Aircraft Materials: Composite & Non-Metallic Practice Flashcards

Vocabulary-style flashcards covering composite material advantages, reinforcing fibre types, fabric construction, resins, core materials, plastics, and structural sealants for aircraft.

Composite

Two or more materials combined to form a much stronger structure than either material by itself.

E-glass

A type of fibreglass used for electrical applications due to its large resistance to current flow; the most common type for reinforcement.

S-glass

A type of fibreglass used when high tensile strength or modulus is required.

Aramid (Kevlar)

An aromatic polyamide polymer introduced by DuPont in the 1970s, often used in areas prone to impact damage.

Black Graphite

The American term for carbon fibre, used for manufacturing primary structural components like ribs and floor beams.

Galvanic Corrosion

The corrosion problem that occurs when carbon fibre is bonded to aluminium; requires a layer of fibreglass for isolation.

Boron Fibres

Fibres made by applying vaporised boron onto a thin tungsten or carbon wire core, primarily used for repairing cracked aircraft aluminium parts.

Ceramic Fibres

Composites used for high-temperature applications, retaining strength and flexibility up to $1200\,^{\circ}\text{C}$.

Warp

The threads running along the length of the fabric as it comes off the roll, designated as $0^{\circ}$, typically the strongest direction.

Weft (Fill)

Fibres that run perpendicular to the warp fibres.

Bias

The fibre orientation running at a $45^{\circ}$ angle to the warp threads, allowing for manipulation into contoured shapes.

Selvage Edge

The edge of the fabric woven to prevent unravelling, which must be removed before the fabric is utilized.

Quasi-isotropic Lay-up

A stack of plies in sequences like $0^{\circ}$, $-45^{\circ}$, $45^{\circ}$, and $90^{\circ}$, resulting in constant strength regardless of loading direction.

Mats

Chopped fibres compressed together, typically used in the marine industry and not commonly used for aircraft repair.

Plain Weave

The simplest and most stable weave form, characterized by a high degree of crimp and low mechanical properties.

Twill Weave

A weave style providing superior wet-out and mechanical properties because of reduced crimp compared to plain weave.

Satin Weave

Modified twill weaves with fewer intersections that cover well and are often used for repairs.

Resin Matrix

The bonding material that surrounds reinforcing fibres and transfers stress to them.

Thermoplastic

A category of plastic that softens when heated and hardens when cooled, allowing it to be reshaped multiple times.

Thermosetting

A category of plastic that, once moulded or cured, cannot be reshaped or softened by reheating.

Pre-pregs

Fabrics pre-impregnated with the correct amount of resin by the manufacturer, often requiring cold storage.

Sandwich Composites

A construction consisting of a core bonded between two thin sheets, providing an extremely high strength-to-weight ratio.

Honeycomb

A common composite core construction, often made from aramid paper, chosen for its excellent strength-to-weight ratio.

PEEK (Polyetheretherketone)

A semi-crystalline organic polymer with an operating temperature up to $232\,^{\circ}\text{C}$ and excellent hydrolysis resistance.

Polyamide-imide (Torlon)

A plastic with high mechanical strength up to $260\,^{\circ}\text{C}$, often used in aircraft thrust reverser assemblies.

PTFE (Teflon)

A fluorocarbon polymer used as an electrical insulator for wires and cables due to high tear-resistance and low flammability.

Monolithic Plastic

Transparent plastic sheets manufactured in single solid uniform sheets.

Two-part Sealants

Compounds consisting of a base sealing compound and an accelerator that must be mixed to cure.

Application Time

The time in hours after thawing during which a sealant can be readily extruded from a gun and applied.

Squeeze-out Life

The time in hours after thawing during which a faying surface sealant can be squeezed out of a joint when fasteners are installed.

Tack-free Time

The time after thawing/application required for a sealant to cure enough that it doesn't transfer to a finger.

Anaerobic Adhesives

Adhesives that cure in the absence of oxygen and the presence of metal ions, used for thread locking and sealing.