Investigation on the Shock Response of Vitreous Carbon

The dynamic response of vitreous carbon to uniaxial strain loading has been investigated by means of the plate impact experiments. The two x cut shorted quartz gauges assembled with impactor and target were used to obtain the wave speeds in material and the stress histories at the sample gauge interface. The wave speed and stress histories were analyzed to determine the peak state in the sample. For compressive stress up to 4 0 GPa, the wave profiles were observed to be simple and steady, the uniaxial strain response is essentially nonlinear elastic, and no inelastic deformation has been found. All the experiment results indicate that the Hugoniot curve of vitreous carbon is concave downward just like that of fused silicon. There is no shock wave but the compressed wave propagating in the impacted samples.

Dynamical Mechanical Properties for AD90 Alumina

The dynamic response of polycrystalline alumina was investigated in the pressure range of 0 - 13 GPa by planar impact experiments. Velocity interferometer system for any reflector（VISAR） was used to obtain free surface velocity profile and determine the Hugoniot elastic limit, and manganin gauges were employed to obtain the stress-time histories and determine Hugoniot curve. Both the free surface particle velocity profiles and Hugoniot curves indicate the dispersion of the ＂plastic＂ wave for alumina. With the measured stress histories, the complete histories of strain, particle velocity, specific volume and specific internal energy are gained by using path line principle of Lagrange analysis. The dynamic mechanical behaviors for alumina under impact loading are analyzed, such as nonlinear characteristic, strain rate dependence, dispersion and declination of shock wavein the material.

The Shock Response and Spall Mechanism of Mg-Al-Zn Alloy:Molecular Dynamics Study

Shock responses of Mg-Al-Zn alloy are investigated by the molecular dynamics(MD)method.The wave propagation,plastic deformation behavior and failure mechanism along the[0001]and[1010]orientations are analyzed.For both orientations,simulation results show that the shock wave has an obvious double-wave structure(plastic-elastic)under a piston velocity of 1200 m/s.A higher Hugoniot elastic limit(HEL)is observed for[0001]-oriented shock.When the shock pressure is along the[1010]direction,the distance between plastic and elastic waves is closer,and higher dislocation density and more twins are observed.Moreover,the spall strength for[1010]-oriented shock is predicted to be higher.In addition,the wave interactions,HEL and spall strength predicted for Mg-Al-Zn alloy are compared with the experimental results and MD simulation results of Mg single crystal in the literature.It is concluded that the shock performance of Mg-Al-Zn is better than that of Mg single crystal.