Zhi Jun Han

Compressive Buckling of Composite Plates with a Delamination

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.

Research on the Dynamic Buckling of Composite Laminated Plates with One Edge Fixed and Three Edges Simply-Supported

Taking into account the effects of stress wave and the moment of inertia, the governing equations of composite laminated plate under the axial step load are derived by using Hamilton principle. Based on Variable Separation Method, the analytical expression of the critical dynamic buckling load for symmetry composite laminated plates with one edge fixed and three edges simply-supported can be deduced by considering the characteristics of the buckling solution, and the buckling mode is also acquired. Using MATLAB software, the relationship between the critical load and length can be obtained. The influences of different layer parameters and the order of the mode on the dynamic buckling are discussed.

The Influence of First Order Shear Deformation on Dynamic Buckling of Composite Bar

Taking stress wave propagation into account, the governing equations of composite bar with the clamped-fixed boundary conditions considering FSDT (first order shear deformation theory) are derived on the basis of Reddy’ theory and solved by the variable-separated method. The analytic expression of the critical buckling load is obtained basing on the characteristics of homogeneous linear equations having nonzero-solution. The results of the theoretical study and the numerical calculation indicate that FSDT has influence on dynamic buckling of composite bar, and the critical buckling load is small when FSDT is considered. They also show that the magnitude of effect taken by FSDT is small when the layer angle is big.

Dynamic Buckling of Elastic Cylindrical Shells under Axial Step Load

Considering the effect of stress wave, the dynamic buckling of circular cylindrical shells under an axial step load is discussed using the classical shell theories and the state-space technique in the paper. Based on the Hamilton’s principle, the dynamic buckling governing equations of shells are derived and solved with the Rayleigh-Ritz method. If the linear homogeneous equations have a non-trivial solution, the determinant of the coefficient matrix must be equal to zero, so the expression of the critical load on the dynamic buckling is got. The relationship between the critical load and length is obtained by using MATLAB software. The influences of boundary conditions, thickness, the number of circumferential waves and the number of axial waves on the dynamic buckling loads are discussed based on numerical computation.

Numerical Simulation and Experimental Study on Fluid-Filled Hemispherical Shell under Impact

The dynamic response of fluid-filled hemispherical shell in mass impact is studied by experiment using DHR9401. Combining the time history of impact force with experimental observation of the deformation process, it can be seen that the dynamic response can be divided into four stages: the flattening around the impact point, the forming and expanding outward of shell plastic hinge, the plastic edge region flatten by the punch, and elastic recovery. The experimental results show that: Because the shell filled with liquid, the local impact load that the shell suffered is translated into area load and loads on the inner shell uniformly, so that it has a high carrying capacity. Numerical simulation is used to study the time history of energy absorption of different shell structures. The result shows that the crashworthiness of sandwich fluid-filled shell is improved greatly. Under the certain impact energy, deformation of its inner shell is very small, which can provide effective security space.

Computer Simulation of Cylindrical Shell Penetrated by Rigid Projectile

Computer simulation of cylindrical shell subject to lateral impact by rigid projectile is carried out. The effects of three kinds of typical rigid projectiles, geometric parameters of cylindrical shell and constraint conditions on critical speed are analyzed. The results indicate that the shape of projectile and size of cylindrical shell have a great influence on penetration, and the tapered projectile has a minimum critical speed. The influence of constraint conditions on penetration has a great relationship with thickness of cylindrical shells; energy distribution varies with different thickness of cylindrical shells.

Numerical Analysis of Long-Short-Pile Composite Foundation with Cushion or No Cushion

With the Drucker-Prager yield criterion, the ANSYS software is used to analyze the long-short-pile composite foundation by using three-dimensional nonlinear finite element method. The influences of load on axial stress and maximal axial stress of head of pile with cushion or not have been investigated by simulating composite foundation through nine long piles and sixteen short piles. The result indicates the cushion can reduce the stress concentration in head of pile effectively with increase of load. This conclusion has a certain value for engineering.

Computer Simulation of Static Buckling of Double-Layer Portal Frame

The buckling of no-way double-layer portal frame that column is fixed is simulated by using ANSYS. Through analyzing the portal frame subjected to different loads on the roof of the structure that are uniform load, trapezoidal load and triangular load, the critical buckling load of the double-layer portal frame and buckling mode are obtained. The regular between the critical buckling load and the form of the load on the roof can be acquired by the analysis of the results, which can be used as a reference for engineering application.

Dynamic Buckling of Composite Bars Subject to Axial Impact

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.

The Chaotic Behavior of Symmetric Laminated Composite Arch

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.