Preparation Of Bionic Sandwich Packaging Materials Based On Luffa Sponge And Its Cushioning Property Research

The sandwich structure is widely used in the field of shock absorption,energy absorption,impact resistance,etc.Luffa sponge has excellent cushioning performance due to its special porous grid structure.Therefore,this paper takes the luffa sponge as the bionic object based on the principle of bionics,and applies the luffa sponge bionic structure to the design of the core layer structure of the sandwich panel,which is used to prepare a lightweight and high-strength cushioning sandwich packaging material.Firstly,the mechanical properties of luffa sponge are studied to obtain the characteristic structure with cushioning properties.Luffa sponge were researched from macro and microstructures.The luffa sponge cushioning mechanism was explored which combined with the quasi-static compression experiment.The results show that the excellent mechanical properties of luffa sponge are the total influence obtained by the combined action of various parts of the structure,but the thick inner surface fibers provide the main impact resistance.The luffa sponge compression deformation includes two instability modes:diamond and symmetry.The energy absorption can be achieved by folding the fiber ribs,which can be used in the subsequent cushioning structure design.Then design the luffa sponge bionic structure.During the growth of the luffa sponge,fibers arrangement have a high degree of self-similarity and symmetry,which conforms to the characteristics of fractal patterns.Therefore,the fractal theory is used to guide the modeling of bionic structures.Combining mechanics experiments to determine the symmetrical characteristic structure as the basic design unit.Finally,a bionic prototype structure of luffa sponge was designed innovatively based on the fractal principle.Secondly,the 3D printing technology was used to prepare the bionic structure samples of luffa sponge and characterize the mechanical properties.The three-dimensional model was imported into finite element software for related numerical calculation and analysis.In addition,a series of quasi-static compression tests were performed on the printed model to verify the accuracy of the simulation calculation results.The results show that the cushion properties of luffa sponge bionic model prepared by 3D printing was close to the natural luffa sponge.The folding angle(?)and length(a)of the ribs of the bionic structure were taken as parameters,and the specific energy absorption(SEAm)was taken as the design goal to optimize the design of the bionic structure.Results showed that the folding angle of the rib has less influence on the energy absorption value.Reducing the length of the rib increases the specific energy absorption value.When the folding angle is around 11 degrees and the length of the rib is less than 4 mm,it can be obtained the maximum cushioning performance.Finally,the preparation process of the bionic structure was optimized,and the design and finite element analysis of the paper bionic sandwich panel were carried out based on the origami theory.Based on the existing research on the bionic structure of luffa sponge,this study proposed to prepare bionic structure packaging materials based on the origami theory,and the planar two-dimensional corrugated paper was folded to obtain the three-dimensional bionic structure.Compared with the existing material,the cushioning performance is between honeycomb and EPE materials.This research provides relevant theoretical research foundation for the design of luffa sponge bionic sandwich structure.Origami theory is adopted into the preparation of biomimetic materials innovatively.It can reduce the cost of preparation greatly,improve the production efficiency,and enrich the choice of cushioning packaging materials.