An Air Coupled Ultrasonic Array Scanning System for In-Situ Monitoring and Feedback Control of Additive Manufacturing

The majority of additive manufacturing (AM) processes are plagued by a lack of online process control. Most existing quality assurance methods involve an inspection of the finished part rather than online quality control, leaving a need for an online inspection system that can assist in the amelioration of flaws during the manufacturing process. Thus, a monitoring method to optimize the manufacturing process, increase part quality and reduce time/energy spent on post-process quality control/remanufacture is highly desirable. In this proposal, X-wave Innovations, Inc. (XII) and the University of Dayton Research Institute (UDRI) propose an Air Coupled Ultrasonic Array Scanning (ACUAS) system for in-situ monitoring and feedback control of AM processes. The end result of ACUAS is to provide high- resolution ultrasonic images of AM part properties which are subsequently used to augment the AM process control parameters (e.g. laser speed/power) resulting in the compensation of manufacturing defects. In Phase I, XII will prototype a system and demonstrate the feasibility of the proposed ACUAS technique for in-situ, measurement and feedback control of powder bed AM process. The focus of the Phase I program will be the overall ACUAS system design and prototyping, including design of the transducer array, signal/image processing algorithms, derived measurement of part properties, and feedback control strategies. The proposed ACUAS provides a means of measuring, and compensating defects formed in parts resulting from a powder bed AM process. The enabling technique will allow a fundamental understanding of the relationship between process parameters, and the formation of defects, as well as a means of ameliorating those defects so that they do not lead to failure of the finalized components. Thus, the proposed ACUAS system will have a significant impact on many industrial and military applications, as AM is being adopted rapidly in nearly all fields. Of particular interest to the DOE, would be the application of ACUAS in the AM of polycrystalline diamond compact drill bits for oil and gas exploration/extraction, or in the production of gas turbine fuel injectors.