Study On Impact Energy Absorption Characteristics And Optimization Design Of Metal Cylindrical Shell Structure

The thin-walled shell structure can absorb a large amount of impact kinetic energy through its own compressive plastic deformation during impact,so as to effectively mitigate the impact load.With the development of impact resistance research,metal cylindrical shell structures are widely used in ships,aviation,rail transportation and other fields as important energy absorbing components.It is important to study the energy absorption characteristics of thin-walled structures for their impact resistance and safety.The research work of this paper focuses on the dynamic problem of metal cylindrical shell under impact.The cushioning energy absorption characteristics of metal cylindrical shell are systematically studied by dropping hammer impact test,and the dynamic response process of metal cylindrical shell under impact is simulated by finite element method.On the basis of understanding the collapse deformation modes and energy absorption characteristics of metal thin-walled cylindrical shells under different loading conditions,several optimization design methods of basic thin-walled cylindrical shells are put forward,and the advantages of energy absorption and impact resistance of optimized cylindrical shells are further analyzed and demonstrated.The specific research contents are as follows:（1）In view of the practical engineering problem that the elastic support device of the reactor pressure vessel consumes energy through the internal thin-walled cylindrical shell structure when the vessel is subjected to non-contact explosion load.The energy absorption evaluation system was determined by designing the test specimen of thin walled metal cylindrical shell.The energy absorption characteristics were evaluated by specific energy absorption,stroke efficiency and average collapse load.The plastic deformation mode and energy absorption characteristics of the structure under different impact energy were obtained by impact test on the specimen with Changchun KEXin JLY-6500 model.Further,the optimal scale specimen with energy absorption characteristics was determined by impact test（the optimal aspect ratio was determined as 2:1）within the reasonable design range of the specimen with reduced size.（2）Based on ANSYS/LS-DYNA software,a cylindrical shell energy absorption structure test model is established,and the numerical simulation results are consistent with the test.Based on the analysis of the characteristics of high-performance thin-walled energy absorption structures,the limitations of the basic metal shell in energy absorption performance are found.In order to improve the energy absorption performance of metal thin-walled structures,a metal cylindrical shell structure with functional gradient wall thickness is proposed.The efficiency coefficient method,objective programming method and explicit finite element analysis were used to solve the multi-objective optimization problem,and the optimal design parameter of the multi-objective optimization problem was₁T（28）2.0₂T（28）2.175.The results show that the energy absorption evaluation indexes（specific energy absorption,stroke efficiency and average load）of the cylindrical shell with gradient wall thickness are improved to a certain extent within the impact energy range of[20KJ,27.5k J],and the optimization effect is obvious.（4）Comparative study on energy absorption of functionally gradient cylindrical shell and base shell under oblique impact.Considering the limitations of axial impact in actual working conditions,this paper makes a comparative analysis of energy absorption characteristics of functionally gradient cylindrical shells and basic shells under different angles of oblique impact（0°,10°,20°,30°）:It is found that the plastic deformation mode of the structure under oblique impact is different from that under axial impact,and the functionally gradient wall thickness cylindrical shell has larger critical loading Angle,better stability and better comprehensive energy absorption characteristics.