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 Compression Wood
Mar 29, 2015
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
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
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
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
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
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
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
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
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
Non-symmetric laminate
De-hydration / Maturation
Shape change (curvature)
normal wood
tension wood
THE UNIVERSITY OF READING
CENTRE FOR BIOMIMETICS
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
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
THE UNIVERSITY OF READING
CENTRE FOR BIOMIMETICS
Wood Matters – A celebration of the work of John R. Barnett
Tension or Compression Wood “Cell” element
THE UNIVERSITY OF READING
CENTRE FOR BIOMIMETICS
Wood Matters – A celebration of the work of John R. Barnett
“Tissue / Organ” element
Tension wood side
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
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
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
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