Lightweight Design Of Joist Frame Of The Rail Grinding Device

With the rapid development of railways,the rail milling-grinding train as a rail maintenance vehicle,is playing an increasingly important role.At present,China is in the stage of introducing and learning the relevant technology of milling-grinding vehicles monopolized by foreign countries.The weight of self-developed grinding equipment exceeds the one required at home due to immature technology.The joist frame of grinding device in the rail milling-grinding train is the supporting part of the entire grinding unit.Taking into account the complexity of the joist frame structure and the diversity of the loading conditions,the analogy structure and the conservative design with an increased margin are adopted.In particular,the integrated design of the overall configuration and the internal rib structure have been carried out in a simple and intuitive way so it is necessary to study the lightweight of the joist frame.Under the premise of ensuring the rigidity of the joist frame and the low-order modal frequency,the compromise programming method has been applied to the multi-objective topology optimization of the joist frame.On the basis of the multi-objective topology optimization model,the work has redesigned the joist frame structure,after which the optimum size has been found using the size optimization.The main content of the paper is as follows:(1)Static analysis and modal analysis of joist frame have been established.Starting from the function of the grinding device,the paper has carried out the structure design of the grinding device and established a three-dimensional model of the grinding device for the rail milling-grinding train.Based on the three-dimensional model,the force analysis of the joist frame under typical working conditions has been performed to obtain the boundary load.Basing on the finite element model in the hypermesh,static analysis and modal analysis of the typical working conditions of the joist frame have been set up.The results show that there is a large margin and a good dynamic performance in stiffness and strength of the joist frame.(2)A multi-objective topology optimization of the dynamic and static characteristics of the joist frame has been applied to find the optimum structure of the joist frame.The SIMP method contributes to establish two mathematical models:the static stiffness optimization model and the first three-order frequencies optimization modal while the compromise programming method helps to achieve the multi-objective topology optimization model.The multi-objective topology optimization of the dynamic and static characteristics of the joist frame through the appropriate volume fraction has been realized,which leads to the optimum structure..(3)Joist frame structure has been redesigned on the basis of topology optimization model.According to the results of multi-objective topology optimization,the work has put up the principals of the redesign of joist frame modal by taking a full consideration of manufacturing process of steel plate and assembly relations of joist frame.The dynamic and static finite element analysis of the redesigned joist frame can verify the effectiveness of multi-objective topology optimization.(4)The optimum size of redesigned joist frame model has been determined.The section size optimization has been realized in the optistruct by taking the minimum weight as optimization object and the stress as constraint.In comparison with the dynamic and static performance and weight of the joist frame before lightweight,the stiffness,strength and low-order modal frequencies of the new joist frame have been greatly improved,and the weight has been reduced by 20%.