Study On The Influence Of Laser Processing Parameters On Surface Quality And Electromagnetic Properties Of Inoperable FSS

Frequency Selective Surface(FSS)is a periodic frequency selective structure withspatial filtering characteristics.Because of its special electromagnetic characteristics FSS is widely used in the stealth field of aircraft which can make the aircraft perform filtering in complex electromagnetic field.There are still many problems in the manufacturing of FSU,especially on the undevelopable surface.In this study,the aperture type cross element is used as the research object,and the surface of the inexpandable hemispherical shell is processed by laser processing method.FSS,and finish the frequency selection unit processing quality analysis and machining accuracy analysis.Through the comparison and analysis of the electromagnetic simulation software HFSS simulation data and the measurement size of the frequency selection unit,the electromagnetic characteristics are indirectly obtained.In order to investigate the effect of laser machining on the quality of frequency selective unit,the laser servo machining system was constructed.In the aspect of hardware,by comparing different laser processing methods,the oscillator laser with high performance-to-price ratio is selected as the main equipment of laser processing,and it is equipped with servo machining system.In order to realize the automatic control of laser and servo system,a set of automatic control program based on C development environment is established through the establishment and programming of algorithm model,and the automatic control is realized.After the equipment is built,the aperture type cross frequency selection unit is machined on the surface of the undevelopable hemispherical shell.Because the size of the experiment is too small,it can not be electromagnetic test.In this paper,the method of simulation is proposed to indirectly characterize its electromagnetic characteristics.By measuring the size of the machining unit and the periodic dimension between the units,the laser machining accuracy of the whole system is discussed,and the range of dimension fluctuation is obtained.The two-dimensional plane simulation and the radar cross section simulation of the unit and the FSS are carried out by HFSS software.Combining with the range of the dimension fluctuation,the effect of the laser processing results on its electromagnetic characteristics is obtained.In order to evaluate the quality of unit machining,this study first proposed the use of transmittance and distortion rate to comprehensively characterize the effect of unit processing,and through the laser parameterization test,the effect of laser processing parameters on the processing quality was discussed.The parameters of laser processing are optimized and the optimal parameters range of laser machining is obtained.Based on the structural characteristics of non-developable surfaces,by comparing the influence of laser processing parameters of different element layers on the laser machining parameters,the effect of surface structure on laser machining parameters is obtained,which provides a theoretical basis for the processing of general surfaces.Finally,in the aspect of processing method of high curvature FSS,this paper puts forward the method of block processing of unit.By dividing the unit into two pieces,three pieces and four pieces of "spacer gap" and "overlapping gap" processing,this paper discusses the influence of different block laser processing methods on the machining quality and machining accuracy of the processing unit.It provides a technological basis for the processing of high curvature FSS in the later stage.