A projection basis adaptation scheme for the update of reduced order models using vibration measurements

A methodology is proposed for updating Reduced-Order Models (ROMs), constructed from a linear, high-fidelity Finite Element (FE) model, based on experimental vibration measurements. The ability of ROMs to represent experimentally measured responses is maximised by updating the Reduced-Order Bases (ROBs) employed in their construction. To render this update efficient, the updated ROBs are formed by adapting initial bases of higher dimensionality via a linear transformation, which is parametrised in a way that preserves desirable qualities of the original bases, such as mass orthogonality. It is also shown that only updating ROBs can limit the range of natural frequencies of the updated models, thus additional parameters, in the form of substructure-stiffness modifiers, are introduced in the updating process. The resulting methodology is demonstrated in two experimentally-tested structures, one where a model with good initial correlation is available, and one where the available model is very poorly correlated, but a large quantity of experimental measurements is available. In both cases, the proposed approach produces models with excellent correlation to the measurements, while in the second one it is also shown to accurately expand mode shapes in sensor locations that are not used for updating. • A methodology is proposed for updating projection-based reduced order models. • Apart from model parameters, such as stiffness modifiers, the reduction basis is also updated. • An adaptation process is introduced to preserve orthogonality during the basis update. • The approach is tested on experimental structures where vibration measurements are available.