Damping Of Dampers Research Articles

A self-sensing approach for estimating suspension displacement and velocity in semi-active electromagnetic dampers

Electromagnetic damper (EMD) suspension systems have gained significant recognition for their fast response and precise control capabilities. Nonetheless, the necessity of sensor-based control escalates system costs too high and limits its application. This paper introduces an innovative self-sensing approach for semi-active EMD that aims to autonomously acquire vehicle suspension state information without external sensors. The goal is to improve the performance of vibration damping while remaining cost-efficiency. Initially, the EMD is designed and modelled, followed by an analysis of the variable damping principle of the permanent magnet synchronous motor (PMSM). The variable damping EMD model is formulated using the machine-electric coupling equation. Subsequently, a detailed explanation of the principle behind the proposed self-sensing approach is presented. Simulation results confirm its precise capability to estimate the suspension displacement and velocity even in the absence of external sensor input. Moreover, bench experiments for the EMD are conducted to validate the effectiveness of the variable damping and self-sensing approach. Experimental results indicate that the damping characteristic of the EMD can be controlled by manipulating external resistance value. In addition, accurate estimation of suspension displacement and velocity can be achieved under varying excitation conditions, even with changes in damper damping.

Vibration Performance Analysis and Multi-Objective Optimization Design of a Tractor Scissor Seat Suspension System

The combination of characteristic parameters is the key and difficult point to improving the vibration attenuation of scissor seat suspension. This paper proposes a multi-objective optimization method based on entropy weight gray correlation to optimize the combination of characteristic parameters with better vibration attenuation. The differential equation of seat suspension motion is derived through mechanical analysis, and a simplified driver seat suspension single degree of freedom model is constructed. The range of spring stiffness and damper damping is calculated theoretically. Through main effect analysis and analysis of contribution, the main influencing factors of seat suspension vibration attenuation are studied, and the influence correlation of the main factors is analyzed. On this basis, the spring stiffness and damper damping are taken as control variables, and the upper plane acceleration, displacement, and transfer rate of the seat suspension are taken as optimization objectives. The Optimal Latin Hypercube Sampling (OLHS) was used to sample the Design of Experiments (DoE), fit the RBF surrogate model, and screen the optimal solution based on the MNSGA-II algorithm and entropy weight gray relation ranking method. The comparative analysis of the performance before and after optimization shows that the vibration reduction performance response indexes of the acceleration, displacement, and transmissibility of the optimized seats are increased by 66.41%, 2.31%, and 8.19%, respectively. The design and optimization method proposed in this study has a significant effect on the vibration reduction of seats, which provides a reference for the optimization of the vibration reduction performance of seat suspension.

GENETIC ALGORITHM OPTIMAL ARRANGEMENT OF POSITIVE AND NEGATIVE STIFFNESS DAMPERS FOR HYBRID DAMPING BASED ON SEISMIC WAVES METHOD

Increasing negative stiffness may lead to enhanced interlayer displacement. Therefore, the influence of many factors between pseudo-negative stiffness dampers and interlayer displacement should be analyzed. In order to reveal the qualitative relationship between hybrid damping and structural parameters, a novel method that optimizes the structural parameters of dampers based on based on seismic waves method with the help of MATLAB and the SAP2000 OAPI function platform is proposed. First, a negative stiffness damper was approximately simulated by the combination of a parallel damper unit and a multiline elastic unit, and the corresponding benchmark model was investigated. Second, the optimization program of structural damper damping based on a genetic algorithm was developed. Optimization analysis of the mixed damping of positive and negative stiffness dampers was conducted on the 20-story steel frame benchmark model. The damping of different stiffness was summarized on the basis of the analysis results, and the general arrangement principle of the device in the high-rise structure was discussed in the study. Finally, the hybrid damping was formed by the pseudo-negative stiffness damper and the traditional positive stiffness damper. The layout principle and vibration reduction effect of the hybrid damping were verified by experiments under MATLAB and the SAP2000 OAPI function platform. Results show that the top floor acceleration of the structure under the action of the El Centro wave and Kobe wave is reduced by approximately 15% when the pseudo-negative stiffness damper is used. Meanwhile, the displacement of the lower part of the structure is increased by only 5%. Furthermore, enhanced control results can be obtained by the different control strategies and a thorough analysis of the influencing factors used in layers 2–12 and 13–20. The proposed method provides references for optimizing the experimental platform construction and experimental evaluation of hybrid damping dampers. Keywords: Negative stiffness damper, Structural parameter damping, Interlayer displacement peak, Genetic algorithm, Parameter optimization

Dynamic Analysis and Optimization of the Planar Model of the Trolleybus Škoda 21Tr

The article deals about modelling, dynamic analysis and optimization of stiffness and damping parameters of the main suspension of the Skoda 21Tr trolleybus. The trolleybus is excited by a ride on a rough road modelled using the Shinozuka method with the specified spectral power density. After examining the impact of tire stiffness and damping on the effective values of driving comfort characteristics, dynamic tire-to-road forces, and relative displacements between sprung and unsprang mass, the effect of spring stiffness and damping of dampers in main suspension are investigated. After selecting appropriate optimization parameters, the stiffness and damping parameters of the main suspension are optimized using the MATLAB Optimization Toolbox. The objective function is the sum of the effective values of the suspension mass acceleration and its angular acceleration. The results are the improved driving comfort without increasing the dynamic forces between the tires and the road and the relative displacements between the sprung and unsprung masses.

Simulation of vertical characteristics and in-wheel motor vibration of electric vehicles with asymmetric suspension damper under road impact

For wheel-drive electric vehicles (WDEVs), it has become an urgent problem how to eliminate the adverse effects of the in-wheel motor on ride comfort and to reduce the road impact on the motor. The aim of this paper is to explore the effect rule of the suspension damper damping on the vertical characteristics and the motor vibration of WDEVs under road impact, so as to provide theoretical guidance for the design of WDEVs. Firstly, by considering the nonlinear damping characteristics of the damper, the nonlinear dynamic model of WDEVs is established. Secondly, according to the national standard GB/T 4970-2009, the triangular bump model is created and the evaluation indexes are introduced for WDEVs under road impact. Thirdly, through a case study, the evaluation indexes of a WDEV with different damper damping characteristics are numerically simulated and analyzed. Finally, the evaluation indexes are normalized and the comprehensive performance evaluation is carried out using a radar chart. The results show that under the triangular bump impact, the WDEV with the damper rebound damping less than the compression damping behaves better in terms of comprehensive performance, which is more favorable to avoid the motor damage.

Simulation of Nose Landing Gear Shimmy with Flexible Airframe Considered

Shimmy stability of the nose landing gear of an aircraft is studied in this paper. Firstly, Shimmy model was built considering the dynamic characteristics of the airframe. Then the critical damping, critical velocity and frequency range of the shimmy are obtained by introducing relevant parameters into the shimmy model. The research shows that the problem of shimmy is a tire type shimmy caused by insufficient damping of dampers and brings coupled resonance with the vibration mode of the airframe, which can be avoided by increasing the damping of the shimmy. At the same time, the influence of airframe dynamics and tire stiffness on the shimmy characteristics of the landing gear is also studied. With the increase of tire torsion and lateral stiffness, the critical velocity, maximum critical damping value and shimmy frequency of the landing gear increase. However, the elasticity of the airframe makes the frequency of the aircraft landing gear lower and the stable region of the shimmy smaller, so that the phenomenon of shimmy is more likely to occur. Therefore, the influence of airframe dynamic characteristics can not be ignored when studying the shimmy stability of the landing gear of a modern large passenger aircraft.

Seismic analysis of parallel structures coupled by lead extrusion dampers

In this paper, the response behaviors of two parallel structures coupled by Lead Extrusion Dampers (LED) under various earthquake ground motion excitations are investigated. The equation of motion for the two parallel, multi-degree-of-freedom (MDOF) structures connected by LEDs is formulated. To explore the viability of LED to control the responses, namely displacement, acceleration and shear force of parallel coupled structures, the numerical study is done in two parts: (1) two parallel MDOF structures connected with LEDs having same damper damping in all the dampers and (2) two parallel MDOF structures connected with LEDs having different damper damping. A parametric study is conducted to investigate the optimum damping of the dampers. Moreover, to limit the cost of the dampers, the study is conducted with only 50% of total dampers at optimal locations, instead of placing the dampers at all the floor level. Results show that LEDs connecting the parallel structures of different fundamental frequencies, the earthquake-induced responses of either structure can be effectively reduced. Further, it is not necessary to connect the two structures at all floors; however, lesser damper at appropriate locations can significantly reduce the earthquake response of the coupled system, thus reducing the cost of the dampers significantly.

A general solution for performance evaluation of a tall building with multiple damped and undamped outriggers

SummaryThis paper presents a general solution for performance evaluation of a tall building with multiple damped and undamped outriggers. First, general rotational stiffness (GRS) is proposed to model an outrigger that consists of the stiffness of perimeter columns and an outrigger connection and the damping of dampers in an outrigger. By utilizing the dynamic stiffness method, the GRS can be represented by complex stiffness in an outrigger element. To analyze the dynamic characteristics of a tall building with multiple outriggers, a dynamic transcendental equation is obtained from the combination of the GRS and dynamic stiffness method. The structural responses can be calculated through the Fourier transform based on this equation. Moreover, the GRS can also be blended into a finite element (FE) model to generate an augmented state‐space equation for the analysis of the dynamic characteristics and structural responses. Applications to various outriggers are illustrated. In the numerical analysis, good agreements are found between the GRS and the FE that validates the proposed method, and the performances of various outrigger systems are evaluated parametrically. As the results of a tall building with multiple damped or undamped outriggers, the proposed method is capable of providing an optimally parametric design with respect to the position of outriggers, damping, and core‐to‐column and core‐to‐outrigger stiffness ratio. Copyright © 2015 John Wiley & Sons, Ltd.

Particle swarm optimization of tuned mass dampers

Tuned mass dampers (TMD) have been widely used to attenuate undesirable vibrations in engineering. Most optimization problems of TMD are solved by either numerical iteration technique or conventional mathematical methods that require substantial gradient information. The selection of the starting values is very important to ensure convergence. In this paper, we use a novel evolutionary algorithm of particle swarm optimization (PSO) for optimization of the required parameters of a TMD. Optimum parameters of the TMD system attached to a viscously damped single degree-of-freedom main system are obtained by minimizing some response quantities, for examples, the mean square displacement responses and displacement amplitude of the main system under various combinations of different kinds of excitations. The excitations considered include external force and base acceleration modeled as Gaussian white-noise random processes. Harmonic base acceleration with frequency invariant amplitude is also considered. The PSO can be used to find the optimum mass ratio, damper damping and tuning frequency of the TMD system and can be easily programmed for practical engineering applications. Explicit expressions of the optimum TMD parameters are given for engineering designers.

Particle swarm optimization of TMD by non‐stationary base excitation during earthquake

AbstractThere are many traditional methods to find the optimum parameters of a tuned mass damper (TMD) subject to stationary base excitations. It is very difficult to obtain the optimum parameters of a TMD subject to non‐stationary base excitations using these traditional optimization techniques. In this paper, by applying particle swarm optimization (PSO) algorithm as a novel evolutionary algorithm, the optimum parameters including the optimum mass ratio, damper damping and tuning frequency of the TMD system attached to a viscously damped single‐degree‐of‐freedom main system subject to non‐stationary excitation can be obtained when taking either the displacement or the acceleration mean square response, as well as their combination, as the cost function. For simplicity of presentation, the non‐stationary excitation is modeled by an evolutionary stationary process in the paper. By means of three numerical examples for different types of non‐stationary ground acceleration models, the results indicate that PSO can be used to find the optimum mass ratio, damper damping and tuning frequency of the non‐stationary TMD system, and it is quite easy to be programmed for practical engineering applications. Copyright © 2008 John Wiley & Sons, Ltd.

Base-isolated building connected to adjacent building using viscous dampers

Seismic response of multi-storied base-isolated building on various isolation systems connected using viscous dampers to an adjacent dissimilar base-isolated or fixed-base building is investigated. The multi-storied buildings are modeled as a shear type structures with lateral degree-of-freedom at each floor, which are connected at different floor levels by the viscous dampers. Performance of this novel combination is studied by deriving the governing equations of motion and solving it in the incremental form using Newmark's step by-step method of integration. The variation of top floor absolute acceleration and bearing displacement under different real earthquake ground motions is computed to study the behavior and effectiveness of the connected systems. It is concluded that connecting the two adjacent base-isolated buildings with the viscous dampers is helpful in controlling large bearing displacement in the base-isolated structures; thereby, eliminating isolator damages arising due to instability at large displacement or pounding with adjacent structures during the earthquakes. Parametric studies are also performed to identify optimal parameters such as damper damping and distribution pattern of viscous dampers to achieve the maximum response reduction in the damper-linked adjacent buildings. The connection of viscous dampers to adjacent structures are found to be most effective when: (i) the adjacent base-isolated and fixed-base buildings are connected, (ii) dissimilar isolation systems are used for the two adjacent buildings, (iii) the time periods of adjacent structures are well separated, and (iv) the superstructure flexibility is higher.

Green's function of support‐excited structures with tuned‐mass dampers derived by A perturbation method

AbstractA tuned‐mass damper is a small damped spring‐mass system which vibrates in resonance with the main structure to which it is attached so as to be able to dissipate vibration energy and reduce the structural response. In this paper, explicit forms of Green's function for the transient response of main structures equipped with the tuned‐mass damper and subjected to support excitation are derived by perturbation techniques and provide an insight into the characteristics of the damper. It is found that there exists a critical damping level for the tuned‐mass damper. If the damper damping is higher than this critical damping level, increasing the damper damping will enhance the structural response. When the damper damping is below this critical value, something called ‘beat phenomenon’ occurs where the structure will have a smaller response in the first beat cycle, but have a higher rebound in the following beat cycles.