The Crashworthiness Design Of Thin-walled Tubes Based On Origami And Kirigami Methods

Thin-walled structures are considered as indispensable collision energy absorbing devices in vehicles,because of its irreversible energy conversion,lightweight,high specific energy absorption,low cost,and easy installation,etc.At present,scholars have carried out very extensive research on the energy absorption performance of thin-walled structures.The most common thin-walled structures are conventional tubes.However,the conventional tube has a larger initial peak force and a lower mean crushing force,which is considered to be a kind of inefficient energy absorption device.In order to improve the energy absorption performance of the tubes,many scholars have carried out a series of structural designs and material designs on the basis of conventional tubes.The structural design is carried out with the goal of reducing the initial stiffness or increasing the plastic deformation of the structure,such as multi-cell tubes,window tubes,and bionic tubes.However,some simple tubes are easy to process but have poor performance,some complex tubes have excellent performance but also have a complex process.The material design is carried out to reduce the mass of the tube,for example,carbon fiber composite tube,glass fiber composite tube.However,the composite tubes are more prone to deform in brittle fracture.Recently,the crashworthiness design of thin-walled structures based on the origami and kirigami methods has attracted the attention of researchers.The introduction of the origami and kirigami not only reduces the initial peak force of the structure,but also guides the structure to deform according to the preset creases,which can improve the mean crushing force effectively.In addition,the thin-walled structure based on the origami is simple to process and only needs to be molded by molding.Thus,based on the origami and kirigami method,this paper introduces the preset origami patterns and kirigami patterns into the thin-walled metal tubes and metal/composite hybrid tubes.Through a large number of quasi-static axial crushing experiments,numerical simulations,and theoretical analysis,the mechanism of the origami and kirigami in thin-walled structures is studied.For the problem that the extensional mode of the conventional square metal tube is difficult to trigger in the natural state,the kirigami square tube is proposed based on the kirigami method which can collapse in extensional mode successfully.For the problem that the origami crash box may collapse in the incomplete diamond mode,the origami-ending tube with simple processing is proposed based on the origami patterns which can collapse in diamond mode.For the problem that the performance of metal/composite hybrid straight tubes in natural mode is difficult to fully release and the initial stiffness is large,a design method based on origami-ending patterns is proposed for metal/CFRP(Carbon fiber reinforced polymer)hybrid tubes,which can realize the diamond mode of the hybrid tube.The specific research content and results are as follows:1.The extensional mode is the best collapse mode to occur "naturally" in the conventional square tube.However,it is the most difficult type to trigger among all the "natural" modes.Therefore,in this paper,the triangular kirigami patterns were introduced into the corner regions of the conventional square tube to obtain the kirigami tube.The quasi-static experimental and numerical results present that the kirigami patterns can not only reduce the initial stiffness but also guide the tube to deform in extensional mode successfully and stably.Compared to conventional square tubes,the initial peak force can be significantly reduced,while the mean crushing force is increased significantly.Additionally,in the analysis of the parameters of the kirigami tube,it is found that the kirigami tube can deform in the extensional mode within a large parameter range.This greatly increases the possibility of a tube deformed in extensional mode.(Section 2)2.The origami crash box can deform in the stable and efficient diamond mode,but the energy absorption performance of the origami crash box is still limited by the dihedral angle,and the manufacturing process of the box is still relatively complicated.In this paper,the triangular origami patterns were introduced into the ends of the thin-walled tube to obtain the origami-ending tube.Through a large number of quasi-static axial experiments and numerical simulations,it is found that the origami-ending tube can collapse in the diamond pattern stably.Compared to conventional tube,the initial peak force of origami-ending tube is not only reduced but the mean crushing force is nearly doubled.It also shows after parametric analysis that the origami-ending tube can deform in the diamond mode within a larger parameter range.Moreover,compared to the origami crash box,the origami-ending tube has better performance and simpler processing technology.(Section 3)3.In order to obtain a thin-walled structure with a long effective stroke,this paper carried out research on the crashworthiness of the long origami-ending tubes based on the origamiending module.The long origami-ending tube can also deform in the diamond mode successfully through quasi-static experiments.However,in experiments,it was also found that some tubes deform in the corner symmetric mode and the mixed mode.This significantly reduces the energy absorption performance compared to the diamond mode.After analyzing these two collapse modes combined with numerical simulations,it was found that the corner symmetric mode was caused by the local buckling imperfections at the module junction,and the mixed mode was caused by the concave imperfections.Therefore,the local reinforced design and convex design of the long origami-ending tube were carried out.The performance of the reinforced tube was also verified through the quasi-static experiments.(Section 4)4.The metal/composite hybrid tube combines with the advantages of lightweight of composite and stable deformation of the metal.However,most of the hybrid tubes still belong to straight tubes,and the initial peak force is relatively high.Therefore,in this paper,the welldesigned origami patterns were also introduced into the ends of the metal tubes of the hybrid tubes to propose the origami-ending hybrid tubes.Based on a large number of quasi-static experiments,it was found that the metal tubes of metal/CFRP/metal hybrid tube can deform in diamond mode under the guidance of the origami patterns,and then force the composite tube to deform the same high-performance collapse mode.The interaction between the metal tubes and the CFRP tube causes the CFRP tube to be broken more thoroughly,and the metal tube also improves the load-bearing performance.Compared to the conventional metal square tube and the CFRP square tube,its specific energy absorption can be greatly improved.Additionally,based on the basic folding element theory,the formula of mean crushing force of metal/CFRP/metal hybrid tube is derived,which can accurately predict the energy absorption performance of the origami-ending hybrid tube.Besides,the introduction of origami patterns can effectively reduce the initial peak force,and its CFE is much higher than that of other hybrid tubes.Moreover,the origami was only applied to the end of the metal tubes in the hybrid tube,which ensured that the CFRP tube was still a straight tube,which was extremely convenient for processing and manufacturing.(Section 5)...