Semi-active Damper System Research Articles

Generalization and optimization of switching controller to control free vibration of a multi-linear state space system

This paper studies the optimized quadratic integral of a generalized multi-linear state space system under free vibration. The general formulation of the optimization problem is presented and can be solved by the standard numerical procedure. For demonstration, two examples are examined thoroughly and analytically. First, the minimized integral of mechanical energy for a single-dof semi-active damping or stiffness controlled system are shown analytically and compared with the best active and passive ones. The Pontryagin Maximum Principle is used to prove the true optimality of the presented semi-active damping control. The Linear Quadratic Regulator on/off or continuous clipping controller is shown to be truly optimized in the first example. In the second example, the maximized dissipation energy of the single-dof on-off damping system is studied and verified by a sensorless experiment.

Experimental Evaluation of Modified Groundhook Car Suspension with Fast Magnetorheological Damper

The car suspension setting is always a trade-off between comfort and handling. The semi-active damper system seems to be an option for reducing the compromise between the two demands. This paper deals with the effect of the magnetorheological damper setting on a car’s suspension performance, especially tire grip, which was directly measured. A unique test rig was developed, and an experimental trolley with a fast magnetorheological damper (response time of 3 µs) was used in the paper. The damper was controlled by a modified Groundhook algorithm. Compared with the passive regime, the experiments showed a 30% improvement when using the Groundhook algorithm and when the damper was adequately set. The experiments proved the trends that were set by simulations.

Lightweight semi-actively damped high performance milling tool

Long cantilevered high performance milling tools tend to vibrate during machining operation due to process excitation. This impairs the quality of the workpiece surface and limits the achievable material removal rate. An optimisation of the dynamic properties of these tools enables an increased machining performance. This paper introduces a lightweight design of a shell end milling tool with an integrated semi-active damping system based on magnetorheological fluids. The investigations show that this approach allows an adjustment of the dynamic behaviour of the tool. In machining experiments a significant increase of the material removal rates and improved surface quality are achieved.

Multi-objective optimization design for a magnetorheological damper

As one of the most important components in the semi-active damping system, the performance of MR damper directly determines the damping capacity of the damping system. In order to make the damping system has excellent damping effect, it is necessary to optimize the working performance of the MR damper. Therefore, Non-Dominated Sorting Genetic Algorithm version II (NSGA-II) was applied to optimize the structure of MR dampers in this paper. Firstly, the structural scheme of MR damper was proposed. Secondly, the design principle of MR damper was described, and the magnetic circuit material and MR fluid were selected. Thirdly, taking the maximum dynamic range and the minimum number of turns of electromagnetic coil as the optimization objective, the structure of MR damper was optimized by NSGA-II. The structural parameters of MR damper were determined in the Pareto optimal solution set based on the principle of minimum mass. Finally, through the magnetic simulation and the performance testing of the MR damper, it was verified that the MR damper has reasonable magnetic circuit and excellent performance. And the design results meet the requirements. The proposed optimization method can provide a theoretical basis for the optimal design of related damping devices.

The functioning investigation of the network semi-active damping system for wheeled vehicle

The tasks related to the construction of a united semi-active system for damping vibrations of the supporting platform (chassis) of a wheeled vehicle (WV), taking into account the real road profile were considered. The influence estimation of the network on the functioning resulting quality of the entire united damping system is carried out. The modeling of the network united of the model of one wheelset, the possible law of control of the suspension, the central processor and the physical model of the CAN network by using the National Instruments equipment is performed. The results of the experiments, both purely mathematical and with a physical network model, showed the performance of the proposed solutions. Keywords CAN-tire; semi-active suspension system; identification; modeling

Smart-tuned liquid column damper for reducing structural vibrations in offshore structures

This paper describes the dynamic behaviour of offshore structures modelled as discrete dynamic systems with the installation of innovative smart-tuned liquid column dampers (TLCDs). The use of advanced nano-fluids enhances the mechanical properties of the TLCD and allows the conventional passive system to be modified into a semi-active damping system. The magnetic force is modelled as an additional non-linear stiffness applied on the main structure once the magnetic field is activated. This new approach brings novel perspectives in reducing structural vibrations with respect to conventional TLCD systems. The aim of the study is to present a numerical investigation of the parameters involved in the dynamic behaviour of these systems subjected to random forces. In particular, a comprehensive analysis of a simplified structural model as a two-degrees-of-freedom system is given. Mathematical details and procedures using magneto-rheological-TLCD dampers without the need for commercial frameworks are presented. The present coupled system of ordinary differential equations is solved in a Matlab environment by using the built-in Runge–Kutta implementations for the solution of non-linear equations. This allows engineers and designers to obtain an initial estimation of the structural behaviour prior to in-depth simulations and analysis.

Investigation of an off-road vehicle equipped with magnetorheological dampers

At present, owing predominantly to advances in measurement technology, microprocessor control and development of smart materials have witnessed a widespread adoption of semi-active damping systems ...

Performance-based design procedure of a novel friction-based cladding connection for blast mitigation

Cladding systems are conventionally designed to provide buildings with environmental protection against wind, temperature, humidity, moisture, etc. Recently, researchers have proposed to leverage these systems to provide additional protection against manmade (e.g., blast) and natural (e.g., earthquakes, hurricanes) hazards. This can be achieved, for example, by redesigning the connection between the cladding and the structural system to provide energy dissipation via friction. While promising, the use of flexible cladding connection has only been considered for singular hazards. In this study, the authors propose a novel semi-active damping system to connect the cladding to the structure via a variable friction mechanism. By varying the normal force applied on friction plates through a system of adjustable toggles, it is possible to mitigate vibrations over a wide frequency range, therefore enabling mitigation of different types of hazards (i.e. to achieve multi-hazard resistance). In its passive in-situ mode, the device is designed to provide very high stiffness and friction resistance to mitigate the effects of blast.The objective of this paper is to enable a holistic integration of said device within the structural design process by developing a performance-based design procedure. The study will focus on the passive in-situ mode of the device, which will provide a stepping stone for the development of performance-based design procedures for its semi-active (i.e. actuated) capabilities. The proposed performance-based design procedure consists of the following: 1) determine the design performance criteria, including the blast properties and allowable connection gap between the cladding and structure; 2) select design properties for the cladding connection, including stiffness and damping; and 3) design a rubber impact bumper located between the structure and the cladding in order to mitigate slamming of the cladding into the structure for very high blast loads.

Real-Time Variable Multidelay Controller for Multihazard Mitigation

AbstractHigh performance control systems (HPCS), including semiactive, active, and hybrid damping systems, are effective solutions to increase structural performance versus multihazard excitations....

Semi-active Outrigger Damping System for Seismic Protection of Building Structure

The outrigger structural system is one of the most widely used lateral load-resisting structural systems for high-rise buildings. To increase the energy dissipation capacity of the outrigger system, an outrigger damping system has been proposed as a novel energy dissipation system. In this system, the outrigger and perimeter columns are separate and vertical viscous dampers are equipped between the outrigger and perimeter columns. In this study, the control performance of a semi-active outrigger damping system for the seismic protection of a building structure was investigated. Semi-active damping devices, such as magnetorheological (MR) dampers instead of passive dampers, are installed vertically between the outrigger and perimeter columns to achieve large and adaptable energy dissipation. A fuzzy logic control algorithm was used to generate a command voltage sent to the semi-active MR dampers. A genetic algorithm was used to optimize the fuzzy logic controller. An artificial earthquake load was generated for the numerical simulation and a simplified numerical model of a damped outrigger system was developed. Numerical analyses showed that the semi-active damped outrigger system could effectively reduce both the displacement and acceleration responses of the tall buildings compared to a passive outrigger damper system.

Double-layer vibration suppression bilinear system featuring electro-rheological damper with optimal damping and semi-active control

Based on the analysis of a double-layer vibration suppression bilinear system, the limitation of the classic passive vibration suppression technology was solved in case of relatively complex input force mixed signals. Using the maximum value principle and the constrained gradient method, the optimal damping semi-active control (ODSAC) curve of this system model was obtained. Due to the strong nonlinear characteristics of the controlling curve and even a non-derivable problem being existed, a pulse function was introduced, and a theoretic deduction was performed. The defects, that a curve with non-derivable points could not be solved, were overcome so that the proposed method was applicable to a bilinear system model. The stability of the controller was discussed in detail. Finally, the effects of the vibration suppression of the ODSAC method were compared with that of the passive damping system and that of the semi-active skyhook damping system under the excitation of the mix signal of single-frequency sine and pulse input signal, the mix signal of random and sine signal, the mix signal of random and impact input signal. The experiments of electro-rheological fluid (ERF) damper with single damping duct and simulation results show that the ODSAC strategy of a double-layer vibration suppression bilinear system is the best of the five kinds of vibration suppression effect of control strategies, and the vibration reduction effect with respect to the random and shock input mixed signal is remarkable, the vibration suppression effect of the new method is satisfactory.

A new adaptive hybrid electromagnetic damper: modelling, optimization, and experiment

This paper presents the development of a new electromagnetic hybrid damper which provides regenerative adaptive damping force for various applications. Recently, the introduction of electromagnetic technologies to the damping systems has provided researchers with new opportunities for the realization of adaptive semi-active damping systems with the added benefit of energy recovery. In this research, a hybrid electromagnetic damper is proposed. The hybrid damper is configured to operate with viscous and electromagnetic subsystems. The viscous medium provides a bias and fail-safe damping force while the electromagnetic component adds adaptability and the capacity for regeneration to the hybrid design. The electromagnetic component is modeled and analyzed using analytical (lumped equivalent magnetic circuit) and electromagnetic finite element method (FEM) (COMSOL® software package) approaches. By implementing both modeling approaches, an optimization for the geometric aspects of the electromagnetic subsystem is obtained. Based on the proposed electromagnetic hybrid damping concept and the preliminary optimization solution, a prototype is designed and fabricated. A good agreement is observed between the experimental and FEM results for the magnetic field distribution and electromagnetic damping forces. These results validate the accuracy of the modeling approach and the preliminary optimization solution. An analytical model is also presented for viscous damping force, and is compared with experimental results The results show that the damper is able to produce damping coefficients of 1300 and 0–238 N s m−1 through the viscous and electromagnetic components, respectively.

Semiactive Friction Damper for Lightweight Pedestrian Bridges

In many cases, structural damping of lightweight structures is quite low. Therefore, additional damping systems have to be applied. These systems are, in most instances, passive ones. Concerning lightweight structures, live loads become decisive with respect to the eigenfrequencies of the system affected. Resultant changes in dynamic behavior lead to a loss of the optimal adjustment of the passive systems, which is often followed by disturbing vibrations. This in turn leads directly to an impairment of serviceability. Semiactive damping systems can solve these problems by actively reacting to changes of the system. The following article focusses on the development of a semiactive friction damper using piezoelectric stack actuators in order to reduce the vibrations of a large-scale model of a pedestrian bridge.

Reduction of wheel force variations with magnetorheological devices

At present, owing predominantly to advances in measurement technology and microprocessor control, development of a new generation of smart materials may lead to widespread adoption of semi-active damping systems into everyday life. An important class of such materials includes so-called “intelligent” magneto-rheological. A dominant feature of these materials is that their physical properties can be altered relatively easily under the influence of an external magnetic field. In this paper, a simplified model of a vehicle equipped with in-time controlled semi-active magneto-rheological suspension system is presented. Moreover, simple algorithms employed to control it are described and their efficacy studied by computer simulation and direct experiment. Torsional as well as reciprocating vibration magneto-rheological dampers (MRD) were used as in-time semi-active controls. In addition, a magneto-rheological rotary brake (MRB) was employed as a torsional vibration damper. As a result of direct experiments and simulations we were able to obtain characteristics of both devices showing dissipative features and relationship between model parameters. The main goal of this paper is to present methods for assessing the impact of changes in properties of MRD and MRB dampers for a reduction in variations in vertical wheel forces. These properties are controlled by demonstrated optimization algorithm responsible for an optimal selection of friction in magneto-rheological dampers. Also, an optimization criterion has been proposed. A control algorithm presented in this paper has been verified by means of conducting an extensive experimental investigation employing a Ford Transit van. Based on the results of our numerical and experimental studies it has been proved that through properties changes in MRD and MRB dampers it had been possible to reduce the variations in vertical wheel forces. Thus, an increase in the safety of the vehicle is possible.

A semi-active mass damping system for low- and mid-rise buildings

A semi-active mass damping (SMD) system with magnetorheological (MR) dampers focusing on low- and mid-rise buildings is proposed in this paper. The main purpose of this study is to integrate the reliable characteristics of the traditional tuned mass damper (TMD) and the superior performance of the active mass damper (AMD) to the new system. In addition, the commonly seen solution of deploying dense seismic dampers throughout the structure nowadays to protect the main structure is also expected to switch to the developed SMD system on the roof with a similar reduction performance. In order to demonstrate this concept, a full-size three-story steel building representing a typical mid-rise building was used as the benchmark structure to verify its performance in real life. A numerical model with the interpolation technique integrated was first established to accurately predict the behavior of the MR dampers. The success of the method was proven through a performance test of the designated MR damper used in this research. With the support of the MR damper model, a specific control algorithm using a continuous-optimal control concept was then developed to protect the main structure while the response of the semi-active mass damper is discarded. The theoretical analysis and the experimental verification from a shaking table test both demonstrated the superior mitigation ability of the method. The proposed SMD system has been demonstrated to be readily implemented in practice.

Measurement of mechanical and electrical energy flows in the semiactive piezoelectric shunt damping system

The analysis of the mechanical and electric energy flows in the semiactive vibration control system, which is made of a piezoelectric actuator shunted by a negative capacitor, is presented. The vibration control system is designed to suppress the vibration transmission in a narrow frequency range. Using a proper adjustment of the electronic circuit elements, the transmissibility of vibrations has been suppressed by 35 dB at the frequency of 1.5 kHz. The results of our measurements indicate that the average apparent electrical power in the electric part of the vibration control device is about 100 times larger than the mechanical power, which is supplied to the system from the source of vibrations. The rules for designing the highly efficient and low-power electronic parts of semiactive vibration control systems are discussed.

Vibration Isolation with Semi-Active Friction Damping

This study explores the effect of semi-active friction damping on vibration isolation systems by means of numerical simulation. Since the Lugre friction model can describe many phenomena observed in laboratories, it is chosen to provide accurate friction force model for the analysis and simulations. The drawback of the passive friction damping system is that it decreases the resonance response at the cost of worsening the performance for high frequencies. A semi-active control method (skyhook method) is used to tune the normal force so that the energy dissipated by the friction force is maximized. Such semi-active friction damping system is simple but efficient, and it can achieve result almost as good as that of active systems. Results from numerical simulations show that compared with passive system, semi-active control method decreases the response significantly for both low and high frequencies, with harmonic and random excitations.

Analysis of capability for semi-active or passive damping systems to achieve the performance of active control systems

Linear quadratic regulator (LQR)-based control force is composed of an elastic restoring force component and a damping force component. According to the analysis of the proportions of the elastic restoring force and the damping force to the total active control force, two indices are defined to quantify the damping characteristics and negative stiffness characteristics of an active control force. Because a semi-active damping system behaves like a damping device with adjustable parameters, these two indices can be used to quantify the capability of a semi-active damping system and a passive damping system achieving the performance of a fully active control system. Numerical studies are conducted to investigate the damping characteristics and negative stiffness characteristics of an active control force in an active control system. Semi-active damping systems and passive damping systems are designed to replace the active control systems and then the capability of the semi-active control and passive control achieving the performance of fully active control is further studied through the numerical study. Finally, the negative stiffness characteristics realized by semi-active magnetorheological (MR) damping systems are demonstrated through an in situ field test of a stay cable in the Binzhou Yellow River Highway Bridge. Copyright © 2010 John Wiley & Sons, Ltd.

Semi-active particle-based damping systems controlled by magnetic fields

This paper reports the design of a semi-active particle-based damping system in which a dry magnetic particle bed is used to dissipate the energy of a vibrating piston. The system is magnetized by a magnetic field generated by an electromagnetic coil. Hysteresis-free, ferromagnetic materials are selected for both the piston and particles. The damping efficiency increases as the magnetization of the piston and particles increases up to saturation. Semi-active control is achieved by varying the electric current supplied to the coil, which changes the magnetization and allows for real-time tunability of the damping rate. During the process of magnetization and demagnetization, the damping is reversible and temperature-independent over a wide temperature range. This system can be useful in aerospace, automobile and structural engineering applications, particularly in harsh environments.

Adaptive base-isolation of civil structures using variable amplification

Semi-active dampers are used in base-isolation to reduce the seismic response of civil engineering structures. In the present study, a new semi-active damping system using variable amplification will be investigated for adaptive base-isolation. It uses a novel variable amplification device (VAD) connected in series with a passive damper. The VAD is capable of producing multiple amplification factors, each corresponding to a different amplification state. Forces from the damper are amplified to the structure according to the current amplification state, which is selected via a semi-active control algorithm specifically tailored to the system’s unique damping characteristics. To demonstrate the effectiveness of the VAD-damper system for adaptive base-isolation, numerical simulations are conducted for three and seven-story base-isolated buildings subject to both far and near-field ground motions. The results indicate that the system can achieve significant reductions in response compared to the base-isolated buildings with no damper. The proposed system is also found to perform well compared to a typical semi-active damper.