Thermally Induced Vibration Analysis And Control Of The Rigid Hub-Flexible Attachment System

When satellites with flexible attachments go in or come out of the shadows of Earth,they may go through thermally induced vibration or even the worst thermal flutter.Taking this phenomenon into account,satellitesusually have its' unique control law to remain its' pointing accuracy.The majorconcern of this thesisis when the thermal flutter will happen and how toevaluate the varying attitudes of the satellite with PID control when going in and coming out of the shadows of Earth.For simple plane motions,this work calculates system's kinetic energy andpotential energythen applying Hamiltonprinciple to obtain systemequilibrium equationsand boundary conditions.And using weighted residual method to obtain dynamic equations by assumingreasonable displacement functions.Along with temperature differential equations,we are able toapply Lyapunov stability theory to analyze system's stability.The results show that system will diverge no matter which angle the incident sun heat flux comes in if there are no damping effect nor control laws exist.Then the equivalent thermal-structural models are established for plates and solid beams with the same idea that this model should guarantee the equivalency in mechanical and thermalnature,which implies that tensile rigidity,torsional rigidity,flexural rigidity and total mass and absorbing,storing,conductingand radiating heat abilitiesshould be equal.With these equivalent conditions,mechanical and thermal parameters for thin walled beams are obtained.Based on this method,two examples are verified respectively for plates and solid beams.The results ensure engineering accuracy.Then the Fourier FEM is adoptedto model the flexible appendages.Numerical resultsof the thermal-structural response of a typical GEO satellite with two solar arrays under PID control are presented in detail.