Fractography and Tensile Strength of “Tokkuri-byo” Disease-Infected-Hinoki (Chamaecyparis obtusa Sieb. et Zucc.)

Abstract

In this paper, the fractography and tensile strength of “Tokkuri-byo” disease-infected-Hinoki (Chamaecyparis obtusa Sieb. et Zucc.), which had a very large growth at the root and contains a lot of abnormal cells, were investigated. The results obtained are summarized as follows:
(1) The distribution of annual ring width showed the existence and degree of “Tokkuri-byo”.
(2) “Tokkuri-byo” disease-infected-Hinoki had much less tensile strength than normal Hinoki.
(3) The abnormal cells contained in “Tokkuri-byo” disease-infected-Hinoki showed different fracture types from those of normal Hinoki, depending on these tissue structure properties. Consequently, the macroscopic fracture type of “Tokkuri-byo” wood depends on the quantity and quality of those abnormal cells.
(4) In the tensile test, “Tokkuri-byo” wood produced more radiate ray-type fractures different from the normal one.