Research On Structural Performance And Optimization Of Mobile Car Machine

Mobile car machine is important lifting equipment in the maintenance of EMUs and subway vehicles.Every four cranes simultaneously lift one carriage to meet the maintenance requirements.At present,the domestic research on mobile car machine is mainly focused on the research and improvement of schemes,maintenance and synchronization control.There is less research on structural mechanical properties.Therefore,this paper will analyze the mechanical properties of the structure of the mobile car machine,and further study its lightweight.This article takes a mobile car machine with a lifting weight of 12 t as the research object.Considering the situation of eccentric load when the mobile car machine is lifting the carriage normally during normal work,an equivalent space mechanical model of the bracket structure of the mobile car machine is constructed.The expressions of the force of the frame and the screw on the bracket structure are obtained.Based on this,the influence of the structural parameters and the friction coefficient of the rollers on the load coefficient is researched based on the structural parameters of the crane itself and a qualitative analysis is performed.After simplifying the structure of the mobile car machine,the ANSYS software was used to establish a finite element model,and the static analysis was performed to check the stiffness and strength of the car machine structure.The simulation results show that the structural strength and rigidity of the mobile car machine meet the design requirements.In addition,when the telescopic bracket is loaded,the contact area between the bracket and the bracket is a concentrated stress portion.In order to explore the true force situation in this area,the non-linear contact analysis and joint degrees of freedom coupling analysis are performed on the telescopic bracket structure,and the differences between the two calculation models are analyzed to study the feasibility of using linear analysis instead of nonlinear analysis.The results show that when there is relative slip between the two contact surfaces in the contact area and the contact is not close enough,the coupling model of the degree of freedom node is similar to the contact model with a larger friction factor.When the two contact surfaces in the contact area only have small relative slippage or no relative slippage,the node coupling model is approximately the same as the contact analysis model.Therefore,in practical engineering applications,for some mechanical structures that do not require high accuracy,linear analysis of couplings with degrees of freedom can be considered instead of contact nonlinear analysis based on contact pairs.Aiming at the problem of redundant structure design of the mobile car machine,firstly take the plate thickness and structural size of some components of a mobile car machine as input design parameters,and take stiffness,strength and structural weight as output responses.Sensitivity analysis using the optimal Latin hypercube test design method in ISIGHT software to obtain the final design variables.Secondly,through ANSYS and ISIGHT software,a response surface approximation model was constructed,with the stiffness and strength of the mobile car machine as constraints,and the lightest weight of the structure as the optimization goal.Multi-island genetic algorithm was used for global optimization.The simulation results show that the optimization method not only improves the optimization efficiency to a large extent,but also reduces the structural weight of the mobile car machine by 12.16%,and the weight reduction effect is obvious.