PSI - Issue 48

Gašper Fašun et al. / Procedia Structural Integrity 48 (2023) 19–26 Fašun et al/ Structural Integrity Procedia 00 (2023) 000–000

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safe domain that identifies the combinations of maximum pressure and maximum allowed crack or defect size that ensure high fatigue cycle life. 4. Fatigue life as a function of the initial crack length or defect size If the combination of maximum applied pressure on the barrel and the crack or defect size falls in the unsafe zone of the graph, the crack or defect could grow to lead to barrel failure. In this case, a fatigue life can be estimated by integrating Eq. (1) between a i and a crit for a given maximum pressure, which gives the number of cycles necessary to propagate an initial crack length until the failure of the cannon barrel. Figs.5 (a) and (b) show, for material A and B respectively, the relationship between the initial crack length and the fatigue life to fracture for four different maximum pressures.

(b)

Fig. 5. Number of cycles to failure depending on the initial crack length for materials A (a) and B (b) for different maximum pressures.

Although the differences found between both materials are not very important, the analysis shows that the barrel made with material B could operate at a somehow higher pressure or that it could shoot a greater number of projectiles at the same pressure. 5. Concluding remarks This work investigates the integrity and fatigue life of a barrel made with an alloy using two different heat treatments. A fracture mechanics approach is applied to analyse the fatigue resistance curve, crack growth, and propagation properties. The study provides a safe domain of use for the barrel, estimates the fatigue life for unsafe conditions, and identifies areas of improvement for increasing the material's fatigue resistance. The choice of material with a higher threshold value for crack propagation can greatly affect the lifetime of the barrel, allowing for higher pressure and longer projectile range without reducing lifetime. Accurately measuring crucial parameters is essential for improved accuracy in predictions.

Acknowledgements

Authors acknowledge the Slovenian Research Agency ARRS for the research program P2-0137 Numerical and Experimental analysis of Nonlinear Mechanical Systems. References [1] M.R.A, “Prediction of cannon barrel life,” Journal of Achievements in Materials and Manufacturing Engineering, vol. 30, Sep. 2008.