Variation in multiring basic structures as a function of impact angle

Previous studies have demonstrated that the impact process in the laboratory varies as a function of impact angle. This variation is attributed to changes in energy partitioning and projectile failure during the impact and, in simple craters, produces a sequence of progressively smaller and more asymmetric crater forms as impact angle decreases from approximately 20 degrees. Variations in impact angle can produce differences in the appearance of multiring impact basins. Comparisons of Orientale to the more oblique impact structure at Crisium also suggests that these differences primarily reflect the degree of cavity collapse. The relative changes in massif ring topography, basin scarp relief, and the distribution of peripheral mare units are consistent with a reduction in degree of cavity collapse with decreasing impact angle. The prominent uprange basin scarps and the restriction of tectonically derived peripheral mare units along uprange ring structures also may indicate an uprange enhancement of failure during cavity collapse. Finally, although basin ring faults appear to be preferred pathways for mare volcanism, fault-controlled peripheral mare volcanism occurs most readily uprange of an oblique impact; elsewhere such volcanism apparently requires superposition of an impact structure on the ring fault

Hypervelocity impact study: The effect of impact angle on crater morphology

The Space Power Institute (SPI) of Auburn University has conducted preliminary tests on the effects of impact angle on crater morphology for hypervelocity impacts. Copper target plates were set at angles of 30 deg and 60 deg from the particle flight path. For the 30 deg impact, the craters looked almost identical to earlier normal incidence impacts. The only difference found was in the apparent distribution of particle residue within the crater, and further research is needed to verify this. The 60 deg impacts showed marked differences in crater symmetry, crater lip shape, and particle residue distribution. Further research on angle effects is planned, because the particle velocities for these shots were relatively slow (7 km/s or less)

Sputtering of benzene sample by large Ne, Ar and Kr clusters : molecular dynamics computer simulations

Molecular dynamics simulations are employed to probe the role of an impact angle on emission efficiency of organic molecules sputtered from benzene crystal bombarded by 15 keV $Ne_{2953}$, $Ar_{2953}$, and $Kr_{2953}$ clusters. It is found that both the cluster type and the angle of incidence have significant effect on the emission efficiency. The shape of the impact angle dependence does not resemble the dependence characteristic for medium size clusters ($C_{60}, Ar_{366}$), where sputtering yield only moderately increases with the impact angle, has a shallow maximum around 40° and then decreases. On the contrary, for the large projectiles ($Ne_{2953}, Ar_{2953}$, and $Kr_{2953}$) the emission efficiency steeply increases with the impact angle, has a pronounced maximum around 55° followed by rapid signal decay. It has been found that the sputtering yield is the most sensitive to the impact angle change for Kr cluster projectiles, while change of the impact angle of Ne projectile has the smallest effect on the efficiency of material ejection

Erosion-corrosion maps for carbon steel in crude oil/water slurries : impact angle and applied potential effects

In studies of erosion-corrosion, there have been few investigations into the effect of tribological issues, such as particle impact and impact angle, on erosion-corrosion of materials in oil field production. Despite this fact, erosion-corrosion in such environments is a major issue. In such conditions, it is important to define regimes where the effect of lubricating oil may modify the erosion properties of the materials. In this study, the combined effects of erosion and corrosion were investigated in three environments, crude oil (high API gravity 52), reservoir water, and 20% reservoir water with crude oil at a range of applied potentials. Erosion-corrosion maps were constructed, based on the results, showing the change in mechanisms and wastage rates as a function of impact angle and applied potential. Regimes of erosion-corrosion were described on such maps using such an approach. From this work, it can be seen that the corrosion contribution was increased with an increase in the percentage of reservoir water. In the crude oil environment, it was shown that the erosion contribution (Ke) was generally higher than that for corrosion suggesting that corrosion was reduced in crude oil. The results are interpreted in terms of the effect of the crude oil environment in modifying the impact properties of the particles therefore providing surprising resistance to particle impacts in nominally aggressive corrosion environments