Failure modes of irregular ceramic foam under compression: Development of a new image based strut segmentation strategy

Abstract

The work investigates the failure modes of microstructure of an irregular ceramic foam subjected to uniaxial compression loading. The foam material is manufactured using direct foaming method and has polydispersed pores homogeneously distributed in the microstructure. The effective stress–strain curve and the macroscopic strength of the material differs significantly from the predictions of the Gibson-Ashby model which assumes regular microstructure. The objective of this work is to determine the reasons. The work builds upon an image segmentation algorithm that utilizes skeletonization method followed by geometric pruning strategies to isolate the struts in the foam microstructure. In this work, a novel pruning strategy defined by a physics-based significance measure is proposed which identifies the struts whose failure leads to macroscopic failure of the material. The stresses in the struts are calculated by a finite element simulation which are then utilized to determine their failure modes. This also reveals the relationship between the struts’ orientation and their failure modes. The energy dissipated by the individual failure modes as the loading is increased shows that there are two dominant modes which are different from the tension/ simple bending failure reported in the Gibson-Ashby model. These failure modes are anti-symmetric double bending and compression.