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Finite element analysis of locomotive bogie frame strength

the frame is one of the most critical parts of the locomotive bogie, and is also the installation basis of other parts of the bogie. It plays the role of transmitting traction force, braking force, lateral force and vertical force in the traction operation of the locomotive. Therefore, the reliability of the locomotive bogie frame has a significant impact on the performance and safety of the locomotive. The traditional reliability evaluation of bogie frame strength is mostly through some tests of physical prototype, and then through metal flaw detection, magnetoelectric flaw detection and other methods... The cost is high and the development cycle is long. Therefore, it is of great significance to use the finite element theory to model the bogie frame, and use the finite element analysis software to carry out stress analysis and strength calculation to ensure the reliability of the locomotive bogie frame. This paper makes an attempt here

before gb1040 (2) 006 in this part is used in dumbbell (type I-V), rod and tubular sample types, finite element analysis software developed by several famous foreign companies, such as MSC, ANSYS, i-deals, has been widely used in many domestic designs. The finite element software provided by MSC company has unique processing methods in finite element modeling, structural analysis (static and transient dynamics), heat, electromagnetic field, fluid problems and their coupling problems, contact, strong nonlinearity, collision, etc. This paper introduces in detail the application of the pre and post-processing software MSC/Patran and the structural analysis software MSC/NASTRAN in the strength calculation and analysis of locomotive bogie frame

1 establishment of finite element strength calculation model

locomotive bogie frame is generally a box girder structure. The finite element calculation model can adopt thin plate element to model according to the actual size on the design drawing, and determine the density of the lattice according to whether each part of the frame bears load, and generate the finite element calculation lattice model in MSC/Patran software. In this paper, a locomotive bogie frame which has passed the physical prototype test and passed the strength test is selected for analysis. It is a "sun" shaped structure welded by two side beams, a cross beam and two end beams. The whole frame calculation model has 20225 thin plate elements and 27848 nodes, as shown in Figure 1

2 loads and boundary conditions for finite element strength calculation

in the finite element calculation and analysis of locomotive bogie frame, the principle of imposing constraints and loads is to apply loads at the active force application position of the frame and constraints at the passive force application position:

when the locomotive is running, the loads acting on the frame can be divided into static loads and dynamic loads. The static load has a fixed value and direction during operation, including the weight of the upper part of the locomotive, the weight of the bogie and various devices installed on the bogie, the weight of the traction motor of the electric drive diesel locomotive and electric locomotive, the weight of the intermediate gearbox of the hydraulic drive diesel locomotive, etc; Dynamic load refers to the load whose direction and size change with time during operation, including the additional vertical dynamic load caused by vehicle body vibration, the longitudinal force acting on the frame when the locomotive is pulling, the lateral force acting on the frame when the locomotive passes the curve, the vibration load used by the traction motor for the frame, the counter torque or resistance braking counter torque during operation, the counter torque and braking force when the gearbox is working The twisting force of the framework caused by the line and other reasons. The size and direction of locomotive bogie load shall be determined according to specific design requirements and actual conditions. The calculated load value of the research object in this paper is shown in Table 1

3 selection of calculation conditions

according to TB/T 2368-1993 "test method for static strength of internal combustion and electric locomotive bogie frame", the calculation conditions of locomotive bogie frame are composed of different types of load conditions. Generally, it can be divided into two categories: combined load cases and independent load cases. The combined load case mainly simulates various limit load cases to investigate whether the frame has enough static strength to meet these limit cases; Independent load cases are used to assess the fatigue strength of the frame

3.1 combined load condition

1) condition 1, vertical static load condition. Including vertical static load of vehicle body and vertical static load of gear box

2) condition 2, starting condition. Including vertical static load of vehicle body and gearbox, longitudinal starting traction force and starting traction counter torque

3) condition 3, emergency braking condition. Including car body and teeth, and analyze the elasticity and friction one by one; Finally, the vertical static load of the wheel box, the longitudinal emergency braking force and the emergency braking force of the mounting seat are analyzed

4) condition 4, curve passing condition. Including vertical static and dynamic loads of vehicle body and gearbox, and longitudinal continuous traction. Continuous traction counter torque, lateral load

3.2 independent load cutting condition

1) condition 1, vertical static load of vehicle body

2) working condition 2: vertical static load of gearbox

3) working condition 3. Lateral load

4) working condition 4, vertical dynamic load of vehicle body

5) working condition 5: vertical dynamic load of gearbox

6) condition 6, longitudinal continuous traction

7) working condition 7, continuous traction counter torque "explained Christopher Wilson, senior vice president of ultra-high polymers of Solvay polymer global business line

8) working condition 8, longitudinal service braking force

9) working condition 9, service braking force of mounting base

the purpose of calculating the independent load condition is to check the fatigue strength of the frame. The specific check method is: calculate the average stress with half of condition 3 and the sum of conditions 1 and 2, then calculate the stress amplitude of traction condition with half of condition 3 and the root mean square of conditions 4, 5, 6 and 7 respectively, and calculate the stress amplitude of braking condition with half of condition 3 and the root mean square of conditions 4, 5, 8 and 9

after obtaining the above average stress and stress amplitude, according to the recommendation of 95j01-l "code for strength and dynamic performance of power car of high speed test train", in the case that China currently does not have its own fatigue limit diagram, refer to the Goodman fatigue limit diagram in 0re B12 report to check the strength of the structure

4 analysis of calculation results

4.1 analysis of calculation results of combined load cases

see Table 2 for the maximum von Mises stress and its location in the four combined load cases in the calculation example. Among them, the curve passing condition is the worst, and the maximum von Mises stress is 109.0mpa. Through the absorption and introduction of advanced technology and concepts of German passive houses through the cooperative project, the stress distribution is shown in Figure 2

Table 3 lists the maximum value of deformation and its area under four working conditions, among which the deformation under emergency braking condition is the largest, which is 0.526 mm. Figure 3 shows the deformation cloud diagram of this working condition

combined load case is to simulate various limit load cases. Inspect whether the frame has enough static strength to meet the requirements. The material of the frame in this paper is 16 MNR. Yield limit of 16 MNR σ a=225 MPa。 Strength limit σ B=420 MPa, safety factor of 1.65, allowable stress[ σ]= 136．364MPa。 In the above strength calculation results, the maximum von Mises stress under the worst working conditions is less than the allowable stress; The maximum deformation also meets the design requirements, and the frame structure meets the static strength requirements

4.2 verification of the fatigue strength of the frame

Table 4 lists the area and size of the peak value of the average stress and the stress value range of the two stress amplitudes in this area. Table 5 and table 6 respectively list the area and size of the peak value of the two stress amplitudes under traction and braking conditions and the stress value of the average stress in these areas. In addition, table 4, table 5 and table 6 also give the stress amplitude limit values corresponding to each average stress obtained from Goodman fatigue limit diagram

it can be seen from table 4, table 5 and table 6 that the stress amplitude values of the locomotive bogie frame in this paper are lower than the stress amplitude limit corresponding to the average stress value of these areas at the occurrence of each stress peak value, so the simulation results can also be obtained that the frame meets the fatigue strength requirements

5 conclusion

combined with examples, this paper introduces in detail the method of calculating and analyzing the strength of locomotive bogie frame with finite element analysis software msc/patran and msg/nastran. For the frame in this paper, the conclusion that it meets the requirements of static strength and fatigue strength can be obtained according to the calculation results. This paper further discusses the method of evaluating the strength reliability of locomotive bogie frame with finite element theory and corresponding software, so that the method of computer simulation can be further popularized in improving the safety and reliability of bogie frame application. Greatly reduce production costs. (end)

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