PSI - Issue 75

Robert Goraj et al. / Procedia Structural Integrity 75 (2025) 691–708 Goraj / StructuralIntegrity Procedia (2025)

702 12

6.4. Transient solution The time dependent SA stress ( , ) according to (22) is plotted in Fig. 10.

Fig. 10. Transient course of the longitudinal stress present in the bearing spoke for = The period 2 T needed in (1) is set for the visualization purpose to a relatively small value of 1 second. However, T is still high enough for nearly reaching - after approx. 0.3 ms- the steady state vibration (indicated with an ellipse in Fig. 10). The maximal and the minimum stress equals to: max[ ( , )] = 201 MPa, min[ ( , )] = -89 MPa accordingly. The stress course is compared with the FEM output obtained using the solver SOL109. Fig. 11 shows a comparison of the longitudinal stress after the propeller switch on.

Fig. 11. Comparison of longitudinal stress in transient For better visualization purpose the time scale is restricted to 100 µs in the upper part of Fig. 11. The difference between the results is indicated with Δ in the lower part of Fig. 11. The maximal and the minimum stress obtained with FEM equals to: max[ ( , )] = 199 MPa, min[ ( , )] = -90MPa accordingly. However, due to a certain shift in time, the absolute difference stays in the range of± 16 MPa. The entire comparison of obtained verification results is shown in Table 3.

Table 3. Comparison of structural results parameter

denotation 1 |

SAM

FEM 1.46

unit mm

solver

1.46 ( 1 − 2 )| 0.38 0.38 mm SOL101 22.6 22.6 N/mm SOL101 SOL101

displacement of rotating components

1

cap deflection cap stiffness