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THE UNIVERSITY OF READING
CENTRE FOR BIOMIMETICS
Wood Matters – A celebration of the work of John R. Barnett
REACTION WOODS
INSPIRATION FOR SMART MATERIALS
AND STRUCTURES
George Jeronimidis
CompressionWood
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THE UNIVERSITY OF READING
CENTRE FOR BIOMIMETICS
Wood Matters – A celebration of the work of John R. Barnett
WHAT IS INTERESTING ABOUT REACTION WOODS ?
IS THERE SOMETHING USEFUL TO LEARN ?
INSPIRATION FOR ENGINEERING SOLUTIONS
CONCLUSIONS
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Reaction wood is used by trees to modulate shape of trunk and branches
Why aren’t all trees the shape of weeping willows ?
Adaptive shape change
THE UNIVERSITY OF READING
CENTRE FOR BIOMIMETICS
Wood Matters – A celebration of the work of John R. Barnett
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Wood microstructure
20-30m
Fibres provide the key organisational elements for functional self-assembly
THE UNIVERSITY OF READING
CENTRE FOR BIOMIMETICS
Wood Matters – A celebration of the work of John R. Barnett
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Creating functional fibre architectures in plant cell walls
Barnett & Jeronimidis, 2003Clair, 2001
Cave, 1980
THE UNIVERSITY OF READING
CENTRE FOR BIOMIMETICS
Wood Matters – A celebration of the work of John R. Barnett
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Physical interactions between cell walls during maturation
THE UNIVERSITY OF READING
CENTRE FOR BIOMIMETICS
Wood Matters – A celebration of the work of John R. Barnett
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Hygro- or thermal expansivity of angle-ply structures
THE UNIVERSITY OF READING
CENTRE FOR BIOMIMETICS
Wood Matters – A celebration of the work of John R. Barnett
Interesting effects result from coupled deformations in anisotropic laminated structures
Neither component in the laminate (fibres / matrix) has a negative or zero thermal exapansion coefficient
Yet, the laminate can be designed to have negative or zero expansivity for some specified fibre angles
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Depending on the microfibrillar orientation in the various cell walls and their relative thickness, their interactions during maturation can produce axial shrinkage, axial expansion, radial shrinkage, radial expansion and twist
Axial contraction in tension woodAxial expansion in compression wood
THE UNIVERSITY OF READING
CENTRE FOR BIOMIMETICS
Wood Matters – A celebration of the work of John R. Barnett
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Partial or total suppression of deformation (twist) due to cell-cell adhesion = high internal stresses at interfaces
THE UNIVERSITY OF READING
CENTRE FOR BIOMIMETICS
Wood Matters – A celebration of the work of John R. Barnett
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Non-symmetric laminate
De-hydration / Maturation
Shape change (curvature)
normal wood
tension wood
THE UNIVERSITY OF READING
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Wood Matters – A celebration of the work of John R. Barnett
Differences between reaction wood and normal wood provide mechanism for shape change
Coutand et al, 2004
Poplar – Normal Wood Poplar – Tension Wood
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Inspiration for engineering solutions
THE UNIVERSITY OF READING
CENTRE FOR BIOMIMETICS
Wood Matters – A celebration of the work of John R. Barnett
Adaptive roof element
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THE UNIVERSITY OF READING
CENTRE FOR BIOMIMETICS
Wood Matters – A celebration of the work of John R. Barnett
Tension or Compression Wood “Cell” element
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THE UNIVERSITY OF READING
CENTRE FOR BIOMIMETICS
Wood Matters – A celebration of the work of John R. Barnett
“Tissue / Organ” element
Tension wood side
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THE UNIVERSITY OF READING
CENTRE FOR BIOMIMETICS
Wood Matters – A celebration of the work of John R. Barnett
Tension wood side
Compression wood side
Element combining “tension” and “compression” wood
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Stretching-Bending
Different materials
Different scale
Different actuation
…………………………….but
SAME FUNCTIONALITY
THE UNIVERSITY OF READING
CENTRE FOR BIOMIMETICS
Wood Matters – A celebration of the work of John R. Barnett
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DIFFERENTIATION AT THE “MATERIAL” LEVEL
(Anisotropy, Heterogeneity, Hierarchies)
FUNCTIONAL INTEGRATION AT THE “SYSTEM” LEVEL
+DIFFERENTIATION AT THE “STRUCTURE” LEVEL
(Shape, Dimensions, Geometry)
THE UNIVERSITY OF READING
CENTRE FOR BIOMIMETICS
Wood Matters – A celebration of the work of John R. Barnett
Conclusions
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THANK YOU JOHN FOR THE INPIRATION AND SUPPORT DURING ALL THESE YEARS
YES !!! IT IS ONE OF YOUR PICTURES
THE UNIVERSITY OF READING
CENTRE FOR BIOMIMETICS
Wood Matters – A celebration of the work of John R. Barnett