Form-Finding Design Of Cable-membrane Composite Structure Considering The Influence Of The Mechanical Properties Of Metal Mesh

Metal mesh is a key component of cable-mesh antenna,and it is laid on the cable-net structure to form a reflector mesh.Warp knitted form,hole shape and ductility of metal mesh directly affect the shape accuracy of cable-mesh antenna and thus affect the electrical properties.To ensure the structural and electrical performance of antenna,this paper focuses on analysis of the mechanical properties of warp knitted metal mesh,equivalent of the mechanical model of metal mesh,and form-finding design of the cable-membrane structure based on the mechanical equivalent of metal mesh.The major contents are as follows:1.A method for analyzing the mechanical properties of warp-knitted metal mesh considering contact was proposed.Firstly,data points of the loop geometry were defined according to the Goktepe three-dimensional loop model,and the NURBS curve was used to fit the monofilament trajectory of the loop of metal mesh,so as to establish the geometric model of whole metal mesh.Secondly,based on the augmented Lagrange multiplier method,constraint equations of bonded contact were substituted into potential energy functional,and the incremental finite element equation that considered contact problem was deduced.Finally,the biaxial tensile test of metal mesh was performed,and the accuracy of the mesh mechanics analysis method was verified by comparing the simulation results with the experimental data.The mechanical analysis method can't only provide theoretical guidance for the manufacture and laying of metal mesh in the actual project,but also lay the foundation for the equivalent mechanical model of metal mesh structure.2.An equivalent method of metal mesh mechanics model was proposed.Considering the complicated structure of metal mesh,it is difficult to directly establish the mechanical model of the cable-mesh composite structure.For this reason,according to the structural characteristics of metal mesh,the mechanical model was equivalent to an orthotropic membrane.The elastic parameters and the thickness of membrane were design variables,to minimize the transverse and longitudinal strain errors of the mesh and the membrane,an optimized equivalent mechanical model of the mesh structure was established.The equivalent membrane structure obtained by this method showed the same mechanical properties as the metal mesh structure under the same boundary conditions and load conditions.This equivalent model laid the foundation for the form-finding design of the cable-mesh composite structure.3.A method of form-finding design of cable-membrane composite structure considering the influence of the mechanical properties of warp-knitted metal mesh was proposed.Firstly,based on the nonlinear finite element method,the "two-step method" was used to realize the form-finding design of the cable-membrane structure.Then,the effect of mechanical properties of mesh on the form-finding design results of the cable-membrane composite structure was analyzed through the simulation case.Finally,corresponding physical models of the structure were produced respectively,and photogrammetry was performed on them.By comparing the simulation results with the experimental data,the rationality of this form-finding design method was verified.The results show that the mechanical properties of metal mesh have a great influence on the form-finding design results of the cable-membrane composite structure.Considering the practical mechanical properties of the mesh,the form-finding design of cable-membrane structure can effectively avoid prestress error of the mesh caused by neglecting the actual mechanical properties.The initial RMS of the physical model guided by this method was better,which can reduce the workload of the physical model surface adjustment.