Damage quantification using modal parameters

Natural frequencies and mode shapes of a structure change whenever a structure has any kind of damage. However, detection of location and magnitude of damage has always been difficult. This paper presents a technique to locate and quantify the damage when the natural frequencies and mode shapes of undamaged and damaged structure are known. First, the structure is modeled using finite element formulation. Each element is assigned a damage index that is initially zero for undamaged condition. Modal analyses of undamaged and damaged structures are performed. The damage indices are computed using non-negative least squares method. Results based on aluminum beams are presented to establish the effectiveness of this method.