Variable Stiffness Technique for Turbomachinery using Shape Memory Alloys

Wischt, Rachel J.; Garafolo, Nicholas G.

doi:10.2514/6.2015-1850

Cited by 9 publications

(9 citation statements)

References 5 publications

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“…An experimental study by Nakshatharan [24] using SMA wire applied externally to a clamped-free beam with a constant excitation frequency confirmed that beam tip amplitude reduction of approximately 60% can be achieved in first bending mode. The introduction of the shape memory effect, whereby the shape memory alloy material acts as both a damper and a means of variable stiffness have been confirmed for HCF mitigation [16,17,18,19] using thin sheet metal SMA topically adhered onto a clamped-free beam. This study highlights an amplitude reduction of 92% in the second bending mode with constant excitation frequency.…”

Section: Sma Vibration Controlmentioning

confidence: 92%

Vibration Control of a Flexible Beam with Embedded Shape Memory Alloy Wire

Garafolo¹,

McHugh²

2018

JMDV

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Structural vibrations can damage systems and lead to high cycle fatigue, excess noise or even catastrophic failure. The research presented herein aims to quantify the effect of embedded shape memory alloy (SMA) wire as an active suppression system to mitigate such vibrations in a flexible clamped-free beam. A silicone beam with embedded SMA wire was designed. Natural frequencies were calculated using a frequency response function (FRF) at varying temperatures. Experiments resulted in an average natural frequency shift of 44.7% and an amplitude decrease of 34% at the tip of the beam. Control samples were created using the same dimensions and silicone material. One control sample contained embedded aluminum wire while the other sample contained no embedded material. The addition of the unactuated SMA wire resulted in an average natural frequency shift of 160% and amplitude decrease of 44.6% while the actuated SMA wire resulted in a shift of 258% and amplitude decrease of 63.6%. The natural frequency of the embedded aluminum wire sample remained the same at low and high temperatures, leading to the conclusion that the frequency shift of the SMA sample was a result of the shape memory effect.

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Section: Sma Vibration Controlmentioning

confidence: 92%

Vibration Control of a Flexible Beam with Embedded Shape Memory Alloy Wire

Garafolo¹,

McHugh²

2018

JMDV

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“…To initiate the stiffness modulation, RFD employs piezoelectric materials due to their rapid response times. Researchers have also employed shape memory alloys to initiate this variablestiffness effect that, although offering larger potential differences between available stiffness states, appear limited by their slow response times when considering transient excitations [12,13]. By exploiting this variable-stiffness effect, RFD provides robust performance to any unexpected parameter variations and has the ability to target vibration for a number of resonance crossings, provided the piezoelectric elements remain located in a region of high modal strain.…”

Section: Resonance Frequency Detuningmentioning

confidence: 99%

“…12 shows the blisk mode shapes with the color scheme corresponding to the sum of the modal strains at each spatial location. The left plots correspond to patch configuration A and show…”

mentioning

confidence: 99%

Vibration Reduction of Mistuned Bladed Disks Via Piezoelectric-Based Resonance Frequency Detuning

Lopp

Kauffman

2018

Journal of Vibration and Acoustics

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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.

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“…Numerous studies exist illustrated changes in natural frequency through embedded SMA wires in composite structures [5,6,7]. In additional, variable stiffness has been shown to reduce component amplitudes and create a change in the eigenvectors (i.e., mode shape vector) [2]. Modeling has afforded the ability to understand the fundamental nature of these systems [8,9].…”

Section: Introductionmentioning

confidence: 99%

“…This behavior is due to a solid-solid phase change in the material from martensite to austenite. The introduction of the shape memory effect, whereby the shape memory alloy material acts as both a damper and a means of variable stiffness is a novel technique for HCF mitigation [2,3]. Figure 1.…”

Section: Introductionmentioning

confidence: 99%

Active Stiffness Method for High Cycle Fatigue Mitigation using Topical Thin Foil Shape Memory Alloy

Garafolo¹,

Collard²

2017

JMDV

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The strong need for high cycle fatigue mitigation has resulted in numerous techniques resulting in added weight, increased operational costs, and lower performance. The experimental investigation presented was a foundational effort towards mitigating HCF through the use of shape memory alloy in a composite system. The research objective was to quantify changes in eigenvalue, eigenvector, and amplitude of a vibrating cantilever beam with a thin SMA topical treatment; as quantified during SMA phase transformations and through comparison with a control. A composite beam consisting of a nitinol thin SMA foil adhered to an Aluminum Alloy 6061 substrate was designed and fabricated. The three configurations were utilized: (1) a full-span SMA treatment designed for maximum eigenvalue shift and maximum amplitude reduction, (2) a half-span SMA treatment designed for eigenvector shift, and (3) a full-span aluminum treatment for a control. Through a complete modal analysis, results illustrated that thin foil SMA treatments led to a significant shift in eigenvalue, up to 6.53%. Highlighting the reduction in amplitude was a 92% reduction in amplitude at second bending with constant excitation frequency with the full-span sample. Spanwise scans on the half-span sample with and without SMA actuation illustrated a 0.77% shift in node location.

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Variable Stiffness Technique for Turbomachinery using Shape Memory Alloys

Cited by 9 publications

References 5 publications

Vibration Control of a Flexible Beam with Embedded Shape Memory Alloy Wire

Vibration Control of a Flexible Beam with Embedded Shape Memory Alloy Wire

Vibration Reduction of Mistuned Bladed Disks Via Piezoelectric-Based Resonance Frequency Detuning

Active Stiffness Method for High Cycle Fatigue Mitigation using Topical Thin Foil Shape Memory Alloy

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