This paper presents a novel structural damage detection indicator, i.e., fourth-order voltage statistical moment (FVSM) based on the electromechanical impedance (EMI) principle, and then proposes a two-step damage detection method based on the novel indicator and a differential evolution algorithm (DEA). In this study, several lead zirconate titanate (PZT) sensors bonded to an experimental steel beam were utilized to acquire the time-domain voltage responses. On this basis, the fourth-order voltage statistical moments (FVSMs) of the voltage responses are computed to locate the damage element in the detected structure, and the proposed damage detection method is utilized to quantify the damage. In addition, theoretical PZT voltage responses are also calculated based on the piezoelectric theory and the spectral element method (SEM). Experimental results verify the accuracy of the theoretical voltage values and the effectiveness of the proposed damage indicator. Results indicate that the FVSM is effective in locating the damage element. Integrated with DEA, the proposed technique is capable of quantifying damage.

The Laplace transform-based spectral element method (LTSEM) can avoid some limitations of the conventional Fourier transform-based spectral element method (FTSEM) in handling finite-length structures, such as the wrap effect. In this paper, a damage identification technique based on the LTSEM and strain statistical moment (SSM) is proposed, which is combined with a general genetic algorithm. The dynamic responses of beam structures were first analyzed using the LTSEM and were validated by finite-element analysis results. Then, the strain statistical moment was used as the damage indicator; the damage location and severity for beam structures were numerically identified on the basis of the proposed technique. Finally, an experimental investigation for damage detection on a simply supported steel beam was also implemented. The experimental results verified that the proposed damage identification technique is feasible and has robust antinoise performance.