Seminar Schedule – Spring 2015

Tuesday, March 3, 2015
Time: TBA
Place: TBA

The effect of microstructure on the stiffness of random open-cell foams

Andy Kraynik, Institute for Theoretical Physics I, University of Erlangen-Nuremburg

Ordered structures, such as the Kelvin and Weaire-Phelan foams, are natural starting points for modeling low-density open-cell foams but they lack two key features of real materials: random cellular morphology and polydispersity. Finite element analysis is used to calculate Young’s and bulk modulus of random polydisperse foams (with up to 1728 cells) based on three classes of structure: 1) Voronoi polyhedra from random packings of monodisperse spheres of varying density, 2) Laguerre polyhedra from dense packings of polydisperse spheres, and 3) soap froths produced by minimizing surface area with the Surface Evolver. The cell vertices are connected with straight beams of uniform Plateau-border cross section to model the network of struts in open-cell foams. The Young’s moduli of the Voronoi foams are the highest and increase with polydispersity, while the Young’s moduli of the more realistic structures based on soap froth geometry are the softest and relatively insensitive to polydispersity. All of the Young’s moduli differ by less than a factor of two. The bulk moduli of all of the structures decrease with polydispersity. The application to simulations of quasi-static and dynamic crushing of Al open-cell foams will be shown.

For more information, contact Dr. Andy Kraynik at amkrayn@gmail.com.