A frequency-change correlation approach to damage detection

It has long been recognised that structural damage produces changes in a structure's natural frequencies. The paper presents a new assurance criterion which uses the frequency changes in a number of modes to identify the location of damage. Frequency changes are small in the early stages of damage and tolerance to measurement error is therefore an important issue. A number of numerical and experimental case studies are used to illustrate their effect and if is shown that the method can tolerate typical frequency estimate error levels and still be able to successfully detect a local stiffness change of 20%. The paper also discusses the influence of the number of modes included in the assessment on the prediction success.