Non-Destructive Evaluation of 3D-Printed Parts Using Algorithm-Aided Infrared Thermography

Abstract

Additive manufacturing has grown in popularity due to its advantages over more traditional forms of manufacturing. However, it remains unreliable for mainstream manufacturing due to its high prevalence of flaws. Quality control monitoring is used to detect and reduce flaws. There are two types of quality control monitoring. One is nondestructive evaluation (NDE), which has grown in popularity because it does not alter the part. There are many promising types of NDE techniques, including infrared thermography. However, they often lack a connection to the physics of their processes, which renders them less useful than they could be. This research discusses using heat transfer principles in combination with infrared technology to explore a nondestructive evaluation method that estimates the thermal conductivity of 3D-printed parts using heat transfer models. Tests were performed on three different specimens to test the viability of this method on isotropic and anisotropic materials. The three materials tested were epoxy, epoxy with an imposed flaw, and a 3D-printed specimen made of acrylonitrile butadiene styrene (ABS). Two identical tests were performed for each material. The two epoxy tests generated average thermal conductivities within industry values, demonstrating that this technique was viable in homogeneous, isotropic specimens. Additionally, the epoxy with hole tests showed that areas closer to the hole produced lower thermal conductivities than areas further from the hole, demonstrating that this technique was able to detect flaws within the specimen. Lastly, in the 3D- printed specimens, the direction of the bead print on the surface layer was shown to consistently fall within the industry range for thermal conductivity of ABS. Similarly, the direction of the thickness was shown to consistently be less than the industry range for thermal conductivity of ABS. The direction perpendicular to the bead print on the surface layer was not consistent between tests. Therefore, this technique is a potentially viable method for determining the thermal conductivity of 3D-printed parts in the direction of the thickness and the bead print on the surface layer. Further research is needed to determine the viability of this method in the direction perpendicular to the bead print on the surface layer.