Failure Behavior of Wood (Japanese cypress) under Combined Axial Force and Torque. Effects of Loading Method and Loading Path.

Abstract

Mechanical behavior of wood subjected to normal-shear combined stress conditions was examined. Wood specimens of rectangular bars of Japanese cypress were cut into those whose long axis coincided with the longitudinal direction. These specimens were loaded and twisted in and around the long axis, respectively, according to the following two loading methods, that is, the proportional deformation loading method and the initially constant loading method which has two loading paths. The obtained results are summarized as follows : (1) When the torsional moment was applied to the specimen slightly, the obtained failure strength tended to be measured larger than the pure normal strength. (2) The failure loci of whole testing data could be expressed by the ellipse formula. (3) The failure loci seemed not to be influenced by the loading method and loading path, although the failure mode seemed to be influenced by the loading path.