3 Basics of Vibration Measurement by Torben Licht

 

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

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  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")

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IEEE-SA member.

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

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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

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  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

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  Vibration Transducers

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  Vibration instrumentation and analysis software

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  Transducer Calibration

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  Calibration and standardisation

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  calibration methods and systems Primary

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  Secondary calibration methods and systems

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  Questions  

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Introduction to Vibration  

What is vibration Why measure vibration  

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Signal  types

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Vibration Signal Descriptors    

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Intr ntrodu oducti ction on to Vibr Vibra atio tion n

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Wha hatt is vib vibra ratio tion n   Why measure vibration

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Signal  Types

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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 sinnt

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  2f 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  

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To plan maintenance on machines  

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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

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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

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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 = D2f 

  2 2 sin t v= d d = D  dt2

 Acceleration, a

Time a minimum

a = D2 = D42f 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

Filename, 53

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

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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

 kx 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 

FF 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

QpC  SF pC / N  FN

+-

+-

+-

+-

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

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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%

Filename, 79  

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 !!

QUESTIONS ?