木材の破壊形態

木材の構造から見た基本形と用語

抄録

The failure modes of wood were outlined and their basic types were illustrated in schematic diagrams and pictures. The broken ends of cells and the fractured surfaces of cell walls in the fractured wood pieces had complicated forms and structures. Their fractured types were classified into several categories in relation to wood structure, and their technical terms were proposed.
In tension parallel or perpendicular to grain, failure modes of cellular structure are divided into two main categories, namely, “intercellular (interwall)” and “transcellular (transwall)”. The intercellular failure occurs at or close to the intercellular layer (middle lamella), and the fractured surface is almost parallel to the fibers. The transcellular failure shows the following fracture types, “longitudinal split”, “cross”, “oblique” and “splintering”. As to the transwall failure of the wall layers and lamellae, there are six fracture patterns, “cross”, “oblique”, “plicate-pattern”, “split”, “splintering” and “interlayer (or interlamellar)”. The fractured surfaces of nonfibrillar type are often found on the broken ends of lingnin-rich wall.
In compression parallel to grain, minute failures are detected as wrinkles on the lumen surface, or as slip planes or bendings of cell walls. They progressively develop from microscopic failure lines to macroscopic ones. In compression perpendicular to grain, a remarkable deformation occurs in the cross-sectional shape of cells.