Initial load of 'Kushidango' metallic hollow sphere structure under compression

We have developed a new porous metal, 'Kushidango' metallic hollow spheres (MHS) structure, to apply to car parts as a lightening material. 'Kushidango' MHS is a tubular component and it has a shape of a string of hollow spheres. The component is made by tube bulging from a thin tube of small diameter within dies and then the components are stacked and joined to be the structure. Mechanical properties of the structure can be changed by arrangement of the components. 'Kushidango' MHS has anisotropy between radial and axial directions due to tubular shape and the resistance to axial compression is larger than the radial. In this research, compression resistance of the structure from some angles was examined. When the structure was compressed in the longitudinal direction of the tubular components, increasing ratio of the initial resistance is large. However, since the components were brazed by tin solder and the joint strength was small, each buckled components were separated and the structure was easily collapsed. As the result, radial compression has the highest reliability of performance. In case of radial compression of the structure with relative density of 0.08, the elastic modulus became 0.3 similar to 0.5GPa. In order to apply to load dispersing plate put under a heavy structure, the performance was also examined by testing a plate of 'Kushidango' MHS structure. The plate was loaded at the center from upper and then pressure distribution between the plate and the ground was observed. Because plate thickness of porous metal becomes large, performance of the load dispersion becomes good. (C) 2014 Elsevier Ltd. This is an open access article under the CC BY-NC-ND license.