Lawrence Livermore National Laboratory

A goal of the project is to provide an accelerated qualificatioon and certification strategy for additively manufactured metals along with the tools required to achieve the acceleration. It is broadly recognized in the AM community that qualification and certification are the “long poles in the tent.” But what embodies a certification strategy? Frazier, in his vision and roadmap paper from the Navy Workshop entitled “Direct Digital Manufacturing of Metallic Components: Affordable, Durable, and Structurally Efficient Airframes” held 11‐12 May 2010 points out that, “An accelerated qualification process is closely linked to a number of factors including (i) an understanding of machine-to-machine variability and repeatability, (ii) accurate, predictive process models for microstructure and properties, and (iii) computationally guided processes and closed loop process controls.” (Frazier: 2010) At LLNL, item (i) is being dealt with by instrumenting the additive manufacturing machines to provide characterization of the laser energy and beam profile at the powder bed. Items (ii) and (iii) are key elements of this project. Frazier acknowledges that alternatives to conventional certification methods are not in place and need to be developed.

Our strategy is based on an ICME approach that is tightly coupled with certification methods already employed in the weapons program (NRC: 2008). The graphic below shows the current approach (at top) and the proposed approach (at bottom) with the sizes of the circles indicative of effort or resource requirements. In short, the proposed strategy shifts the emphasis from expensive manufacturing processes and integrated experiments to process aware modeling and simulation (ICME design) and exhaustive material characterization to understand the differences caused by new manufacturing methods. Of course, this new approach will not eliminate the need for quantification of margins and uncertainties and expert peer review.

Current approach

ICME approach

The application of the ICME paradigm to large numbers of materials and manufacturing processes represents a grand challenge for materials engineering…

National Academy of Sciences