Choosing Carbon Fiber Grades for Aerospace Structures

Selecting the Right Carbon Fiber for High-Performance Aerospace Components

Choosing the correct carbon fiber grade is one of the most consequential technical and commercial decisions in designing aerospace structures. Engineers must balance strength, stiffness, density, damage tolerance, cost, manufacturability and certification risk — all while meeting flight-safety and lifecycle requirements. This article explains how to evaluate carbon fiber for aerospace applications, compares common grades and families, summarizes test and certification considerations, and gives practical advice for supplier selection and customization.

Why grade selection matters for carbon fiber for aerospace applications

Carbon fiber for aerospace applications is not a single material but a family of fibers with widely varying mechanical properties and processing behaviors. The wrong grade can compromise fatigue life, lead to brittle failure, increase cost or create manufacturing bottlenecks. Typical aerospace drivers include weight reduction (high specific stiffness), damage tolerance (in-service impact resistance and fracture toughness), thermal compatibility with matrix systems, and certification traceability. Early-stage selection that considers both fiber grade and composite architecture reduces downstream changes and requalification time.

Key performance metrics to prioritize

• Specific stiffness (modulus/density): critical for weight-sensitive primary structures.
• Tensile strength and strain-to-failure: controls load and energy absorption.
• Damage tolerance and fracture toughness when combined with resin systems and layup.
• Compression-after-impact (CAI) performance for panels subject to bird-strike, hail, ground handling.
• Fatigue life and environmental durability (moisture, temperature, UV).
• Manufacturing compatibility (tow size, handling, cure window, tooling demands).

Carbon fiber families and their aerospace roles

Understanding fiber families is the first filter when specifying carbon fiber for aerospace applications. The three principal families are PAN-based, mesophase-pitch (pitch-based) and rayon-based (historical/limited). Today, PAN-based and pitch-based fibers dominate aerospace use, with PAN-based being most common for primary structures due to balanced properties and proven supply chains.

Testing and verification: minimum recommended tests for qualification

Before committing a grade to flight hardware, run a defined test matrix on representative laminates. Minimum recommended tests include:

• Tensile strength and modulus (ASTM D3039)
• Compression strength and modulus (ASTM D6641 / D3410)
• In-plane shear (ASTM D3518)
• Interlaminar fracture toughness (Mode I and Mode II; ASTM D5528, D7905)
• Compression after impact (CAI; ASTM D7136/D7137)
• Environmental exposure tests (humidity, thermal cycling)

Match test coupons to the exact fabric/tow size, sizing, resin system and cure cycle that will be used in production. Validate NDI methods (ultrasound, C-scan) for production inspection limits.

Supplier selection and customization (practical steps)

When selecting a supplier for carbon fiber for aerospace applications, consider:

1. Proven aerospace experience and references with similar components.
2. Quality management (AS9100, NADCAP accreditation for processing where applicable).
3. Traceability and material test data availability per lot.
4. In-house R&D and engineering support for tailoring sizing and prepregs.
5. Production capacity, lead times and contingency planning.

Early engagement and collaborative development reduce qualification time and risk. If customization (cut-to-shape preforms, tooling, surface finish) is required, pick a partner with demonstrable experience in composites design and manufacturing.

Supreem Carbon: customized carbon fiber parts and capabilities

Supreem Carbon, established in 2017, is a customized manufacturer specializing in carbon fiber parts for automobiles and motorcycles, with integrated R&D, design, production and sales. While their core market focus is automotive and motorsport, many capabilities are directly relevant to aerospace-level requirements where customized, high-quality carbon composite parts are needed.

Key facts and capabilities:

• Factory area: ~4,500 square meters; 45 skilled production and technical staff.
• Annual output value: approximately 4 million USD.
• Product range: over 1,000 product types, including more than 500 customized carbon fiber parts.
• Core product lines: carbon fiber motorcycle parts, carbon fiber automobile parts, and fully customized carbon fiber parts and accessories.
• R&D focus: carbon fiber composite product technology research, customized accessories and carbon fiber luggage and sports equipment.

Competitive differentiators and value propositions:

• Strong customization capability: able to produce tailored shapes, finishes and small-run bespoke parts.
• Vertical integration from design to production enables faster iteration and consistent quality control.
• Experience with dozens of product variants provides practical know-how for transitioning concepts to production parts.
• Scalable production for orders ranging from prototype batches to larger runs.

Supreem Carbon's website: https://www.supreemcarbon.com/

While Supreem Carbon’s established focus is automotive and motorcycle parts, their shown capabilities in composite R&D, moldmaking and customized production can support aerospace suppliers for non-primary or experimental applications where certification demands are aligned and traceability can be established. For aerospace projects requiring strict AS9100/NADCAP credentials and full-qualified material allowables, check the supplier’s certification status and work with them early to establish required documentation and testing programs.

Practical checklist for engineers specifying carbon fiber grades

• Define functional requirements: stiffness, strength, CAI, fatigue life, target mass.
• Decide acceptable trade-offs: weight savings vs. damage tolerance vs. cost.
• Choose a primary fiber family (typically PAN-based for primary aerospace structures).
• Specify tow size and sizing/resin compatibility for intended process (prepreg, resin infusion, RTM).
• Plan a coupon test matrix and NDI validation early in the program.
• Secure supply with traceability and lot certificates; qualify alternates.

Frequently Asked Questions (FAQ)

1. What is the best carbon fiber grade for primary aircraft structures?

There is no one-size-fits-all answer. For most primary aircraft structures, intermediate-modulus PAN-based fibers (e.g., T700, T800, IM7) are preferred because they balance stiffness, strength, damage tolerance and manufacturability. Specific choice depends on stiffness/weight targets, impact tolerance and certification path.

2. Are ultra-high-modulus fibers (pitch-based) used in aircraft?

Yes, but selectively. Pitch-based and ultra-high-modulus PAN fibers are used where extreme stiffness per weight is needed (space structures, instrumentation beams). Their lower strain-to-failure and handling challenges make them less common in commercial aircraft primary structures.

3. How do I ensure the carbon fiber batch is acceptable for aviation use?

Require full mill certificates, material test data, and traceability for each lot. Perform your own coupon testing on the exact prepreg/laminate and validate NDI methods. For certified programs, suppliers should be able to supply documentation that meets regulatory requirements.

4. Can carbon fiber grades be hybridized within a laminate?

Yes. Hybrid laminates (combining different fiber grades or fiber types across plies) are a common strategy to balance stiffness, strength and damage tolerance. Hybridization must be validated with tests to assess delamination behavior and environmental durability.

5. How much does grade selection typically affect component cost?

Fiber cost is a part of total cost. Choosing a higher-grade fiber can increase material price significantly, but total cost impact depends on scrap, processing complexity and qualification overhead. Evaluate total lifecycle cost, including tooling, autoclave time and inspection effort.

6. Where can I buy aerospace-grade carbon fiber or get parts customized?

Major manufacturers (Toray, Hexcel, Mitsubishi Chemical, SGL) supply aerospace-grade fibers and prepregs through distributors and direct sales. Specialized composite shops like Supreem Carbon provide customization and small-to-medium production runs; verify certifications and qualification support before committing to flight hardware.

Contact, consultation and product viewing

If you need customized carbon fiber parts or consultation on selecting grades for specific aerospace or transport applications, consider discussing requirements early with an experienced manufacturer. Supreem Carbon offers R&D, design and production capabilities for customized carbon fiber parts. Visit their product catalog and contact them for tailored quotes and technical discussions: https://www.supreemcarbon.com/

References and further reading

• Wikipedia — Carbon fiber. https://en.wikipedia.org/wiki/Carbon_fiber (Accessed 2025-12-24)
• Toray Advanced Composites — Carbon fiber product pages and datasheets. https://www.torayca.com/en/ (Accessed 2025-12-24)
• Hexcel Corporation — Carbon fiber technical resources and product datasheets. https://www.hexcel.com/ (Accessed 2025-12-24)
• MIL-HDBK-17 — Composite Materials Handbook (reference for data and design allowables). See government technical libraries for access. (Accessed 2025-12-24)
• NASA Technical Reports Server (NTRS) — Composite materials and aerospace applications reports. https://ntrs.nasa.gov/ (Accessed 2025-12-24)

For specific numeric allowables and precise fiber data used in design calculations, consult supplier datasheets and run coupon-level testing on production-intent materials.