A military tank is taken for a case study of multi-body structural dynamics. It is modeled as rigid elements and their nonlinear connections with 9 degrees of freedoms. To simulate structural dynamics, AUTOSIM, which is a software package that simulate mechanical systems composed of multiple rigid bodies, is used. Assuming impulsive forces due to firing are applied at the end of gun, some kinds of works are fulfilled to examine the dynamic characteristics. Modal parameters (natural frequency, damping ratio) are obtained by linearization. Sensitivity analysis is performed to investigate how the dynamic characteristics change with initial configurations (elevation angle and azimuth angle of the gun); Vertical displacement as well as stabilizing time at the gun-end under the impulsive force is adopted as the object functions. The adequacy of modeling by 9 degrees of freedoms is investigated by reducing or adding some DOF's.
