Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Beam model for the elastic properties of material with spherical voids   The elastic properties of a material with spherical voids of equal volume are
analysed using a new model, with particular attention paid to the hexagonal
close-packed and the face-centred cubic arrangement of voids. Void fractions
well above 74 \% are considered, yielding overlapping voids as in an open-cell
foam and hence a connected pore structure. The material is represented by a
network of beams. The elastic behaviour of each beam is derived analytically
from the material structure. By computing the linear elastic properties of the
beam network, the Young's moduli and Poisson ratios for different directions
are evaluated. In the limit of rigidity loss a power law is obtained,
describing the relation between Young's modulus and void fraction with an
exponent of 5/2 for bending-dominated and 3/2 for stretching-dominated
directions. The corresponding Poisson ratios vary between 0 and 1. With
decreasing void fraction, these exponents become 2.3 and 1.3, respectively. The
data obtained analytically and from the new beam model are compared to Finite
Element simulations carried out in a companion study, and good agreement is
found. The hexagonal close-packed void arrangement features very anisotropic
behaviour, comparable to that of fibre-reinforced materials, This might allow
for new applications of open-cell materials.

32
The categories of this paper are: atom-ph
17
The categories of this paper are: q-fin
31
The categories of this paper are: ao-sci
8
The categories of this paper are: hep-ex
37
The categories of this paper are: supr-con
28
The categories of this paper are: alg-geom
21
The categories of this paper are: adap-org
19
The categories of this paper are: eess
6
The categories of this paper are: astro-ph
3
The categories of this paper are: physics
5
The categories of this paper are: gr-qc
0
The categories of this paper are: hep-ph
1
The categories of this paper are: cs
20
The categories of this paper are: acc-phys
18
The categories of this paper are: econ
7
The categories of this paper are: hep-th