Particle size effect on strength, failure, and shock behavior in polytetrafluoroethylene-Al-W granular composite materials J. Appl. Phys.Measurement of intergranular stress and porosity during dynamic compaction of porous beds of cyclotetramethylene tetranitramine
Internal ballistics describes the combustion of solid propellant within a closed combustion chamber. This is achieved by modelling a mixture of incompressible solid particles and compressible reactive gases with averaged equations of two-phase flow. The combustion of the solid is described with interaction terms that define the rate of mass, momentum and energy exchange from solid into gas. This work concentrates on modelling ignition and the initial stages of combustion, proposing the concept of 'gaseous ignition' by including time-scales of chemical reaction in the gas phase. These non-equilibrium effects are placed firmly within the context of internal ballistics by making direct comparisons between experimental pressure-time histories. In particular, excellent agreement can be achieved between numerical simulations and experimental work by assuming a two-stage reaction process during which the rate of chemical energy release will significantly differ from a single exothermic reaction.
This research determines how particle size and particle distribution affects the compaction of granular beds. A modelling and experimental effort was recently designed to compare the compaction behavior of two types of granular HMX: prepressed conventional (coarse) HMX material (mean diameter of 40μm) and microfine HMX (mean diameter <5μm) [M. Greenaway, Journal of Applied Physics 97, 093521 (2005)]. The microfine material demonstrated higher levels of granular bed strength. Mesoscale modelling of granular beds that are of fixed initial solid volume fraction but vary in particle size and distribution have been undertaken that include a simple elastic-plastic strength model. These suggest that it is not inherently the “size” of a particle that controls the bed strength but the morphology and distribution of particle grains. These solutions are compared with the behavior predicted from continuum scale models of material compaction.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.