PSI - Issue 58

J.R. Steengaard et al. / Procedia Structural Integrity 58 (2024) 61–67

67

J.R. Steengaard et al. / Structural Integrity Procedia 00 (2024) 000–000

7

5. Discussion

The relative fatigue lives of the back and bottom weld are close to each other. This indicates that the welds are well designed in relation to each other, as they are approximately equally exposed. The fatigue life of a cutterbar in operation will be higher than found in this study since the experimental loading is unrealistically high. Furthermore, the model is only validated and analyzed for load in one direction. For loads in other directions, the fatigue life and the most exposed location may be di ff erent. However, the experimental load direction is close to the upwards pressure from the ground, which is expected to be the most significant load. Thus, the results are still deemed fairly valid. The results can be used to redesign the cutterbar beam to improve the fatigue life. The updated FE model has a low error compared to the experiment, which makes it capable of being used in analyses with high accuracy. The model can also be used for other analyses. For example, a more realistic loading can be applied to the model, which will give more realistic results, while retaining accuracy. A quasi-static experiment has been performed, where a cutterbar was loaded with a transverse force. Strains and deflections were measured in the experiment, and a finite element model of the test setup has been developed. The model was validated by comparing strain values from the experiment and the model. The validation showed a 7.5 % mean absolute error between the experiment and the model. Parameter based finite element model updating was then used to improve the accuracy of the model. The updated model showed a 4.7 % mean absolute error. Three welds were analyzed for fatigue: a weld at the back, bottom, and front. The hot spot approach and the fatigue criterion by the International Institute of Welding were used together with the updated model to evaluate the relative fatigue lives of these welds. The back weld was shown to be most exposed, then the bottom weld, and the front weld least exposed. The relative fatigue lives were found to be 1.0, 1.3, and 5.3 for the back, bottom, and front weld, respectively. These results are based on the experimental loading. However, the updated model has a low error and can be used for future analyses to obtain more realistic results. 6. Conclusions

Acknowledgements

The authors are grateful for the opportunity to analyze the data from the experiment performed at Kverneland Group Kerteminde A / S. The help, setting up and performing the experiment, by Hans-Henrik Olsen and Kasper Wolfhagen from Kverneland Group Kerteminde A / S, is gratefully acknowledged.

References

Arora, V., 2011. Comparative study of finite element model updating methods. Journal of Vibration and Control 17, 2023–2039. Gough, H.J., Pollard, H.V., 1935. The strength of metals under combined alternating stresses, in: Proceedings of the Institution of Mechanical Engineers, pp. 1–101. Hobbacher, A.F., 2016. Recommendations for Fatigue Design of Welded Joints and Components. Springer International Publishing. Koyuncu, A., Go¨kler, M.˙I., Balkan, T., 2012. Development of a design verification methodology including strength and fatigue life prediction for agricultural tractors. The International Journal of Advanced Manufacturing Technology 60, 777–785. Maddox, S.J., 1991. Fatigue Strength of Welded Structures. Abington Pub, Cambridge, England. Paraforos, D.S., Griepentrog, H.W., Vougioukas, S.G., Kortenbruck, D., 2014. Fatigue life assessment of a four-rotor swather based on rainflow cycle counting. Biosystems Engineering 127, 1–10. Tarasiuk, P., Molski, K., Szymaniuk, A., 2013. Fatigue designing of welded agricultural wheels. Eksploatacja i Niezawodnosc 15, 123–128.