A Virtual Test Facility for Simulating Detonation-and Shock-Induced Deformation and Fracture of Thin Flexible Shells

摘要

The coupling of a dynamically adaptive Eulerian Cartesian detonation solver with hierarchical time-step refinement to a Lagrangian thin-shell finite element solver with fracture and fragmentation capabilities is presented. The approach uses a level-set function to implicitly represent arbitrarily evolving solid structures on the Cartesian mesh. The auxiliary algorithm used to efficiently transform the shell solver mesh on the fly into a distance function is sketched briefly. We detail the derivation of the employed engineering combustion model that eliminates the numerical stiffness otherwise inherent to detonation waves and describe our approach to modeling fracture. The thin-shell solver utilizes a subdivision finite element discretization and achieves element separation with interface edges and a cohesive law. For method validation and benchmarking, the simulation of the deformation of a circular thin copper plate under impulsive pressure loading is presented. As a realistic computational application, we consider a three-dimensional setup in which the passage of an ethylene-oxygen detonation wave induces large plastic deformations and rupture of a thin-walled tubular specimen made of aluminum. Special attention is paid to the verification of the hydrodynamic loading conditions. The computational fluid-structure interaction results are found to be in agreement with experimental observations.