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A conventional variable universe fuzzy proportional–integral–derivative control approach is widely used for semi-active control in mechanical engineering. The performance of the controller is dependent on an optimal selection of parameters of the contracting–expanding factors. An improved variable universe fuzzy proportional–integral–derivative control algorithm is developed in this study where these parameters are automatically determined in real-time according to the error in the controlled responses and its change rate based on fuzzy logic control. The proposed method is numerically and experimentally illustrated with a three-story frame structure with a magnetorheological damper. The amplitude of displacement, velocity, and acceleration at all floor levels under the proposed control method are smaller than those obtained from existing proportional–integral–derivative, fuzzy, and conventional variable universe fuzzy methods.

The purpose of this study is to examine the vibration characteristics of a rotating blade whose material distribution varies in the spanwise direction. Formulations for functionally graded materials and beam structural models are carried out in detail and the results are displayed in several figures and tables which is a significant source of information for the authors working in this area. Different parameters such as angular speed, radius of the hub, material properties, power law index parameter, boundary conditions and slenderness ratio are considered in the formulation. Finite Element Method where the element matrices are obtained from potential and kinetic energy expressions is applied as the solution procedure. The calculated results are demonstrated in various tables and figures where it is observed that there is a good agreement with literature.

A large proportion of the fluctuating propulsion forces transmit to the hull structure of an underwater vehicle through the stern support and cause structural vibration and sound radiation. To reduce the influence of the dynamic forces on the hull structure, a control method that uses an active orthogonal support is proposed. The active orthogonal support is arranged in the vertical and horizontal directions to connect the stern bearing and the hull structure and equipped with electromagnetic actuators to generate counter forces. A shaft–hull-coupled system is used to investigate the effectiveness of active orthogonal support, and numerical results indicate that the hull vibration and acoustic radiation can be significantly suppressed. The effectiveness of active orthogonal support was experimented as well. The experimental results have demonstrated that the active orthogonal support with local velocity feedback control is able to attenuate vibration transmission in the shaft–hull-coupled system.

To date, considerable attention has been paid to the development of structural vibration suppression techniques. Among all vibration suppression devices and techniques, the tuned mass damper is one of the most promising technologies due to its mechanical simplicity, cost-effectiveness, and reliable operation. In this article, a critical review of the structural vibration suppression using tuned mass damper technology will be presented mainly focused on the following four categories: (1) tuned mass damper technology and its modifications, (2) tuned mass damper technology in discrete and continuous structures (mathematical modeling), (3) optimization procedure to obtain the optimally designed tuned mass damper system, and (4) active tuned mass damper and semi-active tuned mass damper with the practical realization of the tuned mass damper technologies.

This article introduces the basic principles of four kinds of inerters applied for structural vibration control including a traditional inertial mass damper and ideal clutch inerter damper. The clutch inerter damper with all damping (clutch inerter damper_all damped) and clutch inerter damper with partial damping (clutch inerter damper_part damped) are distinguished in detail. First, a series of energy indexes are defined for further analysis. Second, the control effect of displacement for the uncontrolled structure and the four inerter-based single-degree-of-freedom systems are compared. Finally, considering the total input energy ( E1) and the invalid damping energy ( ECID_ric) as the effective indexes, combined with a large number of numerical simulation results, the variation rules of the two energy indexes with respect to two key parameters (inertia mass ratio and additional damping) are summarized, and the optimal parameters are proposed. The effectiveness of the optimal value is verified by displacement comparison.

Tubular structural systems appear in many industrial applications, such as heating, ventilation, and air conditioning systems, which are responsible for making any enclosed environment remain within a temperature, humidity, and cleanliness range. This kind of system has its applications in the internal environmental comfort of industrial spaces, buildings, and vehicles. Several of these spaces have industrial processes that generate high sound frequencies and mechanical vibrations that need to be adequately controlled to meet both environmental and health norms. With the intention to analyze the structural vibration of tubular systems, the modal analysis technique is a classical methodology for the extraction of natural frequencies and vibration modes. Among the various techniques of modal analysis, numerical methodologies such as the finite element method, and also analytical methodologies such as the Component Mode Synthesis (CMS) can be found. CMS is one of the leading modeling tools for complex systems that are applied to large systems. The method uses a modal superset and consists of separately modeling individual components of a structure and coupling them into a single system. The objective of this work is to demonstrate the application of the CMS technique through the estimation of natural frequencies and vibration modes in a simplified tubular structural system formed by two substructures, using MATLAB and ANSYS. The validation of the results was done through numerical modeling using the finite element method using and ANSYS software. The results obtained were satisfactory, thus demonstrating the feasibility of applying the CMS technique to an analysis of structural vibration in tubular structural systems.

In this article, the effects of damage (delamination) on the structural vibration characteristics of spar wingskin joints (SWJs) made with curved laminated composites are investigated. Three dimens...

Vibration at the stern area is generally the most severe of the entire ship hull, which has always attracted special attention by ship designers and researchers. With reference to a real ship structural layout, a scaled stern model of steel structure was innovatively designed to carry out the mode and response tests. Corresponding finite element (FE) model representing the tested structure was established for verification of commonly-used calculation methods of modal parameters and response. Good agreement between experimental and numerical results demonstrates the credibility of FE method, and some key points of modeling and calculating are discussed. In addition, with the combination of the experiment and calculation, some vibration characteristics of ship stern structure are summarized for future ship design guideline.

This paper proposes a low-cost and efficient piezoelectric tuned mass damper (Piezo-TMD) for structural vibration reduction and energy harvesting. The Piezo-TMD consists of not only a proof mass, piezoelectric materials deforming in the d33 mode, and an electrical resistance, but also a spring and an inductor which enable the mechanical frequency and electrical frequency of the Piezo-TMD to be tuned to the structural resonance frequency. The equations of motion of a structure with the Piezo-TMD are derived, and an optimal design procedure for the Piezo-TMD is proposed to achieve a simultaneous maximum vibration reduction and energy harvesting. The performance of the Piezo-TMD is compared with that of a conventional optimal TMD installed in a footbridge under a pedestrian loading. The simulation results show that the Piezo-TMD performs better than the optimal conventional TMD in terms of vibration reduction while efficiently converting the absorbed mechanical energy to electricity with a high energy harvesting ratio. The innovative development of simultaneously tuning the mechanical and electrical systems leads to a much lower number of PZT stacks (saving 88% of piezoelectric materials in an illustrated case). The parametric study shows that the Piezo-TMD achieves the best performance when the optimal values for the spring stiffness, resistance, inductance, and the number of piezoelectric stacks are adopted from the proposed optimal design. If the selected spring stiffness and inductance are uncertain in a range between 0.94-1.07 times the optimal values, the vibration reduction performance of the Piezo-TMD remains similar, and the energy harvesting performance reduces less than 5%, as compared to the optimal performance. The effect of the number of piezoelectric stacks was also investigated. An insufficient number of piezoelectric stacks reduces the Piezo-TMD performance, and an excessive stack number does not improve the Piezo-TMD performance but increases the Piezo-TMD cost. Finally, the proposed Piezo-TMD employs inductance to significantly reduce the PZT stack number, thereby significantly reducing the cost of Piezo-TMDs.

The hedge algebras theory has the potential to make significant applications in the field of computational intelligence. The purpose of the present study is to improve the control performance of the hedge algebras–based controller by tuning its control rules and apply the hedge algebras–based controller using the tuned rule base in vibration control of structures. The authors propose a “tuning coefficient” to express the impact of each rule of the controller in the control process. These control rules are adjusted by optimizing the above tuning coefficient. The tuned controller is then used to reduce the dynamic response of structures subjected to different excitations. The adjusted rule base is more appropriate for the model to be controlled, and it allows enhancing the control performance of the system. The proposed approach is uncomplicated and transparent, and it allows preserving the monotonous feature of the rule base.

This article presents the use of the analytic signal procedure for processing the large volume of structural vibration data recorded in forced vibration tests. The analytic signal facilitates the computationally laborious task of extracting the steady-state amplitude for each response measure of interest from the recorded accelerations throughout the building at each operated frequency of the forced vibration source. The implementation of the signal processing procedure introduced here is illustrated in deriving the acceleration–frequency response curves from the forced vibration test of the first permanently instrumented building in Turkey. This reinforced concrete building, subsequently strengthened with cast-in-place reinforced concrete infill shear walls, is located in close proximity to the North Anatolian Fault. Later, system identification of the building yields the in situ structural system dynamic properties for the first translational and torsional vibration modes, which are compared with those identified from the ambient vibrations of the building recorded following its forced vibration test. The analytic signal procedure is a convenient tool for the rapid and correct derivation for mode shapes and associated frequencies and damping ratios from forced vibration testing of structural systems.

Smart homes of the future are envisioned to have the ability to recognize many types of home activities such as running a washing machine, flushing the toilet, and using a microwave. In this paper, we present a new sensing technology, VibroSense, which is able to recognize 18 different types of activities throughout a house by observing structural vibration patterns on a wall or ceiling using a laser Doppler vibrometer. The received vibration data is processed and sent to a deep neural network which is trained to distinguish between 18 activities. We conducted a system evaluation, where we collected data of 18 home activities in 5 different houses for 2 days in each house. The results demonstrated that our system can recognize 18 home activities with an average accuracy of up to 96.6%. After re-setup of the device on the second day, the average recognition accuracy decreased to 89.4%. We also conducted follow-up experiments, where we evaluated VibroSense under various scenarios to simulate real-world conditions. These included simulating online recognition, differentiating between specific stages of a device's activity, and testing the effects of shifting the laser's position during re-setup. Based on these results, we discuss the opportunities and challenges of applying VibroSense in real-world applications.

Based on ANSYS finite element software and combined with the physical properties of piezoelectric materials, the actuating properties of the new piezoelectric ceramic tubular actuator was simulated. In addition, the maximum displacement, output and response frequency characteristics of the actuator were obtained. The results shown that the actuator was suitable for the development of structural vibration control device. The intelligent damper for adjusting friction in real-time was proposed by using the above-mentioned new actuator. In addition, the dynamic mechanical properties of the intelligent damper were analyzed, the constitutive relationship under the sinusoidal simple harmonic action and the calculation formula of the energy consumed in one cycle were obtained.

Since the structural vibration deformation of a large antenna under wind disturbance leads to the pointing deterioration, an adaptive anti-wind disturbance system was presented by Liang et al. (Int. J. Antennas Propag., Article ID 2015341, 2019). To further improve the vibration suppression performance, this paper presents a locations-optimization algorithm of multiple cable-drivers for the anti-wind disturbance system. First, according to the spatial geometric relationship among the antenna structure, single slide track, four cables and drivers, the feasible domain of the drivers is determined. Next, the separate optimization method, and the joint optimization method for the locations of the four drivers are proposed, respectively. Finally, the simulation implementation of a 7.3 m antenna under various wind conditions is used to compare the joint optimization method and the separate optimization method.

The tuned liquid damper (TLD) is an attractive option of passive structural vibration control due to distinct advantages of low installation and maintenance costs and easy amenability to design modifications. However, as it has low inherent damping, flow damping devices (FDDs) such as nets, screens, baffles, poles, floating objects, etc., are incorporated in the TLD to enhance its energy dissipation capacity. FDDs induce additional damping by providing hydraulic resistance to the sloshing liquid in the TLD. Each type of FDD has its own specific advantages and disadvantages and it would be beneficial to have a state-of-the-art comparative and comprehensive review of the work that has been carried out on different types of FDDs. This is the focus of the current paper. The present review would help in the assessment of the most suitable FDD for a particular TLD application. An overview of real implementations of TLD-FDD systems in various structures worldwide is provided. Directions of research for further development of FDDs are also identified.

This study investigates the effects of a submerged cylinder on the sloshing responses in a partially filled U-shaped container. The movable cylinder is placed at the horizontal portion of a...

Publisher Summary Structures subjected to dynamic loading, particularly aircraft, vibrate or oscillate in a frequently complex manner. An aircraft, for example, possesses an infinite number of natural or normal modes of vibration. Simplifying assumptions, such as breaking down the structure into a number of concentrated masses connected by weightless beams (lumped mass concept), are made, but whatever method is employed, the natural modes and frequencies of vibration of a structure must be known before flutter speeds and frequencies can be found. This chapter concentrates on the calculation of the normal modes and frequencies of vibration of a variety of beam and mass systems. The determination of natural frequencies and normal mode shapes for beams of non-uniform section involves the solution and fulfillment of the appropriate boundary conditions. However, with the exception of a few special cases, such solutions do not exist and the natural frequencies are obtained by approximate methods, such as the Rayleigh and Rayleigh–Ritz methods.

Continuous structures such as beams, rods and plates can be modelled by discrete mass and stiffness parameters and analysed as multi-degree-of-freedom systems. The analysis of structural vibration is necessary to obtain the natural frequencies of a structure and the response to the external excitation. In this way, it can be determined whether a particular structure will fulfil its intended function and, in addition, the results of the dynamic loadings acting on a structure can be predicted. The lack of a sober analytical research about the vibrational behaviour of the 5-MW wind turbine blade pushed us to investigate about this crucial issue, however, most of the discreet researches are concerned with the aerodynamic effects rather than structural analysis. In this article, Rayleigh–Ritz method was implemented for a typical 5-MW wind turbine blade. MATLAB codes were developed and natural frequencies were obtained for both flapwise and edgewise vibrational behaviour. A good agreement was observed between the analytical results and the manufacturer results.

The purpose of this numerical research is to study a derrick crane under repeated loads. The numerical analyses were carried out considering two different geometrical crane configurations, and two different rope lengths. After a preliminary analysis in order to evaluate both static and dynamic (modal) crane performance, many different analyses were carried out applying different load sequences. These actions were characterized by several impulse loads, which can be applied during the crane active use. Two parameters characterize the impulse load, i.e. the impulse duration and the delay between two successive actions. This load condition, which is not present in the crane design standards, was experimentally checked during the machine use in the marble quarry where it was installed. The results show that in specific crane configurations, characterized by the main arm position and the rope length and with a specific load sequences, both the vibration and the displacement magnitude increase in time, inducing high stress value in the crane components that can collapse the crane itself.