Optimization Of A Composite Lattice Structure-based Auxiliary Converter Cabinet Of High-speed Train

Auxiliary converter is one of the key electrical equipment of the high-speed EMU trains.Only by ensuring the quality and safety of the auxiliary converter cabinet can the normal power supply of the EMU be guaranteed.As an equipment suspended at the bottom of the EMU carriage,the auxiliary converter cabinet often appears fatigue fracture due to poor operating environment.The occurrence of fracture will endanger the safety of the whole vehicle and the life safety of the passengers.However,some studies have shown that 50% ～ 90% of electrical equipment accidents are caused by fatigue fracture.The light weight of the auxiliary converter cabinet can reduce the vibration energy,increase the strength,and prolong the service life of the cabinet.Therefore,on the premise of ensuring the fatigue life of the auxiliary converter cabinet,weight reduction is the core problem of the high row dynamic system mechanism design.In order to improve the overall performance of the auxiliary converter cabinet,based on the lightweight composite pyramid lattice material,a parameterized model of the auxiliary converter cabinet that can complete the global optimization design was established in this paper.Based on this,the experimental design,global sensitivity analysis and global optimization design were completed.In the design process,a homogenization model based on RVE was established to improve the computational efficiency.In order to ensure the lossless information transformation between CAD and CAE models,the integrated CAD/CAE closed-loop optimization based on ABAQUS software development platform was realized.Specific work of related design optimization is as follows:(1)Simplify the lattice structure auxiliary converter cabinet model.Pyramid lattice structure Is chosen as the new material to achieve lightweight of EMU auxiliary converter cabinet.Firstly,the basic mechanical properties of the pyramid structure are analyzed,and the best lattice structure is selected.In order to connect the macroscopic model and microscopic structure of the auxiliary converter cabinet and obtain the physical properties of the pyramid lattice structure,the auxiliary converter cabinet is homogenized by establishing representative volume element.In order to improve the utilization rate of the auxiliary converter cabinet model and make the sub-sequential optimization process automatically close-looped,the established representative volume element model is embedded into the auxiliary converter cabinet model,and an auxiliary converter cabinet model with structural design parameter interface is built by using ABAQUS secondary development language Python.(2)Global sensitivity analysis based on structural parameters of the auxiliary converter cabinet.After the modeling of the auxiliary converter cabinet,the multi-objective function is established according to the cabinet condition of the EMU.In order to verify the influence of design variables on the objective function,RS-HDMR global sensitivity analysis was performed to verify the sensitivity of CAE model structural parameters to the multi-objective function.After screening and verification,four relevant design parameters are left finally.(3)Closed-loop optimization design based on the auxiliary converter cabinet.Random vibration is often related to the fatigue life of parts,while impact condition is often related to strength.In order to improve the strength and life of the auxiliary converter cabinet,the optimization model takes these two aspects as the optimization objectives and simulates the random vibration and impact conditions of the high column in operation.Then the parameters of the lattice structure assisted converter cabinet were optimized,and three common multi-objective optimization algorithms were used: MOPSO,NSGA-III and MOEA/D.The results show that the performance of MOPSO is better than NSGA-III and MOEA/D.According to the comparison between the results of MOPSO algorithm and the traditional auxiliary converter,the lattice structure has a good improvement on the performance of the auxiliary converter cabinet in terms of random vibration and impact.The maximum Mises stress of the lattice structure auxiliary converter cabinet under impact is 70%lower than that of the traditional auxiliary converter cabinet.