Improved damage detection method based on Element Modal Strain Damage Index using sparse measurement

An improved damage detection method based on the concept of Element Modal Strain Damage Index is introduced. The proposed methods attempts to address some of the weaknesses of the damage detection method based on modal curvatures. The use of numerical differentiation procedures is identified as the main cause for the poor performance of the modal curvature method under sparse and noisy measurement. An improved damage index that does not rely on numerical differentiation is then formulated. The proposed damage index can be calculated using only modal displacement and modal rotation. A penalty-based minimization approach is then used to find the unknown modal rotation using sparse and noisy modal displacement measurement. Numerical simulation and experiment validation confirm the relative advantage of the proposed method compared with modal curvature-based approaches.