New time domain approach to detecting tiny damage of structure based on empirical mode decomposition

A time domain approach to detecting tiny damage of structure is proposed. When using the conventional structural damage detection method, especially the frequency domain method, the often used characteristic parameters such as modal frequencies, mode shapes and modal damping ratios, are not sensitive to tiny damage occurring in the structure; and this type of approach is invalid unless the damage accumulates to considerable extent. In contrast to that, in the present work, by considering the features of the empirical mode decomposition (EMD) method which can decompose the response signal of a structure into a series of so called intrinsic mode functions (IMFs), some of these IMFs are much more sensitive to tiny change of the signal than the original signal; thus a structural tiny damage detecting approach is configured. In this approach, the IMFs of the structural response signal are quantified by their shape factors, and the simulation example indicates that the shape factors of IMFs change conspicuously with the introduction of tiny damage to the structure; so the proposed method is valid for detecting tiny damage of engineering structure.