The failure mechanisms in microstructures are influenced by the geometry of the constituent phases. For the most part, the finite-element analyses of material microstructures have used simplified model microstructures, where, for example, the grain structure is represented by regular polygons; particles in powders, spheres; and fibres in composites and cylinders. This research describes a general method for importing experimentally acquired microstructures into an Eulerian finite-element programme. Calculations of the shock densification of an HMX powder, using this technique, explore the assumptions used to model the thermomechanical response of energetic materials. HMX is an energetic material that is used in a large class of polymer-bonded explosives for conventional munitions.

Articles you may be interested inA molecular dynamics study of the early-time mechanical heating in shock-loaded octahydro-1,3,5,7-tetranitro-1,3,5,7-tetrazocine-based explosives J. Appl. Phys. 116, 033516 (2014); 10.1063/1.4890715 Initial chemical events in shocked octahydro-1,3,5,7-tetranitro-1,3,5,7-tetrazocine: A new initiation decomposition mechanism J. Chem. Phys. 136, 044516 (2012); 10.1063/1.3679384Flame spread through cracks of PBX 9501 (a composite octahydro-1,3,5,7-tetranitro-1,3,5,7-tetrazocine-based explosive)Quantitative analysis of damage in an octahydro-1,3,5,7-tetranitro-1,3,5,7-tetrazonic-based composite explosive subjected to a linear thermal gradient J. Appl. Phys. 97, 093507 (2005); 10.1063/1.1879072Monte Carlo calculations of the hydrostatic compression of hexahydro-1,3,5-trinitro-1,3,5-triazine and βoctahydro-1,3,5,7-tetranitro-1,3,5,7-tetrazocine It is the long term goal of our work to elucidate the microscale mechanisms involved in the initiation of porous energetic materials ͑EMs͒ through direct numerical simulation of EM microstructures subjected to dynamic loading. Through this effort it is hoped that we may suggest appropriate continuum level constitutive models ͑reactive and inert͒ for porous EMs. A major obstacle in this effort is the lack of reliable parameters for the constitutive models in current use in computation. In the current study, we examine the theoretical dependence of shock structure upon the viscous nature of the deformation. In particular, we attempt to demonstrate that a unique value of the viscous parameter exists for an elastoplastic strength model in concert with a simple Newtonian viscous shear rate dependence, which allows us to accurately simulate shock structures observed in experimental studies of octahydro-1,3,5,7-tetranitro-1,3,5,7-tetrazocine. In doing this, a reasonable estimate of the viscous parameter is suggested for use in future modeling efforts.