Research On Energy Absorption Of Thermoplastic Lattice And Sandwich Cylindrical Shell

Light-weighting is the eternal theme of aerospace.The new generation of aircraft puts forward new demands for structural efficiency and functional efficiency.Composite lattice structure has become a research hotspot of new lightweight structure because of its high specific strength and specific rigidity.In this paper,the design,preparation and mechanical properties research on the ABS uniform/continuous gradient lattice cylindrical shell structure,the metal skin/ABS continuous gradient core layer lattice cylindrical shell structure and the continuous glass fiber reinforced thermoplastic composite material sandwich cylindrical shell were conducted.And the main works were drawn as following:First,uniform/continuous gradient ABS thermoplastic lattice cylindrical shell structures were designed and prepared.The loading capacity and deformation modes were studied through quasi-static axial compression experiments.It is found that the random defects introduced by the FDM printing process could cause the initial damage position of the uniform lattice cylindrical shell structure to be uncontrollable,and the reasonable gradient design can induce the initial damage position of the structure to always occur from the lowest relative density.And the introduction of gradient design can effectively reduce the initial peak force of the structure.Considering the fracture failure mode of ABS material,finite element models of axial crushing of lattice cylindrical shell structure was established,and its deformation failure modes and load-displacement curve were in good agreement with the experimental results.And on this basis,a series of studies on the influence of the gradient form on the mechanical properties of the structure were carried out.Then,based on the hybrid design ideas and the design strategies summarized by Fleck and Ashby,which may outperform than the existing materials,metal skin/ABS core hybrid lattice cylindrical shell structure were proposed and designed.its deformation modes and loading capacity were investigated by the axial compression experiment.The experimental results show that the load-displacement curves of the uniform hybrid lattice cylindrical shell structure represented equal peak forces,while the continuous gradient hybrid lattice structures show continuously increasing peak forces.Comparing the energy absorption capacity of the sandwich structure and each part,it was found that when the compressive strain is 50%,the energy absorption capacity of the sandwich structure achieves "1+1>2".finite element models of hybrid sandwich cylindrical shell considering the failure of the adhesive interface and the fracture failure of the ABS material were established,and the axial compression mechanical responses of the structure under different gradient settings were studied.Finally,a continuous glass fiber reinforced thermoplastic composite material hierarchical lattice sandwich cylindrical shell structure design and preparation method based on fiber-winding and interlocking process was developed.The loading capacity of orthogonal and unidirectional fiber orientation cylindrical shell structures were tested by quasi-static axial compression experiments,and the main deformation failure modes during compression were analyzed based on DIC measurement technology.Theoretical prediction formula of failure load was established by considering multiple typical failure modes.The normalized compressive strength was compared with the loading efficiency of other sandwich structures,and it is found that the orthogonal and unidirectional fiber orientation skin honeycomb core thermoplastic composite material sandwich cylindrical structure in this paper has highest load-bearing efficiency than the thermosetting composite material foldcore core layer sandwich cylindrical shell structure,thermosetting composite material skin metal pyramid lattice core layer sandwich cylindrical shell structure and thermoset composite material corrugated core layer sandwich cylindrical shell structure.