Rigid–flexible coupled dynamics analysis for solar sails

Abstract

The coupled orbit, attitude, and structural dynamics are established for the sailcraft with sliding mass, which is modeled as the Euler beam and merely experiences the pitch motion. The von Karman’s nonlinear strain–displacement relation and Kelvin–Voigt model are adopted to consider the geometric nonlinearity and damping of the structure, respectively. The torques generated by the gravity gradient of the two-body sailcraft, the center-of-mass (cm) and center-of-pressure (cp) offset, the motion of the sliding mass, and the coupled attitude-vibration motion are deduced in detail, respectively. The dynamics responses influenced by the flexibility of the sail structure are examined by analyzing the simulation results for the dynamics models with (m1) and without (m2) the geometric nonlinearity and the rigid-body model (m3), respectively. The pitch responses and corresponding torques are calculated and compared for various cases adopting a range of velocities and initial positions of the sliding mass to see how the pitch motion is affected by the parameters. The transient and steady-state dynamics responses are also identified in the simulation cases. It is suggested that the full nonlinear model should be adopted for the sailcraft in long duration missions and the restricted position of the sliding mass could be selected elaborately to utilize the resultant torque by the gravitational and cm/cp torques.