Research On Lightweighting And Properties Of Underfloor Lifting System

Underfloor lifting system is indispensable in the process of EMU overhaul of large key equipment.Its whole structure is quite complicated,and the current domestic manufacturers of underfloor lifting system design and manufacture mainly depends on the experience,and has not formed a unified design specifications,each size parameters with larger allowance,so it is necessary to study on lightweight of underfloor lifting system.But most of the current research work focused on the structure design and maintenance and synchronous control,mechanical research field involving less,therefore,this paper will analyse the mechanical properties of underfloor lifting system,and further research on its lightweight.The underfloor lifting system designed by a research institute as the research object in this paper,after simplification structure,a parametric model of underfloor lifting system was established by AN SYS.Static analysis is carried out,and its strength and stiffness are checked.The results show that the strength and stiffness of underfloor lifting system meet the requirements,and a large amount of surplus.Since the contact part of a head structure is the stress concentration region,to explore the actual circumstances of the force.The nonlinear contact analysis of the head structure is carried out,and study the feasibility of using the nodal coupling analysis instead of the contact analysis.The results show that,for the contact of slider and slide rail,when there is relative slip,the coupling model is similar to the contact analysis under large friction coefficient.when there is no relative slip,the results of the two models are not different.Contact analysis based on contact pair is more close to reality,and the result closer to the exact solution,but the modeling process is complex,and the cost of calculate is higher.Therefore,for the calculation of the accuracy is not too high,can use the node coupling method.Traditional design methods of underfloor lifting system tend to be conservative.In order to take full advantage of the bearing performance of material,combining the optimization technique with the response surface approximation model technique,lightweight research based on response surface method of underfloor lifting system is carried out.The method based on finite element analysis software ANSYS and multidisciplinary optimization software ISIGHT.With the sensitivity of the design variables are analized by Optimal latin hypercube experimental design method,the parameters of the larger influence on system response are selected.And the approximate model is optimized by using the multi Island genetic algorithm after the response surface model is established.The results show that this method can not only greatly improve the efficiency of the optimization,but also reduce the structural weight of the underfloor lifting system by 20.64%,achieved the purpose of lightweight,and can effectively reduce the product cost.Since the product quality and performance will be affected by some uncertain factors,the deterministic optimization results tend to have lower reliability and robustness,approximate model technology,Monte Carlo simulation method,reliability analysis and 6σquality design have been combined with to design the robust optimization of underfloor lifting system based on 6σ.Results show that compared with the traditional deterministic optimization,the method can not only make pit type frame car machine structure weight reducing 16.79%,and reduce the sensitivity of the optimization results to the parameter fluctuation,and greatly increase the level of σ and reliability of each parameter.So greatly improves the reliability and robustness of lifting system,which provide theoretical guidance for the design and optimization of underfloor lifting system,and has high practical value in engineering application.