Damped Systems Research Articles

EXTENSION OF HAMILTONIAN MECHANICS TO NON-CONSERVATIVE SYSTEMS VIA HIGHER-ORDER DYNAMICS

Abstract This paper presents a detailed review of the emerging topic of higher-order dynamics and their intrinsic variational structure, which has enabled—for the very first time in history—the general application of Hamiltonian formalism to non-conservative systems. Here the general theory is presented alongside several interesting applications that have been discovered to date. These include the direct modal analysis of non-proportionally damped dynamical systems, a new and more efficient algorithm for computing the resonant frequencies of damped systems with many degrees of freedom, and a canonical Hamiltonian formulation of the Navier-Stokes problem. A significant merit of the Hamiltonian formalism is that it leads to the transformation theory of Hamilton and Jacobi, and specifically the Hamilton-Jacobi equation, which reduces even the most complicated of problems to the search for a single scalar function (or functional, for problems in continuum mechanics). With the extension of the Hamiltonian framework to non-conservative systems, now every problem in classical mechanics can be reduced to the search for a single scalar. This discovery provides abundant opportunities for further research, and here we list just a few potential ideas. Indeed, the present authors believe there may be many more applications of higher-order dynamics waiting to be discovered.

Analysis Comparison of PSMEID With Preview for Controlling Shock Vibration of UAV’s Landing Gear System

Semi-active dampers reduce the effects of shock vibrations because they can operate at specific vibration frequencies at a lower cost than more complex active dampers. PSMEID is one of the alternative methods developed in the semi-active damping system. PSMEID has been developed by adapting it by adding a PSMEID active time prediction system when an impact occurs. This research attempts to compare two types of PSMEID with active time prediction, where the position of each model offered has a different PSMEID mass position when applied to the landing gear damper of an Unmanned Aerial Vehicle (UAV). This comparison aims to give the user a choice among these optimal models suitable for use in multiple conditions. When simulated using the same parameter values, the PSMEID placed on the unsprung mass can reduce acceleration amplitude by up to 6.6 percent when the landing gear is dropped at 0.15 meters from the ground. The model that places the PSMEID on the sprung mass can help reduce the velocity amplitude up to 8.8 percent when dropped at a height of 0.05 meters, and the spring constant value of the PSMEID (KPS) is 1600 N/m. All these simulations show that the PSMEID should be activated just before the landing gear hits the runway surface (TB < TL).

A fractional adaptive type-2 fuzzy structural control system: Theoretical/experimental study

A new modified sliding mode control (SMC) method based on type-2 fuzzy neural networks (T2FNNs) is introduced for the active mass damper (AMD) systems. An adaptive T2FNN is used in the switching part, and another adaptive T2FNN is used to estimate the uncertainty of the AMD system. T2FNNs are adopted to predict the system’s uncertainties and establish a dynamic model of the AMD system, independent of the mathematical model. The chattering phenomenon is also taken into account and analyzed. The stability is studied by using the Lyapunov approach to derive training rules for both T2FNNs in dynamic modeling and switching part. Numerical simulation and experimental verifications confirm the feasibility and effectiveness of the designed T2FNN based SMC. The results reveal that the designed controller outperforms the conventional controllers in reducing the vibration peak and reducing the root mean square (RMS) value of structural displacement and acceleration. It also exhibits good robustness against external disturbances and structural dynamic perturbations. The suggested algorithm combines the advantages of adaptive control and fuzzy logic, addressing the issue of chattering in control and overcoming the lack of self-learning capability in conventional SMCs.

Design of toothed belt driven screw vacuum pumps

Abstract Most screw vacuum pumps use oil-lubricated gears for timing of the rotors. An alternative is a toothed belt to drive and synchronise the screw rotors. In combination with grease-lubricated bearings this drive concept allows the design of completely oil-free pumps. However, belts are less accurate in terms of timing, hence the design of efficient pumps is challenging. In this paper, the development of a new series of belt driven dry screw vacuum pumps is discussed. It covers the overall pump concept including cooling system, material selection and noise damping. Particular attention is paid to the design of the screw rotors with respect to the properties of the belt drive. It is shown that the disadvantage of the inaccurate timing and the need for wide rotor to rotor clearance can be overcome with a high number of wraps. Furthermore, it gives insight to applications and practical field experience.

Vibration isolation performance analysis of laminated double-layer rectangular plate structure

Based on the spectral geometry method, the analytical model of laminated double-layer rectangular plate including elastic floating raft damping system is established. The artificial virtual technology is used to simulate the elastic boundary conditions of the laminated deck, and the three-dimensional damping isolator and elastic raft plate are used to simulate the floating raft damping system. Based on energy principle, the solution equation of vibration characteristics of laminated double-layer rectangular plate system is obtained by Rayleigh Ritz method. Compared these results with finite element method, the reliability of the model is verified. Then the effects of different parameters on the dynamic characteristics of double plate structure are further discussed.

Optimum Design of Hybrid Base Isolation and Tuned Liquid Damper Systems for Structures under Near-Fault Ground Motions

Optimum Design of Hybrid Base Isolation and Tuned Liquid Damper Systems for Structures under Near-Fault Ground Motions

Power quality enhancement using fully informed particle swarm optimization based DSTATCOM in distribution systems

To compensate for the reactive power, inverter-based conditioners have been utilized in recent years due to their faster response. Distribution static synchronous compensator (DSTATCOM) has been utilized to enhance power quality in power system that is an inverter-based device that is widely utilized. To control this type of equipment, a proportional integrated (PI) controller has been utilized to control most of the equipment with respect to certain parameters. The performance of the controller basically does not meet the expectations because of the dynamics and nonlinearity of a system parameters. In this present paper, a probabilistic neural network has been used in a controller with a fully informed particle swarm optimization (FIPSO) algorithm to generate a suitable weight for controlling the axes of various parameters of DSTATCOMs. Using MATLAB/Simulink software, simulations were performed, and the responses were monitored with particular regard to the reference reactive parameter. The results are compared. DSTATCOM improves power system damping.

Seismic Design Study of a Supertall Damped Braced Tube System: Torch Tower

Seismic Design Study of a Supertall Damped Braced Tube System: Torch Tower

A dual-phase strategy for oscillation damping in power systems: transitioning from traditional stabilizers to solar farms using PSSE and PSCAD

A dual-phase strategy for oscillation damping in power systems: transitioning from traditional stabilizers to solar farms using PSSE and PSCAD

Research on the sensing properties and vibration reduction performance of self-sensing self-tuning magnetic fluid damper

Abstract The semi-active control damping system has gained popularity due to its quick response time and versatility. However, external sensors are susceptible to environmental interference, affecting system reliability and increasing complexity and maintenance costs, restricting their use. To address this, a self-sensing self-tuning magnetic fluid damper (SSMFD) is proposed. The vibration-measuring induction coil is wound on the damper to sense the magnetic fluid vibration information in real time, and the vibration signal is communicated to the self-tuning control circuit. The control circuit calculates and determines the dominant frequency of structural vibration, then outputs the relevant current signal to set the damper’s natural frequency to track the excitation frequency, resulting in self-tuning vibration reduction. First, the self-sensing unit’s output induced electromotive force model is created, followed by an expression of the damper’s natural frequency, indicating that the self-sensing unit can achieve self-tuning vibration reduction by tracking the excitation frequency. The multi-field coupling simulation model of the magnetic fluid damper is generated, and the induction coil coupling mode and damper excitation angle are defined to obtain the maximum induced voltage. Finally, an experimental platform was developed to assess the damper’s self-sensing and self-tuning vibration reduction performance. The experimental results show that the proposed SSMFD performs well, making it a feasible solution for achieving self-sensing and self-tuning vibration reduction.

Investigating Lateral Behavior of the Hybrid System of Flat Steel Shear Walls and Cold-Formed S-shaped Steel Plate Dampers Under Cyclic Loading

Investigating Lateral Behavior of the Hybrid System of Flat Steel Shear Walls and Cold-Formed S-shaped Steel Plate Dampers Under Cyclic Loading

Spin wave linear response of three-dimensional structures calculated in the frequency domain

A theory is presented for calculating the spin wave response of a three-dimensional damped magnetic system to an external excitation, in the frequency domain. The equation of motion, written in the Hamiltonian formalism, is discretized within a finite-element method, and the corresponding large system of equations is first linearized and then solved with well-established techniques of linear algebra, leading directly to the spectral response. This approach is therefore particularly suitable for interpreting the results of all-electric microwave measurements of magnonic crystals. The response of a three-dimensional structure, composed of a portion of a square array of circular dots placed in close proximity of a magnetic substrate, is then investigated. A prominent, narrow feature with a large rejection ratio is observed in the spin wave transmission spectrum, making this structure useful as a narrowband notch filter.

Analytical method for random seismic response of structures with tuned parallel inerter mass system and optimal parameters based on reliability

Tuned parallel inerter mass system (TPIMS) composed of tuned mass damper (TMD) and series parallel inerter-Ⅱ system has excellent damping performance. Earthquake action on structures has typical randomness, however the existing methods for outputs of structures with TPIMS only are numerical. In the work, an analytical method for calculating outputs and a globe method for optimizing TPIMS’s parameters was presented. Firstly, using dynamic finite element technique, the general dynamic equation of high-rise structures with TPIMS was established. Secondly, using quadratic decomposition method, the concise unified analytical solutions of zero-, first- and second-order spectral moments (ZFS-OSMs) of structural absolute and interlayer displacement, the inerter’s force and TMD’s displacement were deduced. Finally, three examples were carried out to verify the proposed method, to study influence of number of real vibration modes and to demonstrate the method for optimizing TPIMS’s parameters, respectively. The results show that the quantity of real vibration modes of uncontrolled structures with a participation weight of 100 % has the characteristics of both accuracy and efficiency in output analysis and the proposed optimal method is global.

Investigation on influence factors of optically controlled electrorheological fluid damping system

Abstract Electromagnetic rheological damping control system, as an important control technology, has been widely used in braking, vibration reduction and micro-valve etc. However, the electromagnetic rheological damping control system faces issues of electromagnetic interference due to the high voltage source. To solve this problem, we proposed a novel optically controlled electrorheological fluid damping system. Previous studies have confirmed the feasibility of the optically controlled electrorheological fluid damping control system via numerical simulation and experiment. In this paper, the mechanism and mathematical model of the optically controlled electrorheological fluid damping system are established. The influence factor analyses of the optically controlled damping system, especially the impact of light intensity and microchannel size on system performance, are carried out through experimental and theoretical methods. The research findings of influence factors contribute to a deeper understanding of the working principle of the electrorheological fluid damping system, thereby promoting stability and reliability in microfluidics technology.

Utilizing tuned mass damper for reduction of seismic pounding between two adjacent buildings with different dynamic characteristics

Today, population growth and the need for constructing adjacent buildings have raised the likelihood of pounding between adjacent buildings with different dynamic characteristics. The pounding force applied to adjacent buildings during an earthquake is intensive and may cause total or partial damage to structural elements, leading to collapse. It disturbs and complicates the functioning of buildings during and after an earthquake. Therefore, the main aim of this paper is to minimize and, if possible, eliminate the pounding force between two adjacent structures by considering three objective functions. For this aim, the tuned mass damper is utilized here. Also, this paper aims to reduce the number of collisions between different stories of adjacent buildings through a tuned mass damper system. For this purpose, two adjacent steel moment frames with six and ten stories are nonlinearly modeled and validated using the concentrated plasticity model in OpenSees. Moreover, the pounding element is nonlinearly modeled and validated. Then, tuned mass dampers (TMDs) are used on the roofs of the structures. They are optimized in stiffness, mass, and damping coefficient using the grey wolf optimization (GWO) algorithm. Nonlinear time history analysis (NLTHA) is performed under nine far- and near-field earthquakes. The pounding force and structural responses are analyzed, including maximum story acceleration, maximum inter-story drift, and base shear in the TMD-controlled and uncontrolled adjacent buildings. Finally, the Park-Ang damage index is evaluated for the structures with and without the TMD system. It has been found that the maximum pounding force, the maximum acceleration of the stories, the base shear, the drift ratio, and the number of collisions significantly reduce (or omit) in the presence of TMDs when the objective function is considered to be the minimization of the maximum pounding force. It is shown that the maximum pounding force generally declines to zero for this objective function.

Experimental characterization of the acoustic response of cavity-backed perforated plates to control thermo-acoustic instabilities in gas turbines

Abstract Prediction and control of thermoacoustic instabilities is a major challenge in the development of modern power generation gas turbines and aeroengines. Such instabilities arise from the coupling between flame dynamics and combustor acoustic modes, resulting in severe oscillations that can lead to premature aging of combustor components and structural damage. In many combustors, passive dampers are implemented to increase the acoustic energy dissipation of the system and prevent the onset of these harmful flame-acoustic interactions. In the present study, passive damping systems based on a cavity-backed perforated plate are experimentally analyzed, with a focus on studying the impact of bias flow on the reflection coefficient over a wide range of frequencies. Tests are carried out on two cavity-backed perforated plates characterized by the same porosity but a different number of holes 25 and 49, namely P25 and P49, respectively. It is observed that, for a given plate geometry, a higher bias flow leads to an increase in the plates absorption capacity over a wider range of frequency. This is more pronounced in the P 49 plate configuration. For both tested configurations, comparing the experimental results with Scarpato model proposed in the literature [1], a good match it is observed only for low values of bias flow. The model instead is not able to correctly capture the behavior of the damping systems when higher dissipation is reached.

Research on Vibration Control of FAST Feed Cabin Based on Active Mass Damper

In this paper, an effective active vibration control method was investigated to further improve the positioning accuracy of the Five-hundred-meter Aperture Spherical radio Telescope (FAST) feed cabin. The actual operation data of FAST was collected to analyze the vibration characteristics of the feed cabin in multiple directions. A simplified model of the cabin-cable system was established to evaluate the effects of a mass damper on different vibration frequencies and modes. On this basis, an active mass damper system and control system were designed for the cabin with multiple degrees of freedom and modal variation characteristics. Theoretical calculation and simulation proved that it has a significant effect on improving the damping of the cabin-cable system and suppressing the vibration of the FAST feed cabin.

Cascade control method for hydraulic secondary regulation drive system based on adaptive robust control

The hydraulic secondary regulation drive system employs a hydraulic servo motor to achieve precise position tracking and zero throttling loss, but it faces challenges such as high inertia, low damping, and high system order, leading to suboptimal control accuracy. Traditional adaptive robust control methods struggle with the control challenges of such high-order systems. This paper introduces a cascaded control approach based on adaptive robust control to address these issues. A fifth-order model is developed to account for significant load inertia, dividing the system into inner and outer control loops. The outer loop applies adaptive robust control to handle uncertainties and load disturbances for accurate rotational position control, while the inner loop uses swashplate disturbance compensation robust control to manage torque disturbances and achieve precise displacement control. A cascaded Lyapunov function is designed to address the coupling effects between the errors of the inner and outer loop controllers, ensuring stability across both subsystems. Experimental results show that the proposed method’s position tracking accuracy exceeds that of cascade dual-PID control methods by 50% to 80% and traditional adaptive robust control methods by 30% to 40% under sinusoidal frequency commands of 0.1 Hz and 0.25 Hz.

A Novel Vertical Active Damping System for the Superconducting Electrodynamic Suspension

A Novel Vertical Active Damping System for the Superconducting Electrodynamic Suspension

Review Paper on Vibration Damping System Using Pendulum

Abstract: This paper explores the implementation and effectiveness of vibration damping systems utilizing pendulums, focusing on their ability to mitigate unwanted oscillations in various structures. Pendulum-based dampers operate on the principles of inertia and resonance, allowing them to counteract vibrations causedby dynamic loads, seismic events, and machinery operations. The study examines different configurations, including tuned mass dampers (TMDs) and nonlinear pendulum systems, highlighting their design, functionality,and specific applications in fields such as civil engineering, aerospace, and automotive industries. Through analytical modeling and experimental validation, the paper demonstrates the effectiveness of pendulum dampers in enhancing structural stability and occupant comfort. The results indicate significant reductions in vibration amplitude, showcasing the potential of these systems to improve the longevity andsafety of infrastructure. Furthermore, the discussion addresses the advantages of pendulum-based systems over conventional damping methods, emphasizing their adaptability and efficiency.In conclusion, this study underscores the importance of pendulum vibration damping systems as a viable solution for contemporary engineering challenges, paving the way for future research and development in vibration control technologies.