Geometry

In addition to the computations described in the previous section, we have investigated the behavior of an inclined material boundary under shock loading. The material interface cross-cutting the grid cells requires the use of the Eulerian mode. Here, too, the ANEOS equation of state has been employed. Because the original Eulerian version of SALE can not deal with more than one material, it has been modified to be able to reflect the behavior of mixed cells containing two materials (Ivanov et al. 1997) following techniques used in more recently developed hydrocodes (Shuvalov 1999, Shuvalov et al. 1999). However, even after this extension the possibilities of our code are limited, and we have therefore only worked with two mineralic components and have simulated a dunite flyer plate impacting a dunite sample with wedge-shaped quartzite inclusion. The geometry of this setup is given in Table 2. The shock wave passes first through a horizontal dunite-quartzite interface and then through a quartzite-dunite interface inclined 45 degrees to the shock wave plane.

Fig. 6. Eulerian simulations of a shock wave passing an inclusion with an interface inclined 45 degrees to the shock wave plane. Width of sample: 5 cm. Height of sample: 8 cm. Width of quartzite inclusion: 4 cm. Height of inclusion: 4 cm. Flyer plate thickness: 2.7 cm. a). Displayed at t = 0 (Impact), b). At t = 15 microseconds. Left panels (plastic work field) are mirror images of right panels (temperature field). Resolution: 320 x 320 cells. The occurrence of a zone of concentrated shear with correspondingly elevated temperature near the material interface is reproduced by these simulations. Melt production is not observed because of the employed material model. Various gray shadings correspond to zero (t=0) and total (t= 15 microseconds) damage state of minerals. The location of tracers adjusted to the quartz/dunite interface is shown with a white circle.

Fig. 6. Eulerian simulations of a shock wave passing an inclusion with an interface inclined 45 degrees to the shock wave plane. Width of sample: 5 cm. Height of sample: 8 cm. Width of quartzite inclusion: 4 cm. Height of inclusion: 4 cm. Flyer plate thickness: 2.7 cm. a). Displayed at t = 0 (Impact), b). At t = 15 microseconds. Left panels (plastic work field) are mirror images of right panels (temperature field). Resolution: 320 x 320 cells. The occurrence of a zone of concentrated shear with correspondingly elevated temperature near the material interface is reproduced by these simulations. Melt production is not observed because of the employed material model. Various gray shadings correspond to zero (t=0) and total (t= 15 microseconds) damage state of minerals. The location of tracers adjusted to the quartz/dunite interface is shown with a white circle.

With this approach, we can at least qualitatively demonstrate the principal effects of an inclined material boundary. In Fig. 6 we show two snapshots of the shock wave compressing the sample, displaying the changes in plastic work and temperature by means of gray-scale plots, Fig. 7 shows a logarithmic intensity plot of the accumulated strain in the sample after passage of the shock, and in Fig. 8 the variations of pressure and temperature for two Lagrangian tracers (located close to the quartz/dunite interface) across a horizontal section through the sample are displayed. The peaks of those quantities in the region of the quartzite section bordering the dunite part deserve particular attention because they are signs of localised shear.

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