Bio-Inspired Design

Vermelding onderdeel organisatie

Bio-Inspired DesignMechanical Stiffness and Motion

Faculty of Mechanical, Maritime, and Materials EngineeringDepartment of BioMechanical Engineering

Just Herder

February 7, 2011 2

© 2008 Just L. Herder

Lecture 2: BioconstructionBiostructure & bioenergy (muscle configurations)

• Contents 1st hour (Just): mechanical stiffness & motion: strength at low weight, redundant structures, etc.

• Contents 2nd hour (Paul): hydrostatic stiffness & motion: energetically efficient muscle configurations, stiffness with soft structures.

Mariza

Typewritten Text

http://www.kennethsnelson.net

February 7, 2011 3


• Engineering: System, Shape, Material

• Are there any differences between human engineering and nature, in terms of:• System• Construction elements• Material

Bioconstruction

Raptor by Kraft Telerobotics

Cool JC, 1976

?

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Biomaterials

• Tensile materials (Crystalline Polymers, Silk, Collagen, Cellulose, Chitin)

• Flexible materials (Protein Rubbers, Mucopolysaccharides, Pliant Composites, Mesoglea, Uterine Cervix, Skin, Arterial Wall, Cartilage)

• Rigid materials (Bone, Keratin, Cell wall, Wood, StonyMaterials)

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Biomaterials

• Tensile materials (Crystalline Polymers, Silk, Collagen, Cellulose, Chitin)

• Flexible materials (Protein Rubbers, Mucopolysaccharides, Pliant Composites, Mesoglea, Uterine Cervix, Skin, Arterial Wall, Cartilage)

• Rigid materials (Bone, Keratin, Cell wall, Wood, StonyMaterials)

• No metal!

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Biocomponents

• Tensile components (Skin, Tendon, Fibre)• Compressive/bending components (Skeleton)• Relative motion components (Joints, Compliance)• Active components (Muscle)

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Biocomponents

• Tensile components (Skin, Tendon, Fibre)• Compressive/bending components (Skeleton)• Relative motion components (Joints, Compliance)• Active components (Muscle)

• No multirev bearings, no wheels, no fasteners!

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Vertebrates: joints

• Synarthroses: hardly movable (sutures in human skull)• Amphiarthroses: slightly movable (cartilage attachments in

ribs and vertebrae disks)• Diarthroses: Larger motion range:

• Ball-and socket (e.g. hip, GH-joint)• Ellipsoidal (e.g. fingers)• Condyloid (e.g. knee joint)• Saddle (e.g. part of the wrist joint)• Pivot (e.g. radius/ulna joint)• Hinge (e.g. elbow joint)• Plane/gliding (e.g. scapula joint)

Mariza

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Mariza

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Mariza

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Mariza

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Mariza

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Mariza

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http://www.yalemedicalgroup.org/stw/images/125405.jpg

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Bio-inspired joints

www.aclsolutions.com

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Bio-inspired joints


Rolling/sliding contact

Cross-wise arranged bands

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Bio-inspired joints

Bands

Rollers

Springs


J Verbeek, JL Herder




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Bio-inspired joints

Bands

Rollers

Springs


J Verbeek, JL Herder




Nature does not label…

You hypothesize, investigate, and design.

Physical principles.

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Minimal Access Surgery

• Reduced dexterity• Reduced sensation• Reduced view

Just Herder

February 7, 2011 15


Bio-Inspired rolling joints

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Band is compromise between bending and tension

Most vulnerable parts take highest forces!

1:

2

F MyA I

d MBernouilli EulerR ds EI

F Ey F EdA R bd R

σ

θκ

σ

= +

− = = =

= + = +

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Force directed design

M Horward, JL Herder

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Low friction forceps

• Rolling joint• Flexible band

• Negligible friction• No backlash• No need for

lubrication

M Horward, JL Herder

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Six rolling joints

One-on-onemoment transfer

Herder et al.

Patent pending: US 6447532 M Horward, JL Herder

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Mechanicalefficiency 96%

10 mm shaft

Herder and Horward, 1997Patent pending: US 6447532

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K den Boer et al. (1999)

Pulse in artificial artery can be perceived clearly

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BioDesign

• Unknown loads• Long or short period• Suddenly or slowly• Once or repeatedly• Move while transmitting considerable forces• Accidental overload• Energy-efficient

• Design Principles• Real Organisms

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BioDesign

• Unknown loads• Long or short period• Suddenly or slowly• Once or repeatedly• Move while transmitting considerable forces• Accidental overload• Energy-efficient

• Design Principles• Real Organisms

We cannot see physical principles, we have to hypothesize. From real organisms we can at best find that it might be right

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BioDesign Principles

• Lightweigth: only tension or compression• Reduce tension members to wires, maximize I in other

members• Minimize use of compression members and maximize

use of tensile members, isolate compessive members• In composite material, the stiffer element used to

control strain and maximize resistance to stress• Thin-walled cylinders effectively reinforce against

explosion and buckling by cross-helical fibres• Either resist or permit great forces/deflections

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BioDesign

Linear beam theory: M=Fh, with =σMy/I and I=πr4/4:

σ=4Fh/πr3 hence rmin=(4Fh/πσ)1/3 non-prismatic trunk

Note: in reality many more factors than aerodynamic drag

F

h

Mariza

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www.ifh.uni-karlsruhe.de

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Compliance in design

B Trease, S Kota, Univ of Michigan at Ann Arbor

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B Trease, S Kota, Univ of Michigan at Ann Arbor

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F vd Berg, JL Herder

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BioDesign

M

V

N

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BioDesign

M

V

N

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BioDesign

M

V

N

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BioDesign

M

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N

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BioDesign: Stuctural Optimization

• Other static loading: cross-sectional shape and material properties, deflection by EI

• Careful with maximizing I, e.g. wall thickness in tubes• Minimum weight/strength ratio: minimize density

(since modulus generally fixed), especially wrt buckling• Energy absorption dominant: uniform cross-section, no

local stress raisers, preferably solid round rod• Pure tension: governed by specific strength and

maximum allowable deformation, any shape rods

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Tensegrity on cell level

D.E. Ingber

February 7, 2011 36


Tensegrity on cell level

D.E. Ingber

February 7, 2011 37


Tensegrity on tissue level

• Linear stiffening: stiffness increases with elongation(non-linear stiffness)

• Similar to biological tissue (pull your skin!)• Stress in all members varies

D.E. Ingber

February 7, 2011 38


Tensegrity on organ level

D.E. Ingber, K. Snelson

February 7, 2011 39


Tensegrity in growth…

• Deployable• Disjointed struts• Axially stiff• Axial stiffening• Weak in bending• Bending softening

A.G. Tibert, S. Pellegrino, K. Snelson

February 7, 2011 40


Tensegrity in Delft

Mark Schenk, Simon Guest, Just Herder

9 cables 9 springs

Tensegrity Mechanism

February 7, 2011 41


Conclusion

• Different materials• Different components• Different concepts• Different perspective• Big gap• Lots to do

Documents

Bio-Inspired Design