Reverse Demand For Key Components Of Rail Vehicles Technical Research

With the rapid development of China's rail vehicles,basic research on a series of rail vehicle products including high-speed EMUs and heavy-duty railway wagons is becoming more and more important when taking into account safety.At present,the structural design of the rail vehicle and the design load based on the safety assessment standard are formulated on the basis of experience.However,the dynamic load of the vehicle when it is driving in the actual working environment changes rapidly,and there will be no small deviation from the load standard referenced in the design.Therefore,the structure designed with reference to the load conditions based on experience will inevitably encounter a situation where the actual working load is worse than the design load,and the bearing capacity of the vehicle body or component cannot be accurately measured to ensure safety.However,if excessively high design load is formulated,safety can be guaranteed but it will increase unnecessary cost investment.Therefore,in the aspect of safety design of rail vehicle products,there is a problem of obtaining the load first.The formulation of design load is directly related to the safety performance and economic performance of the rail vehicle products.Based on the previous research work,this paper proposes a method to obtain the strain information generated by the actual external load in the actual working environment by the strain gauge to indirectly receive the real load.In this paper,we have used the finite element method to verify the method from the isotropic material and the anisotropic material through the simulation examples of the key components of the steering frame and the cab skeleton,respectively.Some modifications and optimizations have been made on the results of predecessors,and some theoretical foundations of the method have also been improved.The details are as follows:This thesis takes the key components of rail vehicles as the research object,and uses simulation analysis as the main means to conduct the following research:(1)First,for a specific research object,several strain basis functions was defined using the fitting function on the geometric domain of a given structure.Each strain basis function is defined by a single strain component,and each strain component value is derived from the finite element calculation result.These several strain basis functions constitute a set of real functions.(2)Using the D-optimized exchange algorithm,aiming at the maximum strain determinant required in the D-optimization strategy and the strain gauge placement position as the design variable,the optimal patch position for the measured strain is sought in the approximate fitting envelope function.(3)Study the relationship between strain and load,construct a strain-load decoupling matrix for the linear system,and solve the load spectrum on the real time domain according to the measured strain.(4)Use the Matlab programming environment to develop the platform for the reverse load obtaining process,and the entire reverse load obtaining process from the strain data input,the selection point optimization to solving the real load finally has been realized.