Papers by Keyword: Plate Impact Experiment

Abstract: Stress-strain relationships of polycarbonate (PC) were determined over a very wide range of strain rates including shock wave regime. High-velocity plate impact tests, drop-weight tests, and quasi-static tests using universal and Instron testing machines were used for the high strain rate (107 s-1), medium strain rate (102 s-1) and low strain rate (10-4 s-1) tests, respectively. The revised unsteady wave sensing system (UWSS) for plate impact tests was newly developed to determine the stress-strain relationships and Hugoniot linear relation of PC. The system consists of a powder gun for plate impact tests and three polyvenylidene fluoride (PVDF) gauges embedded in the PC utilizing a newly developed nanosecond UWSS. As originally proposed, UWSS is aimed in obtaining experimental inputs for the Lagrangian analysis used to determine the dynamic behavior of materials. The new method to determine also the shock Hugoniot stress-strain curves is proposed for PC at medium particle velocities up to about 1 km/s. The revised, unsteady wave sensing system (M-UWSS, which we proposed before) using plate impact experiment with three PVDF gauges embedded is applied to construct stress-strain curves under shock loading up to Hugoniot stress σH and Hugoniot strain εH. Linear relationship between shock velocity Us and particle velocity Up: Us = C0 + S x Up, where C0 and S are material constants, is used to determine the constant S, since the constant C0 is determined as bulk sound velocity at ambient pressure. By using the momentum conservation and the mass conservation relations, S = (1 - C0 / CH) /εH, is derived from the linear relationship described above, where , ρ is density and CH ≈ Us.

Abstract: Alumina have been investigated for its distinguished characteristics to be widely used in armor application. One-stage light gas gun were utilized to study the dynamic mechanical properties of alumina subjected to shock loading. Manganin gauges were employed to obtain the stress-time histories at the different Lagrange locations in alumina target. The Hugoniot curves of stress and pressure versus specific volume were fitted based on the experimental data. The compressive behaviors for AD90 alumina are shown to be from elastic to “plastic” below 12GPa and under more higher pressure it will be transferred to similar-fluid state. Adopting LS-DYNA finite element code the dynamic failure of alumina ceramic armor are simulated. It is concluded that nucleation and growth of great number of radial and axial cracks and lateral cracks play dominant role in fractured ceramic target under impact loading.