Inspection of 2D Composite Structures Using Self-Heating-Based Vibrothermography

Polymer matrix composite (PMC) structures due to their superior mechanical performance have been widely used in various industries, including wind turbine, automotive, civil, aerospace, marine, and others. Non-destructive testing (NDT) of such structures plays a key role during their long-term operation and ensures their safety and integrity. Among NDT techniques, infrared thermography is one of the fastest techniques, which has been successfully implemented for the inspection of PMC structures and components. Nevertheless, using active thermography as the NDT technique requires external heat excitation, making this technique difficult to apply in numerous cases, particularly when applying this type of heating source is limited or impossible. To address this issue, the new self-heating-based vibrothermography (SHVT) technique developed by this research group has been used for the detection and identification of damage in 1D (beam-like) composite elements. Previous experimental results proved the effectiveness in the detection and identification of various types of damage in PMCs, leading to further development of SHVT for making it possible to inspect 2D (plate-like) composite structures, which has significant practical meaning and potential for application. The self-heating effect, acting as a heat source in the SHVT technique, occurs in PMCs because of their viscoelastic nature when subjected to vibrations. In this technique, mechanical vibrations induced by the first resonant frequency is applied to excite a plate-like composite structure. This excitation leads to heat generation and manifests itself in the form of increasing self-heating temperature on the surface of a tested structure. This temperature growth is consequently resulting in detecting the damage using an infrared camera. Since the generated heat is equivalent to the mechanical stress resulting from resonant vibrations, the thermal response on the surface of a tested structure has an inhomogeneous character in terms of its spatial distribution. The following study aims to present the recent results of the research group in terms of the extension of the performance of the SHVT NDT technique to 2D composite structures.