Abstract
Additive manufacturing has been recently employed in industrial sectors with the fundamental requirement for zero defect parts. Technological developments in additive manufacturing notwithstanding, there continues to be a scarcity of non-destructive inspection techniques to be exploited during the manufacturing process itself, thus limiting industrial advancements and extensive applications. Therefore, being able to integrate the defect inspection phase within the additive manufacturing process would open the way to enabling corrective actions on the component in itinere, that is, before reaching the final product. For this reason, new methods of in-process monitoring are gaining more and more attention nowadays. In this work, a remote laser thermographic methodology is employed as a mean to detect micrometric defects in additive manufactured samples. Beforehand, a preliminary Finite Element Analysis was carried out in order to optimize the sensitivity of the technique to the micrometric defects. Our results indicate that the technique is proved to be quite successful in detecting flaws, with the added plus of being suitable for integration in the additive manufacturing equipment, thus allowing a continuous in-line inspection.
Highlights
R ecently, additive manufacturing (AM) has been getting more and more attention in the areas of 3D geometries production and high-value parts repair, due to its increased accuracy in creating complex structures as compared to other, more traditional, manufacturing methods
The soundness of AM parts is evaluated by destructive testing or by X-ray computed tomography (CT) [3], which can only be employed after the part completion, causing parts to be rejected at the end of manufacturing process
T aking into account the results of the Finite element analysis (FEA), the experiments on the two samples have been performed using a region of interest (ROI) equal to the ones modelled as ROI 5
Summary
R ecently, additive manufacturing (AM) has been getting more and more attention in the areas of 3D geometries production and high-value parts repair, due to its increased accuracy in creating complex structures as compared to other, more traditional, manufacturing methods. When critical requirements of quality are involved, with the additional complication of dealing with complex geometries, the best option remains a non-destructive technique to be integrated as in-line inspection allowing for the detection of defects as each layer is added. A recently introduced NDT active thermographic technique is the flying laser spot technique, which has been employed for the surface crack sizing with micrometric aperture. Li et al in [11] have developed a thermographic imaging technique using the second spatial derivative of acquired flying laser spot and line thermograms, with the aim of characterizing micrometer cracks in metal samples. The aim of this work is to optimize the parameters used to post-process experimentally acquired thermograms in order to enhance defect sensitivity to micrometric near-surface and surface flaws of additive manufactured parts. Results from the experiments and the numerical model have been compared showing a sound agreement
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