In this paper,the incremental harmonic balance method is employed to solve the periodic solution that a vibration active control system with double time delays generates,and the stability analysis of which is achieved by the Poincare theorem.The system stability regions can be obtained in view of time delay and feedback gain,the variation of which is also studied.It turns out that along with the increase of time delay,the active control system is not always from stable to unstable,and the system can be from stable to unstable state,whereas the system can be from unstable to stable state.The extent that the two times delays impact on the system stability region is mainly related to the relative magnitude of the two feedback gains.The system can maintain the stable state under the condition of the well-matched feedback gains.The results can provide evidence to design the control strategy of time-delayed feedback.
