As additive manufacturing (AM) is more and more used in industry, the quality control of AM parts is becoming increasingly important. Commonly used non-destructive testing (NDT) techniques for parts conventionally manufactured may no longer be adapted for AM parts. Indeed, AM parts can have much more complex geometries, such as lattices, can contained internal features, and their surfaces can be very rough. Several NDT techniques have been investigated for AM parts [1-8]. Among them, the two most suitable for complex geometries are X-ray computed tomography (XCT) [1, 5] and Resonant Ultrasound Spectroscopy (RUS) [1, 5, 8]. They are both volumetric NDT techniques. XCT provides a three dimensional (3D) image of the volume of the parts enabling to detect and localise defects, and to perform dimensional measurements. RUS, including swept-sine and impulse excitation (Fig. 1) methods [8], provides the frequency spectrum of the vibrational modes of a part, mechanically excited, that needs to be compared to the spectra of other parts from the same family to detect change in geometry or density or elasticity of the part, or to detect if the part is defective. XCT and RUS are actually complementary techniques. RUS is a global and comparative technique requiring a set of parts from the same family, but it is fast, cheap, easy to use, and enables testing large and dense parts. XCT is an expensive technique, requiring skills, and is not suitable for large and dense parts, but it provides a 3D image of the whole volume.

The talk will address these two techniques and will show relevant results obtained on AM parts. It will also present the results of studies to evaluate the reliability of these techniques.

References
[1] E, Todorov; R, Spencer; S, Gleeson; M, Jamshidinia; and M, Kelly Shawn; “America Makes: National Additive Manufacturing Innovation Institute (NAMII) Project 1: Nondestructive Evaluation (NDE) of Complex Metallic Additive Manufactured (AM) Structures,” Interim Report, 2014.
[2] “Standard Guide for Nondestructive Examination of Metal Additively Manufactured Aerospace Parts after Build,” E3166-20, ASTM International, West Conshohocken, PA, 2015.
[3] A-F, Obaton; M-Q, Lê; V, Prezza; D, Marlot; P, Delvart; A, Huskic; S, Senck; E, Mahé and C, Cayron; “Investigation of new volumetric non-destructive techniques to characterise additive manufacturing parts”, Weld World, Vol. 62, Issue 5, pp. 1049-1057, 2018, https://doi.org/10.1007/s40194-018-0593-7.
[4] A.-F, Obaton; “Overview of the EMPIR Project: Metrology for Additively Manufactured Medical Implants”, Euspen, 2019, https://www.euspen.eu/knowledge-base/AM19106.pdf.
[5] A-F, Obaton; B, Butsch; S, McDonough; E, Carcreff; N, Laroche; Y, Gaillard; J, Tarr; P, Bouvet; R, Cruz; A, Donmez; “Evaluation of Nondestructive Volumetric Testing Methods for Additively Manufactured Parts”. Structural Integrity of Additive Manufactured Parts, West Conshohocken, PA, pp 51–91, 2020.
[6] J, Wilbig; F, Borges de Oliveira; A-F, Obaton; M, Schwentenwein; K, Rübner; J, Günster; “Defect Detection in Additively Manufactured Lattices”, Open Ceramics 100020, 2020.
[7] “Additive manufacturing of metals - Non-destructive testing and evaluation - Defect detection in parts”, ISO/ASTM TR 52905, 2023.
[8] A.-F, Obaton; “Resonant Ultrasound Spectroscopy Testing Methods in Additive Manufacturing”, Additive Manufacturing Design and Applications, Vol 24A, ASM Handbook, 2023, ISBN: 978-1-62708-437-6.