Additive manufacturing (AM), also known as 3D printing, is revolutionizing how various structural components are manufactured. Laser Powder Directed energy deposition (LP-DED), which is one type of metal AM processes, utilizes a concentrated laser source and metal powders to achieve layer-by-layer deposition of materials. Although significant progresses have been made for the development of DED processes and materials, little work has been done for in-situ nondestructive testing and quality control. In this study, a suit of in-situ nondestructive testing (NDT) and process control techniques are developed, including (1) real-time melt pool depth estimation and control using coaxial infrared camera, (2) real-time porosity inspection based on transient thermoreflectance measurement using femtosecond laser, (3) in-situ mechanical properties estimation based on noncontact ultrafast ultrasonic measurement, (4) real-time porosity reduction and microstructure improvement using a repetitive Nd:YAG pulse laser, and (5) track-wise geometry monitoring using laser line scanner. 

Lessons learned from 2D and 3D characterization of porosity and its impact on fatigue in laser powder bed fusion additively manufactured Ti-6Al-4V

This talk will provide an overview of defect characterization efforts aimed at establishing process-structure-property relationships and a fatigue-based process window for Ti-6Al-4V components produced via laser powder bed fusion additive manufacturing. The emphasis will be on the characterization methods and analysis techniques developed to correlate porosity characteristics, observed through optical microscopy and X-ray micro-computed tomography (μCT), to fatigue performance. The talk will highlight the critical role of advanced characterization in identifying the key defects and underlying defect formation mechanisms that impact the mechanical properties of additively manufactured materials. 

Dr. Narra's research focuses on advancing fundamental knowledge in metal additive manufacturing to enable lightweight, high-performance printed parts. This includes studying process-structure interactions, material behavior, and physics-driven process design paradigms aimed at accelerating industrial adoption. Her group works at the intersection of mechanical engineering and materials science to advance additive manufacturing technologies. Sneha P. Narra received her B.E. in civil engineering from Osmania University in India (2012). She pursued graduate education at Carnegie Mellon University, where she obtained her M.S. in computational mechanics (2013), M.S. in mechanical engineering (2015) and Ph.D. in mechanical engineering (2017). She then completed postdoctoral training at the NextManufacturing Center before joining the mechanical engineering department at Worcester Polytechnic Institute as an assistant professor in 2018. After three years in WPI’s materials and manufacturing engineering program, she joined the CMU mechanical engineering department in 2021. She is currently serving as the Associate Editor of the Additive Manufacturing journal and plays an active role in organizing symposia through the TMS Additive Manufacturing Bridge Committee and other educational and outreach activities.

Metal additive manufacturing methods are increasingly the method of choice when relatively small batches of components with complicated geometries are needed. Although many metal additive manufacturing methods have been proposed, the most popular methods involve deposition and fusion of metal, using energy sources such as lasers, in thin layers to build the component. Extensive studies carried out to date have shown that the dynamics of the melt pool has a strong influence on the microstructure, and hence the quality of the component being built. Failure to control the process parameters within a very narrow window can result in flaws such as pores and keyholes. This presentation describes a new electromagnetic method that is being developed for controlling the dynamics of the melt pool during the deposition process to broaden the process control window. Simulation results obtained to date, using coupled multiphysics models, demonstrate the ability of this approach to control the dynamics of the melt pool. 

Satish S. Udpa serves as an Interim President Emeritus and University Distinguished Professor Emeritus at Michigan State University (MSU). Prior to this, he served in many academic and administrative capacities at MSU including Interim President, Executive Vice President for Administration, Dean of the College of Engineering, Chair of the Department of Electrical and Computer Engineering and University Distinguished Professor. He also served as the President of the Michigan State University Foundation. Dr. Udpa was the Whitney Professor of Electrical and Computer Engineering at Iowa State University and a faculty member at Colorado State University before joining Michigan State University in 2001.

Theodosia Stratoudaki is Senior Lecturer (Associate Professor) at the Electronic and Electrical Engineering of the University of Strathclyde. She is a member of the research Centre for Ultrasonic Engineering and she leads the Remote Ultrasonics and Laser Enabled Sensing team in Strathclyde. Her research focuses on ultrasonic sensing and imaging using lasers with a particular expertise in laser ultrasound arrays and Laser Induced Phased Arrays (LIPAs). She received her PhD in Physics from the University of Warwick (UK) and joined the Engineering faculty in Strathclyde in 2017. She is the Chair of the Physical Acoustics Group of the Institute of Physics (UK) and a member of the Ultrasonics Committee of the British Standards Institute