Potential of moderately compressed wood as an elastic component of wooden composites

Japanese cedar wood was moderately compressed by 50 % in the radial (R) direction. The compressed wooden blocks were glued into the form of a beam with R directions aligned in the longitudinal direction of the beam. The compressed wooden beam (CR) showed excellent ductility and elasticity comparable to synthetic rubbers. The elastic deflection of the CR was further increased when the tensile side was reinforced by a thin compressed wooden plate (CL), because this ensured that the CR was always in a compressed state while tensile stress was supported by the CL. The CR + CL composite exhibited large deflections ten times greater than that of the original cedar lumber, a Charpy value corresponding to the high amount of energy absorbed in impact bending comparable to that of densified wood, and a large critical bending work exceeding that of uncompressed wood in the direction of the fiber. The soft and durable nature of the composite beam was attributed to the softness and elasticity of the moderately compressed wood, in which the folded cell walls behaved as flat springs.