ASTM D2719に規定される, 木質系面材料の面内せん断試験時の隅部の降伏・破壊が試験体のひずみ分布・ひずみ方向に及ぼす影響

抄録

When using wood-based panels as structural members, it is essential to understand its in-plane shear characteristics. Two-rail shear test defined by ASTM D2719 as an in-plane shear test commonly is used in Japan. However it is not enough to examine whether the pure shear stress is uniformly distributed in the specimen. The objective of this reserch is to clarify the phenomenon concerned with axis and distribution of strain in specimens and to clarify how the phenomenon affects the evaluation of the test result. Medium density fiber board and plywood were used as specimen. At first, FEM analysis was carried out. As a result, a stress concentration was observed at the corner of the specimen. Analyzing a model with slits at the corner, change of strain distribution caused by yield and failure at the corner was studied. In the experimental result, shear strain distribution was different from the analytical result of no-slit model. load- x strain curves and load-y ones were classified based on their shapes. As a result, a certain trend was observed about MDF, but it was not observed about plywood. Judging from experimental and analytical study, yield and failure process was determined about MDF, but about plywood, they occurred randomly. It is thought to be because MDF is homogeneous material and plywood is oriented material.