| With the high-speed development of the railway industry,train operating speed has also increased significantly,but it also brought more security issues.To prevent accidents,many countries have taken a variety of protective methods.However,collisions between live intruders and trains usually occur,especially in some countries and regions where protection methods are not perfect.As one of the main components of train anti-collision prevention,the cowcatcher ensures the safety of train operations.However,the existing cowcatcher design is still not perfect.To study the safety of high-speed collision between trains and live intruders and the structural optimization of the cowcatcher,the thesis creates a populated organism model by scanning solids and optimizes the structure of the cowcatcher under high-speed collision by using a topology optimization method,and the optimized structure can ensure the safety of train operation.The main research is developed from the following three aspects:(1)Using the organism pig as a live invasive object,the outline shape of the organism is obtained by physical scanning and the CAD model is obtained by using the reverse engineering design method.Construct a populated biomass finite element model containing skin,rigid bone,cartilage,organs and other tissues based on the anatomical structure of the biomass pig,and assign material properties to different tissues.The validity of the model was verified by comparing the solid collision data with the simulation calculation results through the biomass pendulum side impact and the lower slender bar positive impact tests.The populated biomass finite element model can ensure both computational accuracy and effective computational efficiency.(2)Create a simplified finite element model of the train including the cowcatcher.The influence of the opening angle of the cowcatcher on the collision performance is analyzed under three operating conditions,such as collision with intruders at the left,center,and right positions in the forward direction of the train.Calculated results show that for the equivalent Mises stress,the test optimum is 150° for the opening angle of the cowcatcher and the left side of the collision position,with an average value of 879.3 MPa;For the degree of deformation of the cowcatcher,the test optimal value is also the test optimal value of the cowcatcher opening angle of 150° with the left side of the collision position,the average value of which is 27.5 mm.The equivalent static load method was used to extract the collision loads using the data processing software Excel and Matlab.The topology of the cowcatcher is optimized by the variable density method to minimize flexibility.The optimization results show that the maximum value of plastic deformation of the cowcatcher under different working conditions decreases by 5.07%,25.6%,and 3.9,respectively,and the total mass decreases by 9.94%.(3)According to EN15227-2020 European crash safety standard,the deformation,stress distribution,and contact force of the cowcatcher are calculated by setting different working conditions,and the safety of the barrier is analyzed under static and dynamic conditions respectively.The results show that the maximum stress values of 405 MPa and386MPa are generated in the cowcatcher under static load,which appear in the off-center position and the connection of the lifting seat,and meet the material allowable stress requirements,so the structure of the cowcatcher meets the strength design requirements under these two working conditions;Under the action of dynamic load,the performance of the collision contact force of the optimized cowcatcher row is related to the collision position,but the contact force curves of each collision position are improved to different degrees after optimization,the plastic deformation generated by the collision is smaller,the peak contact force is more reasonable,and the effect of lightweight is obvious,which ensures the safety of the train and animal body under high-speed collision. |
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