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

Garafolo, Nicholas G.; Collard, Rachel J.

doi:10.12691/jmdv-5-1-2

Cited by 6 publications

(5 citation statements)

References 17 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: 93%

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: 93%

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%

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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“…This research effort leverages an extremely large experimental and theoretical base. Test specimens were created and consistent with those used to quantify the eigenvalue, eigenvectors, and amplitude changes in recent studies [1,19,20]. The test specimens consisted of a topical treatment adhered to an aluminum substrate.…”

Section: Test Specimen Designmentioning

confidence: 99%

“…High cycle fatigue (HCF) mitigation requires research into novel materials and techniques to expand the available tools and resources for innovated designs. Recent advances in the use of Shape Memory Alloys (SMA) for controlling the vibration characteristics offer significant potential for HCF mitigation cite [1]. High cycle fatigue, as characterized by high frequencies, low amplitudes, cyclic elastic behavior, and high cycle count, affect a large number of engine components.…”

Section: Introductionmentioning

confidence: 99%

“…It has been shown that the variable stiffness property inherent to shape memory alloys has the capability of shifting the natural frequencies of components made with this material. Along with a frequency shift, variable stiffness has been shown to reduce component amplitudes and create a change in the mode shape vector [1,19,20]. Preliminary damping quantification suggested NiTI effectiveness as a HCF mitigation technique [20].…”

Section: Introductionmentioning

confidence: 99%

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Performance Mapping of an Aluminum - Nitinol Composite Vibrating Beam

Garafolo¹,

Collard²

2017

JMDV

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Dynamic control of a vibrating beam is critical to the efforts of mitigation of high cycle fatigue, as it is a leading cause of component or engine failure. Recent advances in composite structures have afford the ability to control the eigenvalue, eigenvectors, and amplitude of vibration through the use of the shape memory effect of shape memory alloys (e.g. Nitinol). These "smart materials" are proven to create active damping and variable stiffness in engine components is an innovative concept. Research presented herein seeks to quantify the effectiveness of Nitinol as a HCF mitigation technique and map the frequency and damping performance. A composite beam consisting of a Nitinol topical actuator adhered to an aluminum alloy 6061 substrate was designed and fabricated. Test specimens comprised two configurations: (1) a composite beam with the topical treatment encompassing the full span of free length of the beam, and (2) a composite beam with the topical treatment encompassing half the span the free length of the beam. Benchtop tests allowed for the determination both modal frequency and damping of the aluminum-Nitinol composite beam with an 8 in. free length. Modal analyses were taken over a selected frequency range using a single point laser vibrometer, excited using a dynamic shaker. Experimental studies were completed over a frequency range which represented the second bending mode. Quality factor values, Q, of approximately 200 were observed. No correlation, however, with phase transformation was realized. The design space charts for temperature, modal frequency, and beam tip amplitude were compiled for both the full-span and half-span sample for second bending mode. These charts graphically depict how tip amplitude changes with varied temperature and illustrate the design capabilities created through the use of shape memory alloy components in dynamic applications.

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

Cited by 6 publications

References 17 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

Performance Mapping of an Aluminum - Nitinol Composite Vibrating Beam

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