THE DYNAMIC BEHAVIOR OF POLYUREA COMPOSITES SUBJECTED TO HIGH STRAIN RATE LOADING
ALI, MOHAMMAD MAQSUD
Baz, Amr M
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A comprehensive theoretical and experimental study of the characterization of Polyurea composites subjected to high strain impact loading are conducted. The composites under consideration consist of multi-layers of polyurea/aluminum arranged in one dimension configuration. Finite element models (FEM) are developed by describing the dynamics of the viscoelastic behavior of the polyurea using the Golla-Hughes-Mctavish (GHM) mini-oscillator approach. The model enables the predictions of the structural stress, strain, strain rate, relaxation modulus, loss factor of the polyurea composites for different layering arrangements. The predictions of the developed FEM are validated against the predictions of the commercial finite element package ANSYS. Also, the FEM predictions are validated experimentally using the Split Hopkinson Pressure Bar (SHPB) which is used to monitor the dynamics of the polyurea composites at different levels of strain rates. Close agreements are demonstrated between the theoretical predictions and the obtained experimental results. The properties of periodic structures are used to develop an analytical model to create attenuation band gaps in dynamical response of periodically placed polyurea composites. The influence of various design parameters that controls the width of pass and stop-bands including multi layered periodic structures and different material configurations is compared. The presented theoretical and experimental approaches are envisioned to provide invaluable tools for the design of polyurea composites that can be used in impact mitigation and protection of critical structures subjected to high impact and blast loading. Keywords: Polyurea composites, dynamics under high strain loading, finite element modeling, Golla-Huges-Mctavish (GHM) mini-oscillators, Split Hopkinson Pressure Bar (SHPB), periodic structures, Bloch wave propagation theory, band gaps.