Static and dynamic compressive and tensile response of highly stretchable polyurea

The mechanical response of highly stretchable polyurea elastomer at various strain rates is investigated via experiments, theoretical analysis, and numerical modeling. Experiments encompassing quasi-static and dynamic (SHPB/SHTB - split Hopkinson pressure/tension bar) mechanical tests, as well as drop-weight impact tests, are undertaken to identify the nonlinear and rate-dependent relationship between tensile/compressive true stress and deformation of the polyurea studied. Subsequently, a compressible visco-hyperelastic constitutive model for the material is established based on the summation of Cauchy stress components. The proposed model yields good agreement with experimental data, as well as a better description of the tensile response at stretch rates of 103 s−1 than other models (e.g., the YSL2000 model (Yang et al., 2000) and the SYLL2004 model (Shim et al., 2004)). The model is implemented in the commercial finite element code Abaqus/Explicit via a user-defined material (VUMAT) subroutine. Homogenous deformation modes of polyurea, i.e., uniaxial compression and tension, are accurately captured, and non-uniform deformation of polyurea, corresponding to impact by a hemispherically-tipped drop weight, which induces both compression and tension, is also well described. Finally, it is demonstrated that the proposed model is able to characterize the dynamic response of other polyureas reported in literature. The present study is helpful for the design and development of blast and impact-resistant polyurea protective coatings.