Thermally Induced Vibration And Control Analysis Of Large Flexible Appendage Of Spacecraft

For most spacecraft,during orbital flight,they will periodically enter and exit the sunshine area and shadow area,so that it will experience heat and cold alternating and impact thermal load,easy to cause the vibration of flexible attachment on the spacecraft,that is,thermally induced vibration.As a result,unstable factors will be brought to the attitude response of spacecraft and the acquisition of data signals,and it is necessary to study the thermally induced vibration of spacecraft flexible appendage.In this paper,the spacecraft flexible appendages—flexible beam structure and flexible plate structure were taken as the research objects,and their dynamic models were established based on the absolute nodal coordinate formulation,and the elastic force formulas of different models under thermal effects were deduced.The thermalstructural dynamic responses of flexible single beam model,double beam model and flexible cantilever plate model under sudden heating flow were analyzed by numerical simulation.The main research contents and results are as follows:(1)Based on the theory of continuum mechanics,the dynamic equations of flexible single pendulum and double pendulum were established based on the absolute nodal coordinate formulation,and the Newmark algorithm was used for numerical solution.The response analysis of single pendulum and double pendulum under different flexibility was carried out,and their correctness was verified by energy principle.(2)Starting from the energy conservation represented by thermal conductivity,a differential equation of heat conduction was established,and the transient temperature field of structure was obtained.Then,based on the absolute nodal coordinate formulation,single flexible beam model and double flexible beam model with hinge link under the same size were established,and the dynamic equations of two models were deduced with thermal effect taken into account,beyond that,the elastic force and strain energy under the thermal effect were given.The influence of the structural parameters of the two models on the thermally induced vibration response was discussed,at the same time,the thermally induced vibration was controlled by a fluid damper.(3)The solar panel was simplified as a flexible plate structure,and the dynamic models of flexible plate were established by using the thin plate element and thick plate element with the absolute nod coordinate formulation.For thin plate element,the deformation along the thickness direction was ignored.For thick plate element,the transverse shear strain and normal strain along the plate thickness direction were considered.Based on the continuum mechanics theory,the elastic force formulas of the two was given,and their dynamic response was further compared and analyzed.(4)Based on the thick plate element,the calculation expression of elastic force under thermal effect was derived,and the thermal-structural dynamic response of flexible cantilever plate structure under solar radiant thermal load was studied.Aiming at the escape time phenomenon in the thermally induced vibration of flexible cantilever plate,the effects of the structure size and heat flow intensity on escape time were analyzed through numerical simulation examples.