PSI - Issue 45

Xianwen Hu et al. / Procedia Structural Integrity 45 (2023) 20–27 Hu, X., Liang, P., Ng, C.T., and Kotousov, A. / Structural Integrity Procedia 00 (2019) 000 – 000

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Figure 8 shows the β’ value at different fatigue levels. The data were normalised with the β’ of intact condition. It can be observed that the value of β’ increased around 7% and 3% in the material fatigue levels of 0 to 40% and 40 to 80%, respectively. This phenomenon can be attributed to the fast growth of the dislocation of the material substructures at the early fatigue formation stage.

Table 3 Different Fatigue Levels’ Third -Order Elastic Constants of Aluminium (Stobbe 2005)

Fatigue Levels

0%

40%

80%

l (GPa) m (GPa)

-252.2

-266.8 -332.8 -358.3

-271.2 -335.8 -359.8

-325

n (GPa)

-351.2

Fig. 8. β’ at different Fatigue Levels

6. Conclusion This study has investigated the nonlinear behaviour of ES 0 in an aluminium plate through both numerical and experimental approaches. The numerical simulation results are highly matched with the experimentally collected data. This indicates that the nonlinear response of ES 0 in metallic structure can be effectively simulated by ABAQUS/Explicit with subroutine VUMAT which implements Murnaghan’s strain energy equation. The experimentally validated nonlinear FEM has been utilised to conduct a parametric study to investigate the effects of varying fatigue levels (third-order elastic constants) on the nonlinear edge wave features. It is noticed that β’ grows with the development of material fatigue levels (third-order elastic constants). This phenomenon demonstrates the potential of nonlinear ES 0 in detecting and monitoring micro-scale defects, particularly fatigue, in metallic structures. Further studies are required to conduct more experimental tests to further investigate the feasibility of using nonlinear ES 0 to quantify various structural defects. Acknowledgements This work was funded by the Australian Research Council (ARC) DP200102300 and DP210103307 grants. The experimental and numerical studies were carried out during the research project of Mr. Peifeng Liang in his master’s degree. The authors would like to gratefully acknowledge Ka Kin Lam, Thao Ly Nguyen, and Ting Yi Yang for their contribution to this study. References Hughes, J.M., Kotousov, A., and Ng, C.T., 2022. Wave Mixing with the Fundamental Mode of Edge Waves for Evaluation of Material Nonlinearities. Journal of Sound and Vibration 527, 1-11. Hughes, J.M., Kotousov A., and Ng, C.T., 2020. Generation of higher harmonics with the fundamental edge wave mode. Applied Physics Letters