PRODERA SYSTEMS FOR MODAL ANALYSIS

Prodera

PRODERA - 2006 2

PRODERA

PRODERA is a worldwide supplier of :

Systems for In-flight Tests

Systems for Ground Vibration

Tests

Customized products

PRODERA - 2006 3

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

PRODERA - 2006 4

GROUND VIBRATION TESTS

Power amplifiers

Electrodynamics shakers

Accelerometers and charge amplifiers

Others …

P-Sys-Modal®

Suspension systems

PRODERA - 2006 5

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

PRODERA - 2006 6

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, …

PRODERA - 2006 7

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

PRODERA - 2006 8

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

PRODERA - 2006 9

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

PRODERA - 2006 10

AERMACCHI M-346

Ground Vibration Test on Aermacchi M-346

Picture Copyright Aermacchi

PRODERA - 2006 11

AERO VODOCHODY L-159

Ground Vibration Test on AERO Vodochody L-159 equipped with external loads, test performed by VZLU

Picture Copyright VZLU

PRODERA - 2006 12

VZLU

Multipoint excitation system

Picture Copyright VZLU

PRODERA - 2006 13

SNECMA

Engine part test

Picture Copyright SNECMA

PRODERA - 2006 14

Vibration Test on Bouran scale model

Photo courtesy Tsniimach

BOURAN

PRODERA - 2006 15

Vibration Test on Soyouz scale model

Photo courtesy Tsniimach

SOYOUZ

PRODERA - 2006 16

EADS SPACE ARD

Test on the ARD spacecraft

Picture Copyright EADS SPACE

PRODERA - 2006 17

INTESPACE

Test on SILEX satellite

Picture Copyright Intespace

PRODERA - 2006 18

THALES UNDERWATER SYSTEMS

Submarine transducer developed in cooperation with Thales Underwater Systems

PRODERA - 2006 19

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

PRODERA - 2006 20

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

PRODERA - 2006 21

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

PRODERA - 2006 22

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

PRODERA - 2006 23

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

PRODERA - 2006 24

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

PRODERA - 2006 25

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

PRODERA - 2006 26

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

PRODERA - 2006 27

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®

PRODERA - 2006 28

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

PRODERA - 2006 29

I II III

Appropriation

PRODERA - 2006 30

I+II

Symmetric excitation:

Symmetric modes are amplified

Anti-symmetric modes are minimized

Appropriation

PRODERA - 2006 31

I+III

Anti-symmetric excitation:

Symmetric modes are minimized

Anti-symmetric modes are amplified

Appropriation

PRODERA - 2006 32

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

PRODERA - 2006 33

Courtesy VZLU

Appropriation (example)

PRODERA - 2006 34

Courtesy VZLU

Appropriation (example)

PRODERA - 2006 35

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

PRODERA - 2006 36

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

PRODERA - 2006 37

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

PRODERA - 2006 38

MULTIPLIER

Transducerresponse

tsinA

X

Excitation force

tsinF

XQuadrature force

tcosF

Level 1

t2cos2

FAcos

2

FA

Level 2

t2sin2

FAsin

2

FA

Multiplier

PRODERA - 2006 39

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

PRODERA - 2006 40

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

PRODERA - 2006 41

Interface boards

Remote controlpanel

PC

User Interface

PRODERA - 2006 42

Modal analysis software for:

Test management

Data acquisition

Data analysis

Results display

P-WIN-MODAL®

PRODERA - 2006 43

Structure’s data definition

Equipment definition

Operation modes

P-WIN-MODAL®

PRODERA - 2006 44

EQUIPMENT DEFINITION:

Definition of the instrumentation characteristics:

Shakers & power amplifiers

Transducers & charge amplifiers

Equipment Definition

PRODERA - 2006 45

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

PRODERA - 2006 46

STRUCTURE:

For each structure

Different geometries can be defined

Different paths can be defined

Geometry & Path

PRODERA - 2006 47

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

PRODERA - 2006 48

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

PRODERA - 2006 49

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

PRODERA - 2006 50

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

PRODERA - 2006 51

Harmonic Test Menu

PRODERA - 2006 52

Linearity test

PRODERA - 2006 53

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

PRODERA - 2006 54

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

PRODERA - 2006 55

Complex Power

PRODERA - 2006 56

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

PRODERA - 2006 57

Quadrature Forces

PRODERA - 2006 58

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

PRODERA - 2006 59

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

PRODERA - 2006 60

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

PRODERA - 2006 61

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

PRODERA - 2006 62

Printouts

PRODERA - 2006 63

Linearity test

Complex power Energetic analysis

Quadrature forces Phase analysis

Logarithmic decrement

Frequency Response Functions

Several methods but a unique result

IMPLEMENTED METHODS

PRODERA - 2006 64

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

PRODERA - 2006 65

Suspension systems for shakers

Calibration devices

OTHER PRODUCTS FOR GVT

Mechanical links

PRODERA - 2006 66

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

PRODERA - 2006 67

Multi-channel excitation and acquisition system

Excitation devices

Acquisition devices

ELECTRONIC STRUCTURE STRUCSIM-3-D

PRODERA - 2006 68

Multi-channel excitation and acquisition system

STRUCSIM-3D®

ELECTRONIC STRUCTURE STRUCSIM-3-D

PRODERA - 2006 69

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

PRODERA - 2006 70

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

PRODERA - 2006 71

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

PRODERA - 2006 72

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

PRODERA - 2006 73

Excitation system providing a calibrated impulse

• Easy to install

• Does not modify the aircraft

• Very short test duration

PYROTECHNICAL THRUSTERS

PRODERA - 2006 74

PYROTECHNICAL THRUSTERS

PRODERA - 2006 75

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

PRODERA - 2006 76

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 …

PRODERA - 2006 77

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

PRODERA - 2006 78

Thank you for your attention …