期刊
JOURNAL OF APPLIED PHYSICS
卷 104, 期 10, 页码 -出版社
AMER INST PHYSICS
DOI: 10.1063/1.3000631
关键词
aluminium alloys; compressive strength; cracks; densification; filled polymers; fracture; particle size; porosity; pressing; shock waves; tungsten alloys
资金
- Office of Naval Research [N00014-06-1-0263]
- Office of Naval Research Multidisciplinary University Research Initiative Award [N00014-07-1-0740]
- U.K. Engineering and Physical Sciences Research Council
The variation of metallic particle size and sample porosity significantly alters the dynamic mechanical properties of high density granular composite materials processed using a cold isostatically pressed mixture of polytetrafluoroethylene (PTFE), aluminum (Al), and tungsten (W) powders. Quasistatic and dynamic experiments are performed with identical constituent mass fractions with variations in the size of the W particles and pressing conditions. The relatively weak polymer matrix allows the strength and fracture modes of this material to be governed by the granular type behavior of agglomerated metal particles. A higher ultimate compressive strength was observed in relatively high porosity samples with small W particles compared to those with coarse W particles in all experiments. Mesoscale granular force chains of the metallic particles explain this unusual phenomenon as observed in hydrocode simulations of a drop-weight test. Macrocracks forming below the critical failure strain for the matrix and unusual behavior due to a competition between densification and fracture in dynamic tests of porous samples were also observed. Numerical modeling of shock loading of this granular composite material demonstrated that the internal energy, specifically thermal energy, of the soft PTFE matrix can be tailored by the W particle size distribution.
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