A dynamical study of the proposed Space Station type configuration

Abstract

The planar libration-vibration interaction dynamics of the proposed Space Station is studied using a simplified model where the keel and solar panels are represented as beams and the central pressurized modules as a rigid body. In the beginning, the governing nonlinear, nonautonomous and coupled equations of motion are derived using the classical Lagrangian procedure. This is followed by a relatively general finite element analysis of the structure to arrive at the first seven system modes and associated frequencies. Next, a parametric analysis is undertaken, through numerical integration of the equations of motion in conjunction with the modal discretization, to assess the librational and vibrational response of the system. Finally, a closed form-solution of the simplified nonlinear problem is attempted using the variation of parameters (Butenin) method. Its validity is assessed through comparison with the numerical results over a range of system parameters and initial conditions. Results provide information pertaining to the levels of librational and vibrational response and associated acceleration fields, which may prove helpful in appropriately locating experiments and monitoring instruments. It may also aid in the planning of the control system. The analytical approach provides surprisingly close correlation with the more elaborate numerical procedure, thus promising a better physical appreciation of the complex interactions as well as a considerable saving in the computational cost.