COMPRESSIVE DEFORMATION PROCESS OF JAPANESE CEDAR (CRYPTOMERIA JAPONICA )

摘要

We examined the compressive deformation behavior, and methods of compression fixation were considered. Furthermore, we examined the mechanical characteristics of compressed wood for each method of fixation and each compression ratio. As a result of the examination, the deformation behavior was found to differ depending on the direction of compression. The deformation progressed without causing destruction in compression into the tangential surface, but compression into the radial surface caused partial buckling of the cell walls in the process of deformation. The compression stress showed the tendency to decrease as the temperature and moisture content increased. Steam treatment by the closed heating method was compared with heat treatment by the open heating method as methods of fixation. The closed heating method was found to be effective for deformation fixation in a short time. As the result of the mechanical properties of compressed wood, the moduli of rupture (MOR) and elasticity (MOE) increased as the compression ratio increased, and they showed the tendency to be roughly proportional to the increase in density. However, hardness increased only nominally up to 40 % compression and then increased rapidly from 40 %. Moreover, in 480-min heattreatment by open heating, the influence of heat deterioration on impact-absorbed energy was found.