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Non-destructive inspection of carbon-fibre-reinforced polymers using lock-in thermography

Development in composite materials technology has led to wide applications of such promising materials. The detection and characterisation of the wide range of defects requires a number of specialised non-destructive methods. In this article, lock-in thermography was used to identify defects in carbon-fibre-reinforced polymer specimens. The effects of modulation frequency and incident angle were discussed. The amplitude and the phase images were compared. A multi-objective evolutionary algorithm was used to optimise the experimental frequency, time and other parameters of infrared NDT. The temperature difference between the non-destructive and the defect regions was used as evaluation function. The results show this method can provide theoretical parameters for engineering inspection.