Defect detection in additive manufactured products with a new photonics procedure: A case study

We describe a new photonics procedure developed for non-destructive testing of additive manufactured (AM) parts and present a case study for inspection of AM brackets to detect and reject parts containing printing defects. This is an update of a previously presented paper of the work in progress to develop an Authentication Sensing System Using Resonance Evaluation Spectroscopy (ASSURES). The principle of operation is based on the concept that a part's vibration spectrum (set of resonant frequencies) is uniquely determined by its dimensions, material parameters, and interior flaws. The vibration spectrum of a part can be measured remotely with a laser vibrometer, and the presence of defects or a change in material parameters can be inferred from a change in the part's vibration spectrum (shifts in the resonant frequencies). The spectrum of a part can be measured and compared in a few seconds to a known "good" part, a "good" reference spectrum, or to other parts in the batch.