Deployment Dynamic Analysis And Modal Analysis Of Circular Membrane Solar Arrays

In order to achieve a high deployment rate,a new kind of flexible solar arrays,named as circular membrane solar arrays,have been developed,which has been widely applied aboard in spacecraft.The problems of large flexibility,strong nonlinearity and high coupling exist in the deployment process of the circular membrane solar arrays,which makes the deployment process complex.For the deployed and locked solar arrays,since the natural frequency of low order modes is low,it is easily excited extensive motions by the vibration,impact,noise from the space environment,which may result in the degradation of the shape surface precision of membrane structure and even the destruction of the membrane structure.In this thesis,based on the finite element method,through the SAMCEF software,both the dynamic research of deployment process and the static research and the modal analysis for the locked state for the cicular membrane solar arrays are studied.Firstly,taking the rigid-flexible coupling and self-contact collision into account,the configuration change,stress distribution and energy change of the solar arrays in the deployment process are analysied using the SAMCEF software.Meanwhile,the influences of gravity and the angular velocity on the stability of the deployment process are studied,and it found that the gravity effect and smaller angular velocity are good for the smooth deployment of the solar arrays.Secondly,based on the dynamic analysis of the deployment process,the structure optimization and trajectory optimization of the solar arrays are carried out in order to achieve a steady deployment process and suppress the residual vibration in the locked state.The structure optimization shows under the condition that the beam material is carbon fiber,the oblique beam position is 1100 mm and the beam section height is 20 mm,the deployment process is steadiest.Moreover,when the the number of the solar array gores is12 or 18,the kinetic energy of the deployment process is small and residual vibration in the locked state is well suppressed.The trajectory optimization shows that the high-order control function,the cycloid control function and the cosine control function are all good for the smooth and steady deployment process of the solar arrays,among which the cosine control function has the best suppression effect for the residual vibration of the solar arrays in the locked state.These conclusions have some practical guiding effects for the configuration design of the circular membrane solar array and engineering application.Finally,the static analysis and modal analysis of the circular membrane solar arrays in the locked state are carried out using SAMCEF.The comparison for the modal frequency between the result from modal analysis by SAMCEF and the NASA Ultra Flex-175 test are in good consistency with the error is within 6.77%,which conforms to the TRL6 standard of American and validates the accuracy and the effectiveness of the FEM numerical model containing the gravity unloading spring.By studying the influences of gravity,unloading springs and the beam structure parameters on the modal of the solar arrays,it is found that the gravity and the unloading springs improved the modal frequency and the larger the spring stiffness,the higher the low-order natural frequency of the solar arrays.When the beam material is carbon fiber,the section height is 30 mm and the oblique beam position is1.2m,the solar arrays have the highest natural frequency.These results may be instructive to the ground modal tests and the design of the circular membrane solar arrays.