Reaserch On Wheel Profile Optimization And Laser Texturing Adhesion Test

As the speed of high-speed railway trains continues to increase,the problem of adhesion coefficient control has become increasingly prominent.It is particularly important to carry out a series of studies on adhesion coefficient control.Abnormal wheel-rail adhesion coefficient will not only produce abnormal vibration during train operation,but also reduce the smoothness of train operation.In the process of wheel traction or braking,if the adhesion coefficient is too small,it will cause the wheels to spin,which is easy to cause the wheels and rails to scratch,which seriously affects the safety of train operation.Combining the above background,the main research content and conclusions of this article are as follows:（1）Aiming at the problem of abnormal vibration of worn wheels,a mathematical model based on arc-radius is established,and GA-BP genetic algorithm is used to solve the optimal wheel profile that can improve the running stability of the vehicle and reduce the amount of wheel wear.Abnormal vibration of worn wheels.The results show that:compared with the standard wheel tread LMB,the wheel-rail contact range when the optimized profile LMB-opti is matched with the CN60 rail is increased from[-10,+2]mm to[-10,+8]mm,which is equivalent The taper value is reduced to 0.12;the root mean square value RMS of LMB-opti lateral vibration acceleration is reduced by 30.3%;the root mean square value of LMB-opti’s running stability is increased by 32.2%.Dynamic simulation results based on the Archard wear prediction model:After the train runs 50,000 km and 100,000 km,compared to the LMB profile,the wear depth of the optimized profile LMB-opti is reduced by 4.7%and 2.5%,respectively.（2）Based on the theory of laser texturing and melting,use laser texturing technology to texturize the wheel samples _IP,P_II,P_{II I}and P_IV,and measure the surface roughness,surface hardness and wear of the texturing surface.Based on the measured parameters,the influence of the laser texturing power on the physical characteristics of the wheel sample is analyzed.The results show that in the rolling test,as the rolling time increases,the surface hardness of the four samples first increases and then decreases,and the order of the surface hardness from small to large is P_{II I},P_II,P_IV and _IP.（3）According to the test sample standard of GPM-30 rolling test machine,design the test plan and analyze the change of sample adhesion coefficient.In the process of rolling test,change the parameters such as load and number of revolutions,and explore the changing law of adhesion coefficient under different running mileage and rolling time.The results show that with the increase of the number of revolutions,the adhesion coefficient fluctuates between 0.015 and 0.025;the test samples are divided into four groups according to the surface roughness of 0.4 to 1.0μm,6.0 to 8.7μm,9.6 to 11.8μm,and 15.5 to 17.8μm.Under the microscopic morphology,as the longitudinal depth increases,the surface hardness of the white layer,the deformed layer,and the original layer area increase in turn.（4）Establish a finite element model based on the two-dimensional and three-dimensional inelastic contact theory,and combine the test sample roll model and the fractal rough surface simulation model to analyze the fractal dimension of the rough surface and the change and distribution of the rough surface contact stress.The results show that when the friction coefficient（adhesion coefficient）is 0.3,the fractal dimension D=1.2,and the speed is 60km/h,the contact stress of the sample _IP is 9.21×10⁴N;when the fractal dimension D=1.4,the speed is 120km/h When the contact stress of the sample P_II is 1.42×10⁵N;when the fractal dimension D=1.7 and the speed is 240km/h,the contact stress of the sample P_IV is1.63×10⁵N;when the speed is 120km/h,240km/h,respectively,The friction coefficient（adhesion coefficient）of the sample P_III is between 0.15 and 0.6,and the contact stress varies from 6.67×10⁴ N to 2.516×10⁵N[66.7kN,251.6kN].