Method and apparatus for detecting damage in structures

A method comprising:

• providing time series structural response data from a structure;
• generating a plurality of linear surrogate data series from the time series structural response data;
• estimating a generalized correlation function for each linear surrogate data series of the plurality of linear surrogate data series to generate a confidence interval;
• estimating the generalized correlation function for the time series structural response data, thereby generating an output of the generalized correlation function applied to the structural response data;
• comparing the output of the generalized correlation function applied to the structural response data to the confidence interval;
• indicating a damage-induced nonlinearity in the structure when the output of the generalized correlation function applied to the structural response data is outside of the confidence interval.

An apparatus comprising:

• a first portion operable to receive time series structural response data from a structure;
• a second portion operable to generate a plurality of linear surrogate data series from the time series structural response data;
• a third portion operable to estimate a generalized correlation function for each linear surrogate data series of the plurality of linear surrogate data series to generate a confidence interval;
• a fourth portion operable to estimate the generalized correlation function for the times series structural response data and to generate an output of the generalized correlation function applied to the structural response data;
• a fifth portion operable to compare the output of the generalized correlation function applied to the structural response data to the confidence interval;
• a sixth portion operable to indicate a damage-induced nonlinearity in the structure when the output of the generalized correlation function applied to the structural response data is outside of the confidence interval.