3 Basics of Vibration Measurement by Torben Licht
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Vib ibratio ration nC Ca ali libr bra ati tion on T Te ech chni niqu que e and basics basic so off Vib Vibratio ration nM Me easu sureme rement nt Singapore September 2011 Torben R. Licht
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Torbe or ben n Rask Lich Li cht, t, B&K B& K Denma nm ark
Product Manager Vibration Calibration Systems MSc EE, solid state physics, 1968
43 years at B&K Career
– 9 Years R&D, Vibration Transducers/Calibration – 3 Years R&D & Marketing Acoustic Emission – 7 Years Vibr. Transducer R&D Group Manager – 6 Years International Product Manager Vibration Transducers & Calibration Systems – 3 Years Technology Monitoring and Innovation – 3 Years Project Manager Customized Projects – 4 Years Project Manager Innovation – 5 Years Product Manager Calibration Systems – 2 Years Vibr. Transducer R&D Group Manager Filename, 2
Sta tand nda ard rdis isa ati tion on w wor ork k
Chair of TC108/SC3, "Mechanical vibration and shock - Use and calibration of vibration and shock measuring instruments")
IEEE-SA member.
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Chair of IEEE 1451.4 ”Smart Transducer Interface for Sensors and Actuators”. Member of the Danish S-206 “Mechanical vibration and shock” As representative representative for the Danish Primary La Laboratory boratory of Acoustics (DPLA) participating in EURAM EURAMET ET and CCAUV
Au A u d i en enc ce p prr o f i l e as ass sumptions
more information about vibration Seeking measurement and calibration
Planning to buy new equipment
Needs calibration of equipment
Want to establish calibration facilities
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Involved in vibration measurement
Want to be educated to be able to participate in the above
Ag A g en end da
Introduction to Vibration
Vibration Transducers
Vibration instrumentation and analysis software
Transducer Calibration
Calibration and standardisation
calibration methods and systems Primary
Secondary calibration methods and systems
Questions
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Introduction to Vibration
What is vibration Why measure vibration
Signal types
Vibration Signal Descriptors
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Intr ntrodu oducti ction on to Vibr Vibra atio tion n
Wha hatt is vib vibra ratio tion n Why measure vibration
Signal Types
Vibration Signal Descriptors
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Definition
from Shock and Vibration Handbook
Vibration is an oscillation wherein the quantity is a parameter defining the motion of a mechanical system
Oscillation is the variation, usually with time, of the magnitude of a quantity with respect to a specified reference when the magnitude is alternately greater and smaller than the reference
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Vib ibratio ration n IIn nE Everyd veryda ay Li Life fe
63 7 7 r r e e t t r r f f g k j j j g f l 2 6 l k k d d s d š 6 47 5 k 5 k g g h a p pw w w w po o d d j d d e e o o
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Useful V Vib ibratio ration n
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Mecha ch an ic ica al Paramete Parameters rs and Com ompo ponent nents s Displacement
Velocity
Acceleration
m d v
k
a
c m
F=k×d
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F=c×v
F=m×a
Sim impl ple est Form or m of o f Vibra Vibrati ting ng Sys yste tem m Displacement
d = D sinnt
Displacement
D Time
T 1 T
m
Frequency
Period, Tn in [sec] k
1
Frequency, f n= T in [Hz = 1/sec] n
n= 2 f n = Filename, 12
k m
Mass and Spr prin ing g
time
n 2f n
k m m1
Increasing mass reduces frequency
m1 m
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Mass, Spring and Damper
m 100m
200m
300m
400m
500m
600m
[s]
c +c k
1
2
100m
200m
300m
Increased Damping Increased Damping 500m 600m 700 Reduces Reducesthe theResponse Response
400m [s]
Time Time
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Forced or ced Vib Vibratio ration n Displacement
e m i T
F Frequency
m k
dm c d
Magnitude
dm = df
F
Phase
Frequency
+90° 0° -90° Frequency
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Respo sp o ns nse e Mod ode els .
Single Degree of Freedom SDOF
Multi Degree of Freedom MDOF
F Magnitude
Magnitude
f 0
Frequency
F
Frequency
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Intr ntrodu oducti ction on to Vibr Vibra atio tion n
What is vibration Why mea measur sure e vibration
Signal Types
Vibration Signal Descriptors
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Why Make F Frequency requency An Ana aly lysi sis s
To make diagnosis of Rotating Machinery
B
C
Amplitude
Amplitude
A
B
E D C
A Time
E D
Vibration
Frequency
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Forces or ces and and Vib ibratio ration n
Forces caused by
Vibration
Imbalance
Parameters:: Parameters
Parameters:
Shock
Friction
Mass Stiffness
Acoustic
Damping
1
Velocity
Displacement
1
20
=
0
100m
10m
-20
10m
Autospectrum(Response) Autospectrum(Respo nse) - Inpu Inputt (Magnitu (Magnitude) de) Mobility : Input : Input : FFT Analyzer
Frequency Response H1 (response, excitation)
x
100m
Acceleration
[m/s²]
Autospectrum(Response) - In Autospectrum(Response) Input put (Magnitude) (Magnitude) Mobility : Input : Input : FFT Analyzer
[m/s²]
Structural
1m 1m 0
100
200
300 [Hz]
400
0
500
Input Forces
x
100
200
300 [Hz]
400
500
System Response =
0
100
200
300 [Hz]
Vibration
400
500
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Wh y Do We We Meas u r e Vi b r at i o n ?
To verify that vibrations do not exceed the material limits To verifybody that Vibrations do not harm the th e human To make diagnosis of Rotating Machinery
To plan maintenance on machines
To construct or verify comput compute er mode m odels ls of structures thereby to be able to n or dampen dampe o and r isol i sola ate vibration sources
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Wh y Do We We Meas u r e Vi b r at i o n ? Vib ibra rati tion on Test stin ing g
To verifylimits that vibrations do not exceed the material
Standard Driven Standards as MIL 810
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Why Vibra Vibr ati tion on Test Testin ing g
After design Qualification test
Test for reliability Realistic vibration simulation in lab
Quality assurance
May require temperature and humidity tests
During qualification test
Visual inspection or frequency response
After qualification
Functional test
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Practi ractical cal exa examp mple le
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Wh y Do We We Meas u r e Vi b r at i o n ?
To verify that vibrations do not exceed the material limits To verifybody that Vibrations do not harm the th e human To make diagnosis of Rotating Machinery
To plan maintenance on machines
To construct or verify comput compute er mode m odels ls of structures thereby to be able to n or dampen dampe o and r isol i sola ate vibration sources
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Mecha ch ani nical cal M Mod ode els of the th e Hum uma an B Bod ody y Wh o l e b o d y
Shoulder girdle (4 - 5 Hz)
Lung volume
Chest wall (50 - 60 Hz)
Lower arm
Han d -ar m Eyeball, intraocular structures (ca. 25 Hz)
Head (axial mode) (20 - 30 Hz)
Abdominal Mass (4 - 8 Hz)
Spinal column (axial mode) (10 - 12 Hz)
Seated person Legs (Variable from ca. 2 Hz with knees flexing to over 20 Hz with rigid posture)
Standi ng person Standing
Hand gripHz) (50 - 200
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Wh y Do We We Meas u r e Vi b r at i o n ?
To verify that Vibrations do not harm the huma hum an body bod y
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Wh y Do We We Meas u r e Vi b r at i o n ?
To verify that Vibrations do not harm the human body
Compliance EU Directive 2002/44/EC
ISO 8041:2005 ISO 2631-1:1997 ISO 5349-1 and 2:2001
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Wh y Do We We Meas u r e Vi b r at i o n ? To verify that Vibrations do not harm the huma hum an body bod y
B y making human Vibration measurements
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Wh y Do We We Meas u r e Vi b r at i o n ?
To verify that vibrations do not exceed the material limits To verify that Vibrations do not harm the th e human body To make diagnosis of Rotating Machinery
To To plan plan maintenance maintenance on on machines machines
To construct or verify comput compute er mode m odels ls of structures thereby to be able to n or dampen dampe o and r isol i sola ate vibration sources
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Diagnosis
To make diagnosis of Rotating Machinery
And thereby plan plan when repair is needed B
C
Amplitude
Amplitude B
E D C
A A Time
E D
Vibration
Frequency
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Wh y Do We We Meas u r e Vi b r at i o n ?
To verify that vibrations do not exceed the material limits To verify that Vibrations do not harm the th e human body To make diagnosis of Rotating Machinery
To plan maintenance on machines
To construct or verify comput compute er mode m odels ls of structures thereby to be able to n or dampen dampe o and r isol i sola ate vibration sources
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Forces or ces and and Vib ibratio ration n
Forces caused by
Imbalance
Shock Friction
Acoustic
1
Parameters:: Parameters
Parameters:
Mass Stiffness
Damping
Displacement
Autospectrum(Response) Autospectrum(Respo nse) - Inpu Inputt (Magnitu (Magnitude) de) Mobility : Input : Input : FFT Analyzer
1
20
=
0
100m
10m
-20
10m
Acceleration Velocity
[m/s²]
Frequency Response H1 (response, excitation)
x
100m
Vibration
Autospectrum(Response) - In Autospectrum(Response) Input put (Magnitude) (Magnitude) Mobility : Input : Input : FFT Analyzer
[m/s²]
Structural
1m 1m 0
100
200
300 [Hz]
400
0
500
Input Forces
x
100
200
300 [Hz]
400
500
System Response =
0
100
200
300 [Hz]
Vibration
400
500
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The Au Auto tomo moti tive ve Indus nd ustr try y
With vibration measurement and models you can: – Reduce development time – Improve NVH Vehicle Quality – less noise and vibration with improved sound quality
By applying solutions for: – Diagnostics and Troubleshooting
– Benchmark and Compliance Testing Investigations – Advanced NVH Investigations – Crash Testing
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Intr ntrodu oducti ction on to Moda odall Testi sting ng 1
Static Testing and Analysis
A science studied studied for over a century
F d
Structural Dynamic Testing
Term differentiating it from Static Testing and Analysis
In contemporary language it is Modal Analysis and Modal Testing
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Intr ntrodu oducti ction on to Moda odall Testi sting ng 2 Present Pre sent day demands
Increasing speed in transportation
Higher fuel economy
More lightweight constructions
The demands achieved by reducing the mass of structures Consequences
Structures become inherently weak Resonances move down into the frequency region of excitation forces
Structures fail because of dynamic loads
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Beyond Beyon dM Mod oda al T Te estin st ing g Fin init ite e Element Element Modelling, FEM
Prediction of test model
Moda od al Testin st ing g
Damping data
Comparison and Validation of Modal Model
Validation
Curve fitting
Validation
Update Final Model Simulation: “What if”
Trouble Shooting
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The Aero Aerosp spa ac e & De Defenc fence e In du dust stry ry
With vibration measurement and models you can: – Reduce time to market – Improve the quality of their products – Comply with legislation
By applying solutions for: world’s largest assortment of – The dynamic transducers
– Complete measurement/ measurement/recording recording solution – Real time analysis for monitoring and validation – Diagnostics and troubleshooting – Benchmark and compliance testing
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Intr ntrodu oducti ction on to Vibr Vibra atio tion n
What is vibration Why measure vibration
Signal Typ ype es
Vibration Signal Descriptors
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Type yp es o off Sign Signa als Stationary signals
Deterministic
Random
Non-stationary signals
Continuous
Transient
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Determ termin inis isti tic c Sig igna nals ls and Harm rmon onic ics s
Time
f 1
2f 1 Frequency
f 1
Frequency
Time
Time
2f 1
Frequency
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Random nd om Sig ignals nals
Time
Frequency
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Imp mpa act ct--Imp mpul ulsese-S Sho hock ck Sig ignals nals .
Time Frequency
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Sig ignal nal T Typ ype es and S Spectr pectrum um Uni nits ts Correct use of Units
Time Determistic, Periodic Signal
Frequency U2
Power
U
PWR Time
Random Signal
U
Freq. U2/Hz
Time
Transient
B U2s/Hz
U
Power Spectral Density PSD
Freq.
Energy Spectral Density ESD
Time T
B
Freq.
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Intr ntrodu oducti ction on to Vibr Vibra atio tion n
What is vibration Why measure vibration
Signal Types
Vibr ibra atio tion Descri scripto ptors rs n Signal De
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Line Li nea ar v vs. s. Osc scil illa lato tory ry Mot otio ion n Displacement
Detroit 35 Miles
D Time
Speed limit 65 MPH
TEST 0-60 MPH in 8.6 second
Velocity V Time
Acceleration A Time
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Con onve vers rsio ion n ffro rom mD Dis ispl pla ace ceme ment nt to Ac Acce cele lera rati tion on d maximum
Displacement, d
d = D sin t
D Time
Velocity, v
d=D
v = dd = D cos t dt
v=0 Time
v = D = D2f
2 2 sin t v= d d = D dt2
Acceleration, a
Time a minimum
a = D2 = D42f 2
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Vib ibrati ration on Parameters rameters Relative Amplitude Ac A c c el eler erat atii o n
100 000 10 000 1000
f=0.1591 Hz
a
a v
100 10
dv dt
v
1 10
Velocity
100
v
D
1000
v
10 000
Displacement
100 000 0.1
1
1
10
100
Frequency
1k
10 kHz
D v dt
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Whi hich ch Parameter rameter tto o Cho hoos ose e
Measurement
Measurement
Measurement
A
B
C
Acc. Acc. Vel.
Vel.
Acc. Vel. Disp.
Disp.
Disp.
Choose Displacement
Choose Velocity
Choose Acceleration
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Uni nits ts of Vibrati Vibration on Sig igna nals ls
Acceleration a
1ms-2 (m/s2)
= 0.102g = 39.4 in/s2
v
1ms-1 (m/s)
= 3.6 km/h = 39.4 in/s
Displacement
1m
= 1000 mm = 39.4 in
Velocity
d
1g 9.80665 ms-2
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“ Real W Worl orld” d” Vibr ibra ation Le Leve vels ls ms-2
dB
1 000 000
240
1000
180
1
120
0.001
0.000 001
60
0
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Vibration Transducers
Types of Vibration Transducers The Piezoelectric Accelerometer Choosing an Accelerometer Using an Accelerometer Calibration
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Th e Me Meas u r em en t Ch ai n Transducer
Preamplifier
Filter(s)
Detector/ Averager
Output
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GIGO
Garbage In = Garbage Out
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920046
Early rl y Meth thod ods s of o f Vibration “ Measu sure reme ment nts” s”
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Mecha ch ani nical cal Lever
A p p l i c ati Ap at i o n : Obsolete, but still found in a few old power stations
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Edd ddy y Current Current Pro roxi ximi mity ty Prob robe es
Ap A p p l i c ati at i o n s :
Relative motion Shaft eccentricity Oil film thickness Etc.
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Veloci lo city ty Pic icku kup p
e = Blv
Limited frequency range: 10 < f < 1000 Hz
Filename, 57
800289
Piezoelectric Accelerometer
Principles of operation
F
F
F V mV F Q pC F
F
V mV F Q pC F
Filename, 58
800290/2
Type yp es o off Acc A cce elerom lerome eters Planar Shear P
ThetaShear ®
Centr ntree-moun mounted ted Compression S
M R B A An n n u l ar Sh Shear ear
M P
R
B
MP B
Delt De lt a Shear ® P
OrthoShear ®
E M P
R M
P M R E
B
B
B
P: Pie Piez zoele oelectr ctric ic Ele Elements ments
E: B Buil uilt-in t-in Electr Electroni onics cs
R: Cla Clampi mping ng Ring
B: Base
S: Spri Spring ng
M: Se Seism ismic ic Mass
Filename, 59
800284
Opera perati tion ona al Range ng e of Vib ibratio ration n Transd ransduc uce ers Relative Amplitude 108:1
Piezoelectric Accelerometer
106:1
10 000:1
Velocity transducer
100:1
Eddy current Proximity probe
1 0.2
2
20
200
2k
20kHz
Frequency
930656
Filename, 60
Cho hoos osin ing g an Ac Acce cele lero rome mete ter r
General Purpose, medium weight and sensitivity
Small, light and high frequency
or
Acceleration ms-2 250,000
1 - 10 pC/ms-2
0.1 - 0.3 pC/ms-2
Weight: 10-50 gram
Weight: 0.5 - 3 g
20,000-100,000
0.003-0.01 0.0001-0.001
Frequency ~0.1
~1
5-12k 15-30k Hz
Filename, 61
800299
B r ü el & K j ær De Dell t a Sh ear ® Des i g n Piezoelectric material Clamping Ring Seismic Mass
Base
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Ac A c c el eler ero o m et eter er Mod Mo d el Sp Sprr i n g -Mas -Mass s Sy Sys s t em xS
mS F
Seismic Mass
F
mB
xB
Fe F0 sin t
0
kx S xB L B
B
L (at rest)
k
F
Accelerometer Base Spring Force:
x
Piezoelectric Element
Centre post
m x F F Force on Base: Force on Seismic Mass: m S x S F
e
Equation of motion:
xS
F
xB m S
FF e m B
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For orce ce S Se ens nsit itiv ivit ity y of Piez iezoele oelect ctri ric c Eleme lement nt Polarisation direction
QpC SF pC / N FN
+-
+-
+-
+-
Q = Generated Charge
+-
+-
SF = Force Sensitivity F = Applied Force
Domain Dom ains s in und undefo eforme rmed d sta state te Applied Force +-
+ q -
+-
+ - + - + -
+ -
+ -
+-
+ -
Compression deformation of domains
+
+ - + - + -
- + -
+ - + -
Applied Force
- + q Shear deformation of domains
Filename, 64
Usefu sefull F Frequ reque enc ncy y Ra Rang nge e Amplification Factor A 30 dB
Vibration of Seismic Mass
20
10
Mounted Resonance Frequency f m
0 ,3 f m 3 dB lim lim it 0 ,5 f m
1 0 % lim it
0
Vibration of Base
-10 0,0001
f / f m 0,001
0,01
0,1
1
10
Relative Frequency
Filename, 65
Sensit ns itiv ivit ity ya and nd Freque requenc ncy y Ra Rang nge e Sensitivity pC/ms-2
31.6 1
0.004
13
42
180
kHz
Filename, 66
800295
Ac A c c el eler ero o m et eter er Mou Mo u n t i n g — Fi Fix x ed Thin doub double le adhesive tape
Level dB
Cementing stud
Stud Mounting
Beeswax
30 20 10 Max.40 °C
0
200
500
1k
2k
5k
10k
20k 30k 50 kHz
Frequency
930616
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Ac A c c el eler ero o m et eter er Mou Mo u n t i n g — Han Hand d h el eld d Magnet
Hand Ha nd h held eld prob probe e
d e t r e v n I
Level dB
e b o r P
30 20 10 0
200
500
1k
2k
5k
10k
20k 30k 50kHz
Frequency
Filename, 68
930617
Iso solatin lating g th the e Ac Accele celero romete meter r Electrical (Prevention of ground loops) Mica washer
dB 20 10 0
Insulating stud Mechanical Mech anical Filt Filter er (Protection against high shocks)
1k
2k
5k 10k Frequency
1k
2k
5k 10k 20k 30k 50kHz Frequency
20k 3 30 0k 50kHz
dB 10 0 -10
Filename, 69
930618
Choo hoosin sing gaM Mount ounting ing Posi ositio tion n B
A
D C
Filename, 70
800305
Loa Lo adi ding ng th the e Test Obj bje ect 0,1 pC/ms-2 0.65 g M>7g
Dynamic Mass 600 g M
1000 pC/ms-2 470 g M > 5 kg
Filename, 71
800304
Env nvir iron onme ment nta al Eff ffe ects ct s
Base Strain
Humidity
Acoustic noise
Corrosive substances
Magnetic fields
Nuclear radiation
Filename, 72
800314
Conclusion
Due Dueto toits itswide widedynamic dynamicrange rangeand andwide widefrequency frequency range piezoelectric accelerometer range the piezoelectric accelerometerisisthe themost most the widely used vibration widely used vibrationtransducer transducer
From Fromthe themechanical mechanicalpoint pointof ofview, view,the thepiezoelectric piezoelectric accelerometer is a seismic transducer employing a accelerometer is a seismic transducer employing a spring-mass system spring-mass system
Velocity Velocitypick-ups pick-upscan canbe bewell wellsuited suitedand andcheap cheapfor for vibration measurements in the mid-frequency range vibration measurements in the mid-frequency range Proximity probes are used for relative, low frequency, Proximity probes are used for relative, low frequency, motion, motion, especiallyfor formonitoring monitoringshafts shaftsin inbearings. bearings. especially
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Vibr ibra atio tion n ins instru trume menta ntatio tion n and ana nalys lysis is sof softwa tware re
The newest from B&K is the PULSE LAN-XI modules with PULSE Software running on a PC.
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LAN LA N-XI Mul ulti ti--Pur urpo pos s e Mod odul ule e Multi-purpo ult i-purpose se modu module: le:
DeltaTron & Microphone conditioning
51.2 kHz freq-range
Microphones (200Vp) Accelerometers Proximity probes DC-Accelerometers (diff. input). AC & DC Charge via DeltaTron converter
+ Dyn-X REq-X TEDS CIC
#1
Filename, 75
Filename, 78
Cos ostt and Tim Time e Savi vings ngs us usin ing g Distrib Distr ibut ute ed Syste System m Reduced complexity Transducer Hub A Traditional Measurement Measurement System System! ! System - Cabling costs reduced 50-70% - Instrumentation time reduced 50-70%
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Transduc ransd uce er C Ca ali libr bra ati tion on Why calibrate – To find the sensitivity
Why recalibrate – Legal obligation - QA requirement – Good instrument practice – Test for damage
Filename, 80
Cali libr bra ation ti on Leve Levels ls Measureme su rement nts s must mu st be b e comp co mpa arable and measu measureme rement nt unc u nce erta rt ainty in ty kno k nown wn
Prima rim ary calib calibration ration –
Often performed as absolute calibration means as close as units possible to that the fundamental physical (MKSA in the SI system)
Seconda con dary ry calibra calibr ation tio n (com (compa paris rison on to to a referenc ref erence) e) –
II
Field c ca alibration lib ration –
Transducers, calibrators, instruments
I
Field calibrators like
III
Field measu measureme rement nts s
IV
Filename, 81
B&K B& K Cali Calibr bra ati tion on Sys ystems tems all PULSE base based d Hydrophones
Instruments
Accelerometers
Microphones
Reciprocity
SLM
Laser
Reciprocity
Comparison
Dose meter
Comparison
Comparison
Octave Filter
Shock 10k
Fr. Resp. Act.
Shock 100k
Phase Comp.
Low-frequency Comparison
Dyn. Linearity
Directional R. Turn-key Systems
Calibrator - instructions on screen - printing of certificates - uncertainty budgets - support Primary
Transverse PULSE based
Conditioners
Low-frequency Fr. Resp. Coup.
Filename, 82
Calibr li bra ation ti on st sta anda nd ard rdis isa ati tion on
Standardisation is important
For vibration there is however far less legal
requirements, but the number is increasing.
Filename, 83
Su r v ey o off t h e ISO 5347/ 7/1 16063 s er i es and s t atu atus s Nu m b er 5347-0 53470:1987
Ti t l e Basic concepts
S t at u s revis rev ised, ed, 16063-1 16063-1:1998 :1998
5347-1 53471:1993
Primary vibra vib ration tion calibra calibration tion by lase laserr interferometry
revis rev is ed, 16 16063 063-11 -11:: 19 1999 99
Primary shock calibration calibration by light li ght cutt ing Secondary vibration calibration
withdrawn revii sed rev sed,, 16063-2 16063-21:2003 1:2003
5347-2:1993 5347-2 3:1993 5347-3 5347-
conf co nfir irmed med 2005/ 2005/20 2010 10
confirmed 2008 5347-4 53474:1993
Secondary shock calibration
revis rev ised, ed, 16 16063 063-22 -22:2005 :2005
5347-5 53475:1993
Ca Calib libration ration by Earth Earth’s ’s gra gr avit atio tion n
conf co nfir irmed med 2004/ 2004/20 2009 09
5347-6 53476:1993
Primary vibra vib ration tion calibra calibration tion at low lo w frequencies
withdrawn
5347-7 53477:1993
Prima Primary ry ca c alibration by centrifuge
conf co nfir irmed med 20 2004 04/2 /200 009 9
5347-8 53478:1993
Prima Primary ry ca c alibration by dual centrif centrifuge uge
conf co nfir irmed med 2004/ 2004/20 2009 09
5347-9 53479:1993
Secondary vibration vi bration ca c alibration by compa comp aris rison on to t o a refere reference nce transducer transduc er
withdrawn
5347-10: 534710:1993 1993
Primary calibration calibration by high hi gh impact shock s
conf co nfir irmed med 20 2004 04/2 /200 009 9
5347-20 534720:1997 :1997
Primary vibra vib ration tion calibra calibration tion by t he reciproc re ciprocity ity method
revis rev ised, ed, 16 16063 063-12 -12:2002 :2002
Filename, 84
Su r v ey o off t h e ISO 5347/ 7/1 16063 s er i es and s t atu atus s Nu m b er 5347-11 534711:1993 :1993
Ti t l e Testing of t ra ransverse nsverse vibration vibration sensitivity
S t at u s revis rev is io ion, n, WD 1606 16063-3 3-31, 1, lack of o f proj pr oject ect leader leader 2010 2010
5347-12 534712:1993 :1993
t ransverse rse shock se sensit nsitivity ivity Testing of transve
confirmed 2004
5347-13:1993 5347-13 :1993 5347-14 534714:1993 :1993
Testing of ba base se strain sensitivity Resona esonance nce frequency testing testi ng of o f undamped u ndamped acceleromete ccelerometers rs on a ste st eel block bloc k
confirmed 2004 confirmed 2004
5347-15 534715:1993 :1993
Testing of o f acoustic sensitivity sensitiv ity
conf co nfir irmed med 2004/ 2004/20 2010 10
5347-16:1993 5347-16 :1993 5347-17 534717:1993 :1993
Testing o off mounti ng torque sensiti sensitivity vity Te Testi sting ng of fi fixed xed tempera temperatur ture e sensit sensitivi ivity ty
confirmed 2004 confirmed 2004
5347-18 534718:1993 :1993
Te Testi sting ng of transie transi ent temperatur temperature e sensit sensitivi ivity ty
confirmed 2004
5347-19 534719:1993 :1993
Testing of ma m agnetic field sensitivity sensitiv ity
confirmed 2004
PWI- 2008
PWI- 2010 5347-22 534722:1997 :1997
Ac A c c el eler ero o m et eter er r es eso o n an anc c e tes t estt i n g
confirmed 2004
-Gene -G eneral ral method m ethods s
1606315:2006
Primary angul angula ar vibration vib ration calibration calibr ation by laser interferometry
confirmed 2010
Filename, 85
Su r v ey o off t h e ISO 5347/ 7/1 16063 s er i es and s t atu atus s Number 1606341:2011
Ti t l e Calib ration of lase laserr vibrometers vib rometers Calibration
St at u s Ap A p p r o v ed 2011
5348
Mechanical mount Mechanical mo unting ing of accelerometers accelerometers
confirmed 2004
The IS ISO O 160 16063 63 series of do cument cumentary ary standards has h as specified specifi ed upgraded and new standard methods metho ds to to allow metrologi cal traceability traceability to be extended extended to all six motion mo tion quantities (vibration and shock).
Filename, 86
Ac A c c el eler ero o m et eter er Chec Ch eck k
In the field
In the lab
– Sensitivity check
– Frequency Response
– Total system check
– Sensitivity Calibration Multianalyzer
Frequency = 159.2 Hz
= 1000 rad/sec
Ac A c c el eler erat atii o n = 10 m ms s -2 +/-3% Calibration Exciter with built-in
Power Amplifier
or external reference accelerometer Filename, 87
Prima ri mary ry cali calibr bra ati tion on meth me thod ods s and and sys s yste tems ms
Filename, 88
Ab A b s o l u t e Cali Cal i b r at atii o n b y L aser as er In Intt er erff er ero o m et etrr y Primary Vibration Transducer Calibration System Type 9636 1993 Similar system used by DPLA since 1990 First system created 1969 and used to calibrate1971 8305 since
Filename, 89
Fring ri nge e co coun unti ting ng pr prin inci cipl ple e ISO 16063-11, m eth thod od 1
Filename, 90
Basic Ba sic formula f ormula
Filename, 91
DPLA ca calib libra ratio tion n his histor tory y Calibration History of Transfer Standards NIST
PTB Transfer Std. 1: B&K Type 3506 n o. 15.3506.5 Transfer Std. 2: B&K Type 3506 n o. 15.3506.4 Transfer Std. 3: B&K Type 3506 n o. 15.3506.11 Transfer Std. 4: B&K Type 3506 n o. 15.3506.12
NIST/PTB - Calibration re. B&K - Calibration at 159.2Hz
1.01
1.01
1.00
1.00
0.99
0.99
1976
1980
1985
1990
1995
2000
2005
SES/JLS , 11.04.2005
Filename, 92
ISO IS OM Meth etho o d 3, 1999 1999
WW 5164
Filename, 93
Pri rimary mary m me eth thod odol olog ogies, ies, ISO metho method d3
10 years of development in technology have changed the available instrumentation considerably – Integrated compact laser-interferometers are available with quadrature outputs – Standard FFT analyzers with high speed and high resolution are available for analysis (=sine approximation) and building on the ever increasing power of the processors in the computers – Integrated compact laser-interferometers are available with direct digital outputs of vibration quantities. These are well suited as precision reference transducers.
Filename, 94
Goa oals ls for f or n ne ew sy syst ste ems acc accor ordi ding ng tto oM Me eth thod od 3
Simpler
to use Easier
Wider frequency range
measurement Phase
Automated to save manpower Higher accuracy
price Lower
Filename, 95
(B&K) B& K) S Se etup tu p wit w ith h quadr q uadra ature tu re outpu out putt (2. (2. Generation neratio n 200 2004) PC with front-ends for Conditioning, data acquisition/generation acquisition/generation Calculation/analysis
Power amplifier 0°
90°
Detectors Shaker Laser
Interferometer
Mirror Accelerometer
Filename, 96
B&K B& K Setup tu p with wi th qua qu adr dra ature tu re outp ou tput ut (2. G Ge enerati neration on 2004)
Filename, 97
Determinatio termi nation no off the t he Mod ang ngle le
The output values can graphically be explained as shown
2 u1(ti), u2(ti)
Mod(ti) 1
Filename, 98
ISO 16063-11: Primary vibration calibration by laser interferometry
Mod ( t i ) arctan
u 2 (t i ) u (t ) 1
p
i
where the integer p has to be chosen properly to avoid discontinuities. In the standard these results are then used to create N+1 equations
Mod ( t i ) A cos t i B sin t i C to be solved using the least squares method to find A, B and C.
i = 0,1,2…N
ˆ M cos s A
ˆ M sin s B
C is a constant ω is the angular frequency of vibration ω=2πf s is the initial phase of the displacement N+1 is the number of samples taken synchronously over the measurement period. f is the vibration frequency known by the system.
Filename, 99
DFT, DF T, FF FFT T and anal analy y ze zerr s Or to make it more clear and after having solved the mathematical particularities
SignalB(t ) x (t ) arctg 4 SignalA(t )
It has been proved that using DFT (or the faster FFT) sampling and taking out with values for appropriate the proper frequency is identical to the the described sine approximation method using least square fitting.
Filename, 100
Laser cal. c al. syst sy ste em Typ Type e 362 3629 u si sing ng PULSE PULSE FFT FFT A naly nalyz zer
Laser with quadrature output
PULSE FRONTEND A/D
Stream data to disk PULSE Time Recorder x(t) Harddisk
PULSE Time FRF Analyse Data FFT
Process data
Apply corrections
a(t) Accelerometer Accelero meter
Harddisk
Calibration Data
Generate simulated raw data
Show results (Application)
Filename, 101
Laserr calibratio Lase calib ration n syst sy ste em us usin ing g PULSE FFT Analyze Analyzer r
Streaming the data directly to the hard disk makes it unimportant how large the files are but naturally large amounts of data take longer time to process.
This approach permits e.g. measurements at very low frequencies, down to 0.1 Hz giving files of several hundred Megabytes each.
Filename, 102
Laserr calibratio Lase calib ration n syst sy ste em us usin ing g PULSE FFT Analyze Analyzer r
Calibration of servo accelerometer 0.1 Hz to 160 Hz on long stroke shaker Filename, 103
Determinatio termi nation no off tthe he Mod ang ngle le at h hig igh h ffreque requenc ncies ies
The Mod angle becomes very small at higher frequencies
2 u1(ti), u2(ti)
Mod(ti) 1
Filename, 104
Determinatio termi nation no off tthe he Mod ang ngle le at h hig igh h ffrequenci requencie es
At high only fraction of theof fraction circle given making theadetermination is frequencies the center and thereby the angle difficult
The dual frequency output in the PULSE analyzer is used to add a suitable low frequency vibration
This ensures a full circle so that the center and thereby the angle can be determined precisely
Filename, 105
Laserr calibratio Lase calib ration n syst sy ste em us usin ing g PULSE FFT Analyze Analyzer r
Wide range (2 Hz to 50 kHz) calibration of reference in shaker Filename, 106
Eva valu lua ation ti on and si simu mula lati tion on The system structure permits injection of raw data has been made to create raw dat data a with A program
– Noise on transducer signal
– Noise on detector signals – Ellipticity (gain difference between detector outputs) – Dual frequency input – Transducer sensitivity input – Vibration magnitude and frequency input
This permits evaluation of the system sensitivity to the different parameters It also permits e.g. yearly performance verification for accreditation purposes The system includes automated calibration of the PULSE front-end using high precision voltmeter giving the highest
accuracy and traceability. Data are stored and used for correction. Filename, 107
Result sul t o off simu s imula latio tion, n, as as s show hown n iin n tthe he appl pplica icatio tion. n.
Elli llipti pticit city y 0.8 Filename, 108
Simulations Amplitude Deviation Result of simulation wit with h Ellipticity 0.8 and 1 Result o off lasersimulations 1 0,8 0,6 % n 0,4 i o t a 0,2 i v e D 0 e d u -0,2 t i l p m-0,4 A
-0,6 -0,8 -1 0,1
1
10
1 00
1 000
1 000 0
10 000 0
Frequenc Fre quenc y [Hz]
Filename, 109
Simulations Am A m p l i t u d e Devi Dev i ati at i o n d i f f eren er enc c e in i n p erc er c ent en t age ag e res r esu ults of simul si mula ation tio n with wit h Elli Ellipti pticit city y0 0..8 and 1 Difference in Resu Results lts of lasersimulations lasersimulations,, El Ellipticity lipticity 1 and 0.8 0.8 0,03
% 0,02 e c n e e r f f 0,01 i D n o i t 0 a i v e D e d u -0,01 t i l p m-0,02 A
-0,03 0,1
1
10
100
Frequenc Fre quenc y [Hz]
1000
10000
100000
Filename, 110
Phase devia deviati tion on results resul ts with wi th ellip ll ipti tici city ty 0.8 and 1. Result Re sult of la lasersimula sersimulations tions 0,02 0,015 0,01 ] ° 0 0,005 e r ° [ 0 e s a h -0,005 P
-0,01 -0,015 -0,02 0,1
1
10
100
Frequency Fre quency [Hz]
1000
10000
100000
Filename, 111
CONCLUSION
It has been proved that a calibration system based on modern analyzers is well suited to perform primary absolute calibrations following ISO 16063-11, method 3.
Filename, 112
Quadratur uadrature e sy syst ste em in i n ra r ack
Filename, 113
Ac A c c ep eptt an anc c e ttes estt
Filename, 114
Qua uadr dra atu ture re syste sys tem m test testin ing g
Filename, 115
Qua uadr dra atu ture re syste sys tem m test testin ing g
Filename, 116
Qua uadr dra atu ture re syste sys tem m test testin ing g
Filename, 117
LNE in inst sta all lla ati tion on
Filename, 118
LNE in inst sta all lla ati tion on
Filename, 119
Unc nce ert rta ainty in ty budg bu dge et
Filename, 120
Uncertainties Frequency Range Rang e (Hz (Hz))
Co n f i g u r at i o n
Mag n i t u d e Expanded Uncertainty
Phase Expanded Uncertainty (°) 0.5
0.1-0.2
LF exciter
(%) 2
0.2-0.4
LF exciter
1
0.5
0 .4 – 2
LF exciter
0 .4
0.5
2 - 10
LF/HF exciter
0 .4
0.5
10 – 2000
HF exciter
0 .3
0.5
2000 - 5000
HF exciter
0.4
0.7
5000 - 7000
HF exciter
0.5
1
7000 - 10000
HF exciter
0.6
1.5
10 to 15 kHz
HF exciter
1.5
2
15 to 20 kHz
HF exciter
2 .5
3
Filename, 121
Conclusion
Laser interferometric measurements have matured to very accurate and efficient tools
The mechanical setups in which these are used will often give rise to errors if the goal was to measure and describe the transducer as it will be used afterwards
More work is needed to give better models and better descriptions of how the reference transducers shall be used
Filename, 122
Second co nda ary ca cali libr bra ation ti on meth me thods ods and sys syste tems ms
Filename, 123
ISO 16063-21, 2003
Vibra ib rati tion on ca cali libr bra ati tion on by comp co mpa ariso ri son n to t o a refe refere renc nce e tr tra ansdu ns duce cer r
Filename, 124
Com ompa pari riso son n se sett-up up 1 Exciter 2 Amplifiers 3 Power amplifier 4 Frequency generator and indicator 5 Reference transducer 6 Transducer to be calibrated 7 Voltmeter 8 Distortion meter for occasional checks 9 Oscilloscope for visual inspection (optional) 10 Phase meter (optional)
Filename, 125
Calibr li bra ation ti on us usin ing gB Ba ack ck--toto -back back meth method od
Multianalyzer
Accelerometer under test Reference Standard Accelerometer
Power Amplifier
Shaker
Filename, 126
ISO 16063-21, 2003 Magnitude uncertainties
Example
Example 2
For accelerometers (0,4 Hz to 1 000 Hz)
2%
5%
3%
10 %
4%
6%
For accelerometers (2 kHz to 10 kHz)
3%
For accelerometers (1 000 Hz to 2 000 Hz)
1%
For displacement and velocity transducers t ransducers (20 Hz to 1 000 Hz)
Filename, 127
ISO 16063-21, 2003 Phase shift (Not mandatory)
At reference conditions (i.e. the level and frequency at which the reference transducer was calibrated)
Outside reference conditions
Example
Example 2
1°
3°
2,5 °
5°
Filename, 128
ISO 16063-21, 2003 Environmental conditions
Example 2
Example
Room temperature
(23 10) °C
(23 5) °C
Relative humidity
Max. 75 %
Max. 90 %
Filename, 129
Com ompa pari riso son n cali calibr bra ati tion on fo forr F For orce ce tr tra ans nsdu duce cers rs
Comparison calibration can be used for dynamic calibration of Force Transducers
Two measurements with two different calibrated masses as load are performed
From this the sensitivity can be calculated.
Filename, 130
Fifth Generation Vibration and Shock Transducer Calibration System Type 3629
Filename, 131
Sys yste tem m Confi Configu gura rati tion on (Vib ibra rati tion on))
Vibration Transducer Calibration System Type 3629
Filename, 132
Ac A c c el eler ero o m et eter er Cali Cal i b r at atii o n Sy Sys s t em Ty Typ p e 3629
Turn-key Accelerometer Calibration System
Calibration by substitution method, direct comparison possible
User only interface with the calibration program
Modular on both Software and Hardware
Accommodate user’s existing hardware hardware Frequency and level range only limited by hardware
Make Random, Sine, Sine+level, & Sine step level calibrations
Write Calibration data to TEDS Handles triaxial units with one certificate
Measures Bias and Offset voltages
Filename, 133
Back Ba ck to Back Back Cali libr bra ati tion on Sys yste tem m 10/100M LAN Interface
3560C Pulse Sound & Vibration Analyzer 5308 Vibration Transducer Calibration S/W
Generator Signal
2647
3629-CTI 3629 system Traceable Initial Calibration
Charge to Deltatron Converter Test Transducer WA0567 Calibration Fixture 4371 Working Standard Accelerometer 4808 Exciter / WH2651
2719 Power Amplifier
4809 Exciter
Filename, 134
Ty p e 3629 Sy s t em Var i at i o n s Av A v ai aill abl ab l e Sys Sy s t em Mod Mo d u l es: es :
Primary Laser Calibration (ISO 16063 - 11)
Secondary Vibration Calibration by Comparison (ISO 16063 - 21) Secondary Shock Calibration by Comparison (ISO 16063 - 22)
– Pneumatically operated piston
– Hopkinson bar with velocity comparison
Conditioner Calibration
Filename, 135
Com ompa pari riso son n ca c ali libr bra ati tion on,, Ba Back ck to ba b ack By back-to back mounting of the accelerometers, both accelerometers are subject to the same vibration. This is assumed to be a perfectly linear motion perpendicular to the accelerometers’ common mounting surface. The sensitivity in this direction of the DUT accelerometer can then be calculated Suut = Sref x (G ref x Vuut ) / (G uut x Vref )
Filename, 136
Calibra lib ratio tion n by substitu subst itutio tion n
Filename, 137
Measu sureme rement nt rre esu sult lts s and and for f ormu mulas las H is the frequency response function S is the sensitivity
S u ( f ) * H B ( f ) S x ( f ) * H A ( f )
H u ( f )
S x ( f ) * H A ( f ) * S r ( f ) * H B ( f )
H r ( f )
giving the result
H u ( f ) S u ( f ) S r ( f ) * H r ( f )
Filename, 138
% Unce ncerta rtaint inty y und unde er dif diffe fere rent nt con condit dition ions s frange
160 Hz
> 2 to 5 Hz
>5 to 10 Hz
> 10 to 20 Hz
> 20 to 40 Hz
> 40 to 500 Hz
> 0.5 to 1,25 1,25 kHz
> 1,25 to 2 kHz
>2 to 4 kHz
>4 to 5 kHz
>5 to 7 kHz
> 7 to 10 kHz
0.33
0.33
0.34
0.41
0.41
0.42
0.56
0.56
0.61
HPL -DUT
0.33
4809 HPL -DUT
0.34
0.42
0.42
0.34
0.34
0.41
0.47
0.47
0.57
0.84
0.84
0.58
0.87
0.71
0.62
0.62
0.62
0.62
0.62
0.63
0.90
0.93
0.58
0.62
0.62
0.58
0.58
0.58
0.58
0.64
0.66
0.95
0.61
0.65
0.65
0.65
0.65
0.65
0.65
0.75
0.77
1.20
4808 OPL -DUT 4808 OPL -DUT 4809 OPL +DUT 4809
+/- DUT means with or without transverse and temperature influence HPL means Highest Precision Laser cal. at all points OPL means One Point Laser Laser calibration only at 160 Hz, plus known reson resonance ance frequency frequency and no slope
Filename, 139
Thank hank you y ou for f or your y our atte tt ention nti on !!
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