Quasi-static Axial Crushing Of Hexagonal Origami Crash Boxes As Energy Absorption Devices

Thin-walled tubes are widely used in energy absorbing devices due to their low cost and ease of processing.In recent years,origami technology has been increasingly incorporated into the design of thin-walled energy absorbing structures by virtue of its mechanical properties.The purpose of this dissertation is to study the energy absorption efficiency of a hexagonal tubular device with crash boxes in a quasi-static axial compression experiment.First of all,this dissertation makes a geometric analysis of the origami pattern of the crash boxes.The pattern is a rigid origami pattern.On the basis of satisfying the rigid folding,the geometry of the pattern also needs to meet the condition of the circumferential direction closure,and thus we obtain the independent geometric parameter relationship that can uniquely determine the structural design.In order to verify the mechanical response of the structural design of the crash box pattern in the quasi-static axial compression experiment,we chose the brass material with good ductility to make the structural physical model.The production steps include making male and female molds,pressing out mountain-valley creases,bending forming,riveting boundaries,and heat treatment to remove residual stress.In order to compare the influence of the introduction of the crease pattern we also made a conventional hexagonal section tube as a control.Quasi-static axial compression tests were performed on an Instron test machine.The upper and lower boundaries of the model are embedded in a cover with a groove to constrain its rotation.The experimental results show that the introduction of the pattern of crash box can successfully trigger the deformation mode of the diamond shape.Compared to the conventional hexagonal tube,the structure can increase the total amount of absorbed energy while reducing the initial peak force in compression.In order to further explore the influence of structural energy absorption properties,especially the choice of geometric parameters,the finite element simulation method has been applied here.In the simulation environment,we input the same material properties,boundary conditions and loading methods as the experiment.In order to ensure that the time hourglass effect and kinetic energy do not have a significant impact in the analysis process,we determine the reasonable analysis time and mesh size by analyzing the convergence of the structure.By comparing with the experimental results,the numerical simulation solution is very close to it,which proves the reliability of this method.Thus,we have further analyzed the two independent parameters of the structure,the dihedral angle and the interlayer height.By setting different dihedral angles,we find that the SEA and initial peak force of the structure increase with the increase of the dihedral angle without breaking the critical value.When the gradient dihedral angle parameter is set,the structure will show a certain change stiffness,but the total SEA remains the same.When the value of the dihedral angle is constant,the SEA decreases as the height between the layers increases,and the initial peak force increases as it increases.When the gradient interlayer height is set,the position where each peak force appears will be shifted due to the value of the height,but the total energy absorption does not change much.Finally,based on the theory of super-folding element,this dissertation deduces the theoretical analytical formula of the mean crushing force during the compression process.After verification of several models,the theoretical analytical solution calculated by the formula is very close to the corresponding numerical simulation solution,which proves the rationality of the solution.Thus,the crash box origami pattern embodies the great potential of its application in the design of energy absorbing devices.