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A thermodynamically consistent equation of state (EOS) was developed for unreacted liquid nitromethane (NM). The specific heat cv, the coefficient of thermal pressure (∂P/∂T)v, and the isothermal bulk modulus BT, were modeled as functions of temperature and volume using existing experimental data. To test our EOS predictions, temperature measurements using time-resolved Raman spectroscopy were obtained from NM subjected to stepwise loading. In contrast to previous EOS developments, calculations using our EOS show good agreement with the measured temperatures. Comparison with previous EOS models shows that simplifying assumptions, such as holding (∂P/∂T)v or Γ/v constant, lead to significant inaccuracies in temperature predictions for shocked NM. The assumption that the Gruneisen parameter Γ is a function of volume only is not consistent with our EOS.

A detailed description of a 10.16 cm gas gun that has been designed and installed at Washington State University is presented. The design velocity is 1.5 mm/μsec; the maximum velocity achieved to date is 0.9 mm/μsec with an 1100 g projectile. Angular misorientation of the projectile with respect to the target surface is consistently below 0.5 mrad. Brief descriptions of ancillary instrumentation and equipment are also given.

A study of shock wave propagation along the 〈100〉 direction in LiF single crystals is presented. Plate impact experiments were conducted to produce elastic impact stresses of approximately 29 kbar. Stress time profiles at the impact surface and rear surface for thicknesses up to 3.2 mm were observed. Experiments were done for two impurity concentrations and three different heat treatments. Material characterization to supplement the shock data was provided by quasistatic yield stress measurements, dielectric relaxation data, initial dislocation density counts, and spectrographic analysis. Elastic wave attenuation is strongly influenced by both Mg++ impurities and heat treatments. Impurity clustering generally reduces the rate of precursor decay. The plastic strain rate at the elastic shock front was computed from the data by a near−exact method which incorporates material nonlinearities. Beyond the first 1 or 2 mm of propagation, significant contributions to stress decay arise from overtaking by relief waves. Application of dislocation theory reveals dislocation densities to be approximately 3 orders of magnitude larger than grown−in dislocations, at least in the region of rapid stress decay. Present analysis contradicts the idea of regenerative multiplication of dislocations causing this large increase in density. A model for heterogeneous nucleation of dislocation based on an energy criterion is proposed which appears to be well suited for explaining large increases in dislocation densities. The present data suggest an applied shear stress of 3−5 kbar as the lower bound at which dislocations can nucleate at heterogeneities present in our crystals. Better material characterization concerning impurity clusters is needed to consider the quantitative aspects of rate and magnitude of heterogeneous nucleation. The mechanism for stress decay in the very soft LiF crystals is still not well understood.

Pressure profile measurements for shock waves in 1060-0 aluminum show a decaying elastic precursor. Its amplitude diminishes from 1.06 kbar at a propagation distance of 1.38 mm to 0.53 kbar at 9.68 mm. Combining these precursor amplitudes with earlier measurements by others yields a curve of amplitude vs distance which runs from 1.38 to 25 mm. Decay rates obtained from this curve yield values of dislocation density 3–80 times greater than those inferred from etch-pit counts on polished surfaces. Rise times in the elastic precursor are greater at large distances than at small, suggesting effects of viscosity.

Experimental techniques are described for electronic time-resolved reflection and transmission spectroscopy in a thin liquid CS2 sample undergoing successive shocks by reverberation. Transmission spectra in the near UV and visible show progressive shifting of the red edges of absorption bands with shock pressure. At 55 kbar, extinction of the transmitted signal is complete for wavelengths between 2500 and 4100 Å, but absent at longer wavelengths. At 120 kbar extinction extends through the visible as well. Reflection experiments suggest that extinction is due to coherent scattering. Relaxation in both reflected and transmitted light at 120 kbar is in accord with other observations relating to shock-induced decomposition.

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The equations of motion of a one-dimensional lattice of mass points connected by nonlinear springs are set forth and compared with the equations of the corresponding continuum. A permanent regime for the damped lattice is obtained by series approximation and shown to agree with that of the continuum. A higher approximation leads to a permanent regime profile for the undamped lattice which oscillates steadily after shock arrival. This is shown to be in qualitative accord with the results of numerical integrations of the transient problem. However, comparison of periods of steady oscillation with those obtained in the transient problem indicate that the series approximation to the permanent regime is quantitatively unsatisfactory, though qualitatively correct. Scaling of the problem with a parameter u1α is noted, where u1 is steady particle velocity behind the shock and α is a parameter of nonlinearity.