Dynamic Characteristics Of Deployable Panels With Clearance Joints Based On Three-dimensional Dynamic Measurement Of Gap Clearance

With the rapid development of deep space exploration,the requirement of motion accuracy,reliability and stability for aerospace mechanism system is boosting.However,the clearance between the hinge pin and the sleeve is unavoidable in engineering practice,which directly affects the dynamic characteristics of the mechanism movement,reduces the mechanism movement accuracy and accelerates the wear of the mechanism.In recent years,dynamics of system considering clearance has become a research hotspot in aerospace field.However,research on joints with three-dimensional clearance is still in its infancy.The purpose of this paper is to establish a mathematical model that can accurately describe the characteristics of joints with clearance.Taking the deployable panel as the research object,a new three-dimensional modeling method for joints with clearance is proposed,and a three-dimensional dynamic measurement experiment is also designed for joints with clearance.The measurement experiment provides experimental data for the theoretical study of the joints with clearance and lays the foundation for the further study of the three-dimensional clearance mechanism.The main work of this article is:First,the dynamic model of a panel joint with clearance is established and numerically solved.According to the law of potential collision point of the joints with three-dimensional clearance and the modeling method of the plane clearance joints,a three-dimensional mathematical model as well as mechanical model for joints with clearance are established.With the “T”-shaped node unit,the deployable panel considering clearance is simplified and a dynamic model with joints with three-dimensional clearance is established.The dynamic equations are numerically solved by the 4th order Runge-Kutta method to analyze the influence law of 3D clearance on the dynamic characteristics of deployable panel.In this way,the relative motion between the inner pin shaft and the sleeve of the clearance joints can be obtained,and the influence of the gap radius and the deployment speed on the internal impact force of the clearance joint can be qualitatively analyzed.Then,the establishment of a three-dimensional clearance gap dynamic measurement experiment system is completed.According to the results of numerical simulation and the actual experiments of the prototype,the two-dimensional gap dynamic measurement scheme of “cross-section ellipse method” and “spatial two-point method” is proposed.And comparative analysis of the scheme is carried out.The error analysis of the measurement system is completed,and roundness error,assembly error and influence of noise on measurement accuracy are eliminated.Besides,gap measurement grouping experiments and analysis of experimental results are completed.The specific scheme and data processing steps of the three-dimensional gap dynamic measurement experiment are introduced in detail;the comparison verification experiment was put forward and the accuracy of the measurement system is verified;The effect of the expansion mode,the structure of the prototype,the clearance radius and the expansion velocity on the motion characteristics of the three dimensional clearance hinge are analyzed by the grouping experiment.Finally,the comparison and analysis of the experimental results and the numerical simulation results are completed.The differences between the experimental results and the simulation results and their causes are analyzed.The experimental results are taken into the theoretical model to quantitatively analyze the influence of clearance radius and deployment speed on the deployment accuracy of the deployable panel.