Development of solid–fluid biomimetic composites: Load dispersion effect of controlled hydrostatic pressure

The purpose of this research project is to apply biomimetic-designed composites to artificial structures. The natural bone is an optimum-designed structural system to support the living body. So, it is very useful in developing original optimum designs of the composite materials to study composite structures of the bone. Looking at the bio-joint mechanism, the solid–fluid composite structure of the cancellous bone has likely important effect in the load transmission. In this study, the solid–fluid composite model of the cancellous bone was made by using honeycomb structure. Static-indentation tests were carried out, and in-plane deformation conditions of the specimens were measured quantitatively. At first, the load dispersion effect of two kinds of fluid was examined by using small cell size Al honeycombs. Air and glycerine were sealed in each hexagonal cell of the specimens with thin films, respectively. But the film adhesion did not affect the deformation of honeycomb structures. Even the hydrostatic pressure of air greatly affects the in-plane deformation condition of the solid phase. Next, the load dispersion effect of the controlled hydrostatic pressure was examined by using large cell size Al honeycombs. The propagation of air hydrostatic pressure in the specimens was controlled by making a small hole in the specific cell walls of the honeycomb structure. Consequently, as for the solid–fluid composite models, the possibility of the optimum control of the compressive load dispersion was expected.