Establishment of characterization methods of compressed wood and analyses of its deformation and failure behaviors

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In this research, various characterization method of compressed wood were examined using spruce, which has a small variation in quality. Compression ratio was variously changed in the fabrication, and several mechanical tests were conducted by the specimens with various compression ratios. Following results were obtained :(1)The influence of compression ratio was more significant in the elastic properties than in the strength properties.(2)Young's modulus in the longitudinal direction increased with the increase of the compression ratio, as was found commonly in the existing works. Therefore, the compression process was thought to be an effective method. In contrast, however, the bending strength did not significantly increase with the increase of compression ratio.(3)When the compressed wood was fabricated under an appropriate compression ratio, Young's modulus in the tangential direction and shear modulus in the longitudinal-tangential plane increased. Nevertheless, Young's modulus i … More n the radial direction and Poisson's ratio and shear modulus in the longitudinal-radial plane tended to decrease. When using the compressed in practical operations, hence, it is necessary to consider the variations of these properties.(4)It was so difficult to measure the tensile strengths in the radial and tangential directions and shear strength in the radial-tangential planes because of the difficulty in cutting the test specimens that the strength properties concerning to the cross section of compressed wood could not be obtained here. Including this issue, further research should be addressed for revealing the strength properties of compressed wood.The influence of the compression ratio on the elastic properties of compressed wood will be published in "Mokuzai Kogyo" in April. As for the issues on the bending and shear strengths and on the elastic properties with concerning to the cross section, articles were submitted to "Wood Science and Technology" and "Forest Products Journal" for publication, respectively. Less