Dajun Yuan successfully defended his Ph.D. dissertation titled "Laser Direct-Write Micro-Fabrication and Patterning" in Ann Arbor on June 5, 2008. Dajun will receive a Ph.D. in Mechanical Engineering from the University of Michigan - Ann Arbor.

An article titled "Rapid Fabrication of Pentaerythritol Triacrylate Periodic Structures on Large Areas by Laser Interference Pattering with ns-Pulses" co-authored by Andres Lasagni, Dajun Yuan, and Suman Das has been accepted for publication in the journal of Applied Physics. In this article, we report on rapid fabrication of two-dimensional periodic structures on pentaerythritol triacrylate (PETIA) using Laser Interference Patterning with ns-laser pulses. Different periodic arrays including line-, cross-, honeycomb- and dot-like structures were fabricated using two and three interfering laser beams. The composition of the photoinitiator was changed from 2 to 15 % w/w to determine the threshold laser fluences necessary to photopolymerize the PETIA solution. The effects of the PETIA layer thickness and periodic geometries on the mechanical stability of the fabricated structures as well as self-organization processes are reported.

A university-industry team comprising Georgia Tech, the University of Michigan, and Honeywell Aerospace led by Professor Suman Das of the Woodruff School of Mechanical Engineering and the Manufacturing Research Center has won a three-year $4.65 million grant from DARPA for their proposal titled "Direct Digital Manufacturing of Airfoils". The team received the grant in support of the Defense Sciences Office initiative on Disruptive Manufacturing Technologies. Direct Digital Manufacturing (DDM) of airfoils is a concept that disrupts the current state-of-the-art process for manufacturing superalloy airfoils by investment casting. DDM of airfoils will eliminate nearly all the tooling, handling, and associated causes for scrap in the lost-wax process and in doing so, will disrupt not only the cost structure of conventional investment castings, but also the speed with which components can be fabricated. Tooling and spares warehouses could be eliminated and parts could be stored entirely as digital data, enabling suppliers to offer digital on-demand manufacturing. DDM of airfoils also opens new possibilities for designing and manufacturing components which would otherwise be difficult or impossible to manufacture conventionally, and it could radically change how the casting of nearly any component that employs temporary cores and molds is done worldwide. DDM of airfoils has the potential of saving up to $310 Million over 10 years on all DoD airfoils alone, and could have a massive impact on the approximately $29 Billion casting industry as a whole.

DDM of airfoils will be achieved by the processing of photocurable ceramic resins through a new direct digital manufacturing technology known as Large Area Maskless Photopolymerization (LAMP). LAMP combines layered manufacturing of complex three-dimensional objects by solid freeform fabrication (SFF) with the fine-feature resolution and high throughput capabilities of maskless lithography to achieve a disruptive breakthrough in build speed and minimum feature dimensions. To demonstrate LAMP and to qualify the process for production, the team will select and produce an airfoil design from a Honeywell gas turbine engine, such as the AGT1500 for the M1A1 Abrams tank. The airfoils will be cast using ceramic molds directly manufactured through LAMP to produce components that are metallurgically identical to those made through conventional investment casting, but without the slow and costly steps of the lost-wax process.

This interdisciplinary research project brings together a three member university-industry team with diverse sets of expertise. Suman Das (PI) is an Associate Professor of Mechanical Engineering and Director of the Direct Digital Manufacturing Laboratory at Georgia Tech. He is well known for his contributions in SFF research, and is co-inventor of two direct SFF methods for high temperature metals. John Halloran (Co-PI) is the Alfred White Collegiate Professor and former Chair of Materials Science and Engineering at the University of Michigan-Ann Arbor, and co-founder of Adaptive Materials Inc. He is well known for his wide-ranging expertise in ceramics processing and manufacturing, and is a co-inventor of ceramic stereolithography. Wil Baker (Co-PI) is an Advanced Technology Program Manager at Honeywell Aerospace in Phoenix, Arizona. He has wide experience in managing advanced technology development programs for rapid prototyping, casting, and ceramic and metallic coatings.