SHOCK HUGONIOT BEHAVIOR OF PARTICLE REINFORCED POLYMER COMPOSITES

The shock Hugoniot of polymers is known to exhibit a non‐linear US‐UP relationship at relatively low pressures and commonly displays a concave curvature with an initially rapid shock velocity. However, the experimentally measured shock Hugoniot of particle reinforced composites shows an opposite effect displaying a convex curvature with an initially rapid change in particle velocity. Transformation to pressure‐volume space shows an initial expansion that is not related to a low‐pressure phase change or reaction. In contrast, the volume expansion is connected to decohesion of solid particles from the polymer matrix. Equation of state experiments conducted for epoxy‐cast Al+Fe2O3 composites show deviation from ideal Hugoniot behavior as a result of damage evolving at a critical impact stress. Two compositions prepared with significantly different volume fractions of the binder phase show damage occurring at approximately the same critical impact stress. The Burch‐Murnaghan equation of state (BM‐EOS) is used to characterize the composite's compressibility and identify the magnitude of the critical damage stress.The shock Hugoniot of polymers is known to exhibit a non‐linear US‐UP relationship at relatively low pressures and commonly displays a concave curvature with an initially rapid shock velocity. However, the experimentally measured shock Hugoniot of particle reinforced composites shows an opposite effect displaying a convex curvature with an initially rapid change in particle velocity. Transformation to pressure‐volume space shows an initial expansion that is not related to a low‐pressure phase change or reaction. In contrast, the volume expansion is connected to decohesion of solid particles from the polymer matrix. Equation of state experiments conducted for epoxy‐cast Al+Fe2O3 composites show deviation from ideal Hugoniot behavior as a result of damage evolving at a critical impact stress. Two compositions prepared with significantly different volume fractions of the binder phase show damage occurring at approximately the same critical impact stress. The Burch‐Murnaghan equation of state (BM‐EOS) is used...