Damage detection in plates structures based on frequency shift surface curvature

This paper presents a novel damage detection method for plate structures based on the curvature of frequency shift surface (FSS). Unlike other commonly used vibration properties like mode shapes which have low accuracy in practice; this method uses the FSS curvature to improve the accuracy because the measurement of frequency gives better accuracy. Furthermore, it is found that the local damage will only cause local change on the FSS curvature which can be considered as abnormality because the FSS curvature of an intact plate is smooth according to the assumption that intact plate structures are often homogenous and smooth. To avoid the usage of prior knowledge of the health structure, the curve fitting technique based on local regression is adopted to simulate the FSS curvature for the intact state so that only the data from the damaged plate structure is required. Compared with traditional methods, this method is more sensitive and accurate.