Papers by Author: Zhi Jun Han

Abstract: The computer simulation of the dynamic buckling on the cylindrical shell subjected to pulse load was carried out by ABAQUS/Expliect. The value of the rectangle and triangle pulse load is the same and the shape is different, and they are applied on the impact end of the cyclindrical shell. The influence of the load amplitude, the shape of load and the effect of the stress wave on the critical buckling time of cylindrical shell were discussed. The radial displacement curve was obtained which indicates that stress wave propagate along the length of the cylindrical shells, and the curve of strain time history is also acquired which is used to judge bifurcation and give the critical time.

Abstract: Compressive buckling of laminate plates with a delamination are simulated using ABAQUS 6.8 software. Effects of sizes, positions, asymmetric and shapes of delamination on the compressive buckling are investigated without the consideration of delamination growth and contact. The results indicate the sizes, positions, asymmetric and shapes of delamination have an important influence on compressive buckling.

Abstract: The dynamic buckling of composite bars subject to axial rigid body impact are simulated using the finite-element software ABAQUS6.8. The critical velocity and the bifurcate time are obtained by stain-time curve and effects of fiber angle and impact velocity on dynamic buckling behavior of composite bars are also investigated. The results indicate that the ply angle and impact velocity have an influence on dynamic buckling of composite bars.

Abstract: Chaotic motion of symmetric laminated composite arch with two hinge supports under transverse periodic excitation was investigated. The nonlinear dynamic equations of the arch are changed into the square-order and cubic nonlinear differential dynamic system by Galerkin method, and its homoclinic orbit parameter equations are also acquired. The critical conditions of horseshoe-type chaos are obtained by using Melnikov function. The influence of loading frequency on chaotic region are analysed by numerical calculation. The motion behaviors of system are described through the bifurcation diagrams, the time-history curve, phase portrait and Poincaré map. The results are given as follows. The influence of loading frequency on chaotic region are significant. When the height of arch reach some value, the system can occur horseshoe-type chaos. The system of symmetric laminated composite arch under transverse periodic excitation may occur steady motion and chaotic motion.

Abstract: The experimental studies on the dynamic buckling of the perfect bars with three kinds of lengths under impulsive axial compression were completed and the boundary condition of clamped-fixed was realized firstly in present studies. The time-history curves of axial strain of bars under different impact velocity were recorded. According to the magnitudes of the axial strain and bifurcate time, the quantitative relation of dynamic buckling load and critical bifurcate length are achieved; according to the curves recorded, the lateral velocity of bars are computed also. The experimental results show that the dynamic buckling load of the bar is distinctly greater than the static one, the front of stress wave can be regarded as fixed and the effect of the axial stress wave in the dynamic buckling of bar must be considered.