Abstract
Yield behavior of wood (Japanese beech : Fagus crenata B1. and Japanese cypress : Chamaecyparis obtusa ENDLICHER) under a combined static axial-shear stresses was examined. The specimen had a rectangular cross section with one of its major axis lying in the fiber (longitudinal) direction. The axial force was applied in the fiber direction (along L) and torque was applied about an axis lying in the same direction as L. Combined loading test was performed according to the proportional deformation loading method. The obtained results were summarized as follows : 1) The determinations of yield points were more influenced by torsion than axial force. 2) The stress-strain relationships of Japanese cypress showed more elastic than those of Japanese beech. 3) The yield loci seemed not to be influenced by the difference between LT and LR planes, and could be expressed by the past yield criteria, like Hill type. 4) It is suggested that the equivalent stress-equivalent strain relation could be used at the determination of yield point.
