DYNAMIC STRESS BRIDGING IN GRANULAR MATERIAL

Through numerical experiments we investigate stress localization in gr anular material with application to plastic-bonded explosives. The res ults shed light on static versus dynamic loading, and on the role of a n interstitial material between grains. Under static loading, we obser ve stress localization and bridging in a lattice of polydisperse cylin ders in two dimensions. Under dynamic loading, we observe a two wave s tructure with stress fingers propagating ahead of a normal compaction wave. When an interstitial material is added (a polymeric binder), for ce fluctuations are substantially reduced under both static and dynami c loading. Under dynamic loading, the structure of the stress wave dep ends upon the material properties of the binder. As the binder stiffne ss increases, stress fingering decreases and is replaced by a planar c ompaction wave. (C) 1998 American Institute of Physics. [S0021-8979(98 )10310-9].