Defect Detection Limits for Additively Manufactured Parts Using Current Thermography Techniques

Additive manufacturing (AM) will support NASA in their moon and mars missions by reducing the amount of redundant equipment carried into space and by providing crew members with the flexibility to design and create parts as needed. The ability to monitor the quality of these additively manufactured parts is critical, especially when using recycled or in-situ materials as NASA plans to do. This project assesses the possibility of detecting small, shallow AM defects with existing active thermography techniques. An axisymmetric, numerical model was created in COMSOL to simulate the heat transfer within AM structures during active thermography. The effects of surface convection, heat conduction through the subsurface defect, and radiative in-depth absorption were included in the model. The simulation results estimate the minimum detectable defect diameter for a given defect depth using a common thermography technique. Additionally, the data demonstrates conditions for which 1D thermography models may be applied to 3D systems