Damage Localisation Using a Displacement–Strain Expansion Process

ABSTRACT Identification of damage using dynamic measurements has been a continued area of research. Defects or damaged regions within a structure can result in an apparent change to the dynamic response of the system. Typical damage detection methods use changes in displacement responses as an indication of damage. However, displacement is relatively insensitive to minor structural variations. Strain‐based damage detection methods are more sensitive to minor structural variations but regularly suffer from poor resolution, which hinders their detection capabilities. To improve on the damage detection process, a strain‐based technique has been developed that uses full‐field data obtained via displacement–strain expansion from a sparse set of measurement points. This expansion method incorporates both strain‐based mode shapes and displacement‐based mode shapes obtained from either a finite element model (FEM) or experimental modal data. In this work, two laboratory structures with a localised structural modification are excited to obtain sparse displacement and strain response measurements. Sparse test measurements are then used to obtain the full‐field strain response, which is compared with the simulated strain response of an undamaged structure subjected to an equivalent excitation. Differences between the damaged and undamaged strain responses are then analysed in the time domain to identify and locate damage within the structures.