PSI - Issue 59

M.G. Shulzhenko et al. / Procedia Structural Integrity 59 (2024) 337–343 M.G. Shulzhenko et al. / Structural Integrity Procedia 00 (2023) 000 – 000

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thirteenth blade, 135% in the eighteenth blade, 148% in the nineteenth blade, 138% in the twentieth blade, and 225% in the twenty-third blade. A significant decrease in the maximum equivalent stresses, when considering kinematic excitation, is observed in the blades located to the right of the damaged one: the twenty-first blade shows a 28% decrease, the twenty-second blade shows a 33% decrease, the twenty-fourth blade shows a 27% decrease, and the twenty-sixth blade shows a 39% decrease. Similarly, to the left of the damaged blade, stress reduction is observed in the twenty-fourth blade (65% decrease), twenty-fifth blade (52% decrease), twenty-seventh blade (33% decrease), twenty-sixth blade (41% decrease), and thirty-eighth blade (37% decrease). It is important to note that the decrease in maximum equivalent stresses when considering kinematic excitation is observed in blades where the stresses without kinematic excitation are already significantly lower than the stresses in other blades of the system. Therefore, the reduction in maximum equivalent stresses in the lower third of the blades, when considering kinematic excitation, may not be considered significant compared to the significant stresses that exist in individual blades even without kinematic excitation. This applies to the first, second, thirty-first to forty-fifth blades to the right of the damaged one, as well as the second to twentieth blades to the left of the damaged one (including the damaged blade itself). Significant stresses are observed in these blades both without considering kinematic excitation and when it is taken into account. In both cases, the highest values of equivalent stresses occur in the thirty-ninth blade. The peculiarities of the distribution of maximum stresses in the blades of the disk-blade system have been established above. The distribution of displacements in the direction of the axis of the bladed disk rotation provides a clearer picture of the obtained results. In Fig. 4, the distribution of the axial displacements of the system is illustrated. The dark blue circular lines represent the maximum displacements in the axial direction from the observer, and the red ones in the opposite direction. Light colors in Fig. 4 correspond to the smallest values (almost zero). In view of the presented results, four sectors of the disk-blade system opposite the rotation of the rotor from the damaged blade can be conventionally distinguished based on the distribution of movements. In the first sector, mostly maximum displacements are observed (dark green color). In the second sector, they decrease, and in the third they acquire minimum values. In the fourth sector, displacements are increasing again. The lightest parts, located at two-thirds of the distance from the disk, correspond to the minimum values of displacements, which are also observed in the first sector near the attachment of the blades on the disk.

Fig. 4. Displacements distribution of the blades in the interval 2000 … 2200 Hz: damaged blade – 0.