Modal equivalent method of full-area membrane and grid membrane

Abstract

Pre-tension rectangular membrane is a promising structure in space engineering due to lightweight, high area-to-weight ratio and excellent folding capability. However, its dynamic characteristic of ground experiment can be largely affected by air, meaning the vibration behavior in air is quite different from the behavior in orbit vacuum. Therefore, a grid membrane is explored as the alternative structure, which can be less affected by air. Based on the small deformation theory, a modal equivalent method is established to make the natural frequencies and vibration modes of the original full-area membrane and the alternative grid membrane identical. A finite element code is utilized to verify this method, and the modals of the two structures are basically same. Meanwhile, a fluid-structure coupling simulation is conducted. The result indicates that the air effect on the alternative grid membrane is quite small compared with the original full-area membrane. Consequently, this grid membrane can be used as the alternative structure of the full-area membrane, as a mean to reduce the air effects in a ground structure experiment.