木材の横引試験方法について

抄録

This investigation is concerned with a new method for tension test perpendicular to grain of wood. According to test method by the author, the test piece has the shape and the dimension of the kind shown in Fig. 1, and the tensile load was loaded in the Amsler testing machine (at 400kg capacity) in hardwoods, and in single lever type tensile test machine (at 100kg capacity) in softwoods. In the cases, the method of clamp for test piece is ‘wedge grip’ in Fig. 2. The elongation of test piece was determined by the Yuasa's mirror extensometer (10^-3mm unit, the 1st method). The gage length of test piece is 20mm or 30mm at the center part (epual dimension) in Fig. 2.
If a prismatical test piece (Fig. 1) of wood be loaded in a testing machine in tension, and if we plot the increase in length Δl of a length l_o chosen in the unstrained condition as abscissae (ε=Δl/l_o) and the tensile stress (σ kgcm²) as ordinates we obtain curves of kind shown in Fig. 3. In the type A the ‘VVolligkeitsgrad’ is about 0.5-0.6 (softwoods); and in the type B it is about 0.6-0.7 (hardwoods).
The results obtained by the author's test is shown in table 1. And then, the test pieces fracture at the center part of equal dimension in Fig. 4, and in the case the surface of fracture is radial face contained wood rayes divided. Finally, the tensile strength obtained by this method seems to be higher as the results in the F. P. L. of U. S. of America, Germany and the others (see table 2 and 3).