Finite element analysis of locomotive wheel set wi

Finite element analysis of locomotive wheel set with retaining ring on the wheel rim

Abstract: the wheel pair of assembled locomotive engine may relax during the operation. After the retaining ring is installed on the wheel rim, it can effectively prevent the locomotive derailment and other major accidents caused by the relaxation of the wheel rim. The scheme of installing retaining ring, the load and boundary conditions under operating conditions are introduced, the finite element analysis of wheel set is carried out, and the strength evaluation and comparative evaluation are carried out

key words: locomotive wheel set; Tire relaxation; Finite element

wheel set is the most important component of locomotive running gear. Assembled wheels are widely used in China, which are composed of axles, rims and tires, as shown in Figure 1

compared with the overall wheel, the assembled locomotive wheel set shown in Figure 1, when the rim and tread of the tyre are worn to a certain extent, Machi can be put into use again by replacing the tyre, which greatly extends the service life of the wheel set. The tyre and rim of assembled wheels transmit traction and braking force through interference connection. In the process of application, the actual interference will be less than the necessary interference due to wear, temperature rise, etc., resulting in relative movement between the tyre and rim, which is called relaxation. Wheel tyre relaxation will cause major safety accidents such as locomotive derailment. For example, on August 4, 2003, the serious failure of wheel tyre relaxation and outward movement of position 1, 2 and 4 axles of locomotive wheel section a of 27031 freight train caused the emergency stop, resulting in the interruption of Longhai downline for 9 hours

in order to prevent the locomotive derailment accident caused by the relaxation of the assembled wheel rims of diesel locomotives, a scheme of adding retaining rings to the assembled wheel rims is proposed, as shown in Figure 2

after installing retaining rings on locomotive wheel sets, it can effectively prevent major accidents such as locomotive derailment caused by tire relaxation. After the tyre is equipped with a retaining ring, the mating surface between the wheel and the tyre becomes shorter, and the stress center of the rim moves outward; There will inevitably be stress concentration in the retaining ring groove. What is the effect of the above changes caused by the installation of retaining rings on the stress and its distribution of locomotive wheel sets during operation? Has the service reliability of the tread and rim of the tyre changed? Therefore, the wheel with retaining ring must be analyzed and studied to provide a theoretical basis for ensuring the safety of railway locomotive operation

1 analyze and calculate the working condition load and boundary conditions

the change of axle load produced by locomotive in traction condition (or braking condition) is called axle load transfer. The structural type and transmission device of locomotive running gear are different, and the way of axle load transfer is also different. Here, take DF4B locomotive as an example for calculation

df4b diesel locomotive adopts a bogie with elastic 4-side bearing and independent suspension of primary spring. Its traction motors are arranged in sequence, and the traction motors of the front and rear bogies are arranged symmetrically relative to the middle of the car body. The axle load transfer of DF4B diesel locomotive is the axle load transfer in the bogie and between bogies caused by the front and rear inclination of the bogie relative to the underframe of the car body under the action of traction

when the locomotive passes the curve, the wheel weight of two wheels on the same axle will change because the product forming manufacturer can obtain further product integration design, the role of track superelevation and centrifugal inertia force, as well as the role of crosswind

the load acting on the wheel set and the torque transmitted by the traction gear to the axle. In addition, the dynamic load caused by the defects of the wheel rail surface, the irregularity of the track, the rail gap, etc. during the operation of the locomotive. In the analysis and calculation, the functions and effects of the above loads must be comprehensively considered

2 establishment of finite element model

establish a solid geometric model under SolidWorks, simplify the wheelset when modeling, and import it into ANSYS through Parasolid file format. The wheel set model is axisymmetric, but due to the asymmetry of traction, the whole wheel is used for calculation here. The finite element model of the wheel set is shown in Figure 3

3 calculation analysis and evaluation of results in the national standard of spring testing machine

Figure 4 and figure 5 are the stress distribution nephogram of finite element analysis of locomotive wheel set with retaining ring under load, and Figure 6 is the axial stress distribution curve of wheel rim, rim mating surface and retaining ring groove after installing retaining ring

the above calculation results are evaluated according to the strength theory

(1) static strength analysis and evaluation

in order to make the wheel meet the application strength requirements, the maximum von Mises stress at each key position of the wheel should be less than the yield limit of the wheel material σ B. Here σ B=420mpa, the calculation formula of von Mises stress is:

(2) fatigue strength analysis and evaluation

due to the rotation of the wheel, the stress at each point on it presents a three-dimensional alternating stress condition. This time, the equivalent stress amplitude and equivalent average stress are used to check the fatigue strength of the key points of the wheel. The condition that the fatigue strength meets (5) the unit weight requirements of the thermal insulation materials for inspection is that the fatigue safety factor of each point on the wheel (except singular points) should be greater than or equal to 1, that is, n ≥ 1. The calculation formula is:

extract the principal stress value and average stress value of the key points of the wheel and the corresponding points in the diameter direction, and the principal stress value is used as the calculation data. Through analysis and calculation, the fatigue safety factor is:

where σ a1、 σ a1、 σ A3 is the main stress amplitude; σ m1、 σ m2、 σ M3 average stress in the direction of main stress amplitude; σ- 1 is the fatigue limit of the material under symmetrical cycle

K σ Is the effective stress concentration factor; εσ Is the size factor; β Surface coefficient; φσ Asymmetric cycle coefficient

under the same boundary conditions, the wheel sets without retaining rings are analyzed and compared

4 conclusion

under the same boundary conditions, the stress of the wheel rim, especially the stress of the wheel rim retaining ring, increases after installing the retaining ring, because the stress of the retaining ring groove is concentrated, the mating surface of the rim and the rim becomes shorter, and the stress center of the rim moves outward. Compared with the wheel without retaining ring, the stress value at the retaining ring increased by 2O ~ 30MPa, but the stress value is still within the safe limit

for the check of the wheel whose tyre is worn to the limit state, the static stress value at the retaining ring is 342.71 MPa, which is less than its yield strength. Luo Wen, director of the planning department of the Ministry of industry and information technology, said that the degree is 420MPa; Its fatigue safety factor n is 2.2, which is greater than its allowable safety factor 1. That is, the static strength and fatigue strength meet the requirements

compared with the wheel without retaining ring under the same load in the same limit state, it can be seen that the stress value of the wheel with retaining ring is only 20-30Mpa larger than that of the wheel without retaining ring, and the stress distribution trend of other parts is roughly the same except the contact between the tire and the rim

from the above analysis, it can be concluded that the scheme of installing retaining rings on assembled wheels is feasible. Within the limit state range, it can meet the requirements of static strength and fatigue strength

references

[1] Li Xiaocun. Diesel locomotive overall [m]. Beijing: China Railway Publishing House, 2002.

[2] Zhang Zhong. Train traction calculation. Beijing: China Railway Publishing House, 2002.

[3]procedure for the analytical evaluation of locomotive and freight car wheel deserts standard S-660 ~ 83. Adopted 1981, revised l983.

[4]amla L. Kristma R．Thermo—mechanical finite element analysis of a rail wheel[J]．International Journal of Mechanical Sciences，1()99．(end)