Influence of the design of a separable junction between the grid composite adapter and the spacecraft hull on their natural oscillation frequencies

Grid composite structures are widely used in rocket and space technology as the payload adapters and the hull load-bearing structures (HLBS) of a spacecraft. An important parameter for these structures, along with the strength characteristics, is the minimum natural oscillation frequency. The article considers layout of the Express-1000 satellite platform consisting of a grid composite adapter and the spacecraft grid composite HLBS with a separable junction between them. The paper studies the influence of the number of pyro-locks and the thickness of the frames on the natural oscillation modes of the adapter and the HLBS assembly. Calculation was carried out by the finite element method, the number of fixing points of the hull to the adapter and the thickness of the end frames were varying, and the forms of natural oscillations and their corresponding frequencies were determined. Using the obtained dependences, it becomes possible to determine the rational number of fixing points and the thickness of the HLBS and the adapter.