Novel structural health monitoring strategies and procedures based on thermal methods for the damage characterization of 3D printed composite materials

The assessment of damage in Structural Health Monitoring (SHM) of real composite components requires innovative approaches capable of operating directly on-site, enabling the evaluation of parts manufactured using advanced 3D processes. In this context, both passive and active thermography have been explored for damage assessment. Active thermography techniques, such as Pulsed Thermography (PT), Step Heating Thermography (SHT), and Lock -in Thermography (LI), require an externalheat source to identify and quantify damaged areas. However, their application is limited for in-service monitoring of components subjected to dynamic loads, restricting their use in SHM. Conversely, other active thermographic techniques, such as Thermoelastic Stress Analysis (TSA), have shown promising results in detecting damage in composite materials. While TSA has demonstrated its potential in various applications, its implementation in SHM with low-cost sensors, particularly for the quantitative assessment of damage extent, remains a challenge. A major limitation of TSA is the high cost of cooled IR sensors, which are often impractical for operational conditions. Recent research has focused on low-cost microbolometer detectors to enhance the feasibility of thermographic techniques, making them more suitable for real-time applications. In this study, Thermoelastic Stress Analysis (TSA) was employed to thoroughly investigate the progression of damage in 3D-printed composite materials during rapid fatigue tests. The acquired data were quantitatively analysed to evaluate damage evolution, comparing results obtained from low-cost IR sensors with those from a cooled Mid-Wave Infrared (MWIR) sensor used as a reference.