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The very fast developments in the technology of composite materials have led to newer and wider applications of such promising materials. Composite materials offer a number of potential advantages in the aerospace field, particularly in safety-critical structures such as primary and secondary aircraft components. The presence of several types of defects such as voids, inclusions, debonds, improper cure, and delamination are almost common during the manufacture and use of composite materials. The proper assessment of such defects is necessary to utilize the full potential of these materials. This present study has been taken up to detect and characterize such defects using a thermal imaging technique. The technique is found to be deterministic in the acceptable level for the assessment of defects in polymer composites. The thermography, ultrasonics (A-scan and C-scan), and also microscopy (photo-microscope and scanning electron microscope) methods were used here to assess the defects. The detection and characterization of the wide range of defects requires a number of specialized non-destructive methods. The proper assessment of defects is essential, particularly in safety-critical structures such as primary and secondary aircraft components, to avoid catastrophic failure.

This paper deals with the study of fracture behaviour of silicon carbide particle‐ reinforced aluminium alloy matrix composites (A359/SiCp) using an innovative non‐destructive method based on lock‐in thermography. The heat wave, generated by the thermo‐mechanical coupling and the intrinsic energy dissipated during mechanical cyclic loading of the sample, was detected by an infrared camera. The coefficient of thermo‐elasticity allows for the transformation of the temperature profiles into stresses. A new procedure was developed to determine the crack growth rate using thermographic mapping of the material undergoing fatigue. The thermographic results on the crack growth rate of A359/SiCp composite samples with three different heat treatments were correlated with measurements obtained by the conventional compliance method. The results obtained by the two methods were found to be in agreement, demonstrating that lock‐in thermography is a powerful tool for fracture mechanics studies. The paper also investigates the effect of heat treatment processing of metal matrix composites on their fracture properties.

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In this work, we describe the fatigue behaviour of silicon carbide (SiCP)‐reinforced A359 aluminium alloy matrix composite considering its microstructure and thermo‐mechanical properties. A variety of heat treatments have been performed for the 20 vol. % SiCp composite, which resulted in different strength and elongation behaviour of the material. The fatigue behaviour was monitored, and the corresponding S–N curves were experimentally derived for all heat treatments. The fatigue strength was found to depend strongly on the heat treatment. In addition, the fatigue behaviour was monitored non‐destructively via the use of lock‐in thermography. The heat wave, generated by the thermo‐mechanical coupling and the intrinsic dissipated energy during mechanical loading of the sample, is detected by a thermal camera.