Study On Dynamic Buckling Of Axial Compression Member Under Impact Load

The theory of stability is one branch of solid mechanics in nature. With the theory research more deeply, the theory of stability has extended from elasticity to non-elasticity and non-linearity, and the load considered is from static to dynamic. Because of introducing the time, the problem of dynamic buckling is much more complex than static one, especially under impact load (i.e. impact buckling) which has few study findings relatively. So some viewpoints have not been consistent. Systematic study is made on dynamic buckling of axial compression member under impact load in this paper for that reasons. This study include impact bifurcation buckling, stress wave effect, initial flaws (residual stress and initial bending), form of impact load, damage of material, local dynamic buckling of plate, and so on. The constitutive relationship of material is assumed linear hardened and two boundary conditions (i.e. simple supported and fixed) are considered. Step load is the main form of impact load adopted.First, systematic study on propagation, reflection and interaction of axial stress wave is made to deduce the calculation equation for axial elastic and plastic stress wave, which fit for analysis of impact buckling of axial compression member. Second, dynamic buckling condition is erected after analysis of perfect axial compression member with different boundary conditions, by which dynamic buckling critical load and corresponding buckling modal are obtained. These indicate the difference between dynamic buckling and static one. Stress wave effect is one important parameter considered in the study and it may have some influence on the dynamic buckling of axial compression member. Third, as one main flaw, residual stress would make the member section into elasto-plasticity in advance. This would be much disadvantage to the dynamic buckling critical load and buckling deformation. Fourth, systematic study on dynamic buckling of axial compression initial bending member through finite difference method, considered residual stress simultaneously, make some valuable conclusions. Final, some problems about axial compression member under impact load are studied, which focus on the form of impact load, damage of material, local dynamic buckling of plate. Some calculation method and research viewpoints are presented.