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Composites in Aerospace: A Practical Material Selection Guide

4 May 2026
4 min read

Why Material Selection Is More Complex in Aerospace

Aerospace composite material selection is not simply choosing the highest-performance material available. It involves satisfying simultaneous requirements for structural performance, damage tolerance, fire resistance, repairability, manufacturing reproducibility, certification traceability, and lifecycle cost — all within a regulatory framework that demands documented evidence for every design decision.

Primary Structure vs. Secondary Structure

  • Primary structure: Failure would result in catastrophic loss of the aircraft. Includes wing spars, fuselage frames, pressure bulkheads, and flight control surfaces. Requires the most rigorous material qualification, tightest process controls, and highest design allowables established through extensive testing.
  • Secondary structure: Failure would not directly compromise flight safety. Includes fairings, interior panels, non-structural floor panels, and most radomes. Allows a wider range of material choices and less stringent qualification requirements.

Fiber Selection for Aerospace Applications

  • IM7: The prevailing choice for US and European primary structure programmes. Extensive MIL-HDBK-17 and ASTM allowables data available. Broad AS9100-qualified supply chain.
  • T800H / T800S: Preferred for Airbus and Boeing commercial aircraft primary structure.
  • T700: Used for secondary structure, fairings, and cost-sensitive structural elements.
  • E-glass and S-glass: Radomes, antenna windows, and fairings requiring RF transparency.

Resin System Selection

  • Epoxy systems: Dominant in aerospace primary structure. Processing temperatures from 120°C to 180°C. Major systems include Cytec/Solvay 977 series, Hexcel 8552, and Toray 2510.
  • Bismaleimide (BMI): For applications requiring service temperatures above 150°C — engine nacelles, leading edges in high-speed applications. More brittle than epoxy.
  • PEEK and PEKK thermoplastics: Growing adoption in primary structure for next-generation aircraft. Weldable, inherently tough, excellent chemical resistance. Higher processing temperature (360–400°C).

Sandwich Structure Considerations

Sandwich construction is standard for control surfaces, interior panels, fairings, and access doors. For primary structure sandwich panels, Nomex honeycomb with film adhesive and autoclave bonding remains the standard. For secondary and interior applications, foam cores with co-cured face skins offer cost and process simplicity.

Certification and Traceability Requirements

Every material used in a certified aircraft structure must be qualified to an approved material specification. This typically involves full material characterisation to ASTM or equivalent standard test methods, lot acceptance testing for every production batch, Certificate of Conformance traceable to the fiber and resin production lot, and storage and handling records for prepregs.

Material procurement must be from sources listed on the programme's Qualified Products List (QPL) or Approved Supplier List (ASL). Introducing a new material source typically triggers a requalification programme.

Repairability

Damage tolerance and repairability are design requirements under FAA and EASA regulations. When selecting materials, verify that repair procedures — wet layup, bonded patch, bolted repair — are compatible with the material system and that approved repair schemes are documented.

GLB Composites supplies aerospace-grade carbon fiber, prepregs, and core materials with full Certificate of Conformance documentation and traceability to primary fiber and resin production lots.