%0 Research article
%T Displacement fields of wood in tension based on image processing: Part 2. Crack-tip displacements in mode-I and mixed-mode fracture
%A Samarasinghe, S.
%A Kulasiri, G. D.
%D 2000
%J Silva Fennica
%V 34
%N 3
%R doi:10.14214/sf.630
%U https://silvafennica.fi/article/630
%X Near tip displacement fields for tensile loaded cracked rubber and wood  with a crack parallel-, perpendicular-to-grain, and a parallel-to-grain  crack inclined 30°, 45°, and 60° to the load axis were obtained from  digital image correlation (DIC). Theoretical displacements were also  obtained for rubber and wood using isotropic and orthotropic fracture  theory, respectively. The results showed that DIC can reveal fine  details of the nature of displacements and the influences of crack tip  in both rubber and wood. Experimental crack tip displacements for wood  compare well with theory; particularly, when load is  perpendicular-to-grain. Some anomalies were found in the tip  displacements in the direction of the tracheids due to the unique nature  of their behaviour not accounted for by theory. Mixed-mode crack tip  displacement fields for wood clearly showed the increasing influence of  crack angle on the displacements, and the displacements perpendicular to  crack compared very well with theory. The displacements parallel to  crack showed some variations owing to the involvement of tracheids.