The effect of grain shape, size distribution, intergranular friction, confinement, and initial compaction state on the high strain rate compressive mechanical response of sand is quantified using Long Split Hopkinson Pressure Bar (LSHPB) experiments, generating up to 1.1 ms long load pulses. This allowed the dynamic characterisation of different types of sand until full compaction (lowest initial void ratio) at different strain rates. The effect of the grain morphology and size on the dynamic compressive mechanical response of sand is assessed by conducting experiments on three types of sand: Ottawa Sand with quasi-spherical grains, Euroquartz Siligran with subangular grains and Q-Rok with polyhedral grain shape are considered in this study. The adoption of rigid (Ti64) and deformable (Latex) sand containers allowed for quasi-uniaxial strain and quasi-uniaxial stress conditions to be achieved respectively. Additionally, the effect of intergranular friction was studied, for the first time in literature, by employing polymer coated Euroquartz sand. Appropriate procedures for the preparation of samples at different representative initial consolidation states are utilized to achieve realistic range of naturally occurring formations of granular assembly from loose to dense state. The results identify material and confining sample state parameters which have
Qualitative evidence of chemical reactions between combustible metal shaped charges in air and water has previously been reported based on high-speed photography, spectroscopy, and calorimetry. This report covers investigations directed towards quantifying the conditions under which reaction occurs and the consequences on terminal encounter with submerged inert steel plates. In order to distinguish effects hypervelocity long-rod and shaped charge jet impact experiments were conducted in inert fluid, water and concentrated hydrogen peroxide. It is shown that reaction causes foreshortening of aluminum penetrators at rates that are more competitive at impact velocities towards the slow end of an effective penetrating jet, and that localized reaction and thermal expansion of ablative particulates prior to and after impact can cause substantial plate deformation. The results are consistent with hydrodynamic penetration theory when modified for reaction induced foreshortening. Predicted impact and penetration effects against submerged steel plates submerged in a chemically inert fluid are shown to agree with experiment, and the effect of density difference between the selected spindle oil inert simulant, water and concentrated hydrogen peroxide are shown to be within experimental variation.
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