Dynamics of a two-mass-spring system which is separated by external input

To control shock responses of mechanical structures, Momentum Exchange Impact Dampers (MEIDs) have already been proposed. They have been applied to reduce floor shock vibration and control lunar exploration spacecraft landing. Most of the previous researches have not focused on rotational motion induced by the shock yet. This paper discusses a design methodology which reduces mechanical structures´ shock responses. The shock responses include both rotational and translational motions. A two-mass-spring system is introduced to discuss the dynamics of shock responses of mechanical structures. The system consists of a body mass and an additional mass. They are connected by a spring. The body mass is subjected to an external input. Two masses are separated by the external input. The system corresponds to a fundamental model of the MEID mechanism including both the translational and the rotational motions. This paper shows the optimal additional mass and its attachment position to reduce both the translational and rotational motion. The robustness against the external input variation is verified by simulations. The rotational momentum and applied force equilibrium is also discussed.