A model-based observer for state and stress estimation in structural and mechanical systems: Experimental validation

• Estimation of stress and strain time histories based on acceleration measurements.
• The proposed observer can be implemented using high-fidelity finite element models.
• Reduced computational cost with respect to Kalman filter, without loss of accuracy.
• Experimental validation of state observers in structural dynamics.
• Robustness against measurement noise and model errors.

In this paper we present the results from a validation study of a recently proposed model-based state observer for structural and mechanical systems. The observer uses a finite element model of the structure and noise contaminated measurements to estimate the state and stress time histories at arbitrary locations in the structure of interest. The initial conditions and unknown excitations are described by random vectors and random processes with known covariance and power spectral density. A laboratory model consisting of an aluminum cantilever beam was used to perform the experiment. Two types of loading conditions were tested: an impact hammer test and a band limited excitation delivered through a shaker. The results obtained with the proposed observer are compared to the measured stress at the locations of interest, and to estimates obtained using well-established estimation methods such as Luenberger observers and the Kalman filter. The main finding is that for all experiments conducted the proposed model-based observer yielded estimates with higher or comparable accuracy to all other methods considered, with the advantage of requiring significantly less computational effort and with a more direct and transparent implementation.