Penn State

Center for Acoustics and Vibration

Structural Vibration and Acoustics Group

Presented as part of the 2012 CAV Spring workshop

Stephen Hambric, Group Leader

15 May 2012

Marty Trethewey Sabih Hayek

Stephen Conlon John Fahnline

Andrew Barnard Robert Campbell

Tim McDevitt Kevin Koudela

Tony Jun Huang Dan Linzell

Micah Shepherd

2/31 15 May 2012

CAV Overview

• Some project highlights – Quiet rotorcraft roof panel study with NASA

• Student Research – Effects of cabin pressurization on TBL-excited panel response

– Parallel acoustic boundary element procedures

– Recharacterization of the CAV hemi-anechoic room

– Fluid-structure interaction of flow-excited cylinder (a precursor to

propeller crashback)

– Static effects on vibration-based structural health monitoring

• Future Projects

• Important upcoming conference

3/31 15 May 2012

CAV

Development of Acoustically Tailored

Composite Rotorcraft Fuselage Panels

Principal Investigators: S.A. Hambric and K.L. Koudela

sah19@psu.edu, klk121@psu.edu

Sponsor:

Collaborators:

4/31 15 May 2012

CAV NASA NRA Project

• Development of

Acoustically

Tailored Composite

Rotorcraft Fuselage

Panels

– Joint with Bell

Helicopter and

Kansas State

University

– Combine treatments:

• Embedded

viscoelastomers

• Band-gap systems

• Tailored composites

5/31 15 May 2012

CAV Assess Baseline Panel

• Beam roof

frame

• Honeycomb

core sandwich

panel center

6/31 15 May 2012

CAV Baseline Panel in NASA SALT

7/31 15 May 2012

CAV Baseline Panel FE and BE Model

• Virtual Transmission Loss analysis with diffuse acoustic

field excitation cross-spectral densities

8/31 15 May 2012

CAV Baseline Panel Transmission Loss

9/31 15 May 2012

CAV Next Steps

• Design and build optimized quiet roof panel

• Test in NASA SALT and compare performance to that

of baseline panel

10/31 15 May 2012

CAV

Optimization of Aircraft Panels Excited by

Turbulent Boundary Layer (TBL) Flow

Advisor: S.A. Hambric

sah19@psu.edu

Student: Micah Shepherd (PhD, Acoustics)

mrs30@psu.edu

Sponsor:

11/31 15 May 2012

CAV Initial Study – Effects of Ribs and

Pressurization on Panel Response

Acoustic radiation

Aircraft panel

1 1

M M

P mnrad m nn m

G r G

HffG h G h

Tff FFG G

{ }

FF p

kk y c y jkx c x c x

G

e e e

12/31 15 May 2012

CAV NASA Designed Test Panel

Stringer thickness: 1 mm

Ring frames thickness: 1.27 mmPanel thickness: 1.27 mm

Critical frequency: 9.5 kHz

Clamped boundary conditions

13/31 15 May 2012

CAV FE Model

15568 linear quad elements

Stringer thickness: 1 mm

Ring frames thickness: 1.27 mmPanel thickness: 1.27 mm

14/31 15 May 2012

CAV Effects of Ribs on Noise

Flow speed: 210 m/s (Uc=147 m/s)

TBL model: Modified Chase-Howe

Corcos

Flow characteristics*: 32,000 ft

Decay constants: α1=0.07, α3=0.70

Assumed damping: 0.01

*Flight data provided by D. Palumbo, NASA Langley

( kx / kc = 50 – 1.3 )

f

15/31 15 May 2012

CAV Effects of Pressurization on Noise

• Cabin pressurization has little effect on isotropic

panels but large effect on ribbed panels

• Pressure loading of 34474 N (5 psi, 25,000ft) applied

to panel

• Modes, wavenumbers and radiated sound power

recalculated

• Temperature effects not included

16/31 15 May 2012

CAV Effects of Pressurization on Noise

Flow speed: 210 m/s (Uc=147 m/s)

TBL model: Modified Chase-Howe

Corcos

Flow characteristics*: 32,000 ft

Decay constants: α1=0.07, α3=0.70

Assumed damping: 0.01

( kx / kc = 50 – 1.3 )

f

17/31 15 May 2012

CAV Next Steps

• Develop procedure to find optimal rib locations for

minimizing key radiating modes

– Attempt to use global optimization routines

– Need fast concept analyses

– Modal approach with component mode synthesis

• Constraints on static response and stress

18/31 15 May 2012

CAV

Parallel Solutions for Rotationally

Symmetric Acoustic Boundary Element

Computations

Advisors: J.B. Fahnline, S.M. Shontz

jbf103@psu.edu

Student: Ken Czuprynski (M.S. Computer Engineering)

Sponsor:

19/31 15 May 2012

CAV Block Circulant BE Acoustic

Matrices

Ax b

1 2 3 4A A A A A

1 2 3 4

4 1 2 3

3 4 1 2

2 3 4 1

A A A A

A A A AA

A A A A

A A A A

Throw away

X Y

Z

V 2

Rotational symmetries

provide block circulant

structure

Store only the

unique blocks.

Solve and reassemble full solution using parallel processing

20/31 15 May 2012

CAV Block Circulant BE Acoustic

Matrices

Number of processors

Speedup improves with problem size

21/31 15 May 2012

CAV

Behavior of Marine Propellers in

Crashback Conditions

Advisors: S.A. Hambric and R.L. Campbell

sah19@psu.edu, rlc138@psu.edu

Student: Abe Lee (PhD, Acoustics)

Sponsor:

22/31 15 May 2012

CAV Initial Study – cylinder in cross

flow

23/31 15 May 2012

CAV

Re-characterization of the

CAV Anechoic Room and Transmission

Loss Suite

Advisor: A.R. Barnard

arb279@psu.edu

Student: Paul Bauch (M.S. Acoustics)

Sponsor:

24/31 15 May 2012

CAV Instrumentation and Data

Acquisition

Traverse Method ISO 3745 (2003)

• 70 points in space

• 12 traverse paths

• 50 to 10k Hz range

CAV TL Suite – Anechoic Chamber (V=93.24m3)

Rev

erb

Room

(V

=132.4

0 m

3)

TL Window (0.9 m X 0.9 m) Traverse Paths

25/31 15 May 2012

CAV Results so far…

• Hemi-anechoic at low frequencies.

• Transitions towards fully anechoic at

frequencies above 5 kHz due to carpeting.

• Deviation from free field is within allowable

tolerance described in ISO 3745 for f < 10kHz.

• Further study at frequencies 10kHz< f < 20kHz

is in progress.

0 0.5 1 1.5 2 2.5 3-4-3-2-101234

Deviation from free field propagation f < 630 Hz

Distance from Physical Source Center (m)

Devia

tion (

dB

)

Measured Dev. 95% confidence

Acceptable Dev.

0 0.5 1 1.5 2 2.5 3-4-3-2-101234

800 < f < 5000 Hz

Distance from Physical Source Center (m)

Devia

tion (

dB

)

0 0.5 1 1.5 2 2.5 3-4-3-2-101234

6300 < f < 10,000 Hz

Distance from Physical Source Center (m)

Devia

tion (

dB

)

500 1k 1.5k 2k 2.5k 3k 3.5k 4k 4.5k 5k100

120

140

160

180

Frequency (Hz)

Norm

aliz

ed S

PL r

ef.

20

Pa/(

m3/s

)

CAV Anechoic Chamber Experimental vs. Theory (Traverse #4 pos. 5)

Experimental (FRF)

Hemi-Anechoic

Full-Anechoic

26/31 15 May 2012

CAV

Investigation of Static Load Effects on

Vibration Based Structural Health

Monitoring

Advisor: S.C. Conlon

scc135@psu.edu

Student: Justin Long (B.S. Aerospace Engineering)

Sponsor:

27/31 15 May 2012

CAV Research Focus

Justin was awarded the Anthony E. Wolk Senior Thesis Award

Quantify static loading effects for active vibration based damage detection

Develop procedures to enhance / optimized damage detection

• Varying tensile and compressive load conditions

can effect the vibrational characteristics of

damage

Beam-skin Joint

Lap Joint

UH-60A Black Hawk:

Transmission Frame

28/31 15 May 2012

CAV Key Outcomes

• Increased static loading results in decreased detection sensitivity

• Challenge for newly emerging nonlinear vibration based NDE techniques

• Significant sensitivity regained by re-optimizing (active) drive frequency & amplitudes

• Sensitivity can even be enhanced in the case of compressive loads

• Study also showed nonlinear vibration based detection features outperformed linear counterparts

• Important results for future development of embedded SHM systems

Critical fatigue damage zones –

significant static / quasi-static

loading

29/31 15 May 2012

CAV Future Projects

• Modeling of sonic fatigue

in jet engine discharge

regions

– CFD simulations of nozzle

and discharge flow (led by

Dr. Phil Morris, Aerospace)

– Finite element and/or

Statistical Energy Analysis

simulations of nozzle and

discharge panel response

(led by Drs. Hambric and

Campbell)

• Students: Matt Shaw

(PhD, Acoustics), Unmanned Air Vehicle(UAV)

30/31 15 May 2012

CAV Future Projects – DoE Cyber

Wind Facility

WAKE-

TURBINE

INTERACTIONS

(wind plant)

*BLADE AND *TOWER

ELASTIC DEFORMATION

(FEM + Modal model)

*BLADE AERODYNAMICS,

SPACE-TIME LOADINGS

(Hybrid URANS/LES + Overset)

WAKE TURBULENCE

BLADE-WAKE-ATMOSPHERE

(Actuator Vortex Body

Embedding within LES)

MESO-SCALE, WEATHER

(URANS)

*MARINE ATMOSPHERIC

BOUNDARY LAYER

TURBULENT WINDS

(4-D LES + Overset)

*sensors,

controllers,

diagnostics

*PLATFORM-WAVE

HYDRODYNAMICS

6-DOF MOTIONS

(Hybrid URANS/LES

+VOF+ Overset)

*Shaft Torque, *Gearbox Loadings

• Objective: Develop a “Cyber Wind Facility” to generate the

highest fidelity, most well-resolved 4-D data possible

simultaneously over an entire off-shore wind turbine

• Involves high-performance computing of fully-coupled

CFD/CSD for turbine-platform-wake interactions with the

atmosphere and ocean

• James Brasseur (ME, PI)

• Eric Paterson (ARL/ME, Co-PI)

• Sven Schmitz (AERSP, Co-PI)

• Robert Campbell (ARL, Co-PI)

31/31 15 May 2012

CAV Welcome to the Big Apple

Inter-Noise 2012

Quieting the World’s Cities

New York City , USA

19-22 August 2012

Stephen Hambric, General Chair

Stephen Conlon, Technical Chair

www.internoise2012.com

NCAD

Strong Participation Over 1000 papers expected (1430 abstracts)

1200-1500 attendees

70 exhibitors