Bi-laminar Multilayer Benders or Bimorphs Prepared By: Brad Crook ECE 5320 Mechatronics Assignment...

Bi-laminar Multilayer Bi-laminar Multilayer Benders or BimorphsBenders or Bimorphs

Prepared By: Brad CrookPrepared By: Brad Crook

ECE 5320 MechatronicsECE 5320 Mechatronics

Assignment #1Assignment #1

Actuator OutlineActuator Outline

ReferencesReferences Major ApplicationsMajor Applications Basic Working PrincipleBasic Working Principle Sample ConfigurationSample Configuration Major SpecificationsMajor Specifications LimitationsLimitations Best Choice For ApplicationsBest Choice For Applications Cost ValuesCost Values

ReferencesReferences

http://www.http://www.americanpiezoamericanpiezo.com/products_services/stripe_actuators.com/products_services/stripe_actuators.html.html

http://www.ulb.ac.be/scmero/documents/http://www.ulb.ac.be/scmero/documents/these/Piefort01.pdfthese/Piefort01.pdf

http://www.physikinstrumente.de/producthttp://www.physikinstrumente.de/products/prdetail.php?sortnr=103000s/prdetail.php?sortnr=103000

Major ApplicationsMajor Applications

Nano-positioningNano-positioning Needle control in textile weavingNeedle control in textile weaving Braille machinesBraille machines AccelerometersAccelerometers Opening/closing valvesOpening/closing valves Small volume pumpingSmall volume pumping Switching applications-touch switchesSwitching applications-touch switches Cooling devicesCooling devices

Basic Working Principle (cont)Basic Working Principle (cont)

A bi-laminar actuator is made from a A bi-laminar actuator is made from a piezoelectric smart material that returns piezoelectric smart material that returns to its original shape after a force is to to its original shape after a force is to applied to it.applied to it.

A piezoelectric material can act as both a A piezoelectric material can act as both a sensor and an actuator.sensor and an actuator.

http://www.americanpiezo.com/products_services/strhttp://www.americanpiezo.com/products_services/stripe_actuators/stripe_background.htmlipe_actuators/stripe_background.html

Basic Working PrincipleBasic Working Principle

““A flexing or bending actuator is A flexing or bending actuator is designed to produce a relatively large designed to produce a relatively large mechanical deflection in response to an mechanical deflection in response to an electrical signal.” electrical signal.”


Basic Working Principle (cont.)Basic Working Principle (cont.)

““Two thin strips of piezoelectric ceramic Two thin strips of piezoelectric ceramic are bonded together, usually with the are bonded together, usually with the direction of polarization coinciding, and direction of polarization coinciding, and are electrically connected in parallel.”are electrically connected in parallel.”

Courtesy of American Piezo



““When electrical input is applied, one When electrical input is applied, one ceramic layer expands and the other ceramic layer expands and the other contracts, causing the actuator to flex.”contracts, causing the actuator to flex.”

+ - + -

Vin>0V

Vin=0V



““Deflections are large, but blocking Deflections are large, but blocking forces are low, relative to forces forces are low, relative to forces developed by stack actuators.” developed by stack actuators.”

Courtesy of American Piezo



““Parallel electrical configuration ensures Parallel electrical configuration ensures high sensitivity to input; bias voltage high sensitivity to input; bias voltage circuitry can prolong the life of the circuitry can prolong the life of the actuator by eliminating the potential for actuator by eliminating the potential for depolarizing the ceramic layers.”depolarizing the ceramic layers.”

http://www.ulb.ac.be/scmero/documents/these/Pieforhttp://www.ulb.ac.be/scmero/documents/these/Piefort01.pdft01.pdf

Sample ConfigurationSample Configuration

A bilaminar design consists of two A bilaminar design consists of two piezoelectric substrates bonded together piezoelectric substrates bonded together with polarization coinciding and with an with polarization coinciding and with an electrode sandwiched in-between.electrode sandwiched in-between.

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PZTElectrode

Sample Configuration (cont.)Sample Configuration (cont.)

The outer surface is coated with the The outer surface is coated with the another electrode, and a laminate is another electrode, and a laminate is placed on top to protect the actuator.placed on top to protect the actuator.

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Electrode PZT

Electrode

Electrode

Sample Configuration (cont.)Sample Configuration (cont.) The outer electrodes are tied to an optional The outer electrodes are tied to an optional

positive or negative electrode, and the inner positive or negative electrode, and the inner electrode is tied to the opposite pole of the electrode is tied to the opposite pole of the outer. This determines the direction of outer. This determines the direction of bending.bending.

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ElectrodePZT

Electrode

Electrode

+

-

Sample Configuration (cont.)Sample Configuration (cont.)

Other configurations are pre-bent into a Other configurations are pre-bent into a C-shape that can straighten, or bend with C-shape that can straighten, or bend with applied voltage, or sense a forced applied voltage, or sense a forced compression.compression.

Courtesy of Vincent Piefort

Major SpecificationsMajor Specifications

Each actuator specification is described Each actuator specification is described by its:by its:

1.1. Dimensions- total length, free length, width, Dimensions- total length, free length, width, and thickness.and thickness.

2.2. DeflectionDeflection

3.3. ComplianceCompliance

4.4. Blocking forceBlocking force

5.5. Resonant frequencyResonant frequency

Major Specifications (cont.)Major Specifications (cont.)

Total Deflection is determined by the Total Deflection is determined by the following equation.following equation.

Lf: free lengthLf: free length

H: ThicknessH: Thickness

V: VoltageV: Voltage

Results are in mmResults are in mm

2.2

Vh

lf

2

26102.2


Compliance is found by the equation:Compliance is found by the equation:




Results do not have a unitResults do not have a unit

2.2

Vh

lf

3

25104.26


Blocking Force is found by:Blocking Force is found by:

Results are in N (Newtons)Results are in N (Newtons)

2.2

Compliance

Deflection


Resonate Frequency is found by:Resonate Frequency is found by:3.2 x 105 x ( [ h ] / [ lf ]2 ) 3.2 x 105 x ( [ h ] / [ lf ]2 )




Results are in HZ (Hertz)Results are in HZ (Hertz)

2.2

21052.3

lf

h

LimitationsLimitations

There are three major limitations to the There are three major limitations to the bi-laminate piezoelectric actuator.bi-laminate piezoelectric actuator.

1.1. The shaping of the electrodes and laminate.The shaping of the electrodes and laminate.

2.2. The bandwidth.The bandwidth.

3.3. Blocking force.Blocking force.

Limitations (cont.)Limitations (cont.)

The Shaping of the Laminate can be in The Shaping of the Laminate can be in several formsseveral forms

1.1. C-shapeC-shape

2.2. Bar, rectangularBar, rectangular

3.3. DiskDisk Each shape will have a different Each shape will have a different

response time, and Force when a response time, and Force when a specific Voltage is appliedspecific Voltage is applied


Shaping can also effect bandwidth.Shaping can also effect bandwidth. A larger laminar area will cause the A larger laminar area will cause the

bandwidth to drop.bandwidth to drop. As the bandwidth drops the response As the bandwidth drops the response

time also drops.time also drops. This could either be an advantage or a This could either be an advantage or a

disadvantage depending on the plant.disadvantage depending on the plant.


Blocking force is also determined by the Blocking force is also determined by the deflection and compliance of the laminate.deflection and compliance of the laminate.

This is ends up being inversely proportional to This is ends up being inversely proportional to the length.the length.

length

10833.

The longer the lamina the less force it is able The longer the lamina the less force it is able to exertto exert

Best Choice For ApplicationBest Choice For Application

When a choice is made for a multilayer When a choice is made for a multilayer bender it usually comes down to the bender it usually comes down to the limitations as described above.limitations as described above.

For a fast acting bender with a high For a fast acting bender with a high resonate frequency a thicker shorter resonate frequency a thicker shorter bender is needed.bender is needed.

This type of bender would be useful for This type of bender would be useful for optical switching.optical switching.

Best Choice For Application (cont.)Best Choice For Application (cont.)

The shorter bender would also be more The shorter bender would also be more effective for high load applications.effective for high load applications.

For an application that needs little force For an application that needs little force but a large range of movement, like a but a large range of movement, like a weaving machine, then a longer bender weaving machine, then a longer bender would be nice.would be nice.

Cost ValuesCost Values

At this point I have not had any price At this point I have not had any price quote sent to me, and I have not found quote sent to me, and I have not found any listed online.any listed online.

Bi-laminar Multilayer Benders or Bimorphs Prepared By: Brad Crook ECE 5320 Mechatronics Assignment...

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