Papers by Author: Feng Huan Sha

Abstract: The present study focuses on the penetrating resistance of the laminated composite with stepwise graded foam target struck normally by conical-nosed projectiles. The dynamic cavity expansion theory is applied to formulate analytical model. Experimental results verify that this model on account of rigid-perfectly plastic-locking model is suitable for analyzing penetration depth of the projectile into a cellular target. The difference types of foam configurations, with identical areal density, were arranged according to the density of the respective foam. The penetrating process can be divided into 7 stages. Penetrating depth; the effect of mass density and the change of graded/layered core structures of the difference configurations are analyzed. It is found that composite target have a higher penetrating resistance than the monolithic foam material target of equal mass. The analytical results show great potential to reasonable structures for absorbing the dynamics energy and improving the overall penetrating resistance.

Abstract: A theoretical study is presented herein on the penetration of the laminated composite aluminum alloy foam target struck normally by conical-nosed projectiles. Two layers were arranged according to the density of the respective foam; configuration 1 consisted of 10mm/semi-infinite continuous foams and configuration 2 consisted of 20mm/ semi-infinite continuous foams. The dynamic cavity expansion theory is applied to formulate analytical model. The penetrating process can be divided into 6 stages. The resistance equations during every stage are derived. Penetrating depth of projectile are analyzed. The effect of initial velocity, mass density of foam material and the thickness of the upper layered foam on the penetration resistance are investigated. It is found that composite target have a higher penetrating resistance than the monolithic foam material target of equal mass. The analytical results show that configuration 1 outperformed configuration 2 in regards to their penetrating resistance. The thickness of the upper layered foam within 5-20mm has significant influence on penetrating depth. The energy absorption capacity of the composite target material is evaluated.

Abstract: The dynamic buckling caused by propagation of a stress wave in single-wall carbon nanotube subjected to impact torque is investigated. The single-wall carbon nanotube is modeled by a cylindrical shell with semi-infinite length, and the dynamic buckling under impact torque is reduced to a bifurcation problem caused by the propagation of torsion stress wave. The bifurcation problem can be converted to solving a group of nonlinear algebraic equations. The numerical computation is carried out, and the effects of the different parameters on dynamic buckling are discussed. It is found that if critical buckling time of the carbon nanotube is different, the corresponding buckling model is different, too. Relation between the critical buckling stress and the critical buckling time is given. Molecular-dynamic simulations of torsional deformation of a single-wall carbon nanotube have been used to obtain the critical buckling strain, which is 0.064. In this work, the critical buckling strain obtained by the continuum model is 0.061, which is very close to the value 0.064. Single-wall carbon nanotubes have very much powerful anti-impact torque, and the critical buckling shearing stress can reach up to 132GPa.