Introduction

Industry 4.0 is continuously bringing numerous innovations to the manufacturing context. These innovations encompass all areas of engineering and have various branches of study and application possibilities. One of these innovations is digital simulations and, according to SENAI, the term can be defined as "In a clear and direct way, it can be described as the virtual reproduction of processes and environments for factory development and manufacturing." [1]. [1]. 

Railway assets are subjected to many stresses, whether they come from the high loads transported, high vibration rates in these systems, long distances traveled by the trains or the sum of these factors. It is therefore possible to conclude that analysis of these systems is very useful and can yield valuable results. Check out this article about the instrumentation, data collection, analysis and digital simulation work carried out by the Kot Engenharia team on a railway shock and traction system!

In order to evaluate and study the structural conditions of the coupling in different positions of the wagon in the train and different tappet configurations, a company asked Kot to analyze the stresses acting on the components, the accelerations acting on the wagon, the position of the wagon in the travel cycle based on its geographical coordinates and the speeds of the wagon along the route.

Instrumentation

Instrumentation was carried out on the wagon, including strain gaugesaccelerometer and pressure transducers. Data acquisition was carried out continuously during travel cycles. The project included some couplings, rigid rods and central beams of a wagon. Figure 1 illustrates the proposed instrumentation diagram.

Figure 1: Instrumentation diagram. [2]

The rod was calibrated in the laboratory in order to obtain the relationship between the applied load and the deformations obtained in the strain gauges installed on the rod. To carry out the test, a structure was built to fix the rod and hydraulic jacks, which were responsible for applying a known load, as can be seen in Figure 2. Figure 3 shows some of the installation points for the strain gauges on the side of the rod.

Figure 2: Stem calibration. [2]

Figure 3: Strain gauge installation points on the side of the rod. [2]

Evaluating the operating cycle

The operational cycle was evaluated using the absolute values of the acting loads, the value of the accelerations at which the highest load amplitudes occurred and the use of the rainflow method . This was used to count the peak loads to assess the impacts between wagons. Figures 4, 5 and 6 show some of the results obtained, respectively.

Figure 4: Dispersion of acting loads. [2]

Figure 5: Example of peak amplitude in data collection.

Figure 6: Example of peaks and attenuation. [2]

Fatigue analysis

Fatigue analysis was carried out using the damage accumulation rule with peak counting using the rainflow methodology. Each stress peak causes a specific damage through the material's fatigue curve and when the sum of this damage is equal to 1, the component fails. The travel cycles were evaluated individually and the useful life was converted to years.

Tape influence assessment

In short, the different tape configurations are related to the different wheel sizes of the wagons, i.e. the wagon studied may have a larger or smaller wheel size than the wagon to which it is connected and this will cause the coupling assembly to tilt. These differences in tape can influence the distribution of loads as a function of inclination. The results of the evaluation are shown in Figure 7.

Figure 7: Fatigue life according to wagon tape. [2]

Digital Simulation

A digital simulation of the drive train was also carried out. The components were analyzed separately, validated and calibrated according to the data obtained in the field. Figure 8 shows the deformation results for the coupling model.

Figure 8: Results obtained from the coupling model. [2]

It can be seen that the head of the coupling, close to the pin region, is a region susceptible to crack nucleation and propagation, a conclusion reached through the simulation and checks carried out by the finite element model.

Recommendations

With the conclusion of the analysis, Kot recommended reinforcing and changing the material of the coupling used. The new material has better fatigue life characteristics, with a minimum increase of more than 200% compared to the previous one. 

Conclusion

In line with the pillars and foundations of Industry 4.0, digital simulations are essential analyses for compressing effects that are not visible to the naked eye. With them, it is possible to study behaviours, assess points for improvement and indicate changes for optimization. In addition, theoretical-experimental analyses make it possible to support digital simulations, further increasing the assertiveness of the work.

Kot can be your partner in matters related to Industry 4.0, helping you to understand real and complex engineering possibilities and contexts. Contact our team for more information!

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References:

[1] All about digital simulation, one of the main pillars of industry 4.0, SENAI [S.I]. Available at: https://www.senairs.org.br/industria-inteligente/tudo-sobre-simulacao-digital-um-dos-principais-pilares-da-industria-40

[2] Kot Engenharia Collection.