| Most of the researches on the sandwich structures under impact load focus on the performance exploration,response analysis,application development and parameter optimization design,but the topology optimization design of the sandwich structure has not been deeply studied.Due to the time effect of impact load and the nonlinear effect of material structure,the problem of complex objective function and difficult sensitivity analysis is a difficult problem in the optimization design of sandwich structure under impact load.Based on the bi-directional evolutionary structural optimization method（BESO）,this paper establishs the nested loop optimization process.In the outer iteration,ABAQUS finite element software is used to analyze the nonlinear response of materials and structures,and inertial release method is used to obtain the equivalent static load.The nonlinear dynamic optimization problem is transformed into a linear statics optimization problem.In the inner iteration,the BESO method is used to update the design variables to obtain a clear topology configuration,and the dynamic response of the optimization structures are analyzed.The main work is as follows:（1）Based on BESO method,the"ABAQUS-MATLAB"platform integrated optimization is carried out.Aiming at the sandwich structure under impact load,the characteristics of convenient modeling and accurate finite element analysis of ABAQUS are combined with the characteristics of efficient optimization algorithm of MATLAB,and the nested loop optimization process is established.In the outer iteration,ABAQUS is used for nonlinear analysis,and the equivalent static load method is used to equivalent the static load with the same displacement response,and the topology optimization design is carried out in the inner iteration.（2）The sandwich structures are optimized under different impact loads.The dynamic responses of the optimization results under impact loads are analyzed,and the influence of optimization parameters such as target volume fraction（Volfrac）and volume evolution rate（ER）on the optimization results are studied.The deflections of upper and lower panels and the plastic dissipation energy of core are compared between the optimization structure and the solid structure with equal mass under the same working conditions.The results show that the mechanical properties of the optimization structures are better than those of the solid structure with equal mass,such as deformation resistance,energy absorption and impact resistance,and the above mechanical properties of the optimization structures with dynamic load are better than those of the optimization structure with static load,which verifies the effectiveness of the optimization algorithm with dynamic load.（3）The sandwich arch structure under the impact of projectile with initial velocity of v0=100m/s is optimized,and the dynamic response of the optimization results under the impact load is analyzed.The deflections of top and bottom sheets and energy absorption of core of two comparison models with equal mass（Voronoi aluminum foam sandwich arch and solid arch）and optimization arch structure under the impact load with initial velocity of v0=100m/s are compared,and the dynamic responses of three models under different impact velocity are compared and analyzed.The results show that under the same working conditions,the mechanical properties of the optimization sandwich arch structure,such as impact resistance,deformation resistance and specific energy absorption of core,are the best,followed by Voronoi aluminum foam sandwich arch model,and the mechanical properties of solid arch model with the equal mass are the worst.And when the impact velocity is low,the response of the structure is not more than the deformation threshold,the tension bending torsional effect of the core is small,some parts are failed to give full play to the role,the impact resistant performance advantage of the optimization structure is not obvious.The study of the impact velocity range,the higher the impact velocity,the impact resistance of the optimization structure is the better.The effectiveness of the optimization algorithm under impact load is proved.（4）The optimization design of sandwich arch structure under asymmetric load is carried out,and the dynamic responses of the two optimization models under symmetric impact and asymmetric impact are compared.When the structures are subjected to symmetric impact load,the anti-impact performance and core energy absorption of the symmetric optimization structure are slightly better than the asymmetric optimization structure,while the performance of the asymmetric optimization structure is slightly better than that of the symmetric optimization structure.However,the performance of the optimization structures is better than that of the comparison model under two kinds of impact load.The results show that the optimization results under different load conditions are different,and the mechanical properties of the optimization results under each condition are better than other structures. |
