In-situ detection of build defects in additive manufacturing via impedance-based monitoring

In this paper, the authors explore the use of impedance-based monitoring techniques for the in-situ detection of additive manufacturing build defects. By physically coupling a piezoceramic (PZT) sensor to the part being fabricated, the measured electrical impedance of the PZT can be directly linked to the mechanical impedance of the part. It is hypothesized that one can detect in-situ defects of part mass and stiffness by comparing the signatures collected during printing of parts with that of a defect-free control sample. In this paper, the authors explore the layer-to-layer sensitivity of this technique. A control sample is created using Material Jetting and the change in signatures between various layer intervals is measured. To evaluate the technique’s ability to perform in-situ detection, several parts containing designed defects (e.g., internal voids) are fabricated and their layer-to-layer signatures are compared to a control sample. Using this technique, the authors demonstrate an ability to track print progress and detect defects as they occur.