N251-055 TITLE: Reduced Cost Thermoplastic Composite Fabrication by Thermoforming Drapable Pre-pregs

OUSD (R&E) CRITICAL TECHNOLOGY AREA(S): Advanced Materials;Sustainment

OBJECTIVE: Develop and demonstrate technologies to produce high quality thermoplastic composite parts with complex geometries at a high rate using emerging materials and fabrication techniques.

DESCRIPTION: Thermoplastic parts offer unique advantages, such as room temperature storage, recyclability and lighter weight compared to both metals and thermoset composite parts. A common and relatively cost-effective way to make thermoplastic parts is thermoforming. In this process thermoplastic pre-pregs are heated until pliable and then formed over a mold under pressure and/or vacuum.

The challenge in this process is avoiding wrinkles and maintaining tight tolerances of the formed part. This limits the formability especially when large deformation over a mold with complex geometry is required. However, a new generation of drapable "dry" pre-pregs and processing techniques is available now to address these challenges. The drapable materials can closely conform to the shape of the mold. These materials conform to the mold and thus have the potential of forming complex parts. Even for parts that can be formed by traditional methods, these materials reduce the number of steps, while maintaining tighter tolerances and reducing overall time and cost for forming a part.

The available drapable pre-pregs are still limited, but new forms are actively being developed and coming to market. Examples include, KyronTEX® by Mitsubishi Materials and ET40 by Toray. These materials are cited as examples only, and this SBIR topic does not exclude any other suitable material system.

This is not a material development effort. The primary focus of this SBIR topic is to use an available material that can be used as is or with incremental changes to develop and demonstrate it by fabricating a representative aerospace part that demonstrates the capabilities of these drapable prepregs. This is not a material development effort, however, incremental changes with the support of the pre-peg manufacturer to make it more suitable for aerospace applications is acceptable.

PHASE I: Choose one or more aircraft component that has sufficient complexity and yet can be successfully formed with drapable pre-pregs. Examples include deep drawn manifolds, and aircraft rib structures. The Phase I study should include assessment of drapability and formability of the pre-preg. This should include a modeling component to predict drapability, and an experimental campaign to validate. Additionally, coupon level studies should be done to assess changes in porosity and mechanical properties during the process. Wrinkling during forming also should be evaluated. The results should be used to establish the feasibility of the prototype(s). The feasibility assessment should be complete at the end of Phase I base period.

PHASE II: Develop a forming plan for the prototype component. Develop tooling needed for the project. Develop a test plan to assess the prototype qualitatively and quantitatively. Fabricate the part. Assess part quality. Develop and perform a mechanical test campaign to assess strength and stiffness.

PHASE III DUAL USE APPLICATIONS: Support the transition to Navy use. Use of thermoplastic composites is on the increase in navy fixed wing and rotary wing airframes. This is especially true for unmanned air systems. On the civilian side the technology is very relevant to the urban air mobility market.

REFERENCES:

1. Tripaldi, Laura. "Discovering advanced composites: How a new generation of composite materials is revolutionizing engineering." Wevolver, 24 October 2022. https://www.wevolver.com/article/discovering-advanced-composites-how-a-new-generation-of-composite-materials-is-revolutionizing-engineering

2. "Introducing KyronTEX®." Mitsubishi Chemical Group, Mitsubishi Chemical Advanced Materials. https://www.mcam.com/en/products/composites/carbon-fiber/kyrontex

3. "Extensible and Transformable Preform ET 40." Toray. https://www.cf-composites.toray/products/thermoset/others/extensible.html

4. Pipes, R. Byron et al. "Shape Compensation for Carbon Fiber Thermoplastic Composite Stamp Forming." Composites Part B, Engineering 282, Volume 282, 1 August 2024, 111577.

5. Cender, Thomas A et al. "Microstructural Evolution of Highly Aligned Discontinuous Fiber Composites during Longitudinal Extension in Forming." Composites science and technology, Volume 254, 26 July 2024, 110649.

KEYWORDS: Composite manufacturing; lightweight; deep drawn component; affordable airframe; aerospace composite

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