PSI - Issue 72

Mariia Bartolomei et al. / Procedia Structural Integrity 72 (2025) 135–140

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without LSP at a maximum force in the loading cycle of 10 kN. We assume that the number of cycles to failure would also be equivalent. Additionally, a second series of cyclic deformation tests were performed on the specimens after LSP at a maximum force per cycle of 16.5 kN. The results of fatigue experiments on the specimens without LSP with a force of 10 kN and on the specimens with LSP and with a force of 16.5 kN are shown in (Fig 5 d). The obtained experimental result confirmed the result of numerical calculations, by the diagram of cyclic loading we see that the number of cycles for the LSP pattern №2 coincides with the number of cycles for the base specimens.

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Fig. 5. (a) Distribution of stress by width of pattern №1, (b) Distribution of stress by width of pattern №2, (c) Distribution of stress by width of pattern №3, (d) Comparison of the number of cycles before failure with increasing load. 4. Conclusion Thus, for the investigated treatment schemes, the values of possible increase in the maximum external cyclic load within which the compressive field of residual stresses created by LSP remains effective were determined. Through, numerical modeling the value of the maximum force in the loading cycle of the specimens after LSP, at which the stresses in the lateral notch would be equivalent to the stresses in the specimen without LSP at a maximum force in the loading cycle of 10 kN was estimated. Fatigue tests of 3 mm thick specimens made of TC4 titanium alloy with circular lateral notch without and after LSP have been carried out. To verify the numerical result, a second series of fatigue tests was carried out on specimens after LSP with increased external applied cyclic load. The presented results illustrate that numerical simulation can be used for reduction of time and money spent on treatment of structures by decrease or complete elimination of trial tests. The following conclusions can be drawn from the results of the work:  LSP of the stress concentrator area leads to a more significant improvement of fatigue properties of the sample in comparison with the conventional approach when the front and rear surfaces of the sample near the notch are peened.  The proposed LSP pattern increases the fatigue life of specimens with a semi-circular notch by an order of magnitude.