Meso-scale deformation mechanisms of polymer bonded energetic materials under dynamic loading

Abstract

To understand the plastic deformation mechanism of polymer bonded energetic materials, a meso-scale experiment is conducted under dynamic loading. Energetic simulant material with polymer plasticizer are cold pressed using a mold made of stainless steel. An experimental setup is developed to obtain the local strain field at the meso-scale under dynamic loading conditions. The setup consists of a high speed camera with extension tube and microscope objective lens to obtain magnifications ranging from 1× to 50×. A high intensity halogen light source is used for illumination. The field of view for the experiment is 1700 × 690 μm, with a spatial resolution of 4.427 μm/pixel at 100,000 frames/s. Dynamic loading is performed using a split Hopkinson pressure apparatus to obtain a range of strain rates. The strain fields are obtained using digital image correlation technique. To facilitate for the digital image correlation technique, the specimens are speckled using air brush with average speckle size ranging from 12 to 18 μm. Results are presented for the measured strain fields and the associated deformation mechanisms as a function of loading rate.