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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.
February 7, 2011 3
© 2008 Just L. Herder
• 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
?
February 7, 2011 4
© 2008 Just L. Herder
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)
February 7, 2011 5
© 2008 Just L. Herder
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!
February 7, 2011 6
© 2008 Just L. Herder
Biocomponents
• Tensile components (Skin, Tendon, Fibre)• Compressive/bending components (Skeleton)• Relative motion components (Joints, Compliance)• Active components (Muscle)
February 7, 2011 7
© 2008 Just L. Herder
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!
February 7, 2011 8
© 2008 Just L. Herder
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)
February 7, 2011 9
© 2008 Just L. Herder
February 7, 2011 10
© 2008 Just L. Herder
Bio-inspired joints
www.aclsolutions.com
February 7, 2011 11
© 2008 Just L. Herder
Bio-inspired joints
www.aclsolutions.com
Rolling/sliding contact
Cross-wise arranged bands
February 7, 2011 12
© 2008 Just L. Herder
Bio-inspired joints
Bands
Rollers
Springs
www.aclsolutions.com
J Verbeek, JL Herder
www.aclsolutions.com
Rolling/sliding contact
Cross-wise arranged bands
February 7, 2011 13
© 2008 Just L. Herder
Bio-inspired joints
Bands
Rollers
Springs
www.aclsolutions.com
J Verbeek, JL Herder
www.aclsolutions.com
Rolling/sliding contact
Cross-wise arranged bands
Nature does not label…
You hypothesize, investigate, and design.
Physical principles.
February 7, 2011 14
© 2008 Just L. Herder
Minimal Access Surgery
• Reduced dexterity• Reduced sensation• Reduced view
Just Herder
February 7, 2011 15
© 2008 Just L. Herder
Bio-Inspired rolling joints
February 7, 2011 16
© 2008 Just L. Herder
Bio-Inspired rolling joints
February 7, 2011 17
© 2008 Just L. Herder
Bio-Inspired rolling joints
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
= +
− = = =
= + = +
February 7, 2011 18
© 2008 Just L. Herder
Force directed design
M Horward, JL Herder
February 7, 2011 19
© 2008 Just L. Herder
Low friction forceps
• Rolling joint• Flexible band
• Negligible friction• No backlash• No need for
lubrication
M Horward, JL Herder
February 7, 2011 20
© 2008 Just L. Herder
Low friction forceps
Six rolling joints
One-on-onemoment transfer
Herder et al.
Patent pending: US 6447532 M Horward, JL Herder
February 7, 2011 21
© 2008 Just L. Herder
Low friction forceps
Mechanicalefficiency 96%
10 mm shaft
Herder and Horward, 1997Patent pending: US 6447532
February 7, 2011 22
© 2008 Just L. Herder
Low friction forceps
K den Boer et al. (1999)
Pulse in artificial artery can be perceived clearly
February 7, 2011 23
© 2008 Just L. Herder
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
February 7, 2011 24
© 2008 Just L. Herder
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
February 7, 2011 25
© 2008 Just L. Herder
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
February 7, 2011 26
© 2008 Just L. Herder
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
February 7, 2011 27
© 2008 Just L. Herder
Compliance in design
B Trease, S Kota, Univ of Michigan at Ann Arbor
February 7, 2011 28
© 2008 Just L. Herder
Compliance in design
B Trease, S Kota, Univ of Michigan at Ann Arbor
February 7, 2011 29
© 2008 Just L. Herder
Compliance in design
F vd Berg, JL Herder
February 7, 2011 30
© 2008 Just L. Herder
BioDesign
M
V
N
February 7, 2011 31
© 2008 Just L. Herder
BioDesign
M
V
N
February 7, 2011 32
© 2008 Just L. Herder
BioDesign
M
V
N
February 7, 2011 33
© 2008 Just L. Herder
BioDesign
M
V
N
February 7, 2011 34
© 2008 Just L. Herder
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
February 7, 2011 35
© 2008 Just L. Herder
Tensegrity on cell level
D.E. Ingber
February 7, 2011 36
© 2008 Just L. Herder
Tensegrity on cell level
D.E. Ingber
February 7, 2011 37
© 2008 Just L. Herder
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
© 2008 Just L. Herder
Tensegrity on organ level
D.E. Ingber, K. Snelson
February 7, 2011 39
© 2008 Just L. Herder
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
© 2008 Just L. Herder
Tensegrity in Delft
Mark Schenk, Simon Guest, Just Herder
9 cables 9 springs
Tensegrity Mechanism
February 7, 2011 41
© 2008 Just L. Herder
Conclusion
• Different materials• Different components• Different concepts• Different perspective• Big gap• Lots to do