Despite their common usage in armor applications such as lightweight armored vehicles, the dynamic material response of 5083-H131 and 5083-H32 strain-hardened aluminum alloys has not been previously reported in the open literature. Measurement of the dynamic material properties, including the shock Hugoniot equation of state (EOS), provides hydrocode modelers with critical information required for accurate modeling of material response to intense loading. In the work reported here we investigate the Hugoniot EOS and Hugoniot elastic limit over the stress range of 1.5–8.0GPa. All experiments were performed on the Army Research Laboratory 102mm bore single-stage light gas gun. Impact conditions were uniaxial and planar to within 1mrad of tilt. Both direct-impact- and shock-transmission-type experiments were performed using velocity interferometry diagnostics to record particle velocity histories with 0.5ns temporal resolution. The shock Hugoniot for 5083-H131 is extrapolated to 50GPa and compared to the previous high pressure results of Hauver and Melani (1973) [Ballistic Research Laboratory December Technical Report No. BRL 2345, 1973] and to prior shock studies of 5083-O aluminum alloy.

Finite size effects on aluminum/Teflon reaction channels under combustive environment: A Rice-Ramsperger-Kassel-Marcus and transition state theory study of fluorination Abstract. Three experimental techniques have been used to investigate the impact ignition of reactive materials. The three techniques are direct impact, indirect impact, and two-step impact. For the first two techniques, time-resolved light spectroscopy was used to identify reaction species from solid PTFE/Al reactive material. A common observation for these two techniques is that heating and some reaction was observed during initial impact of the PTFE/Al reactive material but the majority of the reaction appeared to occur following material breakup and subsequent impact with a secondary surface. There was no spectral evidence for aluminum-fluorine combustion. For the two-step impact technique, the reactive material was initially pulverized as it passed through a thin plate and then subsequently ignited when the debris cloud impacted a rigid anvil. All three experiments were observed with high-speed photography.

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Strain-induced symmetry changes in diamond have been observed in shock compression experiments. The experimental method utilizes time-resolved Raman spectroscopy to probe the diamond structure behind the shock front. Peak longitudinal stresses to 50 GPA were achieved by uniaxial strain loading. Strain applied along the [100] and [110] directions is predicted to partially or completely lift the triple degeneracy of the ambient Raman line. The degenerate Raman line was observed to split in accordance with the predicted behavior. The observed changes, despite the large nonhydrostatic stresses, are reversible.PACS numbers: 62.50.+p, 78.30.HvOptical spectroscopy and x-ray diffraction measurements in shocked condensed materials [1], though inherently difficult to perform, can address two important scientific problems. First, they provide an insight into the atomic-molecular processes governing the shocked state. Second, because of the fast temporal nature of shock wave loading, time-resolved measurements can permit real time examination of structural and chemical changes due to well defined, large compressions. In solids, the large compressions under shock loading are also accompanied by macroscopically uniform nonhydrostatic loading which permits an examination of deformation tensor effects. In this Letter, we report the first measurements of shock induced splitting of the degenerate Raman line in diamond to demonstrate the symmetry changes in the shocked state.The uniaxial strain state under shock loading may have a lower symmetry depending upon the initial symmetry and the loading direction. Strains and changes in crystal symmetry are expected to alter the vibrational mode frequencies and intensities due to anharmonic effects and changes in selection rules. Symmetry lowering, in particular, is expected to partially (or completely) lift any degeneracies associated with the vibrational modes. Hence, Raman measurements are well suited for exploring shock induced symmetry changes.Diamond was selected because its large Raman cross section [2] permits time-resolved measurements (~10 ns) and because of its importance in many contemporary scientific investigations including static high pressure studies [3][4][5][6][7][8]. In the experiments reported here, the strain-induced symmetry changes in diamond were examined by measuring the first-order Raman spectrum of single crystals shocked along the [110] and [100] directions.