木材の静的曲げにおけるひずみエネルギに及ぼす含水率の影響

概要

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In order to elucidate the effects of moisture content on the strain energy to the proportional limit U_p and that to the maximum load U_m, the mechanical characteristics (σ_p, ε_p: stress and strain at the proportional limit, E : modulus of elasticity in bending, σ_m, ε_m : stress and strain at the maximum load) in bending were determined by the central loading on beams of Sitka spruce (Picea sitchensis CARR,). The measurements were carried out at 20, 30, 40 and 50℃ under the nominal moisture content of 0, 5, 10 and 15%. The strain energy to the proportional limit U_p and that to the maximum load U_m were calculated by finding the respective areas under the load-deflection curve and dividing them by the volume of the span portion of beam. The results obtained are as follows : (1) The values of σ_p, σ_m, ε_p and E decreased almost linearly, and the value of ε_m increased, with the increase of moisture content. (2) The strain energies of U_p and U_m decreased almost linearly with the increase of moisture content. (3) The change of U_p and U_m with moisture content was dependent on the relative relation between the percentage change of stress and strain corresponding to the 1% change in moisture content. In this experiment, the average percentage change in stress (σ_p, σ_m) with the l% change in moisture content was more than that in strain (ε_p, ε_m).
社団法人日本材料学会の論文
1981-07-15