Penn State Center for Acoustics and Vibration

Transcription

1 Penn State Center for Acoustics and Vibration Structural Vibration and Acoustics Group Presented as part of the 2012 Spring workshop Stephen Hambric, Group Leader Marty Trethewey Stephen Conlon Andrew Barnard Tim McDevitt Tony Jun Huang Micah Shepherd Sabih Hayek John Fahnline Robert Campbell Kevin Koudela Dan Linzell

2 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 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 2/31

3 Development of Acoustically Tailored Composite Rotorcraft Fuselage Panels Principal Investigators: S.A. Hambric and K.L. Koudela Sponsor: Collaborators: 3/31

4 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 4/31

5 Assess Baseline Panel Beam roof frame Honeycomb core sandwich panel center 5/31

6 Baseline Panel in NASA SALT 6/31

7 Baseline Panel FE and BE Model Virtual Transmission Loss analysis with diffuse acoustic field excitation cross-spectral densities 7/31

8 Baseline Panel Transmission Loss 8/31

9 Next Steps Design and build optimized quiet roof panel Test in NASA SALT and compare performance to that of baseline panel 9/31

10 Optimization of Aircraft Panels Excited by Turbulent Boundary Layer (TBL) Flow Advisor: S.A. Hambric Student: Micah Shepherd (PhD, Acoustics) Sponsor: 10/31

11 Initial Study Effects of Ribs and Pressurization on Panel Response G FF p k y kc y jk { e x c x e e c x} G ff T G FF G h G h ff H Aircraft panel M M GP rad rmn G m n n 1m 1 Acoustic radiation 11/31

12 NASA Designed Test Panel Critical frequency: 9.5 khz Clamped boundary conditions Stringer thickness: 1 mm Ring frames thickness: 1.27 mm Panel thickness: 1.27 mm 12/31

13 FE Model linear quad elements Stringer thickness: 1 mm Ring frames thickness: 1.27 mm Panel thickness: 1.27 mm 13/31

14 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: α 1 =0.07, α 3 =0.70 Assumed damping: 0.01 f *Flight data provided by D. Palumbo, NASA Langley ( k x / k c = ) 14/31

15 Effects of Pressurization on Noise Cabin pressurization has little effect on isotropic panels but large effect on ribbed panels Pressure loading of N (5 psi, 25,000ft) applied to panel Modes, wavenumbers and radiated sound power recalculated Temperature effects not included 15/31

16 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: α 1 =0.07, α 3 =0.70 Assumed damping: 0.01 f ( k x / k c = ) 16/31

17 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 17/31

18 Parallel Solutions for Rotationally Symmetric Acoustic Boundary Element Computations Advisors: J.B. Fahnline, S.M. Shontz Student: Ken Czuprynski (M.S. Computer Engineering) Sponsor: 18/31

19 Y Block Circulant BE Acoustic Matrices Ax b A A A A A A A A A A A A A A A A A Rotational symmetries provide block circulant structure Throw away A A1 A2 A3 A4 Store only the unique blocks. Solve and reassemble full solution using parallel processing 19/31

20 Block Circulant BE Acoustic Matrices Speedup improves with problem size Number of processors 20/31

21 Behavior of Marine Propellers in Crashback Conditions Advisors: S.A. Hambric and R.L. Campbell Student: Abe Lee (PhD, Acoustics) Sponsor: 21/31

22 Initial Study cylinder in cross flow 22/31

23 Re-characterization of the Anechoic Room and Transmission Loss Suite Advisor: A.R. Barnard Student: Paul Bauch (M.S. Acoustics) Sponsor: 23/31

24 Reverb Room (V= m 3 ) Instrumentation and Data Acquisition Traverse Method ISO 3745 (2003) 70 points in space 12 traverse paths 50 to 10k Hz range TL Suite Anechoic Chamber (V=93.24m 3 ) TL Window (0.9 m X 0.9 m) Traverse Paths 24/31

25 Results so far Anechoic Chamber Experimental vs. Theory (Traverse #4 pos. 5) 180 Normalized SPL ref. 20 Pa/(m 3 /s) 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. Experimental (FRF) Hemi-Anechoic Full-Anechoic 500 1k 1.5k 2k 2.5k 3k 3.5k 4k 4.5k 5k Frequency (Hz) Deviation (db) Deviation (db) Deviation (db) Deviation from free field propagation f < 630 Hz Distance from Physical Source Center (m) < f < 5000 Hz Distance from Physical Source Center (m) Distance from Physical Source Center (m) Measured Dev. 95% confidence Acceptable Dev < f < 10,000 Hz 25/31

26 Investigation of Static Load Effects on Vibration Based Structural Health Monitoring Advisor: S.C. Conlon Student: Justin Long (B.S. Aerospace Engineering) Sponsor: 26/31

27 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 UH-60A Black Hawk: Transmission Frame Beam-skin Joint Lap Joint 27/31

28 Key Outcomes Increased static loading results in decreased detection sensitivity Challenge for newly emerging nonlinear vibration based NDE techniques Significant sensitivity regained by reoptimizing (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 28/31

29 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) 29/31

30 Future Projects DoE Cyber Wind Facility 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) *PLATFORM-WAVE HYDRODYNAMICS 6-DOF MOTIONS (Hybrid URANS/LES +VOF+ Overset) MESO-SCALE, WEATHER (URANS) *MARINE ATMOSPHERIC BOUNDARY LAYER TURBULENT WINDS (4-D LES + Overset) *BLADE AERODYNAMICS, SPACE-TIME LOADINGS (Hybrid URANS/LES + Overset) WAKE TURBULENCE BLADE-WAKE-ATMOSPHERE (Actuator Vortex Body Embedding within LES) WAKE- TURBINE INTERACTIONS (wind plant) *BLADE AND *TOWER ELASTIC DEFORMATION (FEM + Modal model) *Shaft Torque, *Gearbox Loadings *sensors, controllers, diagnostics 30/31

31 Welcome to the Big Apple Inter-Noise 2012 Quieting the World s Cities New York City, USA August 2012 Stephen Hambric, General Chair Stephen Conlon, Technical Chair NCAD Strong Participation Over 1000 papers expected (1430 abstracts) attendees 70 exhibitors 31/31