- Conference date: 20-25 July 2003
- Location: Portland, Oregon (USA)
Many composite materials consist of elastic particles held together by a soft polymeric binder. Usually, the stress in the binder is strain rate dependent. Although in many cases the binder only occupies a few percent of the volume of the material, the macroscopic strain and strain rate of the composite come mainly from the deformation of the binder. For this reason, the strain and strain rate experienced by the binder are usually an order of magnitude larger than the macroscopic strain and strain rate of the composite, and the composite is more sensitive to the strain rate than the binder itself. To model shock wave propagation in the composite, it is essential to correctly account for the stress relaxation in the polymer. Modeling polymer behavior undergoing high strain rate deformations has been a challenge for many conventional polymer models. Recently, based on non‐equilibrium deformation of polymer segments, a new constitutive relation for polymer gels has been developed. A distinguishing feature of the new polymer model is that for a short time, the stress relaxation kernel is inversely proportional to the square root of time. The kernel asymptotes to an exponentially decaying function only for long relaxation times. Based on the newly developed polymer model, a simple model for the particle‐binder composite is obtained. Numerical simulations are carried out to compare shock wave profiles obtained from plate impact experiments at various shock strengths. Excellent agreements are found.
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