Crashworthiness Study Of Sunflower-like Sandwich Cylindrical Shell

With the expansion of human activities and the increasing frequency of interactions,there are more and more collision accidents.These accidents pose a serious threat to people’s lives and property safety.The thin metal wall structure has been widely used in collision kinetic energy dissipation systems of automobiles,airplanes,and trains due to its excellent lightness and crash resistance.Therefore,studying the crashworthiness of metal thin-walled structures under impact load is of great significance for the safe application of metal thin-walled structures in the collision accidents.In this paper,a kind of sunflower-like thin-wall sandwich cylindrical shell energy-absorbing structure is taken as the research object,and numerical simulation analysis is used to study the crashworthiness of thin metal wall structure.The radial and axial loading were applied to the structure,the deformation modes and energy absorption characteristics of the sunflower-like thin-walled cylindrical shell under different conditions were studied.In the radial impact cases,the effects of loading angle,impact velocity,wall thickness,and the number of petals on the deformation modes and energy absorption characteristics of sunflower-like sandwich cylindrical shells were studied.In two loading directions of tip side pressure and gap side pressure,the numerical simulation calculation was performed to obtain the deformation mode,initial peak force,specific energy absorption,and mean crashing force of the sunflower-like cylindrical shell under different impact velocities.The results show that these parameters will have a certain effect on the crashworthiness of the sandwich cylindrical shell structure.The radial deformation mode of the sandwich cylindrical shell is significantly different from the single-wall metal cylindrical shell.The connection between the tip of the petal and the outer shell limits the outward expansion of the outer shell.Under the condition of constant mass,the two loading methods of tip side pressure and gap side pressure have a great influence on the deformation mode of the sunflower-like sandwich cylindrical shell,which is mainly manifested by the difference in the structural load-bearing part.The load-displacement curve of gap side pressure has less fluctuation.With the increase of the shell wall thickness,the energy absorption efficiency of the thin-walled structure under the tip side pressure impact method is reduced,and the specific energy absorption of the gap side pressure is 44.6% higher than that of the tip side pressure;as the number of petals changes,there is an optimal value of the energy absorption efficiency of the wall structure;with the increase of the impact velocity,the initial peak force,specific energy absorption,and mean crashing force of the thin-wall structure are increasing.In the axial impact cases,by combining the initial peak force,specific energy absorption,mean crashing force and other impact resistance evaluation indicators,the influence of factors such as wall thickness,petal number,loading speed and aspect ratio on the deformation mode and energy absorption performance of the sunflower-like sandwich cylindrical shell were studied.It was found that in the 8-petal cases,as the wall thickness of the outer shell increases,the central configuration surrounded by the inner shell changes from a circle to a polygon,and finally to a square,whereas in the models with more petals,the center surrounded by the inner shell remains circular during the deformation process.Under the condition of constant mass,as the impact velocity increases,the initial peak force,specific energy absorption,and mean crashing force of the sunflowerlike sandwich cylindrical shell increase;with the increase of the shell wall thickness,the specific energy absorption and mean crashing force decrease;with the increase of the number of petals,the energy absorption efficiency of the sunflower-like sandwich cylindrical shell gradually shows regularity,that is,there is an optimal value;at different length-to-diameter ratios,the deformation mode of the sunflower-sandwich cylindrical shell may change,and the different deformation modes will lead to differences in energy absorption efficiency.