Static Compression and Resonance Vibration Tests on Cellular Materials Gravity Sintered from Hollow Bronze Spheres

Metallic foams and cellular solids represent a relatively new class of materials with perspective applications in lightweight structures, in acoustic and thermal management, in energy-absorbing parts, etc. Efficient use of these advanced materials requires detailed information on their mechanical behaviour, even when their primary use is not linked to mechanical loading (e.g., thermal insulation, filters, etc.). The most characteristic feature of the materials mentioned is their low density. The large pore volume minimizes the load-bearing cross section. Consequently, the foams and cellular solids usually cannot withstand high tensile forces. Therefore, mechanical experiments are conducted primarily in compression and flexure loads. The cylindrical and rod-shaped specimens were prepared by gravity sintering from Cu-Sn hollow spheres. On these samples, both static compression tests and measurements of resonance frequencies were performed. The compressive stress-strain curves revealed the features characteristic for a closed-cell ductile cellular solid. The removal of in general open porosity among loosely packed closed metallic hollow spheres was recognized as the principal mode of plastic deformation. The approximative effective moduli of elasticity were determined for cellular materials under consideration by means of the measurements of resonance frequencies on rodshaped specimens.