Investigation of the Mechanical Behavior of Open-Cell Ni Foams by Experimental and FEM Procedures

An experimental-computational method was developed to study the mechanical behavior of nickel open-cell foams under tension. The scanning electron microscope equipped with an apparatus of microtension was used, and ex-situ and in-situ micro-tension tests were conducted. The metal foam used in this study was Ni, supplied by INCO, produced by using a polymer pre-form. The tension specimens were cut out with the aid of a matrix manufactured to ensure size reproducibility. The microtest apparatus allowed the performance of tensile or compression tests by gripping the specimen ands with two clamping blocks. The study showed the results as the linear deformation of Ni open-cell foams is very small compared to those of ductile metals with an observed elongation of 3%. The FEM simulation of the foam tensile deformation revealed that the stress develop locally in the struts, leading to the formation of plastic bands and to their eventual failure. Also the FEM calculation were in full agreement with the SEM observations.