Wood structure

Gibson, L. J., and M. F. Ashby. Cellular Solids: Structure and Properties. 2nd ed. Cambridge

University Press, © 1997. Figure courtesy of Lorna Gibson and Cambridge University Press.

Softwood: Cedar

Gibson, L. J., and M. F. Ashby. Cellular Solids: Structure and Properties. 2nd ed. Cambridge

University Press, © 1997. Figure courtesy of Lorna Gibson and Cambridge University Press.

Hardwood: Oak

Gibson, L. J., and M. F. Ashby. Cellular Solids: Structure and Properties. 2nd ed. Cambridge

University Press, © 1997. Figure courtesy of Lorna Gibson and Cambridge University Press.

Wood Structure

Modified; after Fig. 5.14 in Dinwoodie © Van Nostrand Reinhold. All ri ghts reserved. This content i s excludedfrom our Creative Commons license. For more information, see http://ocw.mit.edu/help/faq-fair-use/.

Stress strain curves

Gibson, L. J., and M. F. Ashby. Cellular Solids: Structure and Properties. 2nd ed. Cambridge

University Press, © 1997. Figure courtesy of Lorna Gibson and Cambridge University Press.

Balsa

Figure removed due to co pyright re strictions. See Figure 3: Easterling, K. E., R. Harrysson, et al . "On the

Mechanics of Balsa and Other Woods." Proceedings The Royal of Society. A 383, no. 1784 (1982): 31-41.

Balsa: Tangential

Figure removed due to co pyright re strictions. See Figure 4: Easterling, K. E., R. Harrysson, et al . "On theMechanics of Balsa and Other Woods." Proceedings The Royal of Society. A 383, no. 1784 (1982): 31-41.

Figure removed due to co pyright re strictions. See Figure 7: Easterling, K. E., R. Harrysson, et al . "On the

Mechanics of Balsa and Other Woods." Proceedings The Royal of Society. A 383, no. 1784 (1982): 31-41.

Balsa: Radial

Figure removed due to co pyright re strictions. See Figure 5: Easterling, K. E., R. Harrysson, et al . "On the

Mechanics of Balsa and Other Woods." Proceedings The Royal of Society. A 383, no. 1784 (1982): 31-41.

Balsa: Axial

Figure removed due to co pyright re strictions. See Figure 6: Easterling, K. E., R. Harrysson, et al . "On theMechanics of Balsa and Other Woods." Proceedings The Royal of Society. A 383, no. 1784 (1982): 31-41.

Douglas Fir: Tangential Comp

Figure removed due to copyright restrictions. See Bodig, J., and B. A. Jayne.

Mechanics of Wood and Wood Composites. Van Nostrand Reinhold, 1982.

Douglas fir: Radial comp.

Figure removed due to co pyright re strictions. See Bodig, J., and B. A. Jayne.

Mechanics of Wood and Wood Composites. Van Nostrand Reinhold, 1982.

Norway spruce: Axial comp

Images removed due to copyright restrictions. See Figure 5.14: Dinwoodie,J. M. Timber: Its Nature and Behaviour. Van Nostrand Reinhold, 1981.

Gibson, L. J., and M. F. Ashby. Cellular Solids: Structure and Properties. 2nd ed. Cambridge

University Press, © 1997. Figure courtesy of Lorna Gibson and Cambridge University Press.

Model for wood microstructure

Figure removed due to copyright restrictions. See Figure 2: Easterling, K. E., R. Harrysson, et al. "On the

Mechanics of Balsa and Other Woods." Proceedings The Royal of Society. A 383, no. 1784 (1982): 31-41.

Gibson, L. J., and M. F. Ashby. Cellular Solids: Structure and Properties. 2nd ed. Cambridge

University Press, © 1997. Figure courtesy of Lorna Gibson and Cambridge University Press.

Wood: Honeycomb Models

Gibson, L. J., and M. F. Ashby. Cellular Materials in Nature and Medicine. 2nd ed. Cambridge

University Press, © 2010. Figure courtesy of Lorna Gibson and Cambridge University Press.

Wood: Honeycomb Models

YO

UN

G’S

MO

DU

LUS,

E (

GPa

)

1000

100

10

10

1.0

1.0 3.0

0.1

0.1 0.30.01

0.03

balsa

balsa

spruce

spruce

oak

oak

teak

slope 1

slope 3

teak

pine

pine(LD)

(LD)

(MD)

(MD)

(HD)

(HD)

woods,parallelto grain

woods,perpendicular

to grain

celluloseE = 120-140 GPa

Modulus - Densityfor woods

(HD), (MD), (LD) = High/Medium/Low Density

DENSITY, (Mg/m3)(a)

hemicelluloseE = 5-8 GPa

solid composites ofcellulose, lignin and

hemicellulose liein this envelope

ligninE = 2.5-3.7 GPa

woodcell wall

Diagram removed due to copyright restrictions. See Figure 5b: Gibson, L. J. "The Hierarchical Structureand Mechanics of Plant Materials." Journal of the Royal Society Interface 9 (2012): 2749-66.

Wood in Bending: E1/2/ρ (E* ) (Es ) " ρ

* = s %$ * 'ρ ρ ρ

1/2 1/2

s # &

1/2

Stiffness performance index for wood in bending is similar to that for best engineering composites

Modified from Ashby (1992) © Butterworth Heinemann. All rights reserved. This content is excluded

from our Creative Commons license. For more information, see http://ocw.mit.edu/help/faq-fair-use/.

Wood in Bending: σ 2/3f /ρ

σ f*( )2 /3ρ*

=σ ys( )2 /3ρs

ρsρ*

#

$%&

'(

1/3

Strength performance index for wood in bending is similar to that for best engng composites

Modified from Ashby (1992) © Butterworth Heinemann. All rights reserved. This content is excluded

from our Creative Commons license. For more information, see http://ocw.mit.edu/help/faq-fair-use/.

Figure removed due to copyright restrictions. See The internationalbook of wood. Bramwell, M, ed. Artists House, 1982. pp 186-87.

Engineered Wood Products: A Guide for Specifiers, Designers and Users, S. Smulski Ed. PFS Research Foundation, 1997

Image of graceful glued-laminated timber arch bridge removed due to copyright

restrictions. See Figure 13: Engineered Wood Products: A Guide for Specifiers,

Designers and Users. Smulski, S., ed. PFS Research Foundation, 1997.

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