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ESTEQ has created a smooth running procedure to assist clients with the complicated Thermo-Mechanical analysis requirement of the UIC510-5.

In short, the procedure based on the UIC510-5 requirements is as follows:

**1) Thermal**

**Analysis step 1:** Heat input: The UIC specifies that the magnitude of the maximum braking energy that has to dissipate is 50 kW for 45 min at running speed of 60 km/h based on a wheel diameter in range of 1000 to 840 mm. Rig ventilation must be provided at speed of va/2 (e.g. 0.5 x 60km/h = 30km/h) at a distance of 700mm from the axle. A computational fluid dynamic (CFD) analysis is conducted of the rotating wheel with the heat input on the running surface and the simultaneous cooling air flow over the wheel at half the speed. The output from this analysis is mapped onto the prestressed FEA model to find the cumulative displacement and stresses in the wheel and axle. ESTEQ prefer using FloEFD for its ability to simulate the air flow around the complex bodies while adding the thermal load simultaneously. There is also no need for the user to build the required mesh since this is done automatically. FloEFD futhermore has the ability to map the temperatures and pressures onto the finite element mesh using either the EFD2Patran utility in Patran or the EFD2Nastran utility in FloEFD.

**Analysis step 2:** Cool down: The wheel should cool down until the thread temperature as dropped below 50^{o}C. In the CFD analysis the wheel is allowed to cool down and the resulting temperatures of the complete wheel then mapped again onto the FEA model to optain the cumulative displacement and stresses in the wheel and axle. The same procedure as in step 2 is used to map the results tot the FEA model.

**2) Mechanical**

**Analysis step 3: **Shrink fit: The wheelset should be shrunk onto the axle with the appropriate interference fit as proposed by manufactures or as specified by the client (depending on the manufacturing process followed). The UIC 510-5 make use of a 0.325*mm* mean compression over the diameter. A finite element analysis (FEA) is conducted to calculate the induced stresses due to the shrink fit. ESTEQ prefer using MSC Marc for its supperior ability to simulate the press fit with contact between the wheel and axle and the ability to add the temperature distributions calculated in the CFD analysis ontop of it to obtain a true thermal-structral analysis result.

**3) Thermo-Mechanical**

**Analysis step 4:** The temperatures as calcuated in steps 1 and 2 are mapped onto the FEM as thermal loads and the resulting stresses in the wheel as a hole are then determined. These stresses are then combined with those from the pressfit analyis (step 3) to obtain the combined effect.

**4) Mechanical**

**Analysis step 5:** The UIC-510-5 specifies that three point loads as indicated below should be applied to the wheel’s running surface. The resulting stresses are again calculated using FEA and again combined with the stresses due to the initial pressfit step.

*Load case 1:* Vertical loadcase, tangent track. In addition to the shrinkfit, the specified vertical load is applied in the FEA model.

*Load case 2:* Vertical and lateral loadcase. In addition to the shrinkfit, the specified vertical and lateral loads are applied in the FEA model.

*Load case 3:* Vertical and lateral loadcase, points and crossings. In addition to the shrinkfit, the specified vertical and lateral loads are applied in the FEA model.

**Analysis step 6:** Haigh diagram: The post processing of the FE data has to be done to provide information for a uni-axial fatigue analysis based on a Haigh Diagram.

If you require a Thermo-Mechanical analysis, please contact us because we enjoy solving difficult problems!

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