PSI - Issue 80

Guangxiao Zou et al. / Procedia Structural Integrity 80 (2026) 93–104

103

Author name / Structural Integrity Procedia 00 (2023) 000–000

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Fig. 4. MVDR imaging of the damage at position (a)(235, 200) (b)(200,200).

Fig. 5. MUSIC imaging of the damage at position (a)(235, 200) (b)(200,200).

4. Conclusions

This paper has provided a detailed introduction to the principles of DAS, MVDR, and MUSIC imaging, along with a comparative analysis of their performances. The DAS method, while computationally simple, o ff ers no inherent mechanism for suppressing artifacts and noise. The MVDR method provides a significant improvement by employing a constrained minimization of variance, which selectively suppresses noise while preserving the signal of interest. The MUSIC method is based on the orthogonality between the signal and noise subspaces; it forms an image by identifying locations where the steering vector is orthogonal to the noise subspace. However, this core assumption can be fragile and di ffi cult to satisfy in practice, leading to performance degradation. For future work, two key directions are proposed. First, other state-of-the-art Direction-of-Arrival (DOA) estima tion methods, such as ESPRIT, could be adapted for Lamb wave damage imaging, potentially yielding more robust results. Second, the accuracy of all these methods could be enhanced by developing more sophisticated models for the scattering coe ffi cients and steering vectors, moving beyond simple theoretical assumptions to methods that can account for the complex scattering behavior of real-world damage.