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| PDF : |  05040131.pdf |
| title(En) : | Studies on the Elasticity of Plywood. II. The Effect of Grain Direction on the Elastic Constants of Multilayer Plywood in Tension or Bending. |
| author(En) : | Minoru Sawada, Koichi Kondo, Kenichi Hata |
| information : | Mokuzai Gakkaishi 5(4), 131-138 (1959) |
| assort : | Original Article |
| summary(En) : | The purpose of this report is to present a method for determining the apparent Young's moduli of a multilayer plywood of symmetrical construction. If the plywood is made from a single species, and the grain directions in alternate veneers are at right angles, then the apparent Young's modulus E'Θ at an angle to the grain are given theoretically by the equations (5) in tension and (6) in bending, in terms of the basic constants of all the veneers in the plywood. In the case now reported, the basic constants and their ratios of the veneers in the plywood were determined from the equations (3) and (4) by the tensile or bending tests of the strips, as shown in Fig. 3 of the preceding report, and they lie at the angle Θ with the grain in the outer plies of the sheet, for the values of Θ: 0°, 45° and 90°. In order to determine the basic constants from the equation (3) the following two relations are assumed: E45 = 2ET GLT = E45/(4 - E45/ET2) in this ET≈GLT≈E45/2 The constructions of test plywoods (3-, 5- and 7-ply plates of the same Lauan) are shown in Table 1, and the dimensions in Table 2. The test results in tension and bending are shown in Tables 3 and 5, and the basic constants are as shown in Table 4. The calculated curves in Figs. 1 and 2 were obtained from the equations (5) and (6) using these basic constants. The calculated Young's moduli of test plywoods, in the both cases of tension and bending, agree well with the observed one. |