Identification Of Aviation Aluminum Alloy Characteristic Parameters And Research On Crashworthiness Of Round Tube

Aviation aluminum alloy is widely used in aviation,high-speed rail and automobile fields because of its excellent properties such as high strength,high corrosion resistance and light weight.Its thin-walled tube structure has been applied in various fields as a buffer energy absorbing component.Therefore,it has practical engineering significance to study the crashworthiness of aviation aluminum alloy tube with openings.In this paper,the static and dynamic mechanical experiments of aviation aluminum alloy 7150-t6 are carried out,and the Johnson cook constitutive parameters of the material are obtained by using the reverse calculation technique.Combined with the identified alloy characteristic parameters,a reliable numerical model of 7150-T6 aluminum alloy thin-walled tube under axial impact was established,and the crashworthiness of the tube with different opening shapes was studied.Finally,response surface method and genetic algorithm are used to optimize the unfolding structure of the perforated pipe.This paper mainly carried out the following work:(1)In order to obtain the mechanical response of 7150-T6 under different working conditions,static test and dynamic impact test of split Hopkinson pressure bar(SHPB)were carried out on the material testing machine.The experimental results show that 7150-T6 aluminum alloy has good plasticity,is insensitive to strain rate and has obvious softening effect at high temperature.The microstructure of the sample before and after impact was observed by SEM,and the formation of adiabatic shear band was analyzed.(2)Based on the measured responses of static and dynamic tests of 7150-T6 aluminum alloy,Johnson cook constitutive parameters are identified by reverse calculation method.Firstly,the numerical model of SHPB is established,and the optimization algorithm is used to reverse the sensitive parameters.Then,the results of reverse engineering are substituted into numerical calculation to verify the accuracy of reverse engineering parameters.Finally,the numerical results of reverse and fitting parameters of Johnson cook constitutive model under different strain rates are compared.The results show that the identification parameters based on calculation reverse have better accuracy and universality.(3)In order to obtain an effective and reliable numerical model of 7150-T6 aluminum alloy tube under axial impact,SHPB tests were carried out.Combined with the constitutive parameters of reverse identification,the SHPB finite element model of circular pipe is established.Through the comparison of deformation and crashworthiness with the experimental results,the reliability of the established model is verified.On this basis,the influence of single row hole and multi row hole on the energy absorption performance of circular tube with different opening shapes is studied.The results show that the rectangular perforated tube has better crashworthiness.(4)In order to further improve the crashworthiness of the tube,the structure of the rectangular perforated tube was optimized.The response surface model of peak load and specific energy absorption is established,and the Pareto front solution is obtained by NSGA-Ⅱ multi-objective algorithm.A set of optimal opening parameters are obtained and verified by experiments.The results show that the optimized tube has stable deformation mode and good energy absorption characteristics.