Adaptive Electromagnetic Torsional Tuned Vibration Absorber and its Application in Rotating Equipment

2012 ◽  
Author(s):  
Taher Abu Seer ◽  
Nader Vahdati ◽  
Hamad Karki ◽  
Oleg Shiryayev
Keyword(s):  
Natural Frequency ◽  
Torsional Vibration ◽  
Natural Frequencies ◽  
Vibration Reduction ◽  
Vibration Absorber ◽  
Torsional Vibrations ◽  
Wide Range ◽  
Simulation Results ◽  
Rotating Equipment ◽  
Tuned Vibration Absorber

Rotating equipment is susceptible to torsional vibrations whenever the RPM of the rotating equipment matches one of the torsional natural frequencies. For rotating equipment running at constant RPM, it is easy to control and mitigate the torsional vibrations, but in applications where the RPM is no longer a constant and varies widely or natural frequencies are changing: there is a need for a wide range vibration reduction device. In this paper, a translational adaptive electromagnetic tuned vibration absorber (ETVA) is described where its natural frequency is varied using electronics. The ETVA is modeled and its simulation results correlate very well with experimental results. Later, this concept is used to develop a torsional tuned vibration absorber (TTVA) device. The electromagnetic TTVA can be attached to rotating equipment to control torsional vibrations. The electromagnetic TTVA adapts itself and controls the torsional vibrations as and when the RPM varies. Here in this paper, the rotating equipment and the electromagnetic TTVA are modeled. Analysis results indicate that the torsional vibration of rotating equipment can be easily controlled using this newly developed electromagnetic TTVA.

Control of a Tuned Vibration Absorber Based on SMA Wires

2005 ◽  
Author(s):  
Eric Williams ◽  
Mohammad H. Elahinia ◽  
Jeong-Hoi Koo
Keyword(s):  
Shape Memory ◽  
Natural Frequency ◽  
Constitutive Relations ◽  
Robustness Analysis ◽  
Vibration Absorber ◽  
Primary System ◽  
Frequency Change ◽  
Simulation Results ◽  
Close Loop Control ◽  
Tuned Vibration Absorber

This paper presents the control simulation results of a tuned vibration absorber (TVA) that utilizes the properties of shape memory alloy (SMA) wires. A conventional passive TVA is effective when it is precisely tuned to the frequency of a vibration mode; otherwise, resonance may occur that could damage the system. Additionally, in many applications the frequency of the primary system often changes over time. For example, the mass of the primary system can change causing a change in its natural frequency. This frequency change of the primary system can significantly degrade the performance of the TVA. To cope with this problem, many alternative TVA’s (such as semiactive, adaptive, and active TVA’s) have been studied. As another alternative, this paper investigates the use of Shape Memory Alloys (SMA’s) in passive TVA’s in order to improve the robustness of the TVA’s subject to mass change in the primary system. This allows for effective tuning of the stiffness of the TVA to adapt to the changes in the primary system’s natural frequency. To this end, a close-loop control system adjusts the applied current to the SMA wires in order to maintain the desired stiffness. The model, presented in this paper, contains the dynamics of the TVA along with the SMA wire model that includes phase transformation, heat transfer, and the constitutive relations. The closed-loop robustness analysis is performed for the SMA-TVA and is compared with the equivalent passive TVA. For the robustness analysis, the mass of the primary system is varied by ± 30% of its nominal mass. The simulation results show that the SMA-TVA is more robust than the equivalent passive TVA in reducing peak vibrations in the primary system subject to change of its mass.

scholarly journals Adaptive Torsional Tuned Vibration Absorber for Rotary Equipment

Vibration ◽  
2019 ◽  
Vol 2 (1) ◽  
pp. 116-134 ◽  
Author(s):  
Taher Abu Seer ◽  
Nader Vahdati ◽  
Oleg Shiryayev
Keyword(s):  
Natural Frequency ◽  
Degree Of Freedom ◽  
Vibration Absorber ◽  
Torsional Vibrations ◽  
Rotating System ◽  
Laboratory Test Results ◽  
Innovative Solution ◽  
Bond Graph Modeling ◽  
Rotary Equipment ◽  
Tuned Vibration Absorber

This paper proposes an innovative solution to suppress torsional vibrations in any rotating machinery with a variable frequency of excitation, or a variable natural frequency. The adaptive torsional tuned vibration absorber (ATTVA) was designed using an integrated electromagnetic circuit, which can adapt its natural frequency to match the varying natural frequency of any Multi Degree of Freedom (MDOF) rotating system. A two degree of freedom rotating system was modeled along with the integrated ATTVA using the bond graph modeling technique. Simulation results showed that torsional vibrations can be easily attenuated by controlling the capacitance shunted to the voice coil circuit. The ATTVA was designed, fabricated and evaluated on a test rig in the laboratory. Test results revealed good matching between the mathematical model and the experimental data. Experiments were performed with different configurations of the ATTVA, and the experimental results showed reasonable suppression in vibration magnitude at the desired frequency.

Vibration Control of Slab Breaker Machine by Passive Dual Mass Tuned Vibration Absorber

2014 ◽  
Vol 592-594 ◽  
pp. 2112-2116
Author(s):  
Anant J. Sheth ◽  
Pratikkumar Rajendralal Parmar ◽  
Brijesh L. Solanki ◽  
Nirav Sailor ◽  
Bhavin P. Gohil ◽  
...  
Keyword(s):  
Shock Waves ◽  
Vibration Control ◽  
Dynamic Systems ◽  
Natural Frequencies ◽  
Vibration Reduction ◽  
Vibration Absorber ◽  
Operating Condition ◽  
Tuned Vibration Absorber

Tuned Vibration Absorber (TVA) is the best solution available to control/suppress vibrations of any dynamic systems. Dual mass Tuned Vibration Absorber are designed and implemented for the vibration control. Though the slab barker machine is operating at various natural frequencies, the Dual mass TVA can be designed to mitigate the vibrations depending on the position of mass. The experiments were carried out for various locations of mass. And it is found that the vibration /shock waves of slab breaker machine are absorbed by using a passive TVA system. By keeping the operating condition same it is practically found that at the location of 4cm the optimal vibration reduction obtained and the amplitude is found to be reduced by 37 %.

Maximizing the Fundamental Natural Frequency of Triangular Composite Plates

1996 ◽  
Vol 118 (2) ◽  
pp. 141-146 ◽  
Author(s):  
S. Abrate
Keyword(s):  
Natural Frequency ◽  
Material Properties ◽  
Composite Structures ◽  
Natural Frequencies ◽  
Ritz Method ◽  
Laminated Composite ◽  
Composite Plates ◽  
Mode Shapes ◽  
Fundamental Natural Frequency ◽  
Wide Range

While many advances were made in the analysis of composite structures, it is generally recognized that the design of composite structures must be studied further in order to take full advantage of the mechanical properties of these materials. This study is concerned with maximizing the fundamental natural frequency of triangular, symmetrically laminated composite plates. The natural frequencies and mode shapes of composite plates of general triangular planform are determined using the Rayleigh-Ritz method. The plate constitutive equations are written in terms of stiffness invariants and nondimensional lamination parameters. Point supports are introduced in the formulation using the method of Lagrange multipliers. This formulation allows studying the free vibration of a wide range of triangular composite plates with any support condition along the edges and point supports. The boundary conditions are enforced at a number of points along the boundary. The effects of geometry, material properties and lamination on the natural frequencies of the plate are investigated. With this stiffness invariant formulation, the effects of lamination are described by a finite number of parameters regardless of the number of plies in the laminate. We then determine the lay-up that will maximize the fundamental natural frequency of the plate. It is shown that the optimum design is relatively insensitive to the material properties for the commonly used material systems. Results are presented for several cases.

Sensitivity Analysis and Application of Natural Frequency of Torsional Vibration of Rotor System

2008 ◽  
Author(s):  
Qing He ◽  
Dongmei Du
Keyword(s):  
Sensitivity Analysis ◽  
Electric Power ◽  
Natural Frequency ◽  
Torsional Vibration ◽  
Natural Frequencies ◽  
Electric Power System ◽  
Rotor System ◽  
Analysis Method ◽  
Turbine Generator ◽  
Sensitivity Analysis Method

The disturbance of electric power system makes large-scale turbine-generator shafts generate torsional vibration. A available method to restrain the torsional vibration of turbine-generator shafts is that all the natural frequencies of torsional vibration of turbine-generator shafts must keep away from the working frequency and its harmonic frequencies as well as all the frequencies that possibly bring on interaction between turbine-generator and electric power system so that the torsional resonation of shafts may not occur. A dynamic design method for natural frequencies of torsional vibration of rotor system based on sensitivity analysis is presented. The sensitivities of natural frequency of torsional vibration to structure parameters of rotor system are obtained by means of the theory of sensitivity. After calculated the torsional vibration dynamic characteristics of original shafts of a torsional vibration stand that simulates the real shafts of 300MW turbine-generator, the dynamic modification for the torsional vibration natural frequency is carried out by the sensitivity analysis method, which makes the first-five natural frequencies of torsional vibration of the stand is very close to the design object. It is proved that the sensitivity analysis method can be used to the dynamic adjustment and optimal design of real shafts of turbine-generator.

Torsional Vibration Analysis of Drillstrings in Blasthole Drilling

2008 ◽  
Author(s):  
Omid Aminfar ◽  
Amir Khajepour
Keyword(s):  
Torsional Vibration ◽  
Natural Frequencies ◽  
Element Model ◽  
Drilling Process ◽  
Torsional Vibrations ◽  
Rotary Drilling ◽  
Well Drilling ◽  
State Response ◽  
Drilling Performance ◽  
Overall Performance

Reducing vibrations in well drilling has a significant effect on improving the overall performance of the drilling process. Vibrations may affect the drilling process in different ways, i.e., reducing durability of the drillstring’s elements, reducing the rate of penetration, and deviating the drilling direction. In rotary drilling, which is used to open mine and oil wells, torsional vibration of the drillstring is an important component of the overall system’s vibration that has received less attention in the literature. In this paper, we propose a finite element model for a sample blasthole drillstring used to open mine wells to investigate its torsional vibrations. Boundary conditions and elements’ specifications are applied to this model. In the model, the interaction between the insert and the rock is represented by a set of repetitive impulses according to the insert pattern. The steady-state response of the system to the repetitive impulses is found and natural frequencies, kinetic energy, and potential energy of the drillstring are calculated. The root mean square (RMS) of the total energy can be used as the measure for reducing the torsional vibration of the system. Finally, an optimum combination of inserts on the cone’s rows was found based on minimizing the total vibratory energy of the drillstring. The optimum design can reduce the torsional vibrations of the drillstring and improve the drilling performance.

Simulation of Torsional Vibrations or Multibody Simulation: Which Technique Does the Wind Power Industry Need for Solving the Present-Day Problems?

2003 ◽  
Author(s):  
Berthold Schlecht ◽  
Tobias Schulze ◽  
Jens Demtro¨der
Keyword(s):  
Torsional Vibration ◽  
Natural Frequencies ◽  
Wind Load ◽  
Operating Conditions ◽  
Drive Train ◽  
Torsional Vibrations ◽  
Multibody Simulation ◽  
Vibration Behavior ◽  
Drive Trains ◽  
Load Simulation

For the simulation of service loads and of their effect on the whole turbine the wind turbine manufacturers use program systems whose particular strengths lie in the wind load simulation at the rotor, in the rotor dynamics as well as in the control-technological operation of the whole turbine. The complex dynamic behavior of the drive train, consisting of the rotor, the rotor shaft, the main gearbox, the brake, the coupling and the generator, is represented as a two-mass oscillator. This simplification, which certainly is necessary within the framework of the wind load simulation programs, is by no means sufficient for the exact description of the dynamics of the more and more complex drive trains with capacities up to 5 MW. At first, the extension to a multimass torsional vibration model seems to be useful for the exact determination of the torsional vibrations in the drive train. However, in the turbines of all manufacturers there have been found forms of damage on drive train components (high axial loads in bearings, high coupling loads, radial loads on generator bearings) that cannot be explained even on the basis of a torsional vibration analysis. Moreover, in measurements on drive trains natural frequencies in the signals occurred that can no longer be explained by the torsional vibration behavior alone. Consequently, a real multibody simulation becomes necessary, for which also radial and axial vibrations can be taken into account, in addition to torsion, since these influence the torsional vibration behavior considerably. These dependences become already clear in an analysis of natural frequencies. This is illustrated by the example of a 700-kW turbine as well as by a planetary gearing for a 3-MW turbine. Especially in the dimensioning of the off-shore turbines with several MW output power, which are being planned, the use of multibody simulation will be advantageous, since the testing of turbine prototypes of this order of magnitude under the corresponding operating conditions are surely more cost-intensive and risky than the virtual testing with well validated simulation models.

A Robust Semi-Active Tuned Vibration Absorber for Reducing Vibrations in Force-Excited Structures

2002 ◽  
Author(s):  
Jeong-Hoi Koo ◽  
Mehdi Ahmadian ◽  
Mehdi Setareh ◽  
Thomas M. Murray
Keyword(s):  
Natural Frequency ◽  
Primary Structure ◽  
Equivalent Model ◽  
Design Parameters ◽  
Vibration Absorber ◽  
Structural Systems ◽  
Mass Ratio ◽  
Closed Form Solutions ◽  
Floor Systems ◽  
Tuned Vibration Absorber

A passive TVA is only effective when it is tuned properly; otherwise, it can magnify the vibration levels. Often, inevitable off-tuning of a TVA occurs due to changes in the primary structure mass and stiffness for force-excited structural systems such as a floor. The main purpose of this study is to evaluate the robustness of semi-active groundhook TVAs to structure mass and stiffness off-tuning. In the case of floor systems, adding external mass to an existing floor, such as people and furniture, will increase the floor mass, and reduce the mass ratio. Theses changes result in off-tuning of the frequency ratio, which is defined by the ratio of the natural frequency of the TVA to the primary structure natural frequency. In order to study the effect of off-tuning, a force-excited equivalent model of a groundhook TVA is developed and its closed-form solutions are obtained for dynamic analysis of such systems. Moreover, the optimal design parameters of both passive and groundhook equivalent semiactive TVA models are obtained based on minimization of peak transmissibility. The two optimally tuned models are compared as the primary mass and primary structure stiffness changes. The results indicate that the peak transmissibility of the groundhook TVA is lower than that of passive, implying that the groundhook TVA is more effective in reducing vibration levels. The results further indicate that the groundhook TVA is more robust to changes in primary structure mass and stiffness.

scholarly journals A tuned vibration absorber constituted of shape memory alloy wires for vibration reduction of platform structures: design and implementation

2018 ◽  
Vol 185 ◽  
pp. 00013
Author(s):  
Yun-Ting Liao ◽  
Jia-Hong Lin ◽  
Chun-Ying Lee
Keyword(s):  
Shape Memory Alloy ◽  
Shape Memory ◽  
High Efficiency ◽  
Vibration Reduction ◽  
Vibration Absorber ◽  
Practical Applications ◽  
Operation Conditions ◽  
Tunable Frequency ◽  
Six Degree Of Freedom ◽  
Tuned Vibration Absorber

Machinery can suffer from mechanical vibrations since resonance may be generated from time-varying external excitations under different operation conditions. These detrimental vibrations may significantly influence the device's performance, effectiveness and reliability in operation. In this paper, an innovative, simple and high-efficiency tuned vibration absorber (TVA) consisting of shape memory alloy (SMA) wires, which is referred to a wire-type tuned vibration absorber (WTVA), is proposed to reduce the induced vibration. Experiments are carried out using a six-degree-of-freedom platform which is designed to simulate the frame of precision machinery in practical applications. With the equivalent stiffness of SMA wires adjusted by the controlled electric current, the frequency tunability of WTVA can be achieved. When the natural frequency of WTVA tuned in with the disturbance frequency, the experimental results demonstrate that the efficiency in vibration reduction of the platform is drastically increased even with considerable weight difference between WTVA and the platform. Moreover, the tunable frequency span also increases greatly due to the new design of WTVA and the material characteristics of SMA wires.

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