COMPENSATION OF TEMPERATURE EFFECTS FOR FREQUENCY ESTIMATION OF SLENDER STRUCTURES

Abstract

The paper presents a simple method to identify and eliminate the effects of slow temperature changes on the natural frequencies of slender beams. This temperature compensation is important if frequency evaluation is made for the purpose of damage detection, because these changes may overcome the changes due to the occurrence of the damage. The method is based on a mathematical relation found by the authors, which permits estimating the frequency at a temperature if it is measured at a different temperature. A compensation coefficient derived in a mode by mode manner is applied to the measured frequencies at a given temperature. So, the frequencies are found for the reference temperature at which the natural frequencies of the undamaged structure are known. The dissimilarity test is made by an original metric; in the case of exceeding a threshold previously set the occurrence of damage is signalized.