Structural damage detection and localization using changes in phase angle

A technique to detect and locate damage by measuring the vibration response of a structure is presented. The technique uses measured phase angle between two measuring channels from the healthy structure as reference data, and then monitors vibration measurements during the life of the structure to detect and locate the damage. The technique requires that the excitation forces used for the undamaged and damaged structure must have the same amplitude, location and waveform. The excitation force does not need to be measured and no structural model is needed. The proposed method is based on only the measured data without the need for any modal identification. The method is described theoretically and applied to the experimental data, from a steel bridge model and bookshelf structure. Several damage scenarios were introduced to the members of the test structures. The damage was detected and located accurately using the proposed method