中文摘要：

以受载端简支、远端固支弹性直杆为例，通过对直杆微元的动力平衡分析导出了直杆动力失稳的控制方程，这与用哈密顿原理得出的方程完全一致。利用差分方法求解了动力屈曲方程，解出了动力失稳模态以及临界力参数和动力特征参数的值。特别分析了随着动力特征参数由零增加到一定值后，由静力失稳模态过渡到动力失稳模态的过程。结果表明，对于等效长度直杆，动力失稳临界压力要远大于静力失稳的临界压力。

英文摘要：

Taking the straight bars as an example, which is simply supported at the loading end and clamped at the other end, the governing equations for dynamic instability of bars derived by the analysis of the dynamic equilibrium for a bar element are the same as those obtained in terms of Hamiltonrs theorem. With the finite difference method, the dynamic buckling equations are solved and the dynamic instability mode and the values of the critical load parameter and the dynamic characteristic parameter are obtained. Especially, the process that the static instability mode transforms into the dynamic instability mode is simulated as the dynamic characteristic parameter increases to a certain value from zero. The result indicates that the critical load of dynamic instability is far more than that of static instability with regard to the equivalent length bars.