Shaker training March 2011 Renard Klubnik Applications engineer The information contained in this document is the property of Meggitt Sensing Systems and

Shaker trainingMarch 2011Renard KlubnikApplications engineer

The information contained in this document is the property of Meggitt Sensing Systems and is proprietary and/or copyright material. This information and this document may not be used without the express authorization of Meggitt Sensing Systems. Any unauthorized use or disclosure may be unlawful.

Information contained in this document is subject to U.S. Export Control regulations, specifically the (choose as appropriate) International Traffic in Arms Regulations and / or Export Administration Regulations. Each recipient of this document is responsible for ensuring that transfer or use of any information contained in this document complies with all relevant (choose as appropriate) International Traffic in Arms Regulations and / or Export Administration Regulations.

Page 2© Meggitt Sensing Systems. Proprietary. 15 February 2010

Introduction to shakers

Where do shakers fit in the test market?Reaction mass shakers

– Excite a structure, not shake it– Modal testing– Not for shake testing

No envelope performance curves like MIL 810G– Transfer function measurement – built in impedance head

Point impedance

Transfer impedance– Ability to measure is a function of the readout equipment

and mechanical impedance of test structure– Characterize the unit under test, not vibrate it– Identify natural frequencies and amplification factor

Trunion mounted shakers– Test article testing


Application of shakers

Used in determining mechanical impedance

Measure the dynamic properties of structures and materialsIt is the complex ratio of applied force to resulting velocityIt is frequency related

– Sine– Random

Similar properties for acceleration and displacement components are shown in the adjoining chartUsually done by transfer function measurements of two channel analyzers and supporting softwareEasier setup than trunion mounted designs


Primary applications

Why/where are the shakers used?Understand the mechanics of a test object

– Simulate external forces

Test electrical components

circuit boards

sub assemblies

Determine mode shapes– Assess structural response under

different forms of excitation

Sine

Random

Impulse– Determine a test objects resonant

frequencies– Medical – bones


Reaction mass shakers – Operation principle

Operates on reaction mass principleA reaction force is generated which excites the test structure

– An AC electrical voltage is applied to the coil

– Alternating magnetic field causes relative movement between the permanent magnet outer shell and inner coil

– Like poles of magnet repel each other

Two reaction mass shaker types– Electromagnetic shakers– Piezoelectric shakers

Permanent magnet

Permanent magnet

Typical electromagnetic shaker


Electromagnetic shaker

Operates similarly to a loud speakerA coil is driven within a permanent magnet fieldThe dynamic electromagnetic coil field ‘pushes’ against the heavier outer permanent magnet shellCoil is attached to the structureHeavy ring-shaped magnets are suspended around the coilForce generated is proportional to input currentPowered by conventional methods (audio power amplifier)


Piezoelectric shakers

Utilize piezoelectric ceramic disks which change thickness proportional to an applied voltage

Ceramic disks are sandwiched between a heavy mass and a light fixture which attaches to the test structure

Although displacement is small, the use of multiple disks and high drive voltages produces large forces at high frequencies

Must be driven by high voltage which is provided by an impedance matching network between the power amplifier and shaker

Impedance matching network steps up the power amplifier output drive voltage to a much higher level for the drive voltage of the shaker


Reaction mass shakers


Reaction mass electrodynamic shaker systems

Reaction mass shakersOpen or closed loop measurements

Attach shaker directly to test object

Contact unit under test with built in force gage

Stingers not used


Shaker systems, impedance heads and amplifiers

F3 Electrodynamic design

Nominal 1 lb force output

25 – 10000 Hz

2.26” diameter

Z602WA impedance head or dummy plug

F4 Electrodynamic design


10 – 7500 Hz

5.10” diameter


Materials testing application


F3 shaker


F4 shaker



F5BElectrodynamic design

Nominal 0.4 lb force output

10 – 10000 Hz

1.35” diameter

Z11 impedance head

F10Electrodynamic design


5 – 2000 Hz

8.25” diameter



F5


F10


Piezoelectric shaker systems

Piezoelectric performanceBelow resonance, system output is displacement controlled – ~1 micron per 1000 volts

Above resonance, output is force controlled

Open or closed loop testing

Output of shaker is dependent on the mechanical impedance of the specimen

At higher frequencies shaker is lower impedance



F7Piezoelectric design


500 – >20000 Hz

2.20” diameter

Impedance head built in

Requires impedance matching network

F7-1Piezoelectric design


1 – 80000 Hz

2.20” diameter

No impedance head

Requires impedance matching network


F7 and F7-1 comparison

F7 with impedance head Z7

The Z7 is an integral part of the F7F7-1 (has no measurement electronics)


Construction of F7 and F7-1

F7-1

F7 without impedance head


F7 – testing to 20 kHz


F7-1 testing to 80 kHz



F4/F7Combination design for low and high frequency


10 – >20000 Hz

Requires two power amplifiers for continuous sweep

Requires impedance matching network for F7 shaker


F4/F7 assembly


F4/F7 completed assembly


F4/F7

Two power amplifiers if continuous sweep is desired

One matching network


Trunion mounted shakers


Special order shakers: D60H, D60L, D125

D60H, D60L, D125


Shaker performance

Shaker response is payload sensitiveMass on shaker causes lowering of resonant frequencies

Customer will have to estimate response with his payload

Payload can contribute additional resonances


D125 testing turbine blade

Requires itemsFixturing

Control accelerometer

Measurement accelerometer

Controller – sine or random


Amplifiers and accessories


Impedance heads

Used to measure shaker effectForce transducer

Accelerometer

Positioned between shaker and test articleOption on F3

– Z602WA

Option on F4

– Z820WA

Option on F5

– Z11

Built in on F7

Option on F10

– Z820WA


Impedance heads

Z11 (F5B)Charge output

Z602WA (F3)IEPE power

Z820WA (F4 F10)IEPE power


Amplifiers

PA8HFLow noise and low distortion over its entire range of operation

Designed for small and medium size electromagnetic and piezoelectric shakers


PA8HF specifications


Matching network needed for piezoelectric shakers

N7FS, N8FS, N8FHS Matching networkElectrical interface between amplifiers and piezoelectric shakers

Provide voltage step to drive shakers at full voltage levels

Lower voltage levels at higher frequencies to better match reactive loads


How to choose the right shaker for the application?

Determine the applicationModal

Test article testing

Modal testingDetermine frequency range

Evaluate size and shape of test article

Estimate stiffness of test article

Explore measurement options

Test article testingDetermine frequency range

Evaluate size and shape of the test article

Determine desired amplitude test range

Consider shaker performance with additional payload


Sample configurations

F3 (needs to have dummy plug or Z602WA)Signal source side

– F3 (includes cable to mate with PA8HF)

F3/dummy plug or F3/Z602WA– PA8HF if signal source can’t deliver 10 watts– *Signal source (sine oscillator, random noise generator)– *Cable to connect either the PA8HF or F3 to the signal source

Measurement side– With Z603WA Impedance head (2 x microdot to BNC cables supplied)

2 x IEPE power supplies (P704B)– *Other accelerometers for test article measurement

* - designates additional required instrumentation available from other sources



F5Signal source side

– F5 (includes cable to mate with PA8HF)– PA8HF if signal source can’t deliver 3 watts– *Signal source (sine oscillator, random noise generator)– *Cable to connect either the PA8HF or F5 to the signal source

Measurement side– Optional Z11 Impedance head (2 x 5-44 to BNC cables supplied)

2 x charge converters required (CC701)– Other accelerometers for test article measurement




F4 (needs to have dummy plug, Z820WA or F7)Signal source side


F4/dummy plug or F4/Z820WA or F4/F7 (see separate page)

– PA8HF if signal source can’t deliver 100 watts– *Signal source (sine oscillator, random noise generator)– *Cable to connect either the PA8HF or F4 to the signal source

Measurement side– With Z820WA Impedance head (2 x BNC to BNC cables supplied)





F4/F7Signal source side

– F4 (includes cable to mate with PA8HF)– F7 (includes cable to mate with N7FS)– 2 x PA8HF if signal source can’t deliver 100 watts and customer wants

full bandwidth coverage at the same time– N7FS matching network (includes cable to mate with PA8HF)– *Signal source (sine oscillator, random noise generator)– *Cable to connect the PA8HF to the signal source – user configured

Measurement side– Z7 Impedance head, included (2 x microdot to microdot cables

supplied)

2 x charge converters required (CC701)





F7Signal source side

– F7 (includes cable to mate with N7FS)– 1 x PA8HF– N7FS matching network (includes cable to mate with PA8HF)– *Signal source (sine oscillator, random noise generator)– *Cable to connect the PA8HF to the signal source


supplied)






F7-1Signal source side

– F7-1 (includes cable to mate with N8HFS)– 1 x PA8HF– N8HFS matching network (includes cable to mate with PA8HF)– *Signal source (sine oscillator, random noise generator)– *Cable to connect the PA8HF to the signal source

Measurement side– *Other accelerometers for test article measurement




F10 (needs to have dummy plug, Z820WA or F7)Signal source side


F10/dummy plug or F10/Z820WA or F10/F7 (see separate page)

– PA8HF if signal source can’t deliver 100 watts– *Signal source (sine oscillator, random noise generator)– *Cable to connect either the PA8HF or F10 to the signal source

Measurement side– With Z820WA Impedance head (2 x BNC to BNC cables supplied)





F10/F7Signal source side

– F10 (includes cable to mate with PA8HF)– F7 (includes cable to mate with N7FS)– 2 x PA8HF if signal source can’t deliver 100 watts and customer wants

full bandwidth coverage at the same time– N7FS matching network (includes cable to mate with PA8HF)– *Signal source (sine oscillator, random noise generator)– *Cable to connect the PA8HF to the signal source – user configured


supplied)





The information contained in this document is the property of Meggitt Sensing Systems and is proprietary and/or copyright material. This information and this document may not be used or disclosed without the express authorization of Meggitt Sensing Systems. Any unauthorized use or disclosure may be unlawful.

The information contained in this document may be subject to the provisions of the Export Administration Act of 1979 (50 USC 2401-2420), the Export Administration Regulations promulgated thereunder (15 CFR 730-774), and the International Traffic in Arms Regulations (22 CFR 120-130). The recipient acknowledges that these statutes and regulations impose restrictions on import, export, re-export and transfer to third countries of certain categories of data, technical services and information, and that licenses from the US Department of State and/or the US Department of Commerce may be required before such data, technical services and information can be disclosed. By accepting this document, the recipient agrees to comply with all applicable governmental regulations as they relate to the import, export and re-export of information.'

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Shaker training March 2011 Renard Klubnik Applications engineer The information contained in this document is the property of Meggitt Sensing Systems and