中空骨格を有する多孔質金属材料の圧縮変形挙動

抄録

This study investigated the compressive deformation behavior of hollow-strut cellular materials. The present cellular structure consists of pentagon and/or hexagonal shaped cellular network, where the individual strut cross-section is hollow triangular prism. Uni-axial compressive test is applied to the present material and we investigate macroscopic deformation behavior as well as the changes in microstructure with respected to the applied strain. The macroscopic nominal stress-strain curve showed a linear relationship during elastic deformation, and then a stress plateau region was observed, followed by the gradual increase in plastic flow stress. Next, by using X-ray micro-CT technique, the strut geometry was quantitatively identified, and based on which finite element method (FEM) was carried out to elucidate the relationship between the strut geometry and the microscopic/macroscopic elastoplastic deformation. A three dimensional spatial structure unit model was established to mimic the present open-cell structure, where the employed strut material properties were obtained from micro-indentation experiments. The FEM computational result agrees reasonably with experimental one of the macroscopic Young's modulus and yield stress. It also suggests that the stress concentration occurs in the minimum cross-section of strut, and then plastic deformation starts at this local point. Such a local yield phenomenon becomes a trigger of buckling for strut, leading to macroscopic plastic deformation characteristics.