The Contribution of the Expanding Shell Test to the Modeling of Elastoplaticity at High Strain Rates

The expanding shell test allows to load a material in the domain of high strain levels while strain rate is about 104s−1. This test submits an hemisphere to a radial expanding free flight, using a pyrotechnic device. The experiment (experimental apparatus, measurements…) is described with the difficulties encountered for the interpretation of the experimental data. Under some assumptions, the numerical transformation of radial velocities gives indications about the evolution of the strain, stress, strain rate and temperature rise, this last one being related to plastic work. We show how it is possible to associate both analytical and numerical approaches. Numerical simulation of the test is presented in a companion paper (see [Buy01]). Results obtained for copper, tantalum and TA6V4 are presented. The contribution of this test to the modeling of elastoplastic behavior is discussed and further works are proposed.