RUBY R-LINE SHIFTS FOR SHOCK COMPRESSION ALONG (1(1)OVER-BAR-02)

Experimental measurements of the shifts of ruby R lines, for shock loa ding along the low symmetry r direction, were obtained to evaluate our earlier theoretical formulation regarding the response of R lines in ruby crystals subjected to arbitrary deformations. The experimental re sults show good agreement with the calculated values based on symmetry adapted irreducible strains and, therefore, make a strong case for th e predictive capability of the theoretical model. Additionally, the pa rameters in the theory were augmented to incorporate the previously ob served nonlinear shifts of the R lines for shock compression along the c and a axis. With the general validation of our theoretical model, o riented ruby chips can now be utilized in diamond anvil cell experimen ts to obtain quantitative estimates of stress deviators at high pressu res. These, in turn, can be used to evaluate material strength, and th e role of nonhydrostatic stresses on sample response, at large compres sions. (C) 1998 American Institute of Physics. [S0021-8979(98)07716-0] .