AVI-111 Aircraft Materials - Lesson 12: Introduction to Composite Materials

Vocabulary practice flashcards covering terminology, structural forms, fiber classifications, and properties of advanced composite materials from Lesson 12 of Aircraft Materials (AVI-111).

Composite Material

A material formed by combining two or more distinct constituents that remain physically identifiable, engineered to produce structural properties superior to those of the individual components.

Fiber Reinforcement

The primary structural constituent in a composite material that provides most of the tensile strength and stiffness.

Matrix

The polymer or resin constituent that surrounds and binds reinforcing fibers, transfers applied loads between them, maintains fiber alignment, and provides environmental protection.

Core Material

A lightweight central structure (such as honeycomb, structural foam, or balsa wood) placed between face sheets to increase bending stiffness and resistance without adding excessive mass.

Laminated Structure

A composite structural configuration constructed from multiple plies or layers of fiber reinforcement bonded together in selected orientations.

Sandwich Structure

A structural assembly consisting of two thin, stiff composite face sheets bonded to and separated by a thick, lightweight core material.

Isotropic Material

A material, such as aluminum or titanium, that exhibits identical mechanical and physical properties in all directions.

Anisotropic Material

A material, such as a fiber-reinforced composite laminate, whose mechanical properties vary depending on the direction of applied load and fiber orientation.

Unidirectional Material

A composite reinforcement format where all fibers are parallel in a single direction, offering maximum tensile strength along the fiber axis and virtually no strength across it.

Bidirectional Material

A woven fabric composite featuring fibers oriented along two perpendicular directions, offering strength across both axes though not necessarily equally.

Quasi-isotropic Layup

A composite laminate stacking sequence combining plies at multiple angles (such as $0^\circ$, $90^\circ$, and $\pm 45^\circ$) to simulate isotropic mechanical behavior in all in-plane directions.

Warp Clock

A directional reference diagram used on engineering drawings to designate the orientation angles of individual composite plies.

Filament

A single continuous strand of fiber that serves as the basic individual element of a composite reinforcement.

Tow

An untwisted bundle of continuous filaments gathered together into a strand, also termed a yarn or roving.

Roving

A bundle of continuous, parallel filaments oriented in the same direction without any twist.

Prepreg

A ready-to-mold reinforcing fabric or tape pre-impregnated with a thermosetting resin that requires elevated heat and pressure to fully cure.

Plain Weave

A bidirectional fabric construction where each warp fiber alternates over and under each intersecting fill fiber strand.

Satin Weave

A fabric weave style where warp bundles float over multiple fill strands before interlacing, yielding high flexibility and drapability over compound curves.

Nonwoven Fabric

A multi-axial reinforcing material in which straight, parallel fiber plies are stitched together with fine yarns rather than interlaced or woven.

Whiskers

Tiny, elongated crystalline reinforcing structures that are longer than they are wide, used as discontinuous reinforcement in composite matrices.

E-glass

An electrical-grade fiberglass formulation that provides high resistance to current flow, commonly used in non-structural aircraft parts and radomes.

S-glass

A high-tensile-strength structural fiberglass developed specifically for demanding structural applications.

Kevlar®

A DuPont brand of yellow aramid synthetic fiber known for exceptional tensile strength, lightness, and impact resistance, but prone to moisture absorption and weak in compression.

Kevlar® 49

A high-stiffness grade of aramid fiber widely utilized in aerospace structural components.

Kevlar® 29

A lower-stiffness, highly tough grade of aramid fiber commonly used in military ballistic protection and body armor.

Carbon Fiber

A high-strength, high-stiffness reinforcement with a two-dimensional hexagonal graphene structure, appearing gray or black in color.

Graphite Fiber

A specialized carbon reinforcement produced through extensive thermal processing to create an ordered three-dimensional crystalline lattice, making it stiffer and more expensive than standard carbon fiber.

Galvanic Corrosion

An accelerated electrochemical degradation process that occurs when carbon fiber composite laminates are placed in direct electrical contact with metallic fasteners in the presence of moisture.

Boron Fiber

An exceptionally stiff, high-strength fiber with high tensile and compressive properties, primarily used in military aerospace applications due to high cost and hazardous handling.

Ceramic Fiber

A high-temperature-resistant reinforcement capable of operating at temperatures up to $2\,200\,^\circ\text{F}$, such as in gas turbine engine turbine blades.

Lightning Protection Layer

A conductive outer layer (such as nickel-coated graphite cloth, metal mesh, or conductive paint) applied to composite structures to dissipate high-current lightning strikes.