Studies On Load-bearing And Failure Behaviors Of Composite Mesh And Its Reinforced Structures

At present,the structures of aerospace vehicles are developing towards largescale,lightweight,high storage and high load-bearing trends.The space inflatable deployable structures have become a potential solution to the problems as mentioned above due to its lightweight,small folding volume and high deployment reliability.However,the issues of wrinkles,difficulty in shape retention,and low load-bearing capacity of the space inflatable deployable structures have become the major factors restricting its development.Existing studies have used mesh reinforced membrane to improve the shape stability and load-bearing capacity of the membrane inflatable structures.The mesh includes flexible mesh and rigid mesh.Flexible mesh reinforced membrane structures are basically limited to engineering applications,and there is a lack of research on the cooperative load-bearing mechanism between mesh and membrane,and how mesh reinforced membrane improve the performance of membrane structures is unclear.The load-bearing mechanism of the rigid mesh reinforced membrane structures is not clear,and the rigid meshes have the problem of insufficient storage rate.This paper focuses on the studies on the load-bearing and failure behaviors of composite mesh and their reinforced structures.These studies will have important theoretical and engineering guiding significance for enriching the basic mechanics of mesh reinforced structures and promoting the applications of inflatable membrane structures in the aerospace fields.This paper takes composite mesh and its reinforced structures as the core,and focuses on the load-bearing and failure behaviors of the structures.The 2D flexible mesh reinforced material and structures,2D composite mesh and its reinforced structures,3D composite mesh structures and its reconfigurable design are the primary concerns,and the following research work has been gradually carried out:Through the analysis of the tensile characteristics of the flexible mesh reinforced membrane,the cooperative load-bearing mechanism between mesh and membrane is revealed.The bend-wrinkling mechanical model of the flexible mesh reinforced membrane inflated beam is established,and the performance of flexible mesh reinforced membrane inflated beam is predicted.The critical wrinkling load and failure load are verified by our experiments,and the theoretical results are in good agreement with the experimental results.The bend-wrinkling analysis of the flexible mesh reinforced membrane inflated beam reveals the mechanism of the mesh in improving the anti-wrinkling function of the membrane inflated structure.The inflation and expansion behaviors of the flexible mesh reinforced inflated beam are analyzed,and the shape maintainability of the flexible mesh reinforced membrane inflated structure is evaluated.The tensile and compressive characteristics of the composite mesh reinforced plates are experimentally studied,and the influence of factors such as mesh types,defect,membrane,and preparation process on the tensile and compressive performance of the composite mesh reinforced plates are analyzed.The buckling behaviors of the cylindrical shell composite mesh reinforced structures are studied by experiments and numerical simulations.The load-bearing characteristics of the parabolic composite mesh reinforced structure are analysed,and the influence of the mesh on the stability and load-bearing performance of the membrane inflated structure is investigated.The load-bearing mechanism of the parabolic composite mesh reinforced structures is discussed.The parabolic mixed-triangle composite mesh reinforced inflated structure exhibits the best shape stability and load-bearing efficiency,and presents a unique ladder type progressive failure mode.3D composite mesh structure is designed,and a theoretical model is established to predict its equivalent mechanical properties.A 3D composite mesh structure is fabricated,and its flexural load-bearing behaviors are tested experimentally.The bending failure behaviors of the 3D composite mesh structure are studied,the factors affecting the bending failure modes of the 3D composite mesh structure are discussed,and the failure mechanism is elucidated.The results show that the 3D composite mesh significantly improves the ability of the structure to resist out-of-plane deformation and exhibits a mixed progressive failure mode.The reconfiguratable design and load-bearing performance of the shape memory polymer(SMP)composite mesh structure are studied.The principle of reconfiguratable design of SMP composite mesh structure is described.Considering the viscoelastic properties of SMP,based on the macro-thermodynamic model of SMP,the bending behaviors of reconfiguratable composite mesh structure are carried out,and are verified by our experiments.By establishing a three-point bending finite element model of the 3D composite mesh beam,the load-bearing characteristics of the structure are simulated and analyzed,and the influence of folding on the loadbearing performance and failure mode of the structure is discussed.After the 3D composite mesh beam is unfolded,the residual deformations are generated in the struts of the mesh core.The residual deformations affect the load-bearing performance and failure mode of the structure.