Papers by Author: Hui Lan Ren

Abstract: The plate impact experiments have been conducted to investigate the dynamic behavior of 91W-6.3Ni-2.7Fe. Lagrangian analysis technique was introduced to discuss the mechanical properties of the tungsten alloys under high strain rate and the stress-strain curves of the tungsten alloys were given. Based on the experimental observations, the three-dimensional finite element models of projectile and tungsten alloy target are established by adopting ANSYS/LS-DYNA, Dozens of cases were performed to investigate the dynamic mechanical behavior of tungsten alloy target under impact loading. A good agreement between numerical predictions and experimental results was obtained, which suggests that the finite element model is efficient and credible to simulate the mechanical properties of tungsten alloys.

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.

Abstract: The dynamic response of polycrystalline alumina were investigated in the pressure range of 0-13Gpa by planar impact experiments. Manganin gauges were employed to obtain the stress-time histories. From the free surface particle velocity profiles indicate the dispersion of the “plastic” wave for alumina. Using path line principle of Lagrange Analysis the dynamic mechanical behaviors for alumina under impact loading are analyzed, such as nonlinear, strain rate dependence, dispersion and declination of shock wave in the material. A damage model applicable to ceramics subjected to dynamic compressive loading is developed. The model is based on the damage micromechanics and established on wing crack nucleation and growth. The results of the dynamic damage evolution model are compared to the experimental results and a good correlation is obtained.