Study Of Rigid Flexible Coupling Multibody Dynamics Of Solar Array Considering Joint Clearance

New requirements are put forward for the dynamics and control of deployable rigidflexible coupling on-orbit spacecraft structures due to the development trend of large scale and large flexible spacecraft accessories;New issues are brought forward for the study and analysis of micro-vibration and thermally induced vibration of on-orbit spacecraft structures due to the growing observation demand of high precision and resolution.Ubiquitous joint clearance can cause complex nonlinear mechanical behaviors to the multi-body system.Considering the effect of joint clearance on spacecraft brings an urgent new challenge to the research of space deployable structures with multicoupling and nonlinear characteristics operating in severe conditions.Solar array system,as an almost indispensable space deployable mechanism in the aerospace field,presents typical rigid-flexible coupling characteristics.Whether it can deploy smoothly,reach equilibrium quickly,and operate normally,stably and reliably in orbit,that directly determines the success or failure of space missions.This thesis establishes the rigid-flexible coupling multibody dynamic model considering joint clearance and applies it into deployable solar array system.The dynamic response in deployment process and thermally induced vibration performance in operation process of solar array system with multiple clearance joints are studied.The main contents and achievements derived in this dissertation are listed as follows.The rigid-flexible coupling dynamical model of multibody system is established considering clearance and wear at joints.Thereinto,the rigid body described by Nodal Coordinate Formulation(NCF)and the flexible body described by Absolute Nodal Coordinate Formulation(ANCF).Two-state model is selected to describe the clearance joint.The normal contact force effect and tangential friction effect at clearance joint are considered by using nonlinear contact force model and amendatory Coulomb friction model,respectively.The wear model is established using Archard’s wear model.Generalized-? method is used to solve system equations of motion.Besides,the availability of the proposed model is verified.The rigid solar array system with multiple clearance joints is established under ADAMS software.Parametric studies indicate some rules to design the key parameters of torque spring,CCL mechanism and latch mechanism: on the basis of meeting the basic functional requirements,the torque spring with the larger preload and smaller stiffness,the CCL mechanism with smaller equivalent stiffness and the latch mechanism with the original damping coefficient and the lesser stiffness coefficient may improve the dynamic response of the solar array system in post-lock phase.For the deployment process of the solar array system,the rigid-flexible coupling deployable solar array system considering panel flexibility and joint clearance is modeled based on NCF-ANCF.The availability of the proposed model is verified through comparing with numerical co-simulations of Patran and ADAMS software.Effects of clearance joints on satellite attitude of the solar arrys model considering panel flexibility is bigger than the stiff system model.Besides,the effects of clearance number,clearance size and clearance stiffness on satellite attitude are investigated.And an attitude controller of spacecraft is designed.Furthermore,action of clearance joints is studied to indicate motion property of journal,which reveals the function mechanism of couplping effects of joint clearance and panel flexibility on dynamics of solar array system: coupled with clearance at collision phase,elastic vibration property of flexible panels dominates to cause system shock at initial phase and post-lock phase;while coupled with clearance at contact phase,suspension damping property of flexible panels dominates to steady the system at deployment phase.For the on-orbit operation process of the solar array system,considering solar radiation,a thermal-structural coupling model of planar solar array system with clearance joint is modeled based on NCF-ANCF.Effects of thermal load and adjustment motion on spacecraft attitude,solar panel dynamics and wear prediction of the system with or without clearance joint are investigated.The degree and duration of the shake of the system with clearance joint increase dramatically,and far beyond the superposition of each single condition.The effect of joint connection type on the thermal induced vibration of solar array system is discussed comparing with fixed connection type adopted in the previous studies.Thermal environment effect on wear prediction is significant and nonignorable for the on-orbit spacecraft.