Influence of the cell geometry on the tensile strength of open-cell ceramic foams

摘要

Nowadays used open cell foam ceramic materials are mostly of irregular structure which means that the shape of particular foam cells does not exhibit any regular pattern. On one hand, such foam structures lead to only very slight anisotropic or even isotropic behavior upon the mechanical loading, but on the other hand they do not have an optimal resistance to failure upon given loading conditions and level of porosity. The strength of the ceramic foam structure can be thus further improved by design of cells having various regular shapes. Such foams can finally exhibit an orthotropic behavior from both the elastic and strength point of view. To understand how different types of cells influence the foam characteristics in various directions, foam structures with various cell shapes were thus studied and investigated in terms of their tensile strength within this contribution. The structures were modelled by means of beam element based FE models and by utilization of the stress criterion defining failure of particular struts. Totally six different cell types were analyzed under consideration of the same porosity of the final foam structure and amount of the strength anisotropy was quantified. Relation between orientation of struts with respect to a loading direction and the foam strength was discussed in more details. Recommendations for an employment of particular cell types for specific loading conditions were given.