PolyMUMPS Flexure Design

Garet Kim

Jessica McAlister

Lydia Tse

Overview

• Project Goal

• Design Background

• Pulling Mechanism

• Conclusion

Project Goal

1) A folding/extending stage is to be designed using flexure joints.

2) Produce predictable movement with the zero-backlash flexure.

3) Create a test bench of flexure designs

Flexure Spring Background

Flexures: Advantages

• Simple and inexpensive to manufacture

• Virtually no irreversible deformations

• Displacements are smooth and continuous

• Predictable, repeatable motions– (even at atomic resolution)

• Linear relationship between applied force and displacement for small distortions

Types of Flexures

Leaf Hinge

Distributes deflection over length of hinge -lower stress -higher deflection to beam length ratio

Notch HInge

More immune to parasitic forces

Predicting Motion

• Simple application of bending theory:

xLeafzMz

LeafzMz

x

x

xCirclezMz

CirclezMz

a

ElK

HingeLeafforComplianceAngularK

a

ta

EbaK

HingeNotchCircularforComplianceAngularK

2

____

12

2

2tan

2

16

21

243

2

1

2

31

_____

_

_

1

23

2

2

2

2_

_

Our Design

• Basic flexure (single or cascaded)

• H flexure (single or cascaded)

• Buckling flexure

Our Design

• Test bench: To study the effects of varying different design properties 50 + variations

BEAMWIDTH

BEAM LENGTH AND BEAM RATIO

NECK DESIGN AND LENGTH

NUMBER OF FLEXURESIN CASCADE

JOINTDESIGN

Basic Flexure

Anchor (Poly1 encloses Anchor1)

Neck (Poly1)

33 um,41 um,49 um

1 um,5 um,9 um,11 um,13 um

Beam (Poly1)Length: 60 um, 88 um, 90 um, 120 um, 168 um, 180 um, 248 um, 330 um, 660 umWidth: 8 um, 12 um Ratio: 1 to 1, 1 to 3, 1 to 5, 2 to 1, 3 to 1, 5 to 1, 10 to 1

Beam Length: 60 um Beam Width: 12 um Beam Ratio: 1 to 1 Neck Length: 5 um

Basic FlexureSamples:

Beam Length: 90 um Beam Width: 12 um Beam Ratio: 2 to 1 Neck Length: 13 um

Beam Length: 180 um Beam Width: 12 um Beam Ratio: 5 to 1 Neck Length: 49 um

Beam Length: 168 um Beam Width: 8 um Beam Ratio: 3 to 1 Neck Length: 1 um

Beam Length: 330 um Beam Width: 12 um Beam Ratio: 10 to 1 Neck Length: 33 um

Animation (Basic)

Cascaded Basic Flexure

• Linear (longitudinal) combinations of multiple basic flexures

• Result in increasingly smaller / bigger movements than single basic flexure

Beam Length / Flexure: 248 um Beam Width / Flexure: 8 um Beam Ratio / Flexure: 5 to 1 Number of Flexures in Cascade: 3Type of Joint Used: Spring #3

Beam Length / Flexure: 168 um Beam Width / Flexure: 8 um Beam Ratio / Flexure: 3 to 1 Number of Flexures in Cascade: 2Type of Joint Used: Spring #1

Joint between 2 Flexures (Poly1)

Spring #1 Spring #2 Spring #3

Number of Flexures in Cascade: 2, 3

Beam Length per Flexure: 168 um, 248 umBeam Width per Flexure: 8 um

Beam Ratio per Flexure: 1 to 3, 3 to 1, 1 to 5, 5 to 1Flexure

Connection Between Flexures• Prevents shear effects at the tip

• Experimental. 4 kinds of connections (Flexure, 3 different springs

Animation (Cascade)

‘H’ Flexure• Linear (both transverse and longitudinal) combinations of basic flexures• Transversely join two flexures at their anchors• Longitudinally join flexures as in cascaded basic flexures discussed in the previous section• Do not result in longitudinal movements

Beam Length / Flexure: 660 um Beam Width / Flexure: 12 um Beam Ratio / Flexure: 10 to 1 Number of Flexures in Cascade: 4Type of Joint Used: Spring #3

‘H’ Flexure

Beam Length / Flexure: 660 um Beam Width / Flexure: 12 um Beam Ratio / Flexure: 10 to 1 Number of Flexures in Cascade: 4Type of Joint Used: Spring #1

Beam Length / Flexure: 660 um Beam Width / Flexure: 12 um Beam Ratio / Flexure: 10 to 1 Number of Flexures in Cascade: 8Type of Joint Used: Flexure

Buckling Flexure• Buckling should be avoided? Why?• Disadvantage: Tricky to get the output, need much more force to operate than basic shapes.• Advantage: Various transfer characteristics, most likely linear, and NEW !

Animation (Buckling)

Pulling Mechanism

• Pull-rings

– Ad: Simple, guaranteed to work, easy operation

– Dis: Inaccurate movements, low precision, relatively large

Pulling Mechanism

• Heatuators

– Ad: Relatively simple, high precision and accuracy in movement, practical

– Dis: Small range of movement, need a bank of them to work with flexures, occupy a larger area than a pull-ring

Pulling Mechanism

• Linear Stepper Motor

– Ad: Large range of operation, practical

– Dis: complicated, large units of movement, significant real estate required

Test Bench• Our designs are placed to test effects caused by different

shapes or parameters of flexures.

• Example (Single basic with a regular neck)Different Lengths

NameLeng

th

Width Neck Ratio

basic_660_a13_10to01 660 11 13 X 4 10:01

basic_330_a13_10to01 330 11 13 X 4 10:01

Different Springs

Name Length Width Neck Ratio # Cascades Spring

h2x2_10x1_sn_s3 330 10 11 X 3 10:01 4 s3

h2x2_10x1_sn_s2 330 10 11 X 3 10:01 4 s2

Width 　 　

Name Length Width

Buckling_598_thin_good 598 11

Buckling_598_good 598 16

Test Bench

Different Necks

Name Length Width Neck Ratio

basic_360_a13_05to01 360 11 13 X 4 5:01

basic_360_a11_05to01 360 11 11 X 4 5:01

　 　 　 　 　

basic_180_a13_02to01 180 11 13 X 4 2:01

basic_180_a11_02to01 180 11 11 X 4 2:01

Different Ratios

Name Length Width Neck Ratio

basic_180_a13_05to01 180 11 13 X 4 5:01

basic_180_a13_02to01 180 11 13 X 4 2:01

Conclusion

• Hope all the flexures work as predicted. Let’s cross our fingers!

• Hope our flexures would provide insights for future designs that can produce precise movements on the angstrom scale.

• Any Questions?