Session: 01-03-02: Advanced Manufacturing for Aerospace Structures

Paper Number: 111806

111806 - Moving Towards a Print Then Use Framework for Additive Manufacturing 

A framework that moves from the current post processing intensive workflow to print then use for Additive Manufacturing (AM) will be presented. As a relatively new technology, the adoption of AM in the aerospace industry has been animated by several factors—complex designs, integrated parts, reduced lead times—while being accompanied by another: caution. There are hundreds of standards related to the production of AM parts, relating to everything from operations and raw material storage to process specifications and structural requirements. This includes NASA-STD-6030, Additive Manufacturing Requirements for Spaceflight Systems, and the recent updates to AIAA-S110, “Space Systems — Structures, Structural Components, and Structural Assemblies.” Both of these standards proof tests among many other post-processing and acceptance test requirements. This has been, and continues to, the best practice for AM parts since the technology is still novel.

Yet recent advances combined with increasing years of experience qualifying AM parts have made it clear that sooner or later, manufacturers will seek to eliminate post-production and acceptance testing and put parts immediately into service. That is likely to happen initially where parts are made at forward operating positions, such as submarines, army bases or in space. It will take longer for that approach to achieve sufficient confidence that it could be adopted for high-value payloads such as spacecraft or launch vehicles. Nevertheless, now is the right time to develop that framework, and portions of it could be adopted to reduce the amount of post-processing and acceptance testing required.

The focus of this initial framework will focus on what is needed to eliminate the proof testing requirement. Since pressurized hardware requires proof testing regardless of manufacturing method, this approach is limited to non-pressurized hardware. Having a well-characterized material produced with a proven & stable process is essential to this approach. Additionally, several other aspects of manufacturing will be weighed when determining if a manufacturer can forgo proof testing. These include elements such as witness coupon testing, microstructure analysis, in-situ monitoring, NDE and process simulation to help evaluate off-nominal conditions.

In the further future, some of those elements could be eliminated with sufficient understanding of the manufacturing process. As AM machines become more advanced through process controls (including closed-loop feedback), in-situ process monitoring improves, and process simulation is proven through validation to predict important material characteristics, it may be possible to confidently resolve anomalies in real time or heat-treat parts of the structure in place. Design analysis would need to account for the residual stress state of parts, surface roughness and porosity that govern life, and the qualification articles would need to follow the same process.

The end of the road is to have parts that are Additively Manufactured with real-time monitoring and in-place heat treatment, with tools that simulate the entire part build to determine if there are potential weak spots in the part. This would be in conjunction with other process parameters (such as raw material quality or machine maintenance) that are crucial for producing consistent parts. Eventually, print-then-use could become a viable process for AM parts.

Presenting Author: Jacob Rome The Aerospace Corporation

Presenting Author Biography: Dr. Jacob Rome has worked at The Aerospace Corporation for over 20 years in the Structures Department. Dr. Rome established himself as an expert in composite structural analysis for structures including solid rocket motors, hypersonic vehicles, clamp band separation systems, payload fairings that incorporated composite sandwich panels and rocket nozzles. Over the past decade, Dr. Rome has taken a leadership role in understanding, evaluating and advancing the use of Additive Manufacturing. This includes an early emphasis on process simulation of additive manufacturing. In recent years, Dr. Rome has stepped forth to become a visionary in the field of In-Space Servicing, Assembly and Manufacturing (ISAM). Dr. Rome's team created a roadmap that could enable an Orbital Satellite Factory within a decade, and he is currently leading a team to shepherd and execute that research within Aerospace and with a half-dozen (and growing) partner universities.

Authors:

Jacob Rome The Aerospace Corporation
Vinay Goyal The Aerospace Corporation
Brett Soltz The Aerospace Corporation
Glenn Bean The Aerospace Corporation
Xueyong Qu The Aerospace Corporation
Evgueni Todorov The Aerospace Corporation