In situ velocity measurements of very high power ultrasonic additive manufacturing using a photonic Doppler velocimeter

AbstractTo understand the dynamic structural movements of very high power ultrasonic additive manufacturing, simultaneous in situ velocity measurements of the sonotrode, welding foil and substrate during consolidation were made using a photonic Doppler velocimeter. During consolidation in which the welding foil was successfully bonded to the substrate, the welding foil and substrate had similar vibration phase angles which came into and then out of phase of the sonotrode; in addition to having large changes in relative velocity as the normal force from the sonotrode was applied and then removed. A consolidation pass in which no bonding occurred, consisted of relatively constant velocity amplitude for all structures. The welding foil and sonotrode remained fully coupled and in phase, but was out of phase of the substrate during the entire welding pass. Therefore, by examining velocity and phase data, bonding versus non-bonding conditions can be determined in situ using the photonic Doppler velocimeter system.