Papers by Author: Xiao Peng Yan

Abstract: The counterintuitive phenomena of elastic, perfectly plastic beam, circular plate and square plate are investigated numerically and experimentally. A new unstable slot and asymmetry of dynamic response of beam are revealed. The unsteady areas and uncertainty of response are observed numerically. At the end, the law of thermodynamics and the theorem of Lyapunov instability are employed to state the formation mechanism of counterintuitive behavior.

Abstract: The perforation of composite laminated aluminum foam target against rigid projectiles is studied. The dynamic cavity expansion theory is applied to formulate analytical model and study the perforation resistance of the projectiles. The perforation process can be divided into 11 stages. The perforation resistance expression is derived and applied to analyze the penetration depth of cone-nosed projectiles into the aluminum foam target. The velocity limit and residual velocity are obtained by solving the series of motion equations. The effects of initial velocity, the half-cone angle of the projectile, the density and thickness of each layer on the penetration resistance are investigated. The energy absorption capacity of the composite target material is evaluated.

Abstract: In this paper, the mechanical behaviours of open-cell and closed-cell aluminium foams against spherical-nosed projectile penetration are studied theoretically. An analytical model based on dynamic cavity expansion theory and previous experiment data is presented. The analytical equations are derived for the penetration resistance and the final penetration depth during the whole penetrating process. The effects of the mass density of target material, the geometry and initial velocity of the projectiles on the final penetration depth are investigated in detail. It is shown that the final penetration depth mostly lie on the density of aluminium foams and the kinetic energy of projectile. When the density of target is smaller, the final penetration depth of projectile in the closed-cell aluminium foams target is obviously smaller than that in the open-cell aluminium foams target. Meanwhile, with the increase of density of target and the decrease of initial impact velocity, the difference of the capacity of absorbing energy between open-cell and closed-cell aluminium foams targets becomes gradually narrow.

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: Many structures and buildings such as nuclear power station and chemical plant are often subjected to impact and explosive loadings. The understanding of material response to highamplitude, short-duration, impulse loads is very important, dynamic behavior of concrete under high strain rate has been paid much attention to. In the present paper, experimental study on the dynamic tension behavior of concrete is carried out. Based on the former theoretical introduction, dynamic splitting tensile tests at different strain rates are conducted on 74mm diameter concrete specimens in a Split Hopkinson Pressure Bar to study the effect of strain rate on the dynamic tension behavior of concrete. The mechanism and speed of crack propagation of concrete cylinder planar surface in dynamic splitting tensile test are discussed briefly.