Dynamic Finite Element Analysis Of High Precision Continuous Track Structure Property Of Large Aperture Antenna

With the development of radio astronomy,radio telescope is developing towards large diameter and high frequency band.With the increasing size and weight of antenna,the load level of antenna orbit is also significantly increased.However,the wheel-rail contact deformation of the antenna under heavy load will affect the flatness of the antenna orbit and the accuracy of observation pointing.The traditional spliced track is prone to stress concentration when the roller passes through the joint,which will affect the service life of the antenna track.Therefore,the integral welding technology is generally adopted in the orbit of large aperture radio telescope at present.Due to the high temperature in the welding process and change the internal structural properties of the material,the hardness and strength of the weld joint are different from the orbit.The wheel-rail contact force distribution is characterized by large load and small concentration.When the antenna roller passes through the weld position,the difference between the weld and the base metal may affect the wheel-rail contact force distribution and cause stress concentration.During the orbit service period,the fatigue and wear of the orbit are more likely to occur at the stress concentration position,which will affect the pointing accuracy and structural safety of the antenna.Based on a 110-meter radio telescope,a wheel-rail transient rolling contact model was established in this paper.In the modeling process,the track welding process was taken into account,and the backing welding,surface welding and filling welding at the weld position were refined modeled.Static analysis was carried out by automatic meshing of the system,and the analysis results were compared with the theoretical values to determine the transient analysis model and mesh size.Then in the professional preprocessing software,the wheel-rail model is preprocessed by using the multi-scale meshing technology.Based on the finite element method of wheel-rail transient rolling contact,the preprocessing model was applied to the transient analysis.Finally,the transient responses of wheel-rail interaction forces under different working conditions of large radio telescope were obtained.It provides reference for the design of orbit structure and fatigue life analysis of 110 m radio telescope antenna.In the transient analysis,the influence of weld track surface flatness and friction factor is introduced to analyze the wheel-rail transient response when the roller passes through the track weld.It was found that the surface flatness of the weld had a great effect on the wheel-rail interaction force,and the Mises stress was increased by about 20%.The short-wave flatness had a greater effect on the wheel-rail interaction force than the longwave flatness,which might bring some potential hazards to the track's long-term reliable service.Therefore,it is necessary to regularly detect and maintain the state of the orbit,ensure the clean surface of the orbit,timely deal with the adverse effects caused by the small characteristics of the antenna surface,and ensure the long-term reliable service characteristics of the orbit.