Wood Science and Technology

, Volume 47, Issue 3, pp 481-498

First online:

Stiffness of normal, opposite, and tension poplar wood determined using micro-samples in the three material directions

  • Patrick PerreAffiliated withEcole Centrale Paris, LGPM Email author 
  • , Anh Tuan DinhAffiliated withAgroParisTech, LERFoB UMR1092
  • , Carole AssorAffiliated withINRA, UR BIA
  • , Xavier FrankAffiliated withINRA, LERFoB UMR1092, ENGREF
  • , Gilles PilateAffiliated withINRA, UR0588 Amélioration, Génétique et Physiologie Forestières

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Mechanical tests on micro-samples were performed in the three material directions in normal, opposite, and tension wood collected from a poplar tree. Two custom micro-devices were designed and built in the laboratory to test samples under pure tension in the transverse direction and under 4-point bending conditions in the longitudinal direction. Both devices were designed to handle samples with a small transverse section (a few square mm), which allowed to select zones with homogenous anatomical features. The results indicate a very high longitudinal stiffness in tension wood (up to 35 GPa compared to an average of 18 GPa for normal wood). Considering wood density, the value represents a specific modulus that is nearly 70 % crystalline cellulose. However, tension wood is slightly less stiff in the tangential and radial directions (1,150 vs. 1,500 MPa for normal wood in the radial direction and 430 vs. 530 MPa in the tangential direction).