Research On Impact Resistance Of Honeycomb Structure Based On Memory Alloy Material

As a popular smart material,shape memory alloy has excellent characteristics such as low density,high energy consumption,super elasticity,impact resistance and so on.The memory alloy is used as the base material of regular hexagonal honeycomb to buffer energy absorption.It can improve the energy absorption effect of the structure and protect the body and passengers more effectively.In this thesis,the tensile experiment of the austenitic hyperelastic Nitinol alloy at room temperature is done,and the experimental parameters are used to verify the correctness of the simulation model.On this basis,the Nitinol alloy was used as the base material of regular hexagonal honeycomb for impact resistance and energy absorption,and a large number of numerical simulation studies were done on the coplanar impact performance of Nitinol honeycomb.The main research contents and results of this thesis are as follows:Firstly,the stress and strain values of the Nitinol alloy were measured by using a stretcher,and the phase change strain,elastic modulus and other parameters were calculated.ABAQUS was used to simulate the tensile experiment of the Nitinol alloy.The simulation results agree well with the experimental results,and the overall error is controlled within 6%,which verifies the accuracy and reliability of the simulation analysis.On this basis,the elastic-plastic model of Nitinol alloy was verified with reference to related experiments.The simulation curve is in good agreement with the experimental curve,and the maximum stress error is controlled within 3%,which verifies the correctness of the simulation analysis of the Nitinol elastic-plastic model.Secondly,according to the accuracy requirements of the finite element analysis,the reliability and mesh independence of the cellular simulation model are analyzed.The results show that the energy composition of the model system is relatively scientific and reasonable,and the total energy is conserved.The pseudo-energy is controlled in a very small positive range and less than 5%of the total energy.The finite element model is effective and reliable.By comparing the time-displacement curves of the honeycomb model under different grid sizes,the honeycomb grid is selected as 2mm,which meets the accuracy requirements and will not affect the calculation results of the model.Then,the coplanar impact resistance of Nitinol honeycomb and aluminum honeycomb were compared using finite element software.The results show that the mass specific energy absorption of Ni Ti alloy honeycomb is smaller than that of Al alloy honeycomb.However,the energy absorption,average load and specific energy absorption per unit volume are higher than those of aluminum alloy honeycomb.The deformation of nickel-titanium alloy honeycomb is relatively stable and uniform,and there is no obvious initial"X"deformation band.Compared with steel honeycomb with higher strength,the results show that Nitinol honeycomb is more suitable for the field of energy absorption and has better research and development prospects.Finally,the influence of different thickness,thickness gradient and impact Angle on honeycomb coplanar impact is analyzed.The results show that the energy and mass of honeycomb increase with the increase of the thickness,and the compressible distance decreases.When the thickness increases by 0.1mm,the compressible distance decreases by about 2%-3.3%.The honeycomb arranged by the thickness gradient shows the characteristics of deformation from thin to thick,and the honeycomb arranged by the gradient of 0.5-0.8-1mm and 0.8-0.5-1mm has the best energy absorption effect.The horizontal impact Angle decreases,which increases the contact area between the impact plate and the honeycomb coplane and makes more honeycomb deformation absorb energy.The smaller the horizontal impact Angle is,the more energy is absorbed.For every 10cm~2increase in the area of the impact end,the energy absorbed by the honeycomb increases by about 62J.Different impact positions affect the contact area between the honeycomb coplane and the impact end,and the larger the initial contact area of the honeycomb,the more energy is absorbed.