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• A nondestructive monitoring method of failure behaviors of fiber-winding composites is proposed based on infrared thermography. • The abilities of infrared thermography to evaluate the failure process and failure modes are validated in fiber-wound composites. • Infrared thermography has a certain advantage for comparing fiber volume fractions when professional testing devices are lacking. This paper presents a new method for evaluating the failure and processing technology of fiber-winding composites based on infrared thermography. Firstly, infrared thermography was used to monitor the surface temperature evolution during the loading of Naval Ordnance Laboratory (NOL) rings. Secondly, the mechanical and temperature data were recorded simultaneously until the failure of the NOL rings occurred. Thirdly, the mechanical results were compared with the monitoring results obtained from infrared thermography concerning the failure of the NOL rings. Lastly, an evaluation was conducted regarding the capability of infrared thermography to elucidate the failure of the NOL rings. The experiment results demonstrated that infrared thermography can characterize the failure process and failure modes of fiber-winding composites with limited mechanical or optical technology. Besides, this testing technology provides a significant advantage when comparing fiber volume fractions, particularly in situations where professional testing devices are unavailable. This work provides a new reference for the application of infrared thermography within the domain of fiber-winding composites. [ABSTRACT FROM AUTHOR]

Aiming at the drawbacks of low contrast and high noise in the thermal images, a novel method based on the combination of the thermal image sequence reconstruction and the first-order differential processing is proposed in this work, which is comprised of the following procedures. Firstly, the specimen with four fabricated defects with different sizes is detected by using pulsed infrared thermography. Then, a piecewise fitting based method is proposed to reconstruct the thermal image sequence to compress the data and remove the temporal noise of each pixel in the thermal image. Finally, the first-order differential processing based method is proposed to enhance the contrast. An experimental investigation into the specimen containing de-bond defects between the steel and the heat insulation layer is carried out to validate the effectiveness of the proposed method via the above procedures. The obtained results show that the proposed method can remove the noise, enhance the contrast, and even compress the data reaching at 99.1%, thus improving the detectability of pulsed infrared thermography on metal defects. [ABSTRACT FROM AUTHOR]

• The four stages of the heat dissipation law of vibration fatigue of blade structure based on infrared thermography are proposed. • The advantages of infrared thermography in predicting the vibration fatigue limit with low cost, high accuracy, and convenience are verified. • Infrared thermography can be used as evidence and a complementary analytical tool of crack expansion during blade vibration fatigue. • Infrared thermography is beneficial to timely discover potential weaknesses in the blades and further optimize the structure, thus reducing maintenance costs. In recent years, infrared thermography has been widely used in mechanical testing because of its non-contact, rapidity and high accuracy. In order to explore the advantages of infrared thermography in vibration fatigue monitoring of blade structures, the characterization of the vibration fatigue behavior of blade structures is carried out based on infrared thermography with the validation and assistance of laser vibrometry. Firstly, the numerical simulation and experimental analysis were used to determine the size and location of the maximum stress in blade structures. Afterwards, the linear relationship between the stress and amplitude(σ ν - A curve) of blade structures was calibrated by laser vibrometry, and thus the S-N curve was fitted. Eventually, the heat dissipation law and crack extension process for vibration fatigue of blade structures was analyzed by infrared thermography, and the fatigue limit of the blade structure was predicted by combining infrared thermography and the Luong bilinear method. It is shown that the heat dissipation law and crack extension process for vibration fatigue of blade structures can be effectively analyzed by infrared thermography. Infrared thermography saves some economic and time costs for fatigue limit prediction, and the method is within 2.6% of the results predicted by the Basquin model. This paper provides a certain reference basis for the research methodology for vibration fatigue behavior of blade structures. [ABSTRACT FROM AUTHOR]