Damage Detection in Structures by Modal Vibration Characterization

Abstract

A nondestructive methodology is presented for detecting structural damage in structural systems. The procedure is based on using experimentally measured modes and frequencies in conjunction with vibratory residual forces and a weighted sensitivity analysis to estimate the extent of mass and/or stiffness variations in a structural system. Determination of the residual forces and weighted sensitivity analysis involves the use of an analytical model that is correlated to the experimental baseline data from a reference state. This reference state defines the undamaged structural configuration. The method is demonstrated by using a ten-bay space truss as an experimental test bed for various damage scenarios. The experimental results show that the method can accurately predict the location and severity of stiffness change as well as any change in mass for different damage scenarios. The use of an analytical model that is correlated to the baseline test data is shown to improve the prediction; however, reasonable results are also obtained using an uncorrelated analytical model.