Part of the Air Force 2030 Science and Technology strategy includes the deployment of low-cost Unmanned Aerial Systems in mass to assist in future near-peer engagements. In order to realise this vision, new manufacturing strategies need to be identified which can support the rapid manufacturing of high-quality aerospace components at costs that are lower than what is currently available using legacy manufacturing processes.

The Air Force Research Laboratory’s Manufacturing and Industrial Technologies Division and the contractor team of Cornerstone Research Group, A&P Technology and Spintech LLC, conducted research to quantify the benefits of replacing legacy manufacturing processes with novel processes for the fabrication of an 11-foot long, S-shaped engine inlet duct.

The legacy fabrication process for the inlet duct consists of composite material pre-impregnated with a synthetic resin, applied by hand, to a multi-piece steel mandrel. The mandrel is packaged and placed in an autoclave for processing. An autoclave is essentially a heated pressure vessel which supplies heat to activate resin curing and pressure to ensure there is minimal absorbency in the fully cured composite part.

The approach replaces the hand-applied composite prepreg with an automated over-braid process which applies dry fibre to a mandrel. The very heavy multi-piece steel mandrel was replaced with a light-weight single-piece shape-memory polymer mandrel and the dry braided carbon fibre was processed with low-cost epoxy resin using a vacuum-assisted resin transfer moulding process.

One of the primary goals of this program is to understand the part cost and production time benefits from introducing the new tooling and processing solutions.

The team completed element analysis finalisation of the over-braid architecture, fabrication of a shape memory polymer-forming tool and construction of the SMP mandrel that will serve as the tool during the preform over-braid process.

We believe that the introduction of a reusable shape memory polymer mandrel together with the automated over-braid process and an oven based VARTM composite cure will lead to significant cost and cycle time reductions

 Mr. Craig Neslen, manufacturing lead for the Low Cost Attritable Aircraft Technology Initiative

Because of inlet duct geometrical complexity, multiple iterations were necessary to optimise the over-braid machine settings and thus minimise composite material wrinkling. A total of four inlet ducts will be fabricated and legacy part cost and production time will be compared to the new design.

The final inlet duct will be delivered to the government for further integration into the Aerospace System’s Directorate’s complementary airframe design and manufacturing program. Personnel at the Aerospace Vehicles Division will conduct static ground testing of the integrated braided fuselage and inlet duct structure.

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The partnership is creating a new materials sub-facility called the Materials Solutions Network which will drive composite manufacturing into a physics-based exact science that can be predicted and modelled allowing faster implementation of low-cost, short-term and limited-life technologies.

It is hoped the new facility will allow breakthroughs in materials, processes and designs for aerospace and military components. The ability to process material models faster than ever will enable shorter times toward certification of new materials and difficult processing methods such as additive manufacturing.

The beamline will allow manufacturers and researchers to observe materials in real-time and at atomic scale for structural components such as the stationary section of a rotary system for DOD technologies or additively manufactured articles for limited life applications.

Obtaining tangible measurement data such as material structure in regards to gaps and interfacial quality is now a reality. Problems and processes can be eliminated sooner and refined for quality control and consistency.

Traditionally, composites manufacturing is mainly done by hand. Hence, the processing is as much art as it is science. Predictive modelling relies on numerous assumptions and experimental data. Reproducibility is low and ever-changing to new and improved material.

This development pushes a real-time, high-resolution understanding of the manufacturing of composites. The research reveals processing effects and variations on thermoplastic and thermoset composites during consolidation processes such as stamping and additive manufacturing.

Two new X-ray beamlines – a structural materials beamline (for which higher-energy X-rays are required to penetrate, e.g., metals) and a functional materials beamline (with lower energies for polymers and composites) are housed at the facility.

The structural materials beamline uses high energy X-rays to understand the evolving internal structure of metals, ceramics and composites during service and processing conditions.

The functional materials beamline is designed for analysis of soft materials, such as organic molecule and polymer-based materials and composites used in lightweight structural components and organic electronics, during processing and under real-life load conditions.

The X-ray beam at the functional materials beamline is only one-hundredth of the width of a human hair and can probe interfaces between the matrix and the carbon fibre, between layers of printed composites and of bonded structures. Images can be taken at fractions of a second to enhance quality control in revealing behaviour during processing. The beamline allows quick switching between different operating modes, such as small-angle X-ray/wide-angle X-ray scattering, phase contrast imaging and X-ray computed tomography.

Partnerships between the Department of Defense, industry and academia to address DOD challenges in materials discovery, processing and manufacturing of disruptive technologies will enable advances in materials and designs for a multitude of military components.

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