| The rapid development of automation technology and robot technology brings convenience to human life,and also brings serious electromagnetic pollution.It will not only affect the function of the product and shorten the service life,but also may cause certain tissue lesions,and threatening human health.At present,the requirements for microwave absorbing materials and devices are mainly "wide,light,thin,and strong".In order to solve the problems of insufficient absorption bands of the existing device structure and bulky materials,this study designs a composite database with different loss characteristics and uses genetic algorithm as the optimization method,the minimum reflection loss and the maximum bandwidth as the optimization goals,designs a multi-layer composite absorbing structure with high absorption and wide frequency band.And then use the finite element method to optimizes and reduces the structural quality.The research on multi-layer absorption structures with high absorption,low reflection,wide frequency band and low quality has been completed systematically.The main research work of this article is as follows:1.The research background and significance of the electromagnetic absorbing structure are expounded,and the domestic and foreign research status of non-layered absorbing structure,layered absorbing structure and multi-field coupled electromagnetic absorbing structure simulation are summarized.By summarizing the problems existing in the existing research,the research objectives and research contents of this study are proposed.2.Aiming at the problems that the frequency band of the current multilayer composite absorbing structure is not wide enough,the absorbing performance is not good enough,the frequency band is uncontrollable and the quality is not low enough.The necessity and feasibility of using genetic algorithms and finite element methods as optimization methods are discussed.Based on the transmission line theory,the electromagnetic wave transmission mechanism of the multilayer composite absorbing structure is analyzed.On this basis,a mathematical model with thickness and number of layers as constraints,minimum reflection loss and bandwidth as objective functions is established,and the solution process using genetic algorithm is described.Based on the finite element method and the porous structure as the research object,the optimization method and design process of using the porous structure to optimize the multilayer wave-absorbing structure are given,and the optimized design of the lightweight multilayer composite wave-absorbing structure is completed.3.In order to solve the problems of insufficient absorption performance,insufficient frequency band and uncontrollable frequency band of the multi-layer composite absorbing structure,it is proposed to use electromagnetic parameters of materials with different loss types as the database.The control variable method and engineering requirements were used to determine the limit of the number and thickness of the multilayer composite absorbing structure.The genetic algorithm was used to optimize the multilayer composite absorbing structure with high absorption,wide frequency band and controllable frequency band.The research shows that the total number of layers of the multilayer composite absorbing structure is set to 5,and the thickness limit is set to 5mm,which has great engineering application value.The minimum reflection loss of the multi-layer composite absorber structure optimized using the hybrid database in the 2-18 GHz band is-30.7d B,and the bandwidth below-20 d B is 3.3GHz.Performance parameters such as absorption rate,bandwidth,and thickness are superior to existing similar studies.In addition,sub-band optimization has also been carried out,where the hybrid database can optimize the controllable frequency band in the 10 GHz range,while the single-type database can only realize the controllable frequency band in the 6GHz frequency band or not in the 2-18 GHz.It reflects the advantages of using a hybrid database to design a multi-layer composite wave-absorbing structure.4.In order to reduce the material density and structural quality,the finite element method was used to investigate the effect of the porosity,pore size and pore distribution of the porous structure on the wave absorption properties of the magnetic lossy and dielectric lossy materials.At the same time,the mechanism of the effect of the pore structure on the material's wave-absorbing performance is analyzed,and the multilayer composite wave-absorbing structure is optimized to obtain a light-weight composite wave-absorbing structure.The simulation results show that the designed light-weight multi-layer composite wave-absorbing structure can reach the electromagnetic absorption capacity of 0.4334 d B/mm3,and the overall wave-absorbing property is improved by 8.54% compared with that without holes. |
