Conventional dropweight technique was modified to accommodate low amplitude signals from low strength, cold isostatically pressed energetic ``heavy'' composites of polytetrafluoroethylene (PTFE)/AL/W.~ The fracture strength, strain and post-critical behaviour of fractured samples were measured for samples of different porosity and W grain size (the masses of each component being the same in each case).~ Unusual phenomenon of significantly higher strength (55 MPa) of porous composites (density 5.9 g/cc) with small tungsten particles (1 micron) in comparison with strength (32 MPa) of dense composites (7.1 g/cc) with larger tungsten particles (20 micron) was observed.~ This is attributed to force chains created by a network of small tungsten particles. Interrupted tests at the different level of strains revealed mechanism of fracture under dynamic compression.
*This research was supported by ONR, Award No: N000140610263.
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Authors
John Addiss
Cavendish Laboratory, University of Cambridge, Cambridge CB3 0HE, UK
Jing Cai
Materials Science and Engineering Program, University of California San Diego, CA 92093
Materials Science and Engineering Program, University of California, San Diego, La Jolla, CA 92093-0418
Steve Walley
Cavendish Laboratory, University of Cambridge, Cambridge CB3 0HE, UK
William Proud
Cavendish Laboratory, University of Cambridge, Cambridge CB3 0HE, UK
University of Cambridge
Cambridge University
Cavendish Laboratory, Cambridge University
Vitali Nesterenko
Department of Mechanical and Aerospace Engineering,University of California San Diego, CA 92093
University of California, San Diego
Dept. of Mechanical and Aerospace Engineering, University of California, San Diego, La Jolla, CA 92093-0411
Mechanical and Aerospace Engineering Department, University of California, San Diego
Department of Mechanical and Aerospace Engineering, University of California at San Diego, La Jolla, California 92093-0418
