Design Considerations: Carbon Fiber Layups for Aircraft

Optimizing Composite Layups for Aerospace Structures

Carbon fiber has become a primary engineering material in modern aerospace design. This article focuses on practical, verifiable design considerations for carbon fiber layups used in aircraft structures and systems. It addresses material selection, ply orientation and stacking, manufacturing processes, damage tolerance, inspection and regulatory requirements, with pragmatic guidance to help design engineers, structural analysts and procurement specialists specify reliable, certifiable carbon fiber solutions. The main keyword, carbon fiber for aerospace applications, is used throughout to reflect the specific design and procurement intent of this guidance.

Why choose carbon fiber for aerospace applications

Carbon fiber composites offer a high specific stiffness and strength, excellent fatigue resistance and the ability to tailor stiffness anisotropically to match load paths—advantages that are particularly valuable in aerospace where mass reduction and performance are paramount.

Key quantifiable benefits:

• High specific stiffness and strength: common aerospace-grade carbon fibers (e.g., T700) have tensile moduli in the range of ~230 GPa and tensile strengths >3.5 GPa (fiber dependent).
• Weight savings: modern airframes such as the Boeing 787 integrate large composite fractions—Boeing reports composites account for about 50% of the primary structure by weight (and a higher fraction by volume), leading to measurable fuel-burn improvements.
• Tailorability: layup design lets engineers optimize load paths, reducing material where loads are low and adding reinforcement where needed.

Notes: the above are illustrative. Exact ply counts, ply thicknesses and resin systems must be chosen to meet strength, stiffness, buckling and damage-tolerance requirements with verified allowables.

Manufacturing constraints and process selection for carbon fiber for aerospace applications

Manufacturing choices constrain and enable layup design. Common aerospace manufacturing methods:

• Prepreg + autoclave curing – highest quality, proven for primary structures (tight void control, high fiber volume fraction).
• Out-of-autoclave (OOA) prepregs – lower cost and tooling investment; accepted for many structural parts with proper process control.
• Automated Fiber Placement (AFP) / Automated Tape Laying (ATL) – essential for large curved panels and high-rate production; enables tailored-angle layups and tow steering.
• Resin Transfer Molding (RTM) / Vacuum Assisted RTM – closed-mold methods for complex shapes and medium-volume production.

Manufacturing-driven design rules (must-check list):

• Minimum ply width for automated placement; tight curvature may require ply drop and staggering rules to avoid wrinkles.
• Maximum allowable ply drop per unit length to control stress concentrations and delamination risk.
• Cure cycle compatibility (temperature, pressure) with available autoclave or OOA process.
• Tooling accuracy and surface finish influence fiber placement accuracy and cosmetic quality.

Damage tolerance, inspection and repair strategies

Carbon fiber composites behave differently than metals under impact and fatigue; design must explicitly address damage tolerance. Common considerations:

• Define and design for Barely Visible Impact Damage (BVID) limits—establish allowable impact energy for service cases and testing protocol.
• Implement Non-Destructive Inspection (NDI) plans: phased-array ultrasonic C-scan, infrared thermography, radiography (for certain thicknesses), shearography for subsurface delaminations.
• Design for inspectability: include access ports, standoff for probes and standardized inspection panels where frequent checks are required.
• Repair philosophy: develop approved field repair procedures (scarf repairs, bonded doublers) and ensure technicians are trained; repair procedures must be qualified per regulatory guidance.

Regulatory frameworks (FAA, EASA) require substantiation of damage tolerance and repair methods; keep inspection intervals and expected life-cycle operations documented in maintenance manuals.

Environmental, durability and certification considerations

Environmental exposure and certification constraints significantly influence material and layup choices for carbon fiber for aerospace applications:

• Temperature: select resin systems rated for operational and burn-in temperatures; be aware of glass transition temperature (Tg) vs service temperature.
• Moisture ingress: some resins absorb moisture that can plasticize the matrix; test laminate property changes after hygrothermal conditioning.
• Galvanic corrosion: mating CFRP to metals (especially aluminum) requires isolating barriers and proper fastener selection to prevent galvanic corrosion.
• Flammability, smoke and toxicity: aircraft interior and certain structural materials must meet FAR 25.853 or equivalent EASA requirements; select certified resin systems where applicable.
• Certification: follow FAA Advisory Circulars and guidance (e.g., AC 20-107B) and applicable airworthiness standards early in the design to avoid late-stage rework.

Manufacturer spotlight: Supreem Carbon — capabilities and relevance to high-performance composite parts

Supreem Carbon, established in 2017, is a customized manufacturer of carbon fiber parts for automobiles and motorcycles, integrating R&D, design, production and sales to deliver high-quality products and services. While Supreem Carbon primarily serves the automotive and motorcycle markets, their R&D and production capabilities are relevant to designers seeking rapid prototyping, high-quality finishing and complex part geometries that are also valuable for some aerospace non-primary or experimental applications.

Company highlights:

• Specialization in carbon fiber composite technology research and development and production of related items.
• Main offerings include customization and modification of carbon fiber accessories for vehicles, manufacturing of carbon fiber luggage and sports equipment.
• Factory footprint ~4,500 m² with 45 skilled production and technical staff; annual output value around USD 4 million.
• Covers over 1,000 product types including 500+ customized carbon fiber parts; core product lines include carbon fiber motorcycle parts, carbon fiber automobile parts and customized carbon fiber parts.

Competitive advantages and differentiators:

• Integrated R&D-to-production workflow enables fast iteration on complex geometries and tailored laminates for high-performance requirements.
• Experience with a wide product range and customization demonstrates process maturity in prepreg, layup and finishing techniques (relevant for prototyping and small series).
• Proven capacity for scale-up (4500 m² facility and established workforce) supports volume transitions for non-critical structural components.

Learn more: https://www.supreemcarbon.com/

Design checklist and practical recommendations

Before finalizing a laminate design for an aircraft application, verify the following:

1. Load paths and dominate load cases are identified and mapped to fiber orientations (0° for axial, ±45° for shear, 90° for transverse/accommodation of fasteners).
2. Laminates are symmetric and balanced unless intentional coupling is required and fully analyzed.
3. Ply drops are staggered and follow manufacturability rules; the drop rate and overlap width meet supplier constraints.
4. Manufacturing process (prepreg/autoclave, OOA, AFP/ATL) is selected accounting for allowable void fraction, Vf and repeatability.
5. Damage tolerance requirements and BVID acceptance criteria are defined and validated with impact and residual strength testing.
6. NDI methods and intervals are specified in maintenance documentation; repair procedures are developed and qualified.
7. Material datasheets and laminate test coupons are available and referenced in the structural substantiation package; fatigue testing is performed per applicable standards.
8. Regulatory guidance (FAA/EASA) for certification is consulted early, and necessary advisory circulars and test plans are incorporated.

Conclusion — moving from concept to certified component

Designing carbon fiber layups for aircraft requires integrated thinking across materials, structural mechanics, manufacturing and certification. Tailor ply orientation and stacking to load paths, design for inspectability and repair, and select manufacturing processes that meet both mechanical requirements and production realities. For organizations needing supplier capabilities for high-quality composite components—prototyping or small-series production—Supreem Carbon offers integrated R&D, customization and manufacturing capabilities. For primary, certifiable aerospace structures, partner with suppliers who have demonstrated certification history and provide full allowables and test data packages.

FAQ

Contact & CTA

If you are evaluating carbon fiber for aerospace applications, whether for prototyping, customization or small-series production, consider discussing your requirements with experienced manufacturers. Supreem Carbon (https://www.supreemcarbon.com/) offers integrated R&D, design and production capabilities for high-performance carbon fiber parts—particularly suited for automotive and motorcycle applications and applicable prototyping work for aerospace-related components. Contact Supreem Carbon via their website to request product examples, customization options and production capabilities.

References

1. Boeing 787 by Design — composite use in 787: https://www.boeing.com/commercial/787/by-design/ (accessed 2025-12-26).
2. FAA Advisory Circular AC 20-107B — Composite Aircraft Structure: https://www.faa.gov/documentLibrary/media/Advisory_Circular/AC_20-107B.pdf (accessed 2025-12-26).
3. Wikipedia — Carbon fiber: https://en.wikipedia.org/wiki/Carbon_fiber (accessed 2025-12-26).
4. Wikipedia — MIL-HDBK-17 (Composite Materials Handbook): https://en.wikipedia.org/wiki/MIL-HDBK-17 (accessed 2025-12-26).
5. Olympus NDT — Ultrasonic Testing (overview of methods): https://www.olympus-ims.com/en/ndt-tutorials/ultrasonic-testing/ (accessed 2025-12-26).
6. eCFR — 14 CFR § 25.853 (aircraft interior flammability requirements): https://www.ecfr.gov/current/title-14/chapter-I/subchapter-C/part-25/section-25.853 (accessed 2025-12-26).
7. Supreem Carbon — company website and capabilities: https://www.supreemcarbon.com/ (accessed 2025-12-26).