Plastic deformation due to reflected detonation

Abstract

We report the experimental conditions and results for a series of experiments involving detonation loading of steel tubes alongside computational comparisons performed using an analytic one-dimensional model and a finite element simulation. To achieve plastic deformation, thin-walled steel tubes were filled with a stoichiometric ethylene–oxygen mixture and detonated. The range of initial pressures covered the span from entirely elastic to fully plastic deformation modes. A unique mode of periodic radial deformation was discovered. A model for the pressure load on the tube wall was developed and tested against experimental measurements. Building on the experimental results, we discuss theoretical and computational models describing these experiments. The simplest model considers the oscillation of a single degree of freedom of the tube's cross section. Using this simple model, we explain that the periodic deformation observed in the experiment is the result of interference between the reflected shock wave and the elastic oscillations set in motion by the incident detonation. To capture the effects of boundary conditions and wave propagation, we performed computations using a two-dimensional axisymmetric model of the tube wall. For the mild steel tubes this required material testing, and the resulting constitutive relation proved to be limited. As a result, fidelity with experiments was much greater in the case of the stainless steel tubes.

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