MODAL ANALYSIS OF MULTI-SATELLITE STACK BASED ON LINEAR EQUIVALENT MODEL

Multi-satellite stack is a new type of multi-satellite launching structure layout. The satellites in the stack adopt a flat plate configuration, where the upper and lower abutment of the flat plate satellite contact each other and are compressed as a whole by connecting rods. This article establishes a linear equivalent mechanical model and conducts modal analysis of this type of connected multi-satellite stack structure. Based on the substructure form and force characteristics of each part in the stack, the connecting rod is equivalent to an Euler Bernoulli beam model subjected to axial preload, and the intermediate satellite bonding body is equivalent to an additional lumped mass in the Timoshenko beam model. The vibration mode functions of the two with respect to axial coordinate at a fixed time are calculated. By combining vibration mode functions of the equivalent model of the connecting rod and satellite bonding body, the overall vibration mode function of the composite beam is obtained. Based on the constraint conditions determined by the parallel U-beam boundary coordination principle, the frequency characteristic equation of the composite beam vibration is obtained. The correctness of the theoretical model is verified by comparing the solution results of the finite element model with the solution results of the theoretical model. The influence of preloading force, connecting rod material, support foot material, and effective load mass on the vibration characteristics of stack is explored with conclusions. Through the equivalent method proposed in this article, corresponding guidance can be provided for the structural design and stiffness matching requirements of multi-satellite stack structure in the future.