Structural Damage Identification Based on Principal Curvatures of Mode Shape

Abstract

This paper presents a procedure for damage identification and characterization on plates, based on the principal curvatures of their first mode shape. Each mode shape represents the displacement of the structure at its corresponding natural frequency. Since, variations in the geometry due to cracks or material property degradation, make changes in the mode shapes of the structure, such changes can be used for damage identification methods. The presented procedure only requires the first mode shape of the intact and damaged structure. It is shown that the principal curvatures of the surface defined by the first mode shape of the structure, are sensitive to damage and the maximum principal curvature can be used to highlight damages on the structure. The performance of the developed method is firstly evaluated using finite element analysis. To this aim, the procedure is applied to highlight both single and multi-damages in different locations of the plate with different boundary conditions. It is shown that the location of the maximum curvature variation coincides well with the location of damages and the amount of the maximum curvature change can be used as a parameter to describe damage severity. The accuracy of the proposed method is also experimentally verified by test on an aluminum plate and it is demonstrated that the proposed method remains effective even in experimental condition when only a limited number of measurements are available.