PRODERA SYSTEMS FOR MODAL ANALYSIS
Prodera
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PRODERA
PRODERA is a worldwide supplier of :
Systems for In-flight Tests
Systems for Ground Vibration
Tests
Customized products
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PRODERA
SIMULATIONTheoretical modes
Ground Vibration Test
Real modes
FLUTTER PREDICTION
Simulation of flutter
In-Flight testsVerification of the
flight domain
Mode tuning
Prototype
GVTresults
Validation of the flight domain
Flight domain
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GROUND VIBRATION TESTS
Power amplifiers
Electrodynamics shakers
Accelerometers and charge amplifiers
Others …
P-Sys-Modal®
Suspension systems
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IN-FLIGHT VIBRATION TESTS
Pyrotechnical thrusters Inertial shakers and on-board power amplifiers
Data recordersTelemetry systems
P-Flight-Modal®: Flutter Prediction Software
P-Flutter-Monitoring®: real-time monitoring of flight tests
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SOME REFERENCES
AERMACCHI, ALSTOM, ANTONOV, ASTRIUM, CEA,
DASSAULT AVIATION, D.L.R., EADS AIRBUS, EADS
CASA, EADS LAUNCH VEHICULES, EDF, EMBRAER, EUROCOPTER, INTESPACE, ISRAEL AIRCRAFT
INDUSTRIES, MBDA, MIG, O.N.E.R.A., RAFAEL, RKK
ENERGIA, SOPEMEA, SUKHOI, TAI, THALES, TSAGI,
TSNIIMACH, TUPOLEV, VZLU, …
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EX 520 C50 shakers used during the Ground Vibration Test of the AIRBUS A380-800 performed by a joint team ONERA-DLR (Project leader ONERA)
Picture Copyright AIRBUS
AIRBUS A380-800
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Vertical (1000 N shaker EX 420 C) and lateral (550 N shaker EX 520 C50) excitation of the Rolls Royce internal left engine during the Ground Vibration Test of the AIRBUS A 340/600 carried out in February 2001 in Toulouse,
France (ONERA realization). Picture Copyright Airbus
AIRBUS A340-600
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AIRBUS A318
Horizontal, lateral and vertical excitation of an engine during the Ground Vibration Test of the AIRBUS A 318 carried out by DLR in Hamburg (Germany) – Picture Copyright AIRBUS
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AERMACCHI M-346
Ground Vibration Test on Aermacchi M-346
Picture Copyright Aermacchi
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AERO VODOCHODY L-159
Ground Vibration Test on AERO Vodochody L-159 equipped with external loads, test performed by VZLU
Picture Copyright VZLU
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VZLU
Multipoint excitation system
Picture Copyright VZLU
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SNECMA
Engine part test
Picture Copyright SNECMA
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Vibration Test on Bouran scale model
Photo courtesy Tsniimach
BOURAN
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Vibration Test on Soyouz scale model
Photo courtesy Tsniimach
SOYOUZ
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EADS SPACE ARD
Test on the ARD spacecraft
Picture Copyright EADS SPACE
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INTESPACE
Test on SILEX satellite
Picture Copyright Intespace
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THALES UNDERWATER SYSTEMS
Submarine transducer developed in cooperation with Thales Underwater Systems
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Modal Analysis tests
The target is to identify the behaviour of a structure:
The structure is excited in order to study all its vibration modes, one after one.
Use of modal analysis shakers and current-controlled power amplifiers.
Amplifier
SHAKERS
Amplifier
Charge amplifiers
ACCELEROMETERS
Analysis system
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Complete range of electrodynamics shakers for modal analysis
No influence on the structure
Light and robust moving assembly
Low stiffness
EX 520 C50: 550N (~ 55 kgf) with only 680 g
EX 520 C50: no spiders (no stiffness)
CONSTANT FORCE ELECTRODYNAMICS SHAKERS
FOR MODAL ANALYSIS
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PRODERA constant force electrodynamics shakers can be equipped with the following functions:
Display of the position of the moving assembly
Internal cooling
Kellog rings for an optimum performance at high frequencies
Temperature sensor
TEDS
CONSTANT FORCE ELECTRODYNAMICS SHAKERS
FOR MODAL ANALYSIS
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SHAKER SINE NOMINAL FORCE
(peak value)
(N/lbf)
FORCE
FACTOR
(N/A / lbf/A)
STROKE
(mm / inch)
MOVING
MASS
(g / lbs)
EX 6 No spiders From 3 to 6 /
From 0.67 to 1.34
From 1.5 to 2 /
From 0.33 to 0.44
± 1.5 / ± 0.05 From 8.5 to 13.5 / From 0.01 to 0.03
EX 8 No spiders From 4 to 8 /
From 0.89 to 1.79
From 2 to 2.5 /
From 0.44 to 0.56
± 1.5 / ± 0.05 From 8.5 to 13.5 / From 0.01 to 0.03
EX 12 10 / 2.24 5 / 1.12 ± 5 / ± 0.19 30 / 0.06
EX 24 20 / 4.49 5 / 1.12 ± 5 / ± 0.19 61 / 0.13
EX 20 No spiders 20 / 4.29 5 / 1.12 ± 5 / ± 0.19 35 / 0.07
EX 58 50 / 11.24 6.25 / 1.46 ± 6 / ± 0.23 110 / 0.24
EX 220 / EX 220 SC 200 / 44.96 10 / 2.24 ± 10 / ± 0.39 195 / 0.42
EX 320 C50 No spiders 350 / 78.68 17.5 / 3.93 ± 25 / ± 0.98 625 / 1.34
EX 520 C50 No spiders 550 / 123.64 27.5 / 6.18 ± 25 / ± 0.98 680 / 1.49
EX 1060 A 1.200 / 224.8 20 / 4.49 ± 12,5 / ± 0.49 1.000 / 2.20
EX 2060A 2.040 / 449.6 34 / 7.64 ± 12,5 / ± 0.49 1.000 / 2.20
EX 5080 A 5,000 / 1,124 63 / 14.16 ± 20 / ± 0.78 5.300 / 11.68
CONSTANT FORCE ELECTRODYNAMICS SHAKERS
FOR MODAL ANALYSIS
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CURRENT CONTROLLED POWER AMPLIFIERS FOR MODAL ANALYSIS
Large range of current controlled amplifiers
The relation between the power amplifier’s output impedance and the coil’s impedance is very high
The generated current is proportional to the input voltage, independently of the coils’ movement, even at resonance
No need for force transducer
Due to the amplifier structure
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AMPLIFIER OUTPUT POWER RMS
(W)
MAXIMUM
CURRENT
(Acrête)
MAXIMUM
VOLTAGE
(Vcrête)
INPUT
SIGNAL
(Vcrête)
A 73230 ± 2 ± 30 ± 5
60 ± 4 ± 30 ± 5
A 73560 ± 4 ± 30 ± 5
120 ± 8 ± 30 ± 5
A 648 / A 648 S 400 ± 20 ± 40 ± 5
A 649 800 ± 40 ± 40 ± 5
A 649 HV 800 ± 20 ± 80 ± 5
A 651 S1 1.200 ± 60 ± 40 ± 5
A 651 S2 2.400 ± 60 ± 80 ± 5
A 709 4.000 ± 80 ± 100 ± 5
CURRENT CONTROLLED POWER AMPLIFIERS FOR MODAL ANALYSIS
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Signal generator and acquisition system
PC controlled
Compact 19’’ 7U rack with internal cooling
Uses P-Win-Modal® software
Same architecture as the old PRODERA systems
P-SYS-MODAL®
16 channels of excitation 256 channels of acquisition
P-Sys-Modal® Light based on an OROS type OR 3x system
4 channels of excitation 32 channels of measurement
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Generation InterfacesPCI-DIO-96PCI-6071-E
Internal bus
Power amplifiers & modal shakers
Acq
uis
itio
n
P-Win-Modal® installed on
hard drive of PC PENTIUMSTRUCTURE
Accelerometers & charge amplifiers
P-SYS-MODAL®
Fil
ter
Lissajous
Multiplier
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Sine excitation Impulse excitation (1/3, 1, 2 or 3 octaves)
Ultra stable
Frequency 10-7 Hz Amplitude 5 x 10-3 V
Generator board Appropriation board
16 channels 0 or π phase
TO POWER AMPLIFIERS
Quadrature
P-SYS-MODAL®
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n
1 2
45°
At resonance, damping factor can be approached by:
nn
12
2
If damping factor is in the order of 10-3
is in the order of 10-32
1
ffff.f
by00.0ax00.0
In order to know the exact value of the 4th decimal of the damping factor, the frequencies
must be measured with at least 4 decimals
P-Sys-Modal frequency stability of 10-7 Hz
P-Sys-Modal has 4 significant decimal figures for the frequency
Generator Precision
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I II III
Appropriation
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I+II
Symmetric excitation:
Symmetric modes are amplified
Anti-symmetric modes are minimized
Appropriation
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I+III
Anti-symmetric excitation:
Symmetric modes are minimized
Anti-symmetric modes are amplified
Appropriation
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Appropriation: Method of isolation of a vibration mode based on the fact that, at resonance, the velocities of all the points of the structure are in phase or out of phase with the excitation forces. This method consists in exciting the structure according to its mode shape, by defining:
This method allows the isolation of all the modes, in order to compute the modal parameters with a high accuracy
The number of excitation points
The amplitude of the forces
The position of the excitation forces
In modal analysis, it is critical to identify all the modes, even if they are close / coupled with other modes.
Appropriation
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Courtesy VZLU
Appropriation (example)
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Courtesy VZLU
Appropriation (example)
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Excitation using two forces in quadrature or more
The resulting force is a constant force rotating around a fixed point
Used for axis-symmetrical structures
APPROPRIATION: ROTATION OF FORCES
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TO POWER AMPLIFIERS
4 non correlated channels
Output: 1 Vrms 5 Vpeak signals
Random generator
White noise from 1 to 2048 Hz, with a programmable bandwidth of 1 to 11 octaves
Random generator
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FR
OM
CH
AR
GE
A
MP
LIF
IER
S
TO
PC
Acquisition board
8 in basic system 32 differential inputs
Multiplier board
Real & imaginary parts computation
Acquisition
32 channel low pass filter
4 programmable cut-off frequencies
Filter board
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MULTIPLIER
Transducerresponse
tsinA
X
Excitation force
tsinF
XQuadrature force
tcosF
Level 1
t2cos2
FAcos
2
FA
Level 2
t2sin2
FAsin
2
FA
Multiplier
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t2cos2
FAcos
2
FAtsinFtsinA
Computed each time with the REAL excitation signals, no phase error
Real-time
t2sin2
FAsin
2
FAtcosFtsinA
The resulting levels have a continuous signal proportional to the real or imaginary parts of the FRF
Level 1:
Level 2:
Multiplier
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FR
OM
CH
AR
GE
A
MP
LIF
IER
S
TO
PC
Real-time display of 32 Lissajous curves Transducer response vs. excitation signal
Lissajous board
Lissajous
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Interface boards
Remote controlpanel
PC
User Interface
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Modal analysis software for:
Test management
Data acquisition
Data analysis
Results display
P-WIN-MODAL®
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Structure’s data definition
Equipment definition
Operation modes
P-WIN-MODAL®
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EQUIPMENT DEFINITION:
Definition of the instrumentation characteristics:
Shakers & power amplifiers
Transducers & charge amplifiers
Equipment Definition
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STRUCTURE:
P-Sys-Modal® structures are defined by the assignation of the different transducers to the nodal points. One transducer can be assigned to several nodal points.
1
2
4
3
1
4
2
3
5
67
8
Y
X
Z
5 7 1
6 7 2
6 8 3
5 8 4
1
2
3
4
Nodal point Tr. X Tr. Y Tr. Z
A single structure definition can be used with several geometries
Structure Definition
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STRUCTURE:
For each structure
Different geometries can be defined
Different paths can be defined
Geometry & Path
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IMPULSE TEST:
Multipoint impulse excitation.
1/3 Octaves
0 7.50 15.00 22.50 30.00 37.50 45.00 Hz
2.59K
5.18K
Frequency in Hz
Am
plitude of the P
ow
er S
pectrum Power spectrum, pulse
Different kinds of excitations:
Up to the excitation frequency with different bandwidth
Around the excitation frequency
• 3 octaves• 2 octaves• 1 octave
• Bandwidth 1/3 of octave
Impulse Test
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IMPULSE TEST:
Acquisition of the transducer’s responses and display of:
Temporal signals
FFT
Frequency Response Functions
Power spectra
Identification of the vibration modes
Signed spectra
Impulse Test
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RANDOM TEST:
Acquisition of the transducer’s responses and display of:
Temporal signals
Auto-spectra & Cross-spectra
Coherence functions
Possibility of windowing
Identification of the vibration modes
Random Test
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HARMONIC TEST:
Acquisition of the transducer’s real & imaginary parts:
Linearity test
Logarithmic decrement
Complex power
Quadrature forces method
Identification of the modal parameters
Mode shape
FRF
Harmonic Test
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Harmonic Test Menu
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Linearity test
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LINEARITY TEST:
Verifies the linearity supposition by measuring the resonance frequency for different force levels
200 400 600
M:4.683570E+000 F:39.131
M:9.367140E+000 F:39.156
M:1.405071E+001 F:39.181
General force level
Am
plitu
de
o
f th
e ve
lo
city o
f re
f. tra
nsd
uce
r (IS
)/ R
eso
na
nce
F
re
qu
en
cy in
H
z
Linearity test
Velocity module
Frequency
Linearity test
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LOGARITHMIC DECREMENT:
For two consecutive periods
Quick way to measure the damping factor by analyzing the response decay rate after cutting-off the excitation forces
Computation of the damping factor179.869m359.737m539.606m719.475m899.344m1.079 1.259 1.439 1.619 s
-486.40
-243.20
243.20
486.40
Time in s
Am
plitu
de
o
f th
e re
f. tra
nsd
uce
r (m
ultip
lie
r u
nits)
Temporal signal for reference transducer
20 1cos
nddt teUtx n
3.0121
2ln
22
1
2
1
forTx
xe
x
xdn
Tdn
Logarithmic Decrement
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Complex Power
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COMPLEX POWER:
The power is also a complex magnitude with at resonance:
Active power maximum
Reactive power zero
The velocity of a transducer is a complex magnitude, with its imaginary part zero at resonance
VF2
1P
From the analytical expression of the complex power we deduce the modal parameters
39.10 39.13 39.18 Hz
198.24m
396.48m
594.72m
W
Frequency in Hz
Pow
ers in W
atts
Complex Power
Active power
Active Interp.
Reactive power
Reactive Interp.
Complex Power
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Quadrature Forces
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QUADRATURE FORCES:
With k the damping factor, Tk the inverse of the frequency and T and de frequency and quadrature rate increments
By adding a certain percentage of a quadrature excitation force to the original force, the resonance frequency varies in a linear way
k
0kk
T
T
1
By measuring the natural frequencies for different values of quadrature force rates, we can deduce the modal parameters
-30.0 -20.0 -10.0 10.0 20.0 %
39.0
39.1
39.2
39.3
39.4
Hz
Percentage of Quadrature
Frequency in H
z
Quadrature forces
Quadrature Forces
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MODE SHAPES:
Two mode shapes are computed
With the imaginary part of the responses (mode shape)
With the real part of the responses (quadrature mode
shape)
Mode Shape
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Frequency Response Functions:
Acquisition of the Frequency Response Functions by performing a sine sweep
38.626238.752538.878739.005039.131239.2575 Hz
-606.00
-303.00
303.00
606.00
Frequency in Hz
Real/Im
ag parts in m
ultipliers unit
Power spectrum,Transducer:43
Imag.part
Real part
Frequency Response Functions
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CH : FILE
[Linearity]Mode nb=1Date=12/09/2000Time=12:20:36Structure=Sve3dSession=test sve3dTest=harmonic exciter###1=Ref. Transducer Nb; Point/AxisRef. transducer=2;12/Z###2=Exciter Nb; Point/Axis; Direction; Transducer Nb; Force (N)Line_1=1;12/Z;+;2;+1,600E+001Line_2=2;27/Z;+;18;+1,600E+001###3=General force; Modulus; FrequencyStep_1=400;2,89736614E+001;5,0098Step_2=525;3,83054733E+001;5,0117Step_3=650;4,82711258E+001;5,0117Step_4=775;5,66796417E+001;5,0117Step_5=900;6,66452942E+001;5,0117
[Complex Power]Mode nb=1Date=12/09/2000Time=12:27:46Structure=Sve3dSession=test sve3dTest=harmonic exciter###1=Ref. Transducer Nb; Point/AxisRef. transducer=2;12/Z###2=Exciter Nb; Point/Axis; Direction; Transducer Nb; Force (N)Line_1=1;12/Z;+;2;+3,200E+001Line_2=2;27/Z;+;18;+3,200E+001Phase of ref. transducer (°)=0,00Global phase of significant transducers (°)=3,58Phase shift of ref. transducer at the beginning of the sweep (°)=15,34###3=Frequency; Active power; Reactive powerStep_1=4,9831;8,79504967E+000;+2,45559788E+000Step_2=4,9888;9,03528595E+000;+2,02730799E+000Step_3=4,9945;9,12497425E+000;+1,52499557E+000Step_4=5,0003;9,31415749E+000;+9,98837292E-001Step_5=5,0060;9,37837982E+000;+5,48734963E-001Step_6=5,0117;9,41754055E+000;+2,49141287E-002Step_7=5,0174;9,35706997E+000;-4,72830713E-001Step_8=5,0231;9,29673672E+000;-9,44588304E-001Step_9=5,0289;9,13704205E+000;-1,48973513E+000Step_10=5,0346;8,97789192E+000;-1,95926368E+000Step_11=5,0403;8,72001171E+000;-2,40295792E+000
[Quadrature]Mode nb=1Date=12/09/2000Time=12:31:46Structure=Sve3dSession=test sve3dTest=harmonic exciter###1=Ref. Transducer Nb; Point/AxisRef. transducer=2;12/Z###2=Exciter Nb; Point/Axis; Direction; Transducer Nb; Force (N)Line_1=1;12/Z;+;2;+3,200E+001Line_2=2;27/Z;+;18;+3,200E+001Phase of ref. transducer (°)=0,00Global phase of significant transducers (°)=3,30###3=% Quadrature force; Frequency; Global phase signif. transd.; Response levelStep_1=-30,0;4,9872;3,68;SteadyStep_2=-20,0;4,9944;4,14;SteadyStep_3=-10,0;5,0040;3,16;SteadyStep_4=+0,0;5,0117;3,30;SteadyStep_5=+10,0;5,0207;3,55;SteadyStep_6=+20,0;5,0286;3,56;SteadyStep_7=+30,0;5,0365;4,24;SteadyFrequency (Hz)=5,012Damping=0,01660Normalised generalised mass (Kg*m2)=206,862
[Mode shape]Mode nb=1Date=12/09/2000Time=12:32:12Structure=Sve3dSession=test sve3dTest=harmonic exciter###1=Ref. Transducer Nb; Point/AxisRef. transducer=2;12/Z###2=Exciter Nb; Point/Axis; Direction; Transducer Nb; Force (N)Line_1=1;12/Z;+;2;+3,200E+001Line_2=2;27/Z;+;18;+3,200E+001Phase of ref. transducer (°)=0,00Global phase of significant transducers (°)=3,48Frequency (Hz)=5,0117###3=Response of the ref. transducer; Mode shape; QuadratureResponse of ref. transducer (m)=9,41856019E-003;6,02664222E-005###4=Normalised responses of the transducers; Mode shape; QuadratureTransducer_1=+0,005;+0,007Transducer_2=+1,000;+0,006Transducer_3=+0,897;-0,039
Output Files
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Printouts
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Linearity test
Complex power Energetic analysis
Quadrature forces Phase analysis
Logarithmic decrement
Frequency Response Functions
Several methods but a unique result
IMPLEMENTED METHODS
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P-Flight-Modal®
P-Win-Modal®
PRODERAFiles
Text filesUFF files
15; 55; 58;82; 151; …
P-Flutter-Monitoring®
Finite Element packagesI-DEAS, NASTRAN, ANSYS, CATIA,…
INTERFACES WITH OTHER SOFTWARE
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Suspension systems for shakers
Calibration devices
OTHER PRODUCTS FOR GVT
Mechanical links
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Pneumatic suspension system using the aircraft «jack points»
PNEUMATICAL SUSPENSIONS
Compact system, easy to adapt to the aircraft size
Cut-off frequency around 0.9 Hz
The units can be equipped with a load cell in order to measure the total weight at any time
Different loads following the models, from a few tons up to hundreds of tons
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Multi-channel excitation and acquisition system
Excitation devices
Acquisition devices
ELECTRONIC STRUCTURE STRUCSIM-3-D
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Multi-channel excitation and acquisition system
STRUCSIM-3D®
ELECTRONIC STRUCTURE STRUCSIM-3-D
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Electronic device simulating a glider equipped with:
8 shakers
64 transducers
8 vibration modes, calibrated and traceable
Useful for system calibration and training:
Always the same results
No test preparation
ELECTRONIC STRUCTURE STRUCSIM-3-D
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P-Flight-Modal® software is composed of the following modules:
• “FLUTTER”
DLM subsonic AIC
CPPM supersonic AIC
• “FQTRE”
Transonic CFD
P-Flight-Modal® uses the GVT results
Direct link to P-Win-Modal®
FLUTTER
DLM CPPM FQTRE
P-Win-Modal®
GVT results
Pressures distribution
Flutter prediction
P-FLIGHT-MODAL®
Runs under Linux
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P-FLIGHT-MODAL®
0 .00 200 .00 400 .00 600 .00 800 .00Velocity, m / s
0 .00
2 .00
4 .00
Freq
uenc
y, H
z
NASTRAN test case HA145B
AGARD SMP taileron
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INERTIAL SHAKERS
Electrodynamics systems based on the movement of an oscillating mass.
• Full control of the excitation forces. Appropriation
• Uses on-board current controlled power amplifiers
• Different models:
• EI 797 Vertical 450 N
• EI 799 Horizontal 450 N
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Excitation system providing a calibrated impulse
• Easy to install
• Does not modify the aircraft
• Very short test duration
PYROTECHNICAL THRUSTERS
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PYROTECHNICAL THRUSTERS
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Real-time software for the computation of the frequency and damping factor during the flight tests
• Analysis by fitting the FRF
• Several kinds of test:• Harmonic• Pyrotechnical thrusters• Free air turbulence
• MATLABTM Toolbox• Uses a NI-PCI-6071-E for data
acquisition
P-FLUTTER-MONITORING
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Force transducers not required
Generator frequency stability of 10-7 Hz
Frequency precision of 10-4 Hz, from DC up to 2 kHz
Harmonic, Impulse and Random
2 modal analysis methods: complex power and quadrature forces
Forces appropriation method
Interfaces
In conclusion …
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In-House system (software & hardware)
Customizable products
Robust products, no need for special maintenance
Experience, more than 40 years manufacturing GVT systems
Reactive company, quick reaction 24 hours a day
In conclusion … Full range of constant force modal shakers with no influence on the structure by their low moving weight and stiffness
Full range of current controlled power amplifiers with zero phase shift even at resonance
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Thank you for your attention …
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