Crashworthiness Research And Application Of Reed-inspired Structures Under Lateral Impact

The thin-walled porous structure always plays an important protector in various high-speed collisions,due to its lightweight and excellent energy absorption.To get better crashworthiness,researchers introduce excellent features from various organisms into bionic structural designs.The reed stalks are light,thin,and hollow,but reeds can resist strong winds and remain upright in the wetland environment,which shows that the reed stalks have good bending resistance.Therefore,this paper will design a biomimetic structure with better crashworthiness by studying the microstructural characteristics of the reed stem.The main research includes the following parts:(1)The bending strength of reed stems was studied by quasi-static three-point bending experiments,and it was found that reed stems had higher bending strength than some other grass stems.Then,the microstructures of the cross-section and longitudinal section of the reed stem were obtained by scanning electron microscope.Through the image processing of the cross-section of reed,it was found that the cell tissues were irregular polygons with the characteristics of graded size,and the arrangement of the horizontal cell walls on the longitudinal section was staggered.According to the microstructural characteristics of the reed stem,irregular cellular structure with the gradient of cell size is generated programmatically in the cross-section,and many partitions with different spacings are added to the longitudinal section.Finally,a novel reed-inspired structure with the microstructural characteristics of the reed stem is designed.(2)The finite element(FE)model of the reed-inspired structure under three-point bending conditions is constructed by defining various keywords such as the element type,material constitutive,boundary constraints,and contact settings.The accuracy of the symmetrically constrained model is verified and the mesh size of the model is determined by mesh sensitivity analysis.The structure fabricated by 3D printing technology is subjected to the quasi-static three-point bending experiment.And the experimental results were compared with simulations to ensure the accuracy of the FE modeling method.(3)The impact of different structural parameters on the crashworthiness of the reed-inspired structure under three-point bending conditions was studied.The influence of five parameters(the coefficient of partition plates spacing,the thickness of cell walls,the gradient of the cell size,the thickness of the epidermis,and the radius of the inner circle)on the crashworthiness of the structure was analyzed.When comparing the reed-inspired structure with some other bionic structures of the same quality,it is found that the reed-inspired structure has better crashworthiness.(4)The reed-inspired structure was extended and applied to the vehicle-pier collision example,and the structural characteristics of the reed stem were applied to the protection of the bridge pier.Two new protections of the bridge pier based on the reed-inspired structure were designed.The protective performance of the new protection in the collision between the pier and the vehicle was analyzed by simulation.Compared with other protection of the pier,the protection based on the reed-inspired structure has a good performance in the energy absorption,reducing impact and light-weight.