Application of Chaotic Excitation and Statistical Analysis in Crack Assessment of Plates

Presence of part through cracks with limited length is one of the prevalent defects in plate structures. Due to slight effect of this type of damages on frequency response ofplates, conventional vibration based methods for damage assessment could be challengeablc. In this study for the first time a recently developed time series method whichis based on chaotic excitation is implemented and standard deviation, skewness and kurtosis are proposed as statistical features to analyze the time series response ofcentrally cracked plate. For this purpose using line spring method (LSM) a nonlinear multi degree of freedom model of part through cracked rectangular plate is developed.Tuning of Lorenz type chaotic signal is conducted by crossing of Lyapttnov exponents’ spectrums of nonlinear model of the plate and chaotic signal and in the next stepby varying the tuning parameter to find a span in which tangible sensitivity in statistical parameters can be observable. Damage characteristics such as length and angle of crack are altered and variation of proposed features are scrutinized. Results show that by implementation of tuned chaotic signal, tangible sensitivity and also near to monotonic behavior of statistical parameters versus damage intensity are achievable.

Keywords:

crack. plate , chaotic , SHM