Monitoring friction stir welding process based on weld images is attempted in this research. Well-known fractal theory is applied to images of the welds and extracted features in terms of fractal dimension are correlated to ultimate tensile strength (UTS) of the joints. The correlation shows a decreasing trend that can be an indicator towards monitoring of weld quality. Apart from fractal theory, wavelet transform is also applied to the acquired images and an indicator is proposed relating the information gathered after the decomposition. Interestingly, the proposed indicator also describes a decreasing trend of UTS with the increase in its value. The proposed approaches can be effectively applied in real-time monitoring of the process with appreciable accuracy.
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