Model updating by adding known masses (Q2720011)

The authors introduce new model-updating schemes that adjust the system mass and stiffness matrices from an incomplete set of measured modes. The underlying principle is to add known masses to the physical structure, to measure the modes of vibration of the new system, and then to use this new set of measurements in conjunction with the original set of experimental data to correct the mass and stiffness matrices of the actual structure. The authors describe solution techniques for updating and for undetermined least squares problems. The effects of round-off errors are studied, and heuristic criteria are given for determining the minimum number of modes to be measured in order to ensure sufficiently accurate updated mass and stiffness matrices. Numerical experiments validate the proposed techniques and illustrate how the number of measured modes influences the quality of the updated model.