Numerical study on closed cell foam structure damage mechanisms

Metallic foams are currently being looked at as a new material for automobiles. The main goal of the use of metallic foams in vehicles is to increase sound dampening, reduce the weight of the automobile, and increase energy absorption in case of crashes, or in military applications, to combat the concussive force of IEDs. The metallic foams that are being looked at currently, are aluminum and its alloys due to their low density (0.4-0.9 g/cm3). In addition these foams have a high stiffness, are fire resistant, do not give off toxic fumes, are fully recyclable, have high energy absorbance, have low thermal conductivity, have low magnetic permeability, and are efficient at sound dampening, especially in comparison to light weight hollow parts. In addition, partial addition of metallic foams in hollow parts of the car will decrease weakness points usually associated with car crashes and noisy vibrations. These foams are cheap to cast by using powder metallurgy (as compared to casting of other hollow parts). The aim of the research was to describe and to assess the main mechanisms that appear in the foam structure during the compression. The development process of the finite element model of the closed cell foam microstructure is presented in the paper. The model geometry was based on the real structure research, which was carried out with the use of computed tomography. The model was built with the use of a unique computer code created to transform the scan point cloud into FE raster model based on solid 8-node elements. The experimental and numerical compression test results were compared and showed good compatibility. The stress distributions were studied to describe the main mechanisms in the structure.