Overview of NASA GRC Research on Damping of Jet Engine Blades

National Aeronautics and Space Administration

Overview of NASA GRC Research on Damping of Jet Engine Blades

Kirsten P. Duffy Senior Research Associate

University of Toledo NASA Glenn Research Center

Penn State University Seminar - 12/2009

•

www.nasa.gov 1


• Aircraft Engine

Fan Combustor

Compressor Turbine

..... - ..... --

GE90 Turbofan Engine http://www.geaviation.com/education/theatre/ge90/

Penn State University Seminar - 12/2009 www.nasa.gov 2


Engine Blade Forced Vibration • 700

600

500

www.grc.nasa.gov/WWW/K-12/airplane/caxial .html 100

o

Blade Vibration Modes


R Range 01 operating speeds

2000 4000 RotOf" speed, rpm

Engine order

6

5

_--1

6000

11>1 ~I dlag,.,., IOf" rotOf" blade ahowll"lQ poaalble '~pon .. tondlllon 'rom _ance (denoted by c:lrtlee,.

Reddyet. al. 1993 NASA TP-3406 "A review of recent aeroelastic analysis methods for propulsion at NASA Lewis Research Center"

www.nasa.gov 3


Mistuning

• Blades are manufactured with slight differences • Problem -7 Localized vibration

• Solutions

• Increased damping

• Increased coupling among blades and disk

Response levels higher than predicted

"Advanced vibration analysis tools and new strategies developed for robust engine rotor development" 2005 Research and Technology Report - NASA Glenn Research Center Castanier & Pierre, U. of Michigan - Min, NASA

•



•

Flutter

Flutter • Self-excited oscillation

• Airflow/blade interaction -7 instability

• Increasing damping can reduce the risk of flutter


.....,. ... lIc lnalAlblllty

I SUb~ &hili fluller la Syotom mode lnalJlbYIty II Choke tIutIw III Low-lncIcIence euperaonIc _er IV HIgh-lncidenCII III.,.. lOUie fluller V S......-.Ie bending &hili ttuner

100~ opeod line """'

\

V

eon.ctod ,..... flow

III

c-I Map _ng ptlnclpel typea of tIutIer end regiOnS ot oc:c:un.noe (rei. 4'.

Reddy et. al. 1993 NASA TP-3406 "A review of recent aeroelastic analysis methods for propulsion at NASA Lewis Research Center"

•

www.nasa.gov 5


Future Aircraft • • Embedded engines

Benefits:

• Decreased noise

• Improved efficiency

• Possibility of short takeoff and landing

Problem: Non-uniform flow into engine - blade excitation

Cambridge-MIT Institute (CMI) SAX-40


Distorted Flow into Fan

www.nasa.gov 6


Q) III C 0 Q. III Q)

a:: tl

:;:::; ro -en 0 -Q) III C 0 Q. III Q)

a:: tl

'E ro c >-0 -0 0

:;:::; ro a::

1000

100

10

1

0 .1

0 .75

Solution - Damping 0.020

0.015

_ 0.010 c

i 0.005

Q = 500, T] = 0.002, C, = 0.001 • ~ 0.000 ~ ~ -0.005 ~

0 ..0.010

-0.015

-0.020

Q" 50, "" 0 .02, ~ "O.O'/ '\ 0 1 2 3

~ V ~ t::--.. - -Q= 5, 0 .2, c:; = 0 1

Q = 0.5. I] = 2, C. = 1

I I I 0 .80 0 .85 0 .90 0 .95 1 .00 1.05 1.10 1.15

Ratio of Forcing Frequency to Resonant Frequency «(I)/6>n)


•

• , • 7 • Tlme(.)

I

.,

1.20 1.25

www.nasa.gov 7


Engine Blade Damping • • Sources of damping* r.----Material damping

• -0.02%

• Very low for metals, higher for composites

Aerodynamic damping

• 0.1% - 1%

Structural/mechanical damping

• Friction at the blade root

• Friction at shrouds

• Platform damping

• Added damping treatments

• 0.5% - 3%

• Newer blade designs Integrally bladed disks (blisks) - no friction at blade/hub attachment

Highly-loaded blades - higher efficiency * Y. EI-Aini, R. deLaneuville, A. Stoner, V. Capece, "High Cycle Fatigue of

Turbomachinery Components - an Industry Perspective," AIAA-1997 -3365.


Pratt & Whitney Shrouded Fan Blade

I

I "l

I ':-'p.,l' ~.,.:~::~~.~.~<_ .. . ~J .. _ .L.~J~

" . / >. ~ ("'. <....,. -.J '--...

. ..... l '

.---- ------,J

GE Platform Damper Patent 5,478,207

www.nasa.gov •

National Aeronautics and Space Administration -0 NASA Damping Research

• Turbomachinery blade damping research at NASA Glenn

~ Impact damping

~ Viscoelastic damping of composite blades (with UC San Diego)

~ Plasma-sprayed damping coatings

~ High-temperature shape memory alloys

~ Piezoelectric materials - passive damping and active control

-_ ........ ----Composite Fan Blades - Tested with Viscoelastic Damping



• Aircraft Engine Blade Environment

Typical Target Application - lower-temperature:

• Titanium alloy fan or cold-side compressor blade

• Composite fan blade

Temperature -40 to 30()oC

Vibratory strain amplitude up to 10-3

Mean strain zero to 10-3

(from centrifugal loading)

Frequency 100 to 10~000 Hz

Typical blade loss factor 10-3 or lower

Target blade loss factor 10-2

Note: loss factor 17 = Q-l = 2(;= tan8

Penn State University Seminar - 12/2009 www.nasa.gov '0


• Analysis and Testing Procedure • Analysis - Simple reduced order models, structural finite element models,

aeroelasticity models (fluid/structure interaction)

• Testing - Bench testing, testing in simulated engine environments

• Test Articles - simple beam, flat plate, twisted plate, blade

Penn State University Seminar - 12/2009 www.nasa.gov "


Self-Tuning Impact Damper -e

•

•

Impact Damper

Displacementdependent (nonlinear)

Immobilized at high-g's

g


• •

•

Tuned-Mass Damper

Frequency-dependent

Damping at tuning frequency

g

Displacements may be too large for blade cavity

•

•

g

Tuned Impact Damper

Frequency- and displacement-dependent (nonlinear)

Performs better at high-g's

www.nasa.gov 12


Self-Tuning Impact Damper • 4.0

" "" .~ 3.5 Q. E 3.0 -< " '"' 2.5 .:= .;: c; 2.0 =G ~ 1.5 .. ~ 1.0

0.5

1\ ~

0.0

0.0

Free Decay Envelope

~\ \ '\ \ '" Without Darr ~er

\ ~ \.-. W illl Da'!'Jll'1 I'---

1.0 2.0 3.0

Time (seconds)


0.010

0.009

V' 0.008 ..r ~ 0.007 'u !E 0.006

Q)

8 0.005 OIl .5 0.004 0.. ~ 0.003

Q 0.002

0.001

0.000

r ~ with Irr pact Darr per

I Ill:, '\ ) ~ \ I '\ \

\ ~ \ ~

If "'- I:, \ ithout In pact Dar per

'---....

-

0.00 0.05 0.10 0.15 0.20 0.25 0.30 0.35 0040

www.nasa.gov 13


Self-Tuning Impact Damper • /

/'///,/,

/ Damper

Mass /

a

/, /,////

lJ' 0.012 <l . ~ 0.010 = ... c. e =

0.008

~ 'C ~

0.006 'C 'C

0.004 « 0.002

0.000


0.0

Tuned-Mass Damper vs Tuned Impact Damper

"'Tuned-Mass I-

Damper ...... Impact Damper l-

I--

+ Tuned Impact D: I--

)

~ "A ,...

I

~ '--- - -0.5 1.0 1.5 2.0

Ratio of Tuned-Mass Frequency to Blade Frequency

www.nasa.gov 14


Self-Tuning Impact Damper Plate Top View Side View

Plate Motion



Self-Tuning Impact Damper

Co <-, ~ '? // ~ ~ ~~ 18 Mode ~ ~ ~ 'N100 -- Short Plate ::r: -- ~~1. >-u 80 c::: Q) -----::I 18 Mode 0-Q)

60 Long Plate .... u. Q) u

~:::1 c::: 40 ro

c::: 0 VI Q)

20 Cl: Q) +-' ro c.. a

0 600 1200 1800 2400 Rotor Speed (RPM)

Penn State University Seminar - 12/2009 www.nasa.gov I.


Self-Tuning Impact Damper

0.014 ~-~--~-----r--T.=====::::::J=====::;] -+- N = 3 - 900 rpm

0.012 +--------Ir\-----+-----+---____+_ - N = 4 - 655 rpm V' t -A.-N=5-510rpm <l ~ 0.01 0 -l----Hc+---f-l---Il+----'d-"' +---_____+_ --0 - N = 3 - 1980 rpm ~ 'I' /' l -1J- N=4 - 1375rpm

.0. 0.008 I \ "J \ . \ -6 - N = 5 - 960 rpm E I ~~ , I --Impact Damper

~ 0.006 l .;J \ "0 ~...... ,, ~ \ ~ " ~ 0.004 -"'\. ~ ~~.'-----l,...----l'l/,,---' --,--,, _,,----++ ,'...t __ ----+_----+_---+-__ ----i

«"0 ~, V',,' \ I \

,, ~ .. \ \ \ 0.002 , I ~

+ ___ "L'l'-+-_~_~V+~---- ~r-:::::-,,_ :::::::: ::: i... - _ =::: ...

0.000 W ~

o 500 1000 1500 2000 2500 3000

Rotor Speed (rpm)


•

www.nasa.gov 17


Viscoelastic Damping • •

•

Complex Modulus

• E = E1+i E2 = E1(1+i 11)

• El - Storage Modulus

• E2 - Loss Modulus

• 11 - Loss Factor

• Properties dependent on frequency and temperature

Material Behavior

• Glassy region - polymer chains highly ordered - higher stiffness

• Transition region - high damping

• Rubbery region - lower stiffness, lower damping

• Energy Dissipation

• Through shear stress

• Constrained layer treatment


Glassy Region Transition RegiorRubbery Regiorflow Regi

~ , , ,

E, "5 "'C

~ ..... .§

~ If .3 (/) "'C .§ C III Q) C) III ..... .9 (f)

Temperature Roush-Anatrol

www.nasa.gov '8


Viscoelastic Damping • Composite Fan Blade

Kosmatka, Appuhn, Mehmed AIM Paper 2002-1511

" Design and Testing of Integrally Damped First-Stage Composite Fan Blades"

Fig. 3 Blade componenlS

Kosmatka, Lapid, Mehmed - AIM Paper 96-1598 "Passive vibration control of advanced composite turbo

fan blades using integral damping materials"


High

resonant stress area

Viscoelastic material

• Collaboration between NASA GRC and John Kosmatka - UC San Diego

• Place viscoelastic material within pocket between graphite/epoxy plies

• Locate visco in area of high modal shear stress

)0> Successful demonstration in dynamic spin testing at NASA Glenn

www.nasa.gov 1.


Viscoelastic Damping I«!~

[] -damping sandwich l OC!:.(l

1 0c!~

",,"I

I..,"'"

: I G'Z<J >

ritanituu 1 ~.()&

spar IOe ...

me '"0 U'~ mo leo we lIDO In ,.0 I" 1'"50

Unidirectional graphireJ~xy

Parch definition for optinnuu d<Ullping of first chord-wis .. mode (1581 Hz).

damping -.-I---~sandwich

titanium

Fig. 5 Patch definirion for mmomum damping of first chord-\v~se 1llOde (1581 Hz).

~Q'b:'

Fig 10 Pow« Spoctrum Comparison for the I" Chord""e Mod< at I QQQ RPM

!CC!:4

t.X! .(!

t~!.(J

toe! '(J ~

10;2.:,.l

I )O.! .o'

IY.!~~ __ --~--__ ~--~ ____ ~--~ __ --~

1110 11") 1!9C 1m 1430 160e In 1m 1· .0 1")(, 1:»

~h)

Fit' 21 Pow« SPOCtnllll Comporison for the I" Chord",,,, Mod< .t 3 QQQ RPM

Kosmatka, Appuhn, Mehmed - AIAA Paper 2002-1511 "Design and Testing of Integrally Damped First-Stage

Composite Fan Blades"


•


Damping Surface Treatment • Examples:

• Viscoelastic surface treatment

• Plasma-sprayed damping coating

• Surface-mounted high-damping shape memory alloy

• Surface-mounted shunted piezoelectric patch

Oberst beam - thin layer of damping material on beam surface

• Very thin layer:

1] beam + damping ~ 31] damping


EdamPing

E beam

·.JDltanium . .JllcIY beam with plasma-sprayed

coating

t damping

t beam

www.nasa.gov 21


Plasma-Sprayed Damping Coatings • • Typical coatings currently in use

Thermal-barrier coating

• Allow higher-temperature airflow while insulating metallic blades

Environmental-barrier coating

• Erosion-resistance, durability

Added benefit ~ damping

• Damping mechanism Low temperature (compressor application) -friction between IIsplats" of coating material - strain level dependent

High temperature (turbine application) -elevated damping corresponds with decrease in Young's modulus of the coating-tem peratu re-dependent


Plasma Spray Torch

Sona coat .J ~' 1- • i .. \ I ,'''' .. . . ~" . .. ."

Plasma-Sprayed Coating used for Damping Test

www.nasa.gov 22


Plasma-Sprayed Damping Coatings • High-temp application

Zhu, Miller, Duffy, Ghosn - 2009 "High remperatu re Damping Behavior of Plasma-Sprayed

Thermal Barrier and Protective Coatings" The 33rd International Conference on Advanced Ceramics &

Composites


4500

50 l-

40 r

30 I-

20 r

10 I-

o 4500

5000 5500

I

:::k · • I

1230C~~

I

5000 5500

Frequency (Hz)

6000 6500 7000

, .J' 11 '-

LV\.. ~\...

, :.4 ' ::.,...--..-

• ......-..... . • .......-.. I I

c c ~ ... • • -----..d'.

)\ ..,!'-

./'c. -, I .cI

6000 6500 7000

Frequency (Hz)

7500 8000

~RT

-<>- 258C-heating

---0-- 522C-heating

----<r- 660C-heating

---<I-- 890C-heating

--Q- 9SSe-heating

--- 1032C-heating J -

------ 1123C -heating

..... ;:, -

't-.o-. 7500

-

-

-{}- 1230C-heating - I I 27C-cooling

------ 1036C-cooling

- 95QC-cooling

~ 893C-cooling

---15>-- 776C -cooling

- 659C-cooling

- 523C-cooling

- 259C-cooling

800~ RT-cooling

www.nasa.gov 23


Shape Memory Alloys

Stress

~lal1ensite

Phase nmsfonnation Region

Austenite Phase

MfMs As Af Top Temperamre

.4mtmite • High temperature phase • Cubic Crystal Structure

lI1arlell.f"ite • Low temperature phase • Monoc1ini c Crystal Structure

II Twinned Martensite

smart.tamu.edu Lagoudas

Detwinned Martensite

Coolulg

H~ating Wire Contracts

==>

Weight

Cooling Wire E'ttends

>

Shape Mmlory Alloy Wire Actuator

DetwuUling

Heating Rero,"ery

Figure 1. DiHerent phases of an SMA. F9K'e 3. Schemedc 01 •• tr .... streln.tamperature curve showing the shape memory enacL



High-Temperature Shape Memory Alloys • High-Temperature Shape Memory Alloys are an enabling technology to a host of " smart" structures in jet engines

Shape ch.mging blOldeS Aniculating vanes

Acoustic Flow control liners devices

Advantages of HTSMA

Active Clearance

Control

• High force per volume/weight - compact, lightweight

vectored exhaust nozzles & V~S

• Solid State - eliminates hydraulics, pneumatics, mechanical systems Simple, frictionless , quiet, maintenance free

• Passive control - eliminates sensors, electronics • Can be actively controlled for high-force, precision movements

"Characterization of a New Phase and its Effect on the Work Characteristics of a Near-Stoichiometric Ni30 Pt20 Ti50 (at.%) HighTemperature Shape Memory Alloy (HTSMA)", Garg et. aI., Presentation at The International Conference on Shape Memory and

Superelastic Technologies (SMST) 2008, 21-25 Sep. 2008; Stresa; Italy



High-Temperature Shape Memory Alloys

• HTSMAs - High temperature and force capability

- Low frequency applications

• Potential engine applications Surge control rod for a centrifugal compressor - avoid instability

• "Development of a HTSMA-Actuated Surge Control Rod for High-Temperature Turbomachinery Applications" Padula et. aI. , 15th AIAAlASME/AHS Adaptive Structures Conference; 23-26 Apr. 2007

Supersonic inlet compression ramp - improve engine efficiency • "Development and Test of an HTSMA Supersonic Inlet Ramp Actuator (Future of

SMA)" Quackenbush et. aI. , Proceedings of the 15th SPIE Smart Structures/NDE Annual International Symposium, vol. 6930, 2008, paper 6930-25.

Active blade tip clearance control - improve engine efficiency • "Progress on Shape Memory Alloy Actuator Development for Active Clearance

Control" DeCastro, Melcher, and Noebe, NASA-CP-2006-214383

Adaptive exhaust chevrons - noise reduction • "Benchtop Demonstration of an Adaptive Chevron Completed Using a New High

Temperature Shape-Memory Alloy" Noebe and Padula, NASA GRC 2005 Research and Technology Report

Penn State University Seminar - 12/2009 www. nasa.gov 26


Shape Memory Alloy Damping • NiTiHf samples tested for modulus and damping

properties

Looking for damping in phase-transition region

Purely passive damping properties

Damping is temperature-dependent

•

Tested using Dynamic Mechanical Analysis (DMA) at 0-3000 C and at 0.1-200 Hz

SU'ess

Cit


Martensite Phase

Austenite Phase

MfM. As Af Top Temperanu'e

www.nasa.gov 27


Shape Memory Alloy Damping 2.0 -E

E -c: .2 1.0 1:) Q) ;;: Q)

c 0.0

- - -. -- - --~

Martens ite

Static Force Test

\. ........... Aus ~enite

" i\ "' \ -- -- -- ----

- DMA Test - Low Frequency ~ 100000 .--------,------,---,--------'--,---1 -'------,-----,

- - - _ Modulus ~ 80000 r-----r---",,--t:-=-.......~~:::;;:::;;::;:::;;;;:::~:::r .2 "" /- - - -'" j'"-:::l 60000 +----t-----t--.,,~-+---~_;;/----t-----t-

" ~ 40000 f-- -- Heat!ng f--+-----,_ ---'-----A----+------+

.tII - - - Cooling / / \ Loss / \ § 20000 +-----+--_ - /-----v'--------.-\ ,~acto/--+---+-1"-t------+---+

~ 0 +-~~~~~=i==~~,~~-~-~-~~-~-~~~~~

•

0.5

0.4 !=" ... 0

0.3 -CJ as 0.2

u.. til til

0.1 0 ..J

0.0

o 50 100 150 200 250 300

Temperature (0C) Penn State University Seminar - 12/2009 www.nasa.gov 28


Shape Memory Alloy Damping

100000

- 80000 ns 0-:E -I/) 60000 ::l

I ~

~ Modulus

\ ~ 7 0.1 Hz "" ::l

"0 1 Hz 0 :E .1/) 40000

10 Hz 100 Hz

C) C ::l 0 > 20000 / Loss

Factor

Tested in Heating

L It\ -o o 50 100 150 200 250

Temperature (oC)


0.5

0.4

0.3

0.2

0.1

0.0 300

•

~

.: 0 -u ns u. I/) I/) 0

...J

www.nasa.gov 29


• Piezoelectric Materials

• High-temperature piezoelectric materials Off-the-shelf high-temperature material- Type-II PZT - Tc = 350°C

NASA GRC-developed materials - Tc = 430°C

• Potential engine applications Active combustion control

• Mitigate thermo-acoustic instabilities and/or gas flow control to improve efficiency

Synthetic jets for active flow control

Energy harvesting

- "High-Temperature Piezoelectric Material Developed" Sayir and Sehirlioglu, NASA GRC 2007 Research and Technology Report

- "Doping of BiSc03 -PbTi03 Ceramics for Enhanced Properties" Sehirlioglu, Sayir, and Dynys, Materials Science and Technology Meeting ASMjACERS; 5-9 Oct. 2008; Pittsburgh, PA



High-Temperature Piezoelectric Material -Objective: Piezoelectric material development for damping system for high temperature turbomachinery blade applications.

20000

Slip cast patches of GRC·63L composition developed and processed at NASA Glenn Ceramics Branch

,-----------,

2x10 ')

r~============================~~~ E 12

./ Higher operating temperature ~ c: 8

'/Higher piezoelectric coefficient ,g .~

./ Higher Coercive field ~ 4

o~~==~~_~~o X Lower energy conversion efficiency 0..

~ o 100 200 300 400 sao 10 20 30

•

03

c: .§

0.1 ii5

Temperature ('C) E-field (kV/cm)

l Material 1 r----------------------- --.l Device Comparison to the state of the art material

~"""~"'P."!"I'! Temperature (0C)

Ferroelectric and Electromechanical

Curie Oepoling

GRC-63L 430 352

PZT-II 315 280

Piezoelectric (100 °C) coupling coefficients

Ec (kV/cm)

23

12

d33 (pC/N)

625

585

0.43 0.22

0.52 0.28

.Points of Contact: Ceramics. Branchl Dr. Alp Sehirlioglu, 216-433-6159, Dr. Ali Sayir, 216-433-6254, Dr. Fred Dynys, 216-433-2404

·n ~ c .,

www.nasa.gov 31


Piezoelectric Damping

• Concept: Piezoelectric material under load produces an electric field

Place piezoelectric material in an area of high modal stress in/on the blade

Passive damping technique - place a shunt circuit across the piezo material to dissipate energy

Active vibration control - use piezo materials as actuators and sensors with a control system to actively reduce vibration level


www.wikipedia.org

•

www.nasa.gov 32


Piezoelectric Damping • Metal blades

Require machining to place piezoelectric material and circuits

Possible placement below blade platform

• Composite blades Embed piezoelectric material between plies

Weave piezoelectric fibers into the plies - 15-250 micron diameters

_M

. ,...... ~

•

Hilbert et. al. Patent 6,299,410

Fibers - Advanced Cerametrics Inc.

Damping c=::> if material

High resonant

stress area

Kosmatka et.a!.

•




• Resistive Circuit (R-Circuit) - Energy dissipated through the resistor

Broad frequency range, lower damping

• Tuned Resonant Circuit (RL-Circuit) - Tuned to resonance frequency through

the inductor

Higher damping at target frequency

- Inductor is a simple coiled wire

- fully passive


•

www.nasa.gov 34


Piezoelectric Damping •

Air-Core Inductor


Optimal inductor for 700-800Hz

0.69 H wound inductor:

• 34-gauge wire

• 0.75-inch inner diameter

• 2.6-inch outer diameter

• 0.30-inch length

• SlOW • Too large for blade application

Inductor size required for higher frequencies:

• 2000 Hz - 0.1 H

• 5000 Hz - 0.015 H

www.nasa.gov 35


Piezoelectric Damping • Clamp

• • 3.2 in

••

3B Mode - Modal Deformation


Mide qplOw PZT-SA patch 1.31" x 1.81" x 0.010" thick

Ti 6AI-4V 0.078" thick plate

3B Mode - von Mises Modal Strain

www.nasa.gov 36


Piezoelectric Damping Laser Target

Location

Piezoelectric Patch

25 .. '0

= ... ·S 20 ~ 01

~ = 15 <= .• ... OJ

=

\

I Short Circuit

/

1/\ f \ }

I t

Clamp Accelerometer

Open Circuit J

10 = '"' .. ~ '" 5 = 01

H Rl-Circuit I L ~\ I R-Circuit I

I~ ....::;: '" -- ,:--... .. Eo-

0

670 675 680 Frequency (Hz)

685 690

•



Active Control with Piezoelectrics • E 1 xcitation Excitation/Co

+ Source ntrol System Am 1 o 0

HP dSP

+1 Am

An aly -ACE + o 0

Am I'" _a,

Ben Choi - NASA GRC

Bmr~q_Re~~ __ ~ ____ ~_6_:1 ____ ~~r-____ ~

1111 ~~?-~~:l-~~~-I~-I---~

1-J"'-----·tJncontrolletH-------1

-5611c FlllCtn log Hz ~er~ X:1.62725icHz Y:·8.96386dB


Sensor from the otber ;ide

"~

(

~ QP21b ~ l4.

1 V el et

rom r

2-Stripe Mode Shape

Fr~R~~ CliO; 1 Br---------------------------~

-A----~~L~-- . '~----1 .,-/ ------£!;ontrotterl--

FLrdn Log Hz

www.nasa.gov 38



•

Dynamic Spin Facility Rotor with Tapered Test Plates



~ r.. .s ~ ~

t;;;;.

'" '" Q oJ

0.010

0.008

0.006

0.004

0.002

0.000

2000

Piezoelectric Damping R-Circuit vs. Open Circuit Damping in Spin Rig

·3B-O-C

• 3B-R-C • ... Increase (3B-R-C - 3B-O-C) : • • • • • • • I • I • I • •

I • I , a • • , , • • • 1 t ...

a • • t i ...

2500 3000 3500

Rotor Speed (RPM)

• I I

I I

I I

I I I I

!

,

4000

Spin test: -11] = 0.0018 (average based on tip displacement) Shaker test: -11] = 0.0025 (based on tip velocity)



Current Research Plans

• Plasma-sprayed damping coatings - Measure modulus and damping of individual coatings

• HTSMA damping SMA materials with less temperature hysteresis

SMA materials with phase transitions less frequency-dependent

• Piezoelectric damping Application to metal blades

• Continue spin testing of passive damping with tuned RL-circuit

• Begin spin testing of actively controlled plates

Application to composite fan blades

• Embedding piezoelectric materials/patches within composite blades

Trade studies

• Determine potential weight savings for entire engine

•


Documents

Overview of NASA GRC Research on Damping of Jet Engine Blades