Research On The Forming Mechanism Of Conformal Bearing Antenna Based On Droplet Jet

Conformal bearing antenna is a kind of structural functional component with electromagnetic radiation and structural bearing function.It has the characteristics of small volume,light weight,conformal with carrier platform,small radar cross section and so on.It has a broad application prospect in the field of aerospace.Droplet jet 3D printing is a feasible way to fabricate conformal carrier antenna.Different from the traditional planar stacked 3D printing,conformal carrier antenna needs to print dielectric substrate and conductive pattern on the surface to ensure its electrical performance.Therefore,the accurate spreading of droplets on the surface becomes one of the key problems affecting the forming accuracy and performance.In this paper,the key factors of droplet spreading on undeveloped surface are analyzed,and the prediction model of droplet spreading on undeveloped surface is established.Based on this model,the main printing process parameters are optimized,which lays a foundation for conformal carrier antenna conformal control manufacturing.The main research work is as follows(1)Aiming at the problem of how to control the kinetic energy of the droplet outlet,the dynamic model of the piezoelectric nozzle was established,and the relationship between the nozzle parameters and ink parameters on the droplet outlet velocity and volume was derived.Based on this,a two-phase flow simulation model with six nozzles was established,and the effects of fluid viscosity,surface tension and driving waveform on the kinetic energy of droplet outlet were analyzed quantitatively.Finally,the kinetic energy of the droplet outlet could be effectively controlled by controlling the driving waveform parameters of the piezoelectric nozzle.The accuracy and effectiveness of the two-phase flow model were verified by high-speed camera measurement.(2)The energy conservation model of the maximum diameter of a single droplet spreading on the curved surface was established,and the factors affecting the maximum radius of the droplet spreading on the curved surface were analyzed.According to the kinetic energy of droplet outlet,the spreading diameter of droplet on curved substrate could be predicted,and the experimental results showed that the error was within 5%.In addition,the two-phase flow model of multi droplet spreading on curved surface was established to analyze the influence of different jet kinetic energy and curvature on the position of multi droplet spreading point,and the influence mechanism of pressure wave on multi droplet spreading accuracy was revealed.(3)The experimental platform of conformal bearing antenna printing was developed.The functions of array nozzle surface printing,nozzle driving waveform control,nozzle pressure control,surface contour scanning and five axis closed loop were realized.The performance of the system was tested,which provided an experimental platform for the manufacture of conformal antenna.(4)A multi droplet surface spreading prediction model was proposed,which could predict the surface droplet printing accuracy and iterate the printing parameters according to the prediction results,which provided a basis for the optimization of printing parameters.A Ka band conformal carrier antenna was developed by using the above method.The test results showed that the conductivity was SGM and the return loss at the center frequency of 29.5Ghz is 16.3db.Experimental results verified the accuracy of the model and the effectiveness of the parameter optimization method.