University of Maryland Mechanical Engineering Department ... · University of Maryland Vibration &...

University of Maryland Vibration & Noise Control Lab.

VIRTUAL DESIGN OF QUIET UNDERWATER SHELLSVIRTUAL DESIGN OF QUIET UNDERWATER SHELLS

W. Akl and A. Baz

University of MarylandMechanical Engineering Department

College Park, MD 20742Tel: 301-405-5216

e-mail: [email protected]

FEMCI Workshop 2003 May 7-8, 2003

NASA Goddard Space Flight Center


OUTLINE OF PRESENTATIONOUTLINE OF PRESENTATION

IntroductionIntroduction

Structural Acoustics of Underwater Stiffened ShellsStructural Acoustics of Underwater Stiffened Shells

Virtual Reality Design of The ShellsVirtual Reality Design of The Shells

Performance of the ShellsPerformance of the Shells

ConclusionsConclusions

Future DirectionsFuture Directions


OBJECTIVESOBJECTIVES

Design of Quiet Underwater Shells with Passive Design of Quiet Underwater Shells with Passive Stiffeners using:Stiffeners using:

MultiMulti--Disciplinary Design Optimization StrategiesDisciplinary Design Optimization Strategies

Virtual Reality EnvironmentVirtual Reality Environment


Structural Acoustics

Structural Structural AcousticsAcoustics

Active ControlActive ControlActive ControlMulti-Disciplinary

OptimizationMultiMulti--Disciplinary Disciplinary

OptimizationOptimization

Manufacturing

& Maintenance

Cost

Manufacturing Manufacturing

& Maintenance & Maintenance

CostCost

Virtual Reality

Environment

Virtual RealityVirtual Reality

EnvironmentEnvironment

DESIGN OF UNDERWATER SHELLSDESIGN OF UNDERWATER SHELLS


Stiffened shell configuration & geometrical parametersStiffened shell configuration & geometrical parameters

Width (a) Spacing (s)

Stiffener

Depth (b)

Shell

RRr

Shell Length (L)


STIFFENED, DAMPED & ACTIVE SHELLSSTIFFENED, DAMPED & ACTIVE SHELLS

RibbedRibbedRibbed Damped-RibbedDampedDamped--RibbedRibbed

ShellShell

ShakerShaker

Piezo-PatchPiezo-Patch

Constrained Layer DampingConstrained Layer DampingRibsRibs


TESTING OF TESTING OF STIFFENED, DAMPED & ACTIVE SHELLSSTIFFENED, DAMPED & ACTIVE SHELLS

Scanning Vibrometer

Scanning Vibrometer

Balancing WeightBalancing Weight

Test ShellTest Shell

MotorMotor

Water TankWater Tank

HydrophonesHydrophones

BalancingWeight

TestShell

HangingCables

Motor

WaterTank

Hydrophones


ACTIVE PERIODIC SHELLACTIVE PERIODIC SHELL

d

rϕ

x

vu

w

Coordinate System

kk-1

Actuator

Base shell controller

Active Periodic Shell Assembly


Base Shell

Constraining Layer

Viscoelastic Material (VEM)

GEOMETRICAL AND KINEMATICAL PARAMETERS GEOMETRICAL AND KINEMATICAL PARAMETERS OF THE SHELL SYSTEMOF THE SHELL SYSTEM


FINITE ELEMENT MODELINGFINITE ELEMENT MODELING

)⋅= ϕδ nwwvuxn Tx cos(,,,),(

The nodal deflection vector is:

where n = order of lobar mode, and ϕ = Circumferential angle

Equations of Harmonic Motion of Fluid-Loaded Shell:

[ ( )] [ ( )] [ ( )] [ ( )][ ( )] [ ( )] [ ( )]

( )( )

( )( )

( )

K n K n M n nn K n M n

np n

F nC

f f f

e

e

+ − ⋅ −− ⋅ ⋅ − ⋅

LNM

OQP⋅RST

UVW=RSTUVW

ωρ ω ω

δ2

2 2 0Ω

Ω

Structural Stiff. Control Stiff. Structural Mass Coupling Matrix Structural Defl. Loads

Fluid Stiff. Fluid Mass Fluid Pressure

[ ( )] [ ( )] [ ( )] [ ( )][ ( )] [ ( )] [ ( )]

( )( )

( )( )

( )

K n K n M n nn K n M n

np n

F nC

f f f

e

e

+ − ⋅ −− ⋅ ⋅ − ⋅

LNM

OQP⋅RST

UVW=RSTUVW

ωρ ω ω

δ2

2 2 0Ω

Ω

Structural Stiff. Control Stiff. Structural Mass Coupling Matrix Structural Defl. Loads

Fluid Stiff. Fluid Mass Fluid Pressure


For harmonic motion at frequency “For harmonic motion at frequency “ωω””

Pressure distributionPressure distribution

Finite Element of FluidFinite Element of Fluid--Loaded Stiffened Shells (cont.)Loaded Stiffened Shells (cont.)

Added Mass[ ( )] [ ( )] [ ( )] [ ( )]M n n K n na f fT= ⋅ ⋅ ⋅−ρ Ω Ω1

([ ( )] [ ( )]) ( ) [ ( )] ( ) ( )( ) ( )M n M n n K n n F nae e+ ⋅ + ⋅ =δ δo t m r l q

where

p n K n n nef f

T e( ) ( )( ) [ ( )] [ ( )] ( )m r m r= ⋅ ⋅ ⋅ ⋅−ρ ω δ2 1 Ω


Finite Element of FluidFinite Element of Fluid--Loaded Stiffened Shells (cont.)Loaded Stiffened Shells (cont.)

Sound Intensity (I)Sound Intensity (I) I x r p x rcf

( , , ) ( , , )ϕ

ϕρ

=⋅ ⋅

2

2

External Loads (F)External Loads (F) Fe Fc+External

LoadsExternal

LoadsControl Forces

Control Forces

where Fc = - Kd S δ

S = Actuator / Sensor Placement Matrix

F =


MultiMulti--Criterion Optimization (cont.)Criterion Optimization (cont.)

Objective Functions (Minimize)Objective Functions (Minimize)••Maximum Sound IntensityMaximum Sound Intensity••Maximum Radial Vibration LevelMaximum Radial Vibration Level

••Maximum Tangential Vibration LevelMaximum Tangential Vibration Level

••Maximum Axial Vibration LevelMaximum Axial Vibration Level

••Cost of Added Actuators/SensorsCost of Added Actuators/Sensors

••Weight of Actuator/Sensor MassWeight of Actuator/Sensor Mass

••Control EffortControl Effort

•• -- ControllabilityControllability

•• -- ObservabilityObservability

Actuator LocationsActuator LocationsActuator Locations

StiffenersStiffenersStiffeners

••Cost of Passive StiffenersCost of Passive Stiffeners••Weight of Passive StiffenersWeight of Passive Stiffeners


MultiMulti--Criterion Optimization (cont.)Criterion Optimization (cont.)

ConstraintsConstraints

••No. of Actuators/sensors (NNo. of Actuators/sensors (Naa)) 0 < N0 < Na a ≤≤ NNss

No. of StiffenersNo. of StiffenersNo. of Stiffeners

••Control Gain (Control Gain (KKdd)) 0 0 ≤≤ K K ≤≤ 22××101055

Design VariablesDesign Variables

••Number of ActuatorsNumber of Actuators••Actuator/Sensor LocationsActuator/Sensor Locations••Control GainControl Gain

Actuator LocationsActuator LocationsActuator Locations

StiffenersStiffenersStiffeners


AxialAxialAxial

CircumferentialCircumferentialCircumferential

RadialRadialRadialFrequency [Hz]

[m]

0 500 1000 150010-10

10-8

10-6

10-4

10-2

100

Frequency [Hz]

[m]

0 500 1000 150010-11

10-10

10-9

10-8

10-7

10-6

10-5

Frequency [Hz]

[m]

0 500 1000 150010-10

10-9

10-8

10-7

10-6

10-5

7 stiffeners - Controlled7 stiffeners 7 stiffeners -- ControlledControlled7 stiffeners - Uncontrolled7 stiffeners 7 stiffeners -- UncontrolledUncontrolledPlain ShellPlain ShellPlain Shell

Configuration 3: 3 Actuators on Ribs 1Configuration 3: 3 Actuators on Ribs 1--33--7, 7, KdKd=3,100=3,100(All design Objectives)(All design Objectives)

Vibration FRFVibration FRFVibration FRF


-2

-1.5

-1

-0.5

0

0.5

1

1.5

2 x 10 m-6

7 Stiffeners - Uncontrolled7 Stiffeners 7 Stiffeners -- UncontrolledUncontrolled 7 Stiffeners - Controlled7 Stiffeners 7 Stiffeners -- ControlledControlled

PlainPlainPlain


Shell Vibration Shell Vibration Shell Vibration


110

115

120

125

130

135

140

145

150 dBPlainPlainPlain 7 Stiffeners - Uncontrolled7 Stiffeners 7 Stiffeners -- UncontrolledUncontrolled 7 Stiffeners - Controlled7 Stiffeners 7 Stiffeners -- ControlledControlled

Frequency [Hz]

[dB]

0 500 1000 15000

20

40

60

80

100

120

140

160

7 stiffeners - Controlled7 stiffeners 7 stiffeners -- ControlledControlled7 stiffeners - Uncontrolled7 stiffeners 7 stiffeners -- UncontrolledUncontrolledPlain ShellPlain ShellPlain Shell


Sound Intensity Sound Intensity Sound Intensity


VIRTUAL REALITY DESIGN OF A TORPEDO VIRTUAL REALITY DESIGN OF A TORPEDO SHELLSHELL


WHY VIRTUAL REALITY ENVIRONMENT ?WHY VIRTUAL REALITY ENVIRONMENT ?

•In Virtual Reality (VR), human-computer interface technologyleverages the natural human capabilities.

•Today's interfaces (keyboard, mouse, monitor, etc.) force us to working within tight, unnatural, two-dimensional constraints.

•VR provides engineers with real-time 3D audio, visual & sensory perception in a more intuitive & natural manner.

•In VR, engineers can look and move around/inside a virtual model or environment, drive through it, lift items, hear things & feel things.


MISSION OF VIRTUAL REALITY LABORATORYMISSION OF VIRTUAL REALITY LABORATORY

Interactive & Collaborative Design of SMART StructuresInteractive & Collaborative Design of SMART Structures in:in:

Real time Real time

Environment with:Environment with:

virtual reality virtual reality audioaudio, ,

visualvisual, and , and

sensorysensory capabilities.capabilities.


DESIGN IN VIRTUAL REALITY ENVIRONMENT DESIGN IN VIRTUAL REALITY ENVIRONMENT

• Collaborative Design with other design sites

•• Design is Interactive with Designer in the LoopDesign is Interactive with Designer in the Loop

•• Vary design parameters & monitor response in realVary design parameters & monitor response in real--timetime


Projector

Wand

Mirror

Stereoglasses

Controllers

SGI-ONYXZ2 Computer

Speakers

COMPUTERCOMPUTER--AUTOMATED VIRTUAL AUTOMATED VIRTUAL ENVIRONMENTENVIRONMENT


Goggles

Tracking System

Wand

University of Maryland

UMCP VIRTUAL REALITY LAB


COMPUTER SYSTEM OF VIRTUAL REALITY LAB

SGI/ONYX2 COMPUTER


VIRTUAL REALITY LAB – USERS ROOM


VIRTUAL REALITY LAB - ACOUSTICS

Virtual Acoustics System

Mixers

Power Amplifiers

Top Speakers

Bottom Speakers


COMPUTERCOMPUTER--AUTOMATED VIRTUAL AUTOMATED VIRTUAL ENVIRONMENTENVIRONMENT


The Glove has six small vibro-tactile stimulators on the fingers and the palm.Each stimulator can be individually programmed to vary the strength of touch sensation.

CYBER TOUCH GLOVES


VIRTUAL DESIGN OF ACTIVE STRUCTURESVIRTUAL DESIGN OF ACTIVE STRUCTURES

TorpedoTorpedo


VIRTUAL DESIGN OF A TORPEDOE SHELLVIRTUAL DESIGN OF A TORPEDOE SHELL

SGI/ONYX2

Computer

Cost & Reliability

Virtual Audio

Structural & Acoustical

FEM

Networking

Optimization

Visualization

Input/OutputDevices

Implementation of virtual reality on SGI/ONYX2 Computer


Actuator Active Rib

Propeller

Nose

Damping

VIRTUAL DESIGN OF ACTIVE TORPEDOESVIRTUAL DESIGN OF ACTIVE TORPEDOES


VIRTUAL DESIGN OF A TORPEDO SHELLVIRTUAL DESIGN OF A TORPEDO SHELL


COLLABORATIVE DESIGN OF A TORPEDO SHELLCOLLABORATIVE DESIGN OF A TORPEDO SHELL


No. of stiffeners = 7, Active Stiffeners: 1,3, 7, Frequency 200 Hz

Gain =0



Gain =3000



Gain =0


Gain =3000



VIRTUAL DESIGN OF A TORPEDO SHELLVIRTUAL DESIGN OF A TORPEDO SHELL


FUTURE APPLICATIONS

Car Crash

Space Structures

Vehicle Dynamics & Acoustics


Virtual Reality Design of Helicopter Noise & Vibration Controls


ActivePatches

Shaker

Scanning arm

Scanning Laser

Fuselage

Stiffeners

Cessna Citation II Fuselage

Engineer

CAVE


ConclusionsConclusionsConclusions

1. Underwater Shells with Active stiffeners are designed using Multi-Disciplinary Optimization (MDO).

2. The optimal design parameters of the Actuator/sensor pairs ( Number, Location & Control Gain) are determined in order to minimize the sound radiation, the structural vibration, weight, production & life cycle cost, control effort & maximize controllability & observability.


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