Structural Condition Assessment from White Noise Excitation and Covariance of Covariance Matrix

Abstract

The sensitivity of covariance of covariancematrix with respect to a local stiffness change in the structural system is derived analytically based on the auto/cross-correlation function of the acceleration response, and the original covariance of covariance formula is improved for use with any number of selected structure modes. This paper presents the approach using the improved covariance of covariance matrix of acceleration response for structural condition assessment under white noise support excitation. A simply supported 31 bar plane truss with and without 10% measurement noise is studied numerically. Results show that the sensitivity approach with the covariance of covariance matrix is accurate, and when including the finite impulse response forward and backward filtering technique, themethod would be suitable for industrial application. The covariance of covariancemethod is shown to be insensitive to measurement noise when the measurement time duration is sufficiently long.