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 Notch HInge Distributes deflection over length of hinge -lower stress -higher deflection to beam length ratio More immune to parasitic forces

Predicting Motion Simple application of bending theory:

Our Design Basic flexure (single or cascaded) H flexure (single or cascaded) Buckling flexure

BEAM LENGTH AND BEAM RATIO Our Design Test bench: To study the effects of varying different design properties 50 + variations JOINT DESIGN NECK DESIGN AND LENGTH NUMBER OF FLEXURES IN CASCADE BEAM WIDTH BEAM LENGTH AND BEAM RATIO

Basic Flexure Anchor (Poly1 encloses Anchor1) Neck (Poly1) Beam Length: 60 um Beam Width: 12 um Beam Ratio: 1 to 1 Neck Length: 5 um Anchor (Poly1 encloses Anchor1) Neck (Poly1) 1 um, 5 um, 9 um, 11 um, 13 um 33 um, 41 um, 49 um Beam (Poly1) Length: 60 um, 88 um, 90 um, 120 um, 168 um, 180 um, 248 um, 330 um, 660 um Width: 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

Basic Flexure Samples: 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: 3 Type of Joint Used: Spring #3

Number of Flexures in Cascade: 2, 3 Joint between 2 Flexures (Poly1) Beam Length / Flexure: 168 um Beam Width / Flexure: 8 um Beam Ratio / Flexure: 3 to 1 Number of Flexures in Cascade: 2 Type of Joint Used: Spring #1 Number of Flexures in Cascade: 2, 3 Joint between 2 Flexures (Poly1) Beam Length per Flexure: 168 um, 248 um Beam Width per Flexure: 8 um Beam Ratio per Flexure: 1 to 3, 3 to 1, 1 to 5, 5 to 1 Spring #1 Spring #2 Spring #3 Flexure

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: 4 Type 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: 8 Type of Joint Used: Flexure Beam Length / Flexure: 660 um Beam Width / Flexure: 12 um Beam Ratio / Flexure: 10 to 1 Number of Flexures in Cascade: 4 Type of Joint Used: Spring #1

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 Name Length Width Neck Ratio basic_660_a13_10to01 660 11 13 X 4 10:01 basic_330_a13_10to01 330 Width Name Length Buckling_598_thin_good 598 11 Buckling_598_good 16 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 s2

Test Bench Different Necks Different Ratios Length Width Neck Ratio Name Length Width Neck Ratio basic_360_a13_05to01 360 11 13 X 4 5:01 basic_360_a11_05to01 11 X 4 basic_180_a13_02to01 180 2:01 basic_180_a11_02to01 Different Ratios basic_180_a13_05to01

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?