashpot elements. This allows relative motion of the whole tank with respect to the building. Further, an inerter is employed to improve the efficiency of the compliant damper. Three example buildings, 20-, 30-, and 40-storeyed, are considered and modeled as multi-degrees-of-freedom (MDOF) systems. The CDTDI-MDOF structural system’s motion equations are formulated. An excitation-independent, genetic algorithm-based single-objective optimization is performed to estimate the optimum CDTDI parameters. Sequentially, the 2nd-order or H2 and infinity or H∞ norms of the transfer function of the roof displacement are chosen as objective function. The efficacy of the CDTDI is examined by subjecting the structure to 10 simulated wind excitations. The results reveal the proficiency of the CDTDI in controlling the multiple modes of the structure, alongside providing significant damping. The CDTDI induces up to 25 and 21 % reduction, respectively, in the peak roof displacement and peak roof acceleration of the example buildings. Further, CDTDI with parameters obtained through H∞ optimization is found to be relatively better performing.

Method for extracting the free vibration response of transmission tower

The analysis of the free vibration in transmission towers is aimed at better evaluating their health status. Due to the non-stationarity of the height of non-uniform wind-induced vibration, there is a sustained forced vibration response in the vibration signal of transmission towers. This will lead to a decrease in the stability of vibration characteristics, which brings great difficulty to transmission tower status identification. In order to solve this problem, this paper proposes a method for extracting the free vibration response of transmission towers. By using Void–Kalman filtering (VKF) and generalized demodulation transform (GDT) for modal frequency tracking and pseudo-peak elimination, the signal is maximally cleaned while retaining all modal information. In addition, this paper combines variational theory and time-frequency domain features to decompose all effective modal orders in the vibration response. This not only solves the errors that exist when GDT and VKF directly process the original signal, but also makes the extraction of frequency parameters of each modal orders more convenient. The effectiveness of this approach is demonstrated by extracting the free vibration response of a 110 kV cat-head type tower. And by comparing it with existing mainstream signal processing methods using the example of bolt loosening faults. The results show that the signal processed by this approach can more stably and accurately capture the fault characteristics, providing a new idea for the extraction of free vibration response in the field of transmission tower health monitoring.

Experimental investigation on wind-induced vibration of photovoltaic modules supported by suspension cables

Under the background of the global energy crisis and excessive carbon emissions, solar power stations have increased rapidly in number and size in recent years. To satisfy the construction needs on complex or special sites (e.g. intertidal zone, mountainous area, fishponds, etc.), a suspension cable supported photovoltaic (PV) module was developed recently and quickly aroused market interest; however, such cable-supported flexible PV systems are susceptible to wind loading and associated aerodynamic effects thereon remain unclear. Therefore, both aeroelastic and rigid model wind tunnel tests were conducted to investigate the wind-induced vibration (WIV) characteristics of a typical cable-supported PV module. The effects of module tilt angle, cable pre-tension, and wind speed on the vertical displacement response and the aerodynamic damping were evaluated. Based on wind pressure tests and finite element simulation, the three-dimensional WIV behavior of PV modules could be investigated. The non-dimensional gust loading factor representing the load dynamic amplification was presented based on multi-target equivalent static wind loads. Results show that wind-induced vertical vibration of the PV modules increased with tilt angle but reduced with increasing cable pretension. The fluctuating displacement shows a quasi-linear increase with the square of the wind speed. Negative aerodynamic damping was found for a tilt angle of 10° under high wind speeds. Compared to vertical vibration, horizontal and torsional responses were insignificant for the tested PV modules. The estimated gust loading factor for the PV module with tilt angle of 10° was between 1.1 and 2.5.

An orientation-adaptive electromagnetic energy harvester scavenging for wind-induced vibration

Wind energy is widely distributed, pollution-free and sustainable. Harvesting wind-induced vibration energy is a promising way to build self-powered systems. However, most of the current wind-induced vibration energy harvesters are unidirectional directional and insensitive to the frequently changing in wind direction. To overcome the difficulty, this work proposes an orientation-adaptive electromagnetic energy harvester (EMEH). By introducing a rotatable bluff body, the EMEH could be self-regulated to cater for the wind flow direction. Experimental results showed that the output power of the proposed EMEH could be enhanced greatly with the increase of rotatory inertia of the rotating bluff body. And, when the stiffness of the elastic beam is high, the output performance of the EMEH can be guaranteed by increasing the rotatory inertia of the rotatable bluff body. The output power of the optimized rotating bluff body and the elastic beam is 0.498 mW and 0.673 mW at wind speeds of 5.22 m/s and 8.0 m/s, respectively.

Wind-Induced Buffeting Vibration of Long-Span Bridge Considering Geometric and Aerodynamic Nonlinearity Based on Reduced-Order Modeling

Wind-Induced Buffeting Vibration of Long-Span Bridge Considering Geometric and Aerodynamic Nonlinearity Based on Reduced-Order Modeling

Wind-Induced Vibrations and Gust Response Factors of the Cabin–Cable–Tower System

A large-scale radio astronomical telescope is a typical complex coupled system, consisting of a feed cabin, cables, and supporting structures. The system is extremely sensitive to wind loads, especially the feed cabin, which has high requirements for vibration displacement during operation, and excessive vibration may affect normal operation. To investigate the wind-induced vibration characteristics of such coupled systems, this study takes the Five-hundred-meter Aperture Spherical Radio Telescope (FAST) as an example to conduct research. First, a refined finite element model of FAST is established, and a dynamic analysis using simulated random wind loads is conducted. The influence of the cable boundary on the time–frequency domain responses of the feed cabin is particularly considered. Then, the gust response factor (GRF) for different structural components within the coupled system is calculated. Finally, the evolution law of the GRF under various wind speeds and directions is revealed by parametric analysis. The parameter analysis only considers the wind directions ranging from 0° to 60°, because FAST is a symmetric structure. The results indicate that obvious differences are observed in both the rotational and translational displacements of the feed cabin under northward wind, especially the results along the east–west axis. When the supporting towers are considered, there is no change in the power spectral density (PSD) of the feed cabin in the low-frequency range. However, in the high-frequency range, taking the supporting towers into account leads to an increase in PSD and a resonance near the first-order natural frequency of the supporting tower. The GRF based on the dynamic response exhibits substantial deviations compared to those obtained from design codes, highlighting the need for an independent analysis when determining GRF for such coupled systems.

Aerodynamic interference mechanism of vertical vortex-induced vibration of a ∏-shaped girder paralleled with a truss girder

In this study, the aerodynamic interference characteristics and mechanism of vertical vortex-induced vibration (VIV) of a ∏-shaped steel–concrete composite girder of a highway cable-stayed bridge and a steel truss girder of a railway cable-stayed bridge are investigated via experimental and numerical simulation methods, respectively. To this end, firstly, wind tunnel tests are conducted on section models with a geometry scale of 1:60, consisting of the ∏-shaped girder paralleled with truss girders to investigate their aerodynamic interference behaviors. Moreover, the fluid–structure interaction (FSI) approach based on dynamic mesh and user defined functions (UDF) is applied to study the wind-induced vibrations (WIV) of the single ∏-shaped girder and two parallel main decks for wind attack angle of 0°, respectively. Furthermore, the characteristics of vorticity, surface pressure, and vortex-induced force (VIF) distributions of the ∏-shaped girder and the truss girder are analyzed to investigate the aerodynamic interference mechanism. The results reveal that, the significant vertical vortex-induced vibrations (VIV) of the single ∏-shaped girder are observed, however, no obvious vertical VIV occurs for the single truss girder. Moreover, when the truss girder locates in the windward of the ∏-shaped girder, no obvious vertical VIV responses are observed. However, the ∏-shaped girder and the truss girder both exhibit significant vertical VIV responses for wind from the ∏-shaped girder side, and the maximum vertical VIV amplitude of the ∏-shaped girder is amplified by 32% compared with the single ∏-shaped girder. The vortices shed from the truss girder section disrupt the regular vortex shedding of the ∏-shaped girder section, thus suppressing the VIV of the ∏-shaped girder section. The WIV of the truss girder section is due to the forced vibration caused by the vortex impact of the dominant vortices shed from the ∏-shaped girder section. As the downstream flow field is blocked by the truss girder section, the scale and intensity of the dominant vortices is increased, leading to an amplification of the VIF and the VIV amplitude of the ∏-shaped girder section.

Physics guided wavelet convolutional neural network for wind-induced vibration modeling with application to structural dynamic reliability analysis

Deep neural network (NN) has become one of the common choices of surrogate model for reliability analysis of structural dynamic response under complex wind loads. However, the cost of data acquisition is usually prohibitive, making it hard for NN training to accurately replace the complex wind-structure coupled system using the limited data. In this work, a physics guided wavelet convolutional NN (PGwCNN) is regarded as surrogate model of a wind turbine tower (WinTT) and utilized for wind effects prediction. The law of dynamics is regarded as the prior knowledge and encoded in the NN, which can enhance the learning capability of the trained model. Then, the performance of the PGwCNN is demonstrated through the dynamic reliability analysis of a high and flexible WinTT using probability density evolution method (PDEM). What’s more, the L2 regularization and dropout layers are utilized to alleviate the overfitting issues. N-fold cross validation and grid search method are adopted to maximize the use of the limited training datasets. Results demonstrate that PGwCNN is capable to reach a compromise between efficiency and accuracy for predicting wind effects on the WinTT. In addition, the PGwCNN can effectively enhance the calculation efficiency of the reliability analysis.

Asymmetric and Cubic Nonlinear Energy Sink Inerters for Mitigating Wind-Induced Responses of High-Rise Buildings

Flexible high-rise buildings with low damping are prone to excessive vibration under strong wind loads. To explore a light-weight control device having desirable mitigation effects on responses and sound robustness against deviations in tuning parameters, the performance of two novel inerter-integrated nonlinear energy sinks (NESIs), i.e., asymmetric nonlinear energy sink inerter (Asym NESI) and cubic NESI, on wind-induced vibration control of super high-rise buildings is assessed in the present work. Based on the wind loads obtained from wind tunnel tests, a super high-rise building with a 300 m height is taken as the host structure in the numerical case study. The results show that Asym NESI can achieve reduction ratios of 38.5% and 11.3% on extreme acceleration and displacement, respectively, while the sensitivity indices of Asym NESI on displacement and acceleration control are only 70.5% and 62.5% of those of tuned mass damper inerter (TMDI) having identical mitigation effects. Although the sensitivity indices of cubic NESI are only 5.5% and 29.8% of those of TMDI, the moderate mitigation effects and large nonlinear stiffness ratio may prohibit its practical implementation. Overall, Asym NESI could be an alternative to TMDI due to the same mitigation effects but better robustness against possible detuning.

State-of-the-art review of micro to small-scale wind energy harvesting technologies for building integration

The utilisation of wind power in buildings has gained significant interest, but deploying wind turbines in built environments presents unique challenges due to highly turbulent wind patterns. Existing small wind turbines may not be as efficient in such complex conditions, and their transient loads and vibrations can compromise their durability. This study aims to assess the recent status, challenges, and limitations of building-integrated wind turbines and micro or small-scale wind-induced vibration technologies to enhance their performance, efficiency, reliability, and cost-effectiveness. The research evaluates advancements, applications, and technical features that optimise these technologies to function effectively in non-uniform wind flows and a wide range of wind speeds. Modeling conventional systems, including horizontal axis and vertical axis wind turbines, is well-established using computational fluid dynamics and blade element momentum methods. Micro or small-scale wind-induced vibration technologies have demonstrated power outputs ranging from milliwatts to kilowatts, making them suitable for powering actuators and low-powered sensors used in buildings. The study emphasises the importance of harnessing wind velocity acceleration induced by the building's roof shape when incorporating wind energy harvesting technologies. Nevertheless, research on wind-induced vibration harvesting primarily takes place in controlled environments, neglecting the influence of real buildings. This represents a significant research gap, considering the potential for wind-induced vibration technologies to provide power to off-grid communities and facilitate building integration. The lack of comprehensive analysis concerning the energy, economic, and environmental aspects of micro-energy harvesting technologies hinder their widespread adoption and a comprehensive understanding of their potential. Addressing these research gaps is essential to promote the implementation and efficacy of micro-scale wind energy harvesting technologies in various real-world scenarios.

Dynamic modeling and analysis of hanger cables with spacers and dampers for vibration mitigation

Many suspension bridges are designed with hangers composed of pairs of cables. The hanger cables are featured by low fundamental frequencies and extremely low inherent damping, and thus subjected to various wind-induced vibrations, typically including wake-induced and vortex-induced vibrations. Spacers are required to connect the cables for suppressing wake-induced vibrations, which nevertheless provide nearly no additional damping. Damping devices are also required to suppress other types of vibrations, e.g., vortex-induced vibrations. A combination of spacers and dampers for vibration mitigation of hanger cables leads to a complex dynamic system. This paper focuses on modeling dynamic behaviors of such a system. A generalized and dimensionless numerical model is first established. Parametric analysis is then conducted to investigate the influences of spacers and dampers on system frequency and damping. It is found that equally distributed spacers with a dimensionless stiffness coefficient larger than 102 can be considered as rigid and further increasing stiffness cannot increase the system frequencies but leads to increased number of localized modes. A combination of near-anchorage dampers and viscoelastic spacers can provide adequate damping to both in-phase and out-of-phase cable vibrations. Variation in tension, mass and length ratios of the two cables is not effective in improving damping provided by viscoelastic spacers to in-phase vibrations.