Experimental Dynamic Analysis of Magneto-Rheological Tuned Vibration Absorbers

2003 ◽  
Author(s):  
Jeong-Hoi Koo ◽  
Mehdi Ahmadian ◽  
Mehdi Setareh ◽  
Thomas M. Murray
Keyword(s):  
Active Control ◽  
Primary Structure ◽  
Control Policy ◽  
Vibration Absorbers ◽  
Control Policies ◽  
Output Displacement ◽  
Tuned Vibration Absorbers ◽  
Control Schemes ◽  
Displacement Based ◽  
Magneto Rheological

The primary purpose of this study is to experimentally evaluate the dynamics of a Magneto-Rheological Tuned Vibration Absorber (MR TVA) with several semi-active control schemes. A test rig was built to represent a two-degree of freedom primary structure model coupled with an MR TVA, and four semi-active control policies were considered. The four control policies include: velocity-based, on-off groundhook control (on-off VBG); velocity-based, continuous groundhook control (continuous VBG); displacement-based, on-off groundhook control (on-off DBG); and displacement-based, continuous groundhook control (continuous DBG). Using the test apparatus, a series of tests were conducted to investigate the dynamics of the MR TVA with each control policy. The performances of each of the cases were then analyzed along with the equivalent passive TVA. The performance index was the transmissibility between the input and the output displacement of the structure. The experimental results indicated that the MR TVA with all of the semi-active control policies, outperformed the passive TVA in reducing structural vibrations. Furthermore, the displacement-based groundhook control policies perform better in reducing the resonant vibrations of the primary structure than the velocity-based groundhook control schemes.

In Search of Suitable Control Methods for Semi-Active Tuned Vibration Absorbers

2004 ◽  
Vol 10 (2) ◽  
pp. 163-174 ◽  
Author(s):  
Jeong-Hoi Koo ◽  
Mehdi Ahmadian ◽  
Mehdi Setareh ◽  
Thomas Murray
Keyword(s):  
Control Method ◽  
Optimization Techniques ◽  
Structural Vibration ◽  
Design Parameters ◽  
Vibration Absorbers ◽  
Baseline Model ◽  
Control Policies ◽  
Tuned Vibration Absorbers ◽  
Active Peak ◽  
Displacement Based

The main purpose of this study is to identify a suitable control method for semi-active tuned vibration absorbers (TVAs) in structural vibration applications. Four control policies are considered. The semi-active control schemes include the following: velocity-based, on-off groundhook control (on-off VBG); velocity-based, continuous groundhook control (continuous VBG); displacement-based, on-off groundhook control (on-off DBG); and displacement-based, continuous groundhook control (continuous DBG). A force-excited model that can be representative of many structural systems is adapted as the baseline model for our analysis. Each of the control policies is applied to the baseline model coupled with a TVA. In order to equally evaluate the control policies, the TVA parameters are optimized according to each policy using numerical optimization techniques. The optimal design parameters are obtained based on minimization of peak transmissibility. The performances of each of the optimized cases are then compared along with the equivalent passive model using the peak transmissibility criteria. The results indicate that all of the semi-active peak transmissibilities are lower than those of the passive, implying that the semi-active TVAs are more effective in reducing vibration levels. The results further indicate that on-off DBG performs the best among the considered control polices.

Experimental Validation of a State-Switched Absorber Used to Control Vibrating Continuous Systems

2005 ◽  
Author(s):  
Mark Holdhusen ◽  
Kenneth A. Cunefare
Keyword(s):  
Experimental Validation ◽  
Frequency Component ◽  
Effective Bandwidth ◽  
Continuous Systems ◽  
Vibration Absorbers ◽  
Numerical Work ◽  
Tuned Vibration Absorbers ◽  
Resonance Frequencies ◽  
Magneto Rheological ◽  
The Magnetic Field

A state-switched absorber (SSA) is a device capable of instantaneously changing its stiffness, thus it can switch between resonance frequencies, increasing its effective bandwidth as compared to classical tuned vibration absorbers for vibration control. Previous numerical work has shown that an optimized SSA outperforms an optimized TVA at controlling vibrations of both a beam and a plate. This paper details the experimental validation of these simulation results. An SSA was realized by employing magneto-rheological elastomers to achieve a stiffness change. The stiffness of these elastomers is a function of the magnetic field put across them. Experiments were conducted on both a cantilever beam and a square plate clamped on all sides. Each system was excited by several two-frequency component excitations. For each forcing combination, several tuning configurations of the SSA were applied and the kinetic energy of the system was found. This observed performance was compared to the performance found through numerical simulations of a system with a similar tuning and excitation configuration. It was found that the observed performance follows closely with results found through numerical simulation.

Dynamic Simulation of a Full Vehicle With Magneto-Rheological Damper

2004 ◽  
Author(s):  
Baolin Hou ◽  
F. D. Goncalves ◽  
C. Sandu ◽  
M. Ahmadian
Keyword(s):  
Dynamic Simulation ◽  
Dynamic Characteristics ◽  
Mr Damper ◽  
Control Policy ◽  
Tire Model ◽  
Distribution Law ◽  
Control Policies ◽  
Full Vehicle ◽  
Road Profile ◽  
Magneto Rheological

The numerical dynamic simulation of a full vehicle incorporating a magneto-rheological (MR) damper in the primary suspension is studied using the automatic dynamic analysis package ADAMS and the control software SIMULINK. The full vehicle model is built under ADAMS. The interaction between the tire and the road profile is simulated using the ADAMS/TIRE capabilities. The UA tire model is used to model the dynamic characteristics of the tires. A 3-D road profile model is built based on the spatial power spectrum density of a random road profile. This road profile satisfies not only some random distribution law, but also adapts to the numerical simulation requirement of the tire model. In order to model the dynamic characteristics of the primary suspension MR damper, a non-parametric model of an MR damper is proposed which can conveniently be incorporated into the vehicle dynamic model. Two kinds of control policies, a common skyhook and the so-called ‘non-jerk’ skyhook, are adopted to control the current applied to the MR damper. The simulation results imply that either one of the two skyhook control policies can obtain a good compromise between so-called “soft damping” and “hard damping,” and non-jerk skyhook control policy can curb some higher frequency components which are observed in the acceleration response of the chassis. This study also shows that virtual prototype technology is an effective approach for investigating the dynamic behavior of MR dampers for complex systems.

In Search of a Suitable Control Policy for Intelligent Vehicle Suspensions

2002 ◽  
Author(s):  
Fernando D. Goncalves ◽  
Mehdi Ahmadian
Keyword(s):  
Steady State ◽  
Hybrid Control ◽  
Control Policy ◽  
Control Technique ◽  
Intelligent Vehicle ◽  
Alternative Control ◽  
Control Policies ◽  
Peak Displacement ◽  
Vehicle Suspensions ◽  
Magneto Rheological

Many control policies, such as skyhook and groundhook control, are now being considered for intelligent vehicle suspensions. Past studies have shown the performance limitations of these policies, as well as others that have been considered for vehicle applications. The performance of three semi-active control policies were studied experimentally under steady-state and transient inputs. Experimental results were obtained using a quarter-car rig and a magneto-rheological damper. The commonly considered skyhook and groundhook control policies were employed and evaluated under a steady-state, or pure tone, input and a transient, or step input. An alternative control technique called “hybrid control,” which attempts to merge the performance benefits of skyhook and groundhook control was also considered. Peak-to-peak displacement and peak-to-peak acceleration were used to evaluate performance. The results indicate that while skyhook and groundhook can offer benefits to either the sprung or unsprung masses, hybrid control can offer benefits to both masses. The compromise inherent in both skyhook and groundhook is eliminated with the use of hybrid control. Both the steady-state and transient dynamics of the sprung and unsprung masses can be reduced below those of passive using hybrid control with an α of 0.5. This corresponds to equal contributions from skyhook control and groundhook control.

Experimental Vibration Control of a Two-Degree of Freedom, State-Switched Absorber System

2002 ◽  
Author(s):  
Mark H. Holdhusen ◽  
Kenneth A. Cunefare
Keyword(s):  
Vibration Control ◽  
Vibration Suppression ◽  
Effective Bandwidth ◽  
Vibration Absorbers ◽  
Lumped Mass ◽  
Tuned Vibration Absorbers ◽  
Resonance Frequencies ◽  
Magneto Rheological ◽  
Theoretical Simulations ◽  
Two Degree Of Freedom

A State-Switched Absorber (SSA) is a device capable of instantaneously changing its stiffness, thus it can switch between resonance frequencies, increasing its effective bandwidth as compared to classical tuned vibration absorbers for vibration control. Previous theoretical simulations show that for a system subjected to a multi-harmonic disturbance, using an appropriate logic for switching states, the SSA reduces vibration more effectively than classical tuned vibration absorbers (TVA). This paper considers the experimental performance of the SSA for vibration suppression of an elastically mounted lumped mass base. State switching is achieved using magneto-rheological fluid to connect or disconnect a coil spring in parallel with other coil springs. The stiffness state is controlled by applying or removing a magnetic field across of the MR fluid. Experiments were performed over a range of forcing and tuning frequencies. The SSA system, optimally tuned, outperformed the optimal classical TVA system for all combinations of forcing frequencies.

On the Design of an Intelligent Suspension for Controlling Passenger Vehicle Roll Stability

2002 ◽  
Author(s):  
David E. Simon ◽  
Mehdi Ahmadian
Keyword(s):  
Test Results ◽  
Control Policies ◽  
Performance Improvements ◽  
Additional Information ◽  
Significant Performance ◽  
Improved Performance ◽  
Road Testing ◽  
Vehicle Test ◽  
Displacement Based ◽  
Magneto Rheological

This paper will address the design, laboratory testing, and road testing of a semiactive suspension system for controlling the roll stability of a sport utility vehicle. Four magneto-rheological dampers, specially designed and built for the purpose of this testing, are described along with the vehicle test setup in the laboratory. Additionally, results from a series of tests conducted on the vehicle equipped with magneto-rheological dampers operated according to different control policies are documented. Displacement and velocity-based skyhook control techniques are evaluated among the methods that are implemented on the test vehicle. The test results indicate that neither velocity nor displacement based skyhook control are particularly better than the stock passive suspension (for the system inputs tested in the laboratory). In order to realize any significant performance improvements in practice, it may be necessary to augment the skyhook control methods with additional information, such as the steering angle. The results of this study further indicate that the performance potential of various skyhook control policies is heavily dependent on the tuning of both the controllable damper and the control strategy itself. Additionally, it was shown that velocity based skyhook control exhibits improved performance relative to displacement based skyhook control. It is worth noting that the results presented in this study are greatly affected by the class of vehicle as well as the specific dampers that are used for testing. Testing with a different class of vehicle or with a different type of dampers could result in significantly different conclusions.

A Comprehensive Off-Tuning Analysis of Damping Controlled Tuned Vibration Absorbers

2006 ◽  
Author(s):  
Jeong-Hoi Koo ◽  
Medhi Ahmadian
Keyword(s):  
Numerical Models ◽  
Vibration Absorber ◽  
Vibration Absorbers ◽  
Single Degree Of Freedom ◽  
Tuning Parameters ◽  
Tuned Vibration Absorbers ◽  
Dynamic Performances ◽  
Displacement Based ◽  
Stiffness And Damping ◽  
Tuned Vibration Absorber

The main purpose of this study is to offer a comprehensive off-tuning analysis of a semi-active tuned vibration absorber. A base-excited, single-degree-of-freedom structure with a tuned vibration absorber (TVA) model is adapted as the baseline model for our analysis. Moreover, a non-model based groundhook control (displacement based on-off control or "On-off DBG") is used to control the damping in the TVA. In order to study the effect of off-tuning, numerical models of the damping controlled TVA along with its equivalent passive TVA were developed. Using these models, the optimal tuning parameters of both TVA models were obtained based on minimization of peak transmissibility. The two optimally tuned models were then "off-tuned" by varying the primary structure's mass, stiffness, and damping. Using the peak transmissibility reduction criteria, the dynamic performances of the off-tuned TVAs were evaluated. The results indicate that the peak transmissibility of the semi-active TVA is about 20% lower than that of passive, implying that the semi-active TVA is more effective in reducing vibration levels. The results further indicate that the semi-active TVA is more robust to changes in primary structure mass and stiffness. In summary, the offtuning analyses of the semi-active TVA revealed the practical benefits of using it over the passive counterpart to structures subjected to changes in system parameters.

Experimental Robustness Analysis of Magneto-Rheological Tuned Vibration Absorbers Subject to Mass Off-Tuning

2005 ◽  
Vol 128 (1) ◽  
pp. 126-131 ◽  
Author(s):  
Jeong-Hoi Koo ◽  
Mehdi Ahmadian ◽  
Mehdi Setareh
Keyword(s):  
Primary Structure ◽  
Robustness Analysis ◽  
Steel Plates ◽  
Test Apparatus ◽  
Practical Applications ◽  
Tuning Parameters ◽  
Optimal Tuning ◽  
Tuned Vibration Absorbers ◽  
Magneto Rheological ◽  
Structural Mass

This paper offers an experimental robustness analysis of a semi-active tuned vibration absorber (TVA) subject to structural mass off-tuning, which occurs frequently in practical applications of TVAs. One of the critical problems of a conventional TVA is off-tuning or miss-tuning because off-tuned TVAs may amplify the vibrations of the primary structure. This study intends to evaluate how well semi-active TVAs are able to adapt to structural mass changes (mass off-tuning) as compared with passive TVAs. To this end, a test apparatus was built to represent a two-degree-of-freedom structure model coupled with a TVA. The semi-active TVA considered in this study employed a magneto-rheological (MR) damper as its damping element to enhance overall performance. Using this test apparatus, a series of tests were conducted to identify the optimal tuning parameters of the TVAs. After obtaining each TVA’s optimal tuning parameters based on equal peak transmissibility criteria, the mass off-tuning tests were then performed on the optimally tuned TVAs. In order to off-tune the system, the mass of the primary structure varied from −19% to +19% of its nominal mass using a set of steel plates. Overall, the experimental results show that the semi-active MR TVA outperforms the passive TVA in reducing maximum vibrations. Moreover, the results show that the semi- active TVA is more robust to changes in the primary mass (mass off-tuning) The results further show that the semi-active MR TVA offers larger performance gains as the structure mass increases.

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