Microstructure Design Of Material With Prescribed Temperature Distribution And Analysis Of Tunable Properties Of Deformation-control-based Metamaterial

With the development of advanced equipment and high performance material/structure,utilizing material or structure with specific properties to control the response to physical field outside is becoming an important design requirement.For example,to achieve electromagnetic invisibility or electromagnetic wave bandgap,we need to control electromagnetic wave to diffract or block electromagnetic wave within a specific frequency band;to ensure the temperature lower than a specific value in some area,we need to design media with specific conductivity or thermal protection structure to control the temperature field.On the other hand,it's also of great value to investigate the smart material which can change its own properties with the change of external stimuli in industrial equipment design,i.e.,achieve self-adapted properties.For example,smart invisible cloak can keep its performance when the size of invisible object changes,i.e.,achieve smart or self-adapted invisibility.Therefore,it's very important to investigate on controlling specific physical field by means of designing material or structure with prescribed properties,and analyzing tunable performance and range of the material whose properties are changed with the deformation of its microstructure.In this paper,we investigate on microstructure design of material with prescribed temperature distribution and analysis of tunable properties of deformation-control-based metamaterial.First,we aim at controlling specific temperature field and design an invisible thermal cloak with fiber reinforced material.Then,we construct the implementation of multi-scale analysis method of periodic material nonlinear deformation based on commercial software,to predict the microstructure deformation and the effective properties of metamaterial efficiently and accurately.Finally,we do research on deformation-control-based method to adjust the microstructure deformation and discuss the tunable effective elastic modulus and permittivity of uniformly deformed material and their tunable range.The main work and achievements are as follows.1)The microstructure design of the material with prescribed temperature distribution.Obtain the required material property distribution of thermal invisible cloak and investigate the method to design the structure by using conventional material.We propose an annular structure by using fiber reinforced composite to achieve thermal invisibility to control the temperature field.Using silver as the reinforcement and air as the matrix,i.e.,porous structure,the fiber layout of the invisible cloak is obtained,and its controlling effect of temperature field is validated.2)Implementation of multi-scale analysis method for the effective elastic modulus and large deformation prediction of periodic material based on commercial software.According to the idea of asymptotic homogenization(AH)method,the nonlinear deformation and effective elastic modulus of periodic material under external macro-scale strain are analyzed by commercial software ANSYS.The nonlinear deformation analysis of periodic material is transformed into a series of linear macroscopic problems to improve the efficiency and APDL program of multi-scale analysis method for properties and large deformation prediction using updating Lagrange scheme is coded.Effective elastic modulus of the material and deformation of the microstructure under each incremental step are calculated,and an efficient tool is provided to solve the problem described above.3)Performance analysis of tunable elastic modulus of material based on deformation control.Based on the given microstructure,different nonlinear deformation of material microstructure occurs when applying different kinds of prestrain in the material,leading to the change of effective elastic modulus.The tunable properties of the material under unidirectional and bidirectional initial strain are analyzed by numerical simulation.4)Performance analysis of tunable electromagnetic properties of material based on deformation control.Considering the periodic composite material in plane waveguide,the effective permittivity is obtained base on AH method.By means of microstructure deformation control,the tunable electromagnetic properties of the material under the unidirectional initial strain is analyzed.