PSI - Issue 61

Rachid Azzi et al. / Procedia Structural Integrity 61 (2024) 241–251 Rachid Azzi and Farid Asma / Structural Integrity Procedia 00 (2023) 000 – 000

243

3

"L" takes values from one to five mm with a step of 1mm, which is considered as the possible length of damage occurring on a blade edge after an impact with a foreign object.

S17 S12

S8

S5

S2

Fig. 1. Geometric model of the propeller blade with damage positions.

3. Finite element modelling 3D models for both healthy and damaged blades were imported into Ansys Workbench. The propeller material (Huang et al. (2016)) is 2014-T4 aluminum with a density of 2 800 kg/m 3 , Young's modulus E=75 GPa, and Poisson's ratio ν = 0.33. A mesh is applied to the model of the blade using tetrahedral elements with a mesh refinement near the defect. The intact blade model is discretized into 49640 elements and 82561 nodes. All other damaged blade models have about the same number of elements. Fig. 2 shows a finite element model of a propeller blade with damage in two geometric shapes “I” and “V” on the leading edge. A modal analysis is carried out for the healthy and the damaged blades in the cases of static and rotating conditions. This study focuses on the frequencies of the first, second, and fourth modes. The three frequencies cited above, and their corresponding mode shapes were calculated for the healthy blade and the various damaged blade models.

b

a

c

Fig. 2. Finite element model of damaged and undamaged propeller blade. (a) Undamaged blade. (b) Blade with damage in” I “shape. (c) Blade with damage in “V” shape.

3.1. Modal analysis of non-rotating blade In the case of non-rotating conditions, the propeller blade is constrained to the propeller hub at its base as shown in Fig. 3. Firstly, the modal analysis was carried out under Ansys for the healthy blade and various damaged blade models. The three natural frequencies (1 st , 2 nd , and 4 th ) and their corresponding mode shapes were calculated for each healthy and damaged model of the propeller blade. The obtained natural frequencies and mode shapes of the blade