Mechanical Properties

• type of loading

• Wood tissue structure

• Wood cell wall structure and chemistry

• Density

• Humidity/MC

• Temperature

• Funghi attack

• Stain: e = delta l/l

• Uniaxial stress: roh=F/A

• E=roh/e [MPa]

• Correlation between axial elongation and lateral contraction:

• Fibre load angle: the higher the lower E

• Moisture content: The higher the lower E (contstant at >30%)

• Higher MFA —> lower E Modulus

  
  

• The higher the bulk density the higher the compressive strength

• Anisotropy: tensile strength parallel to fiber grain > compressive

•  tensile strength perpendicular to fibers < compressive

Density, Moisture content, growth ring widths, angle to fibre grain

Torsion

Higher density —> higher bending and compressive strength

W=m*g(H-h)

• 3% best impact strength

• Then it goes down for higher moisture contents

• Higher density —> higher brinell hardness

• Lower moisture conzemz —> higher brilell hardness

• Buolk density

• Width of annual ring

• Amount of fractions

• Fibre deviation

• E-modulus

Deformation of wood under loading as function of time

Stain = elastic + viscoelastic + mechano-sorptive + plastic

• Superimposition of creep and swelling: strong influence of sample cross-section

• Tensile loading + adsoption: Sample length increase due to creep plus due to swelling

• Compressive loading and adsorption: Sample length decrease due to creep but increase due to swelling

Deformation in an alternin climate is higher than in constant climate for the same sorption maxima

• Higher mechanical properties than native wood

• 6x higher tensile strength

• Reason: Higher Fiber volume content (determined by eometry and alignment)

• Water enables shaping of delignified wood —> reduced strength and stiffness

• Matrix infiltration with DMDHEU or Epoxy