Vibration Reduction

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Jeffrey L. Kauffman - One of the best experts on this subject based on the ideXlab platform.

  • Optimizing Piezoelectric Material Location and Size for Multiple-Mode Vibration Reduction of Turbomachinery Blades
    Journal of Vibration and Acoustics, 2020
    Co-Authors: Christopher R. Kelley, Garrett K. Lopp, Jeffrey L. Kauffman
    Abstract:

    Abstract Modern turbomachinery blades have extremely low inherent damping, which can lead to high transient Vibrations and failure through high-cycle fatigue. Smart materials enable Vibration Reduction while meeting strict blade requirements such as weight and aerodynamic efficiency. In particular, piezoelectric-based Vibration Reduction offers the potential to reduce Vibration semi-actively while simultaneously harvesting sufficient energy to power the implementation. The placement and the size of the piezoelectric material is critical to the Vibration Reduction capabilities of the system. Furthermore, the implementation should target multiple Vibration modes. This study develops a procedure to optimize electromechanical coupling across multiple Vibration modes for a representative turbomachinery blade with surface-mounted piezoelectric patches. Experimental validation demonstrates good coupling across three targeted modes with a single piezoelectric patch. Placing the piezoelectric material in regions of high signed strain energy for all targeted modes enables Vibration Reduction across all of the targeted modes.

  • Optimal Placement and Sizing of Piezoelectric Material for Multiple-Mode Vibration Reduction
    Volume 7C: Structures and Dynamics, 2018
    Co-Authors: Christopher R. Kelley, Jeffrey L. Kauffman
    Abstract:

    Modern turbomachinery blades have extremely low inherent damping, which can lead to high transient Vibrations and failure through high-cycle fatigue. Recent research seeks methods to reduce Vibration with minimal effect on the weight and aerodynamic efficiency of the blade. Smart materials present an interesting means to augment the mechanical characteristics of the blade while meeting the strict requirements of the turboma-chinery environment. In particular, piezoelectric-based Vibration Reduction offers the potential to semi-actively reduce Vibration while simultaneously harvesting enough energy to power the implementation. The placement and size of the piezoelectric material is critical to the Vibration Reduction capabilities of the system. Furthermore, the implementation should target multiple Vibration modes. This work develops a procedure to optimize electromechanical coupling across multiple Vibration modes for a representative turbine blade with a surface-mounted piezoelectric patch.

  • Vibration Reduction of Mistuned Bladed Disks Via Piezoelectric-Based Resonance Frequency Detuning
    Journal of Vibration and Acoustics, 2018
    Co-Authors: Garrett K. Lopp, Jeffrey L. Kauffman
    Abstract:

    This paper extends the resonance frequency detuning (RFD) Vibration Reduction approach to cases of turbomachinery blade mistuning. Using a lumped parameter mistuned blade model with included piezoelectric elements, this paper presents an analytical solution of the blade Vibration in response to frequency sweep excitation; direct numerical integration confirms the accuracy of this solution. A Monte Carlo statistical analysis provides insight regarding Vibration Reduction performance over a range of parameters of interest such as the degree of blade mistuning, linear excitation sweep rate, inherent damping ratio, and the difference between the open-circuit (OC) and short-circuit (SC) stiffness states. RFD reduces Vibration across all degrees of blade mistuning as well as the entire range of sweep rates tested. Detuning also maximizes Vibration Reduction performance when applied to systems with low inherent damping and large electromechanical coupling.

  • Effect of Switch Delays on Piezoelectric-Based Semi-Active Vibration Reduction Techniques
    Volume 1: Development and Characterization of Multifunctional Materials; Mechanics and Behavior of Active Materials; Modeling Simulation and Control o, 2015
    Co-Authors: Christopher R. Kelley, Jeffrey L. Kauffman
    Abstract:

    Piezoelectric transducers have been used for semi-active Vibration Reduction in structures by altering the stiffness state and dissipating electrical energy. Common approaches include state switching, synchronized switch damping on a resistor (SSDS), and synchronized switch damping on an inductor (SSDI). Each of these methods requires four switches per Vibration cycle, so any delay in the switch from the ideal moment could have a significant effect on the Vibration Reduction. An experimental investigation into the effect of switch delays on these techniques reveals that the abrupt change in piezoelectric voltage from the switch has the effect of a step input on the structure, which may excite higher order modes and increase the peak strain. This non-ideal switching of boundary conditions has implications towards the design and performance of these state switching techniques. Switching at the peak is classically considered the ideal switch time, but the influence of the switch on the local strain may actually result in a higher peak strain for the structure than with a delayed switch. This paper will examine switch times that lead and lag the ideal case for state switching, SSDS, and SSDI to quantify the level of Vibration Reduction achieved under non-ideal peak sensing.Copyright © 2015 by ASME

  • piezoelectric based Vibration Reduction of turbomachinery bladed disks via resonance frequency detuning
    AIAA Journal, 2012
    Co-Authors: Jeffrey L. Kauffman, George A Lesieutre
    Abstract:

    Piezoelectric-based resonance frequency detuning can alleviate unwanted Vibration of turbomachinery blades, thus reducing the dangers of high-cycle fatigue while also decreasing the blade weight. This semiactive approach applies to structures that are subjected to frequency-sweep excitation and involves altering the structural stiffness (here, by switching the piezoelectric electrical boundary conditions) to avoid a resonant condition, thus limiting the blade response. Detuning requires two switches per resonance/excitation frequency crossing, including a switch back to the original the original state,many fewer than other semiactive approaches that require four switches per cycle of Vibration.Resonance frequencydetuningapplies to anymode of Vibrationwith apositive electromechanical coupling coefficient, and it provides the greatest normalized Vibration Reduction for slow sweeps, low damping, and high coupling coefficient. Yet even for amoderate sweep rate 10 4 andmodal damping 0:1%, optimally detuning a structure with an electromechanical coupling coefficient k 10% provides the same Vibration Reduction as increasing either the sweep rate ormodal damping by an order of magnitude.With a lower sweep rate 10 5 and modal damping 0:01%, detuning with a coupling coefficient of only k 3% provides equivalent Vibration Reduction as an order of magnitude increase in sweep rate or modal damping.

Peretz P. Friedmann - One of the best experts on this subject based on the ideXlab platform.

  • Actuator saturation and its influence on Vibration Reduction by actively controlled flaps
    19th AIAA Applied Aerodynamics Conference, 2001
    Co-Authors: R. Cribbs, Peretz P. Friedmann
    Abstract:

    The influence of actuator saturation on the Vibration Reduction abilities of an actively controlled flap is investigated. An aeroelastic model of a four bladed hingeless rotor with a free wake is used for the analyses. Three methods for constraining flap deflections are studied at two limiting values, two and four degrees, of maximum flap deflection. Results indicate that neither scaling nor clipping of the optimal control flap deflection to the maximum flap deflection provides acceptable Vibration Reduction. A newly developed control method with saturation constraints shows exceptional Reduction of Vibrations. This new control method reduces Vibrations to similar levels as the unconstrained optimal control while constraining maximum flap deflections to the limiting values.

  • Vibration Reduction in rotorcraft using active control - A comparison of various approaches
    Journal of Guidance Control and Dynamics, 1995
    Co-Authors: Peretz P. Friedmann, Thomas A. Millott
    Abstract:

    This paper presents a concise review of the state of the art for Vibration Reduction in rotorcraft using active controls. The principal approaches to Vibration Reduction in helicopters described in the paper are 1) higher harmonic control, 2) individual blade control, 3) Vibration Reduction using an actively controlled flap located on the blade, and 4) active control of structural response. The special attributes of the coupled rotor/flexible fuselage Vibration Reduction problem are also briefly discussed to emphasize that Vibration Reduction at the hub is not equivalent to acceleration Reduction at specific fuselage locations. Based on the comparison of the various approaches, it appears that the actively controlled flap has remarkable potential for Vibration Reduction.

  • Vibration Reduction in helicopter rotors using an actively controlled partial span trailing edge flap located on the blade
    1994
    Co-Authors: Thomas A. Millott, Peretz P. Friedmann
    Abstract:

    This report describes an analytical study of Vibration Reduction in a four-bladed helicopter rotor using an actively controlled, partial span, trailing edge flap located on the blade. The Vibration Reduction produced by the actively controlled flap (ACF) is compared with that obtained using individual blade control (IBC), in which the entire blade is oscillated in pitch. For both cases a deterministic feedback controller is implemented to reduce the 4/rev hub loads. For all cases considered, the ACF produced Vibration Reduction comparable with that obtained using IBC, but consumed only 10-30% of the power required to implement IBC. A careful parametric study is conducted to determine the influence of blade torsional stiffness, spanwise location of the control flap, and hinge moment correction on the Vibration Reduction characteristics of the ACF. The results clearly demonstrate the feasibility of this new approach to Vibration Reduction. It should be emphasized than the ACF, used together with a conventional swashplate, is completely decoupled from the primary flight control system and thus it has no influence on the airworthiness of the helicopter. This attribute is potentially a significant advantage when compared to IBC.

Jarosław Konieczny - One of the best experts on this subject based on the ideXlab platform.

  • Modified Clipped-LQR Method for Semi-Active Vibration Reduction Systems with Hysteresis
    Solid State Phenomena, 2011
    Co-Authors: Marek Sibielak, Waldemar Rączka, Jarosław Konieczny
    Abstract:

    Smart materials are being applied more and more widely in semi-active Vibration Reduction systems. Actuators built with their use are characterized by nonlinearities and hysteretic effects. Their omission in mathematical descriptions may lead to deterioration of the Vibration Reduction systems. For that reason, it is important to take into account these negative phenomena associated with the actuators at the controller synthesis stage. One method for determining the control laws in semi-active Vibration Reduction systems that is frequently discussed in academic literature is “Clipped-LQR”. The present paper proposes modification of that method to allow inclusion in the controller synthesis of the hysteretic properties and other nonlinearities of an actuator. The method developed was verified by determining the controller for the semi-active suspension of a machine operator’s seat. A magnetorheological damper was used as an actuator. The dynamic properties of the foam covering of the operator’s seat were included in model. Simulation tests were performed on the Vibration Reduction system and function of Vibration transmissibility was determined. The semi-active Vibration Reduction system tested was compared to a passive system. The considerations presented herein relate to the semi-active suspension of a machine operator’s seat, and the method presented may be applied to other controlled systems with many degrees of freedom.

  • Mathematical Model of a Shape Memory Alloy Spring Intended for Vibration Reduction Systems
    Solid State Phenomena, 2011
    Co-Authors: Waldemar Rączka, Jarosław Konieczny, Marek Sibielak
    Abstract:

    The article discusses a prototype of a Shape Memory Alloy (SMA) spring intended for controlled Vibration Reduction systems. The spring has been subject to experiments and the article presents selected static and dynamic characteristics. The experiments were conducted at the Dynamics and Control of Structures Laboratory of the AGH University of Science and Technology. They permitted the formulation of a mathematical model for the SMA spring. The model takes into account the phenomena of energy accumulation and dissipation. The parameters of the spring model have been determined, based on the experimental data. The model takes into account the relationship of stiffness and damping to alloy temperature and the frequency of excitation. It has been demonstrated that the properties of the spring may be altered under controlled conditions. The spring model was then used in simulations. They served as the basis for the determination of the frequency response characteristics, which were then compared to the characteristics of a real spring. The mathematical model developed may be applied in the design of passive, semi-active, and active Vibration Reduction systems, as well as in the synthesis of adaptive smart Vibration Reduction systems.

Łukasz Jastrzębski - One of the best experts on this subject based on the ideXlab platform.

  • Experimental Analysis of Power Flows in the Regenerative Vibration Reduction System with a Magnetorheological Damper
    Energies, 2021
    Co-Authors: Bogdan Sapiński, Paweł Orkisz, Łukasz Jastrzębski
    Abstract:

    The aim of the work is to investigate power flows in the Vibration Reduction system equipped with a magnetorheological (MR) damper and energy regeneration. For this purpose, experiments were conducted in the test rig compound of the shaker and the Vibration Reduction system (electromagnetic harvester, MR damper, spring) which are attached to the sprung mass. The experimental data acquired under sine excitations enabled us to analyze instantaneous power fluxes, as well as a rate of inertial energy changes in the system.

  • Electrical Interface for a Self-Powered MR Damper-Based Vibration Reduction System
    Acta Mechanica et Automatica, 2016
    Co-Authors: Łukasz Jastrzębski, Bogdan Sapiński
    Abstract:

    Abstract The study investigates the behaviour of an electrical interface incorporated in a MR damper-based Vibration Reduction system powered with energy recovered from Vibration. The interface, comprising the R, L and C elements, is connected in between the coil in an electromagnetic electric generator and the control coil in the MR damper and its function is to convert the output voltage from the generator. The interface model was formulated and computer simulations were performed to find out how the parameters of the interface should influence the frequency responses of the Vibration Reduction system.

  • CONDITIONING ELECTRONICS IN A SELF-POWERED Vibration Reduction SYSTEM: EXPERIMENTAL TESTING
    Mechanics and Control, 2014
    Co-Authors: Łukasz Jastrzębski
    Abstract:

    The paper summarises the results of laboratory testing of a Vibration Reduction system with energy harvesting capability, implemented in an 2 DOF mechanical application. The Vibration Reduction system comprises a commercially available RD-1005-3 type magnetorheological (MR) damper and an electromagnetic energy transducer (EPE) executing the reciprocating motion. The aim of the experiment was to compare the performance of the Vibration Reduction with two types of power conditioning systems and that in which the MR damper coil is fed directly with energy generated by EPE. Frequency characteristics are provided showing the plots of transmissibility coefficients, MR damper force, voltage generated by EPE, current intensity in the MR damper control coil, supplied electric power and mechanical power dissipated by the damper.

Marcelo A. Savi - One of the best experts on this subject based on the ideXlab platform.

  • Vibration Reduction of the impact system by an SMA restraint: numerical studies
    International Journal of Non-Linear Mechanics, 2010
    Co-Authors: Elena Sitnikova, Ekaterina Pavlovskaia, Marian Wiercigroch, Marcelo A. Savi
    Abstract:

    The dynamic behaviour of an impact oscillator with a shape memory alloy (SMA) restraint is modelled and analyzed. This impact oscillator has the secondary support made from an SMA and the thermomechanical description of the SMA element follows the formulation proposed by Bernardini et al. [1,2]. The thermo-mechanical coupling terms included in the energy balance equation allow to undertake the non-isothermal analysis. Due to the mechanical characteristics of the SMA element and the non-smooth nature of the impacts, five different modes of operation can be distinguished. The undertaken numerical investigations suggest that the system can exhibit complex dynamic responses, which if appropriately controlled can be used for Vibration Reduction. A comparison with an equivalent elastic oscillator is made. It is found out that the low amplitude regimes are not affected by the SMA element. On contrary, for the large amplitude responses, a significant Vibration Reduction may be achieved due to the phase transformation hysteresis loop. Various bifurcation scenarios are constructed and the influence of the SMA element is discussed. In particular, the analysis of the frequency and amplitude variations of the external excitation is given and the parameter ranges where the Vibration Reduction is possible are identified.