In-Line Inspection of Additive Manufactured Parts Using Laser Ultrasonics

At present there are no reliable, cost-effective process control techniques to minimize defect production and for qualification of finished parts fabricated by additive manufacturing (AM). In our Phase I project we have demonstrated the feasibility of filling this gap by applying laser ultrasonic testing (LUT) for nondestructive evaluation of each AM deposited layer in real time as it is formed. This in-line inspection qualifies the part layer-by-layer, directs defect removal during the manufacturing process, and ensures qualified finished parts that require no further testing. In this proposed Phase II project we will team with a manufacturer of powder bed fusion AM machines to develop a three-step layer-by-layer inspection and validation system, consisting of: (1) optical profilometry for defect detection, (2) laser ablation to remove the defect indications and (3) LUT to validate the removal of the defects. The IOS technology development will include advanced signal processing and optimized beam parameters for optimized signal-to-noise, as well as integration of the controls with the AM machine controls. A preliminary and a full-scale prototype LUT system will be developed and tested on the manufacturer’s AM machine. At the beginning of the project we will be at TRL 4; at the end of the project we will be at TRL 6.