*Thermec 2006*,
pp. 1857-1862, 2007

### MICROMECHANICAL MODELS OF METALLIC SPONGES WITH HOLLOW
STRUTS

T. Daxner, R. Bitsche, H.J. Böhm

Institute of Lightweight Design and Structural Biomechanics,

TU Wien,
Vienna, Austria

**Abstract** -
Coating of a precursor structure, which is subsequently removed by chemical or
thermal treatment, is a technology for producing cellular materials with
interesting properties, for example in the form of metallic sponges with hollow
struts.
In this paper idealized models for determining the effective elastic properties
of such materials are presented.
The chosen models for the structures are space-filling, periodically repeating
unit cell models based on idealized models of wet foams, which were generated
with the program `Surface Evolver'.
The underlying topology is that of a Weaire-Phelan structure.
The geometry of the micro-structures can be described by two principal
parameters, viz. the volume fraction of solid material in the precursor
structures, which determines the shape of the final structures, and the
thickness of the metallic coating, which defines their apparent density.
The influence of these two parameters on the macro-mechanical behavior is
investigated.
The elastic properties of the micro-structures are described by three
independent elastic constants owing to overall cubic material symmetry.
The dependence of the effective Young's modulus on the direction of uniaxial
loading is investigated, and the elastic anisotropy of the structures is
evaluated.

(hjb,061124)