Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: High Strain and Strain-Rate Behaviour of PTFE/Aluminium/Tungsten
  Mixtures   Conventional drop-weight techniques were modified to accommodate
low-amplitude force transducer signals from low-strength, cold isostatically
pressed 'heavy' composites of polytetrafluoroethylene, aluminum and tungsten.
The failure strength, strain and the post-critical behavior of failed samples
were measured for samples of different porosity and tungsten grain size.
Unusual phenomenon of significantly higher strength (55 MPa) of porous
composites (density 5.9 g/cc) with small W particles (less than 1 micron) in
comparison with strength (32 MPa) of dense composites (7.1 g/cc) with larger W
particles (44 microns) at the same volume content of components was observed.
This is attributed to force chains created by a network of small W particles.
Interrupted tests at different levels of strain revealed the mechanisms of
fracture under dynamic compression.

25
The categories of this paper are: patt-sol
1
The categories of this paper are: cs
6
The categories of this paper are: astro-ph
21
The categories of this paper are: adap-org
33
The categories of this paper are: plasm-ph
24
The categories of this paper are: dg-ga
31
The categories of this paper are: ao-sci
35
The categories of this paper are: mtrl-th
18
The categories of this paper are: econ
15
The categories of this paper are: nucl-ex
32
The categories of this paper are: atom-ph
10
The categories of this paper are: q-bio
9
The categories of this paper are: nlin
34
The categories of this paper are: chem-ph
2
The categories of this paper are: math
13
The categories of this paper are: quant-ph