Improvement design of structures for the upper stage based on the prediction of mechanical behavior

The upper stages are complex structures. The difference of stiffness and mass between different components of the upper stages is enormous. The upper stages always work under high overload in flight. The vibration mode localization and stress concentration maybe threaten the safety of the structures because of no-reasonable design. In this paper, the mechanical behavior is predicted on PATRAN/NASTRAN software system, and the improved design scheme is presented based on analysis of mode localization and stress concentration. Finally, the dynamic characteristics comparison of upper stages before and after improvement is shown.