AFRL-RX-WP-JA-2017-0316 LARGE FORMAT ADDITIVELY MANUFACTURED TOOLING FOR OUT-OF-AUTCLAVE AEROSPACE COMPOSITES ( PREPRINT )
The aerospace composites industry is plagued with high costs and long lead times for tooling, driving up part costs and delaying design cycles in new production. Tooling also complicates sustainment efforts for the Air Force’s legacy aircraft. Large format additive manufacturing has the potential to address both issues. Printed thermoplastic tools in excess of 0.5 square meters in size will be presented that are capable of curing aerospace-quality epoxy and bismaleimide composites at lower cost and with much quicker lead times compared with conventional tooling. 3D-printable, high-temperature thermoplastics and reinforcing fibers will be investigated to achieve the right balance of strength, dimensional stability, and life from the tooling. A general approach for optimization of print parameters to achieve a high-quality tool will be explored. The ability of these additively manufactured tools to withstand autoclave cures as well as out-ofautoclave processes (some of which will require the tooling to support 7 kg/sq m (100 psi) single-side loading) will be demonstrated. The Air Force’s Low Cost Attritable Aircraft Technology (LCAAT) platform is especially suited for this technology and will be used as a demonstrator for this work.
Effect of Curing Poly( p -Phenylene Sulfide) on Thermal Properties and Crystalline Morphologies
Commercial poly(p-phenylene 
sulfide) (PPS) was thermally cured, which resulted in an increase of molecular 
weight due to cross-linking. Non-isothermal crystallization studies of samples 
cured for up to 7 days at 250?C showed a monotonous increase of crystallization 
temperature compared to pure PPS. However, a further increase of curing time decreased 
the crystallization temperature. The change in the half-crystallization time (t1/2) was similar to the 
crystallization temperature. Thus, the cross-linking of PPS affected 
crystallization behaviors significantly. To a certain 
extent, crosslinks acted as nucleation agents, but excessive cross-linking 
hindered the crystallization. Morphologies observed by polarized optical 
microscopy suggested that thermal curing for as little as 1 day contributed to 
the spherulitic structure having a smaller size, that was not observed with 
pure PPS.
Additive Manufacturing: Status and Opportunities
Additive manufacturing (AM), also referred to as 3D printing, is a layer-by-layer technique of producing three-dimensional (3D) objects directly from a digital model. With markets including prototyping, tooling, direct part manufacturing, and maintenance and repair, the industry has grown significantly to $1.3B of materials, equipment, and services in 2010. Despite significant progress in the field, a number of technical challenges remain. Issues such as material characterization and availability, among many others, have been identified by various groups as areas for improvement. Though many issues are being examined by groups in academia, industry, and government, some challenges would likely benefit from increased coordination and funding opportunities. While some topics, such as achieving better material properties, have been around since the early days of additive manufacturing, new ideas have emerged in recent years. These topics involve basic science including materials, lightweight and exotic structures, bioprinting, and conformal electronics. They also include more applied areas, such as the environmental impact of additive manufacturing and 3D scanning. Many areas of AM R&D and associated technical challenges could benefit from incentive competitions that aim to spur and accelerate innovation. Some competitions involving additive manufacturing have already taken place but more could potentially benefit, especially in areas such as design software and web-based design tools. There is interest at several Federal organizations in advancing research and procurement of additive manufacturing for many types of components. Amid this growing use of additive manufacturing, the government has several opportunities to act as an early adopter to accelerate market adoption, especially in aerospace, defense, and medical applications. Over the years, the number of regular conferences aimed at advancing AM technologies has grown, with events that now take place annually throughout the globe. In addition to conferences, a number of workshops and roadmapping events have also taken place, covering topics spanning from R&D areas to educational needs. Standards play an important role in the adoption of many technologies and, as of 2009, there has been significant activity in developing AM standards through the ASTM International F42 committee. There are currently four technical subcommittees working towards standards in materials and processes, terminology, design and data formats, and test methods. They have produced four standards to date and also charted new territory in iv a partnership with the ISO, signing a cooperation agreement that governs ongoing collaborative efforts between the two groups. Additive manufacturing holds great potential to engage a broad population—not …