Thermographic investigations of metal inclusions in 3D printed samples

Subsurface defects can be well detected by flash thermography evaluating the temperature response at the sample surface. In many cases flat bottom holes or air inclusions are investigated as typical defects. In contrast, in the current paper the main emphasis is placed on metal inclusions hidden in an insulator material. As the thermal effusivity of the metal is significantly higher than of the base material, the temperature decreases quicker above such a defect. Thermal quadrupole calculations and finite element simulations have been used to investigate more closely these temperature signals. Additionally, 3D printed samples have been created, where in the plastic material different metal plates, as steel, aluminum and copper have been introduced. The measurement results on these samples show very good agreement with theoretically calculated curves.