应力波传播对轴心压杆的冲击屈曲有显著影响，目前的相关研究大多未考虑应力波在杆件远端的反射，且认为轴向应力波在波阵面处为固定约束（波前固定）。该做法忽略了杆件无应力段及远端边界条件对杆件冲击屈曲的影响，从理论上看并不严密。对阶跃荷载作用下不同边界条件轴心压杆的动力分岔屈曲进行了分析，以更为合理的波前连续条件代替波前固定对问题进行了求解，得出了杆件弹性及弹塑性冲击分岔屈曲计算结果，获得了一些有价值的结论。

The propagation of stress wave has great influence on impact buckling of axial compression bar significantly. At present, correlation studies have not been involved with the reflection of stress wave at far-end in most cases, and fixed constraint is considered at axial stress wave front (fixed of wave front). This method could not take the unstressing part of bar and boundary condition of far-end into account for impact bifurcation buckling problem of bar, which is not uniform to theory completely. The dynamic bifurcation buckling of axial compression bars with different boundary conditions under step load are analyzed. Continuous of wave front is used to solve the problem more properly in place of fixed of wave front. Some calculation results about impact bifurcation buckling of elastic and elasto-plastic bars are obtained, and valuable conclusions are drawn.