Advanced manufacturing (AM) processes such as laser powder bed fusion (LPBF) are increasingly capable of fabricating components with useful and unprecedented mechanical properties by incorporating complex internal bracing structures. From the standpoint of quality control and assessment, however, internally complex assemblies present significant build-verification challenges. Here we propose a hybrid approach to inspection involving the application of computer-aided speckle interferometry (CASI) and morphological image processing as a rapid, inexpensive, and facile method for AM quality control. A simple optical system with variable sensitivity is shown to be effective for inspection of a titanium honeycomb component subjected to differential pressure. Results are compared to those achieved with computed tomography (CT), immersion ultrasound testing (UT), and optical holographic interferometry. Lastly, we propose several possible processing strategies for automated quality assessment based on this powerful hybrid approach.

Advanced manufacturing (AM) processes such as laser powder bed fusion (LPBF) are increasingly capable of fabricating components with useful and unprecedented mechanical properties by incorporating complex internal bracing structures. From the standpoint of quality control and assessment, however, internally complex assemblies present signi cant build-veri cation challenges.Here we propose a hybrid approach to inspection involving the application of computer-aided speckle interferometry (CASI) and morphological image processing as a rapid, inexpensive, and facile method for AM quality control. A simple optical system with variable sensitivity is shown to be effective for inspection of a titanium honeycomb component subjected to differential pressure. Results are compared to those achieved with computed tomography (CT), immersion ultrasound testing (UT), and optical holographic interferometry. Lastly, we propose several possible processing strategies for automated quality assessment based on this powerful hybrid approach. IntroductionWith the maturation of advanced manufacturing (AM) systems, it is now possible to manufacture lightweight components with internal truss supports that are highly optimized for mechanical performance. These designs, typically referred to as "cellular truss core structures", offer a lightweight alternative to solid components while simultaneously exhibiting greater strength than a fully hollow structure. In some cases, these structures have even shown superior mechanical and/or thermal properties compared to their solid counterparts for the desired application [1]. Using AM methods to make cellular core structures can further improve structures' mechanical strength by reducing the number of weld seams, thus limiting the number of fatigue initiation locations [2]. The advantages offered by these designs are attractive for many applications, notably the fabrication of strong, lightweight structures required by the aerospace industry [3,4].Unlike traditional subtractive methods of manufacturing, AM technology enables the manufacture of cellular truss cores with almost arbitrary complexity. This complexity places a large emphasis on postbuild veri cation which, in turn, poses new challenges for non-destructive validation and testing, especially in a high-volume industrial setting where throughput (i.e., simple pass/fail acceptance testing) and automation may be overriding concerns. Devising practical methods to test for internal aws in these components is therefore essential. Classical methods of non-destructive evaluation such as x-ray Computed Tomography (CT) and Ultrasound Testing (UT) can be challenging to deploy in a high-volume environment. CT can be effective at identifying build aws such as excess porosity and missing or incomplete internal structures but is less effective at identifying cracks or zero-volume aws (i.e., complete but unbonded layers). Furthermore, x-ray CT scanning can be time-consuming and often requires a trade-off between component size and scan resolution. Perhaps...