关键词: 鱼雷 , 纵向运动 , 中心流形 , 跨临界分叉

Abstract: Due to the existence of many nonlinear terms in the equations of motion of a torpedo，the linearized method has its limitation and modern analysis is necessary to deal with the nonlinearity. As an effective means for analyzing the nonlinear problems, the bifurcation theory is employed to analyze the stability of the torpedo. Center manifold is used to reduce the dimension of the system. This re?serves the whole information of the torpedo dynamics in the bifurcation equation. Bifurcation diagram shows the nonlinear effect on the motion and results in the stability，which is the transcritical bifurca?tion.

Key words: torpedo , longitudinal motion , center manifold , transcritical bifurcation