Experimental Diagnosis of Fracture Damage in Structures by the Modal Frequency Method

Abstract

The present paper used the modal frequency method to diagnose the fracture damage experimentally in simple structures, based on the analytical theory of the spring-loaded “fracture-hinge.” It is illustrated that the damage geometry uniquely defines the spring constant of the “fracture hinge,” which is therefore independent of the loading strength, the frequency of vibration, and the damage location. The experiment also measures the change in modal frequencies to locate the damage on the beam. With an accurate analytical model for the experimental samples, the locations of the damages can be predicted to within an accuracy of one percent of the length. The damage intensity is around four percent in accuracy.