Multi-objective Optimization For Basic Brake Device Of Railway Freight Car

With the development trend of speed-up and heavy-haul in China's railway transport industry,the load capacity of railway transport in China is increasing and the running speed is also increasing,which puts forward higher requirements for the braking performance of freight cars.Therefore,improving the performance of the basic braking device of railway freight cars is one of the key factors to ensure the operation safety of railway freight cars.At present,the phenomenon of low transmission efficiency,brake shoe eccentric wear and alleviating bad performance occurs in the operation of the basic brake device of railway freight cars in our country.Usually,the solution to this problem is through replacing wear parts or grinding parts,which can not be solved from the source.In this paper,a multi-objective optimization scheme combining ISIGHT and RecurDyn is adopted to optimize and improve the performance of railway basic brake device.The main research contents and achievements include:1.Summarizing all kinds of maintenance faults of freight car brake system,the analysis results show that there are two main faults:one is the 120 type air control valve in the brake system,the other is the basic brake device of freight car.Taking K6 basic brake device as an example,author studies the working principle and important parameters of the basic brake device,and analyses the causes of the failure.2.Identification of the key factors of the performance of the basic brake device.The factors affecting the performance of the basic brake device include the thickness and size of each lever,the diameter of pin and bushing,etc.By designing orthogonal experiments,the data are obtained in the multi-body dynamics simulation software.The main effect values are used to identify the width of the back groove of the middle tie rod,the thickness of the fixed lever,the inner diameter size of bushing 3 and bushing 4 as the key factors.3.Multi-objective optimization design.Taking the identified key factors as design variables,determining constraints and objective functions,designing Latin hypercube experiments,and obtaining sufficient sampling points in multi-body dynamics simulation software;using response surface model to establish approximate surface,and using complex correlation coefficient R2 and error level to test the fitting accuracy of response surface model;finally using NSGA-II multi-objective genetic algorithm to approximate model The optimal solution is obtained by cyclic approximation.The multi-objective optimization of the basic brake device is realized.4.Discussion and verification of optimization results.The optimum scheme for multi-objective optimization of basic brake device is 26 mm of fixed lever thickness,29.3 mm of slot width behind middle tie rod,36.57 mm of inner diameter of bushing 3 and 36.64 mm of inner diameter of bushing 4.By comparing the optimized results with the original ones,the transverse displacement of the brake beam of the basic brake device is reduced by 31%,the mitigation force is reduced by 36%,and the transmission efficiency is increased by 1.83%.In order to verify the accuracy of the optimization results,the optimized variable design is re-modeled and verified in RecurDyn software that the error is less than 3%.This paper presents a multi-objective optimization scheme for the brake device of railway freight car foundation to provide technical support for the production and design of the product improvement.