Composites

Composites

are engineered by combining two or more materials with different forms or compositions to achieve superior properties that are not attainable by the individual constituents alone.

Matrix

is the continuous phase in a composite that surrounds and binds the reinforcement or filler. It can be a metal, polymer, or ceramic.

• Bind the reinforcement or fillers together

• Transfer load between the reinforcement and itself, provided there is good interfacial bonding

matrix functions

Reinforcement or fillers

the discontinuous phase in a composite and serve as property modifiers.

Metal Matrix Composites (MMCs)

Use metals as the matrix (e.g., non-stick pans).

Ceramic Matrix Composites (CMCs)

Use ceramics as the matrix to improve toughness (e.g., ceramic brake rotors).

Polymer Matrix Composites (PMCs)

Use polymers as the matrix, often with fiber reinforcement.

Particle-Reinforced Composites

Use small particles as the reinforcement.

Fiber-Reinforced Composites

Use strong, stiff fibers embedded in a softer, ductile matrix. The aspect ratio (length/diameter) of fibers is typically greater than 100.

Structural/Laminar Composites

Include sandwich panels and laminates, where layers of materials are bonded together.

Natural Fibers

Naturally occurring, often lower cost, and can replace synthetic fibers (e.g., abaca fibers).

Synthetic Fibers

Man-made fibers such as glass fibers.

Law of mixtures

Used to predict the mechanical properties (like modulus of elasticity and strength) of composites based on the properties and volume fractions of the matrix and reinforcement.

Sandwich Panels

Consist of a lightweight core material sandwiched between two stiff face sheets, offering high stiffness-to-weight ratios.

Wood Composites

is a naturally occurring fiber-reinforced composite and is highly anisotropic, meaning its properties vary in different directions (radial, longitudinal, tangential).

Laminates

Layers of materials joined by adhesives to combine their properties.

Reinforced Concrete

Uses steel, glass, or natural fibers as reinforcement to improve tensile and shear strength.

Anisotropy

Property variation in different directions, common in composites like wood.

Volume Fraction

The proportion of the composite occupied by each phase (matrix or reinforcement).

Load Transfer

The process by which stress is distributed between the matrix and the reinforcement.

Concrete

a ceramic-ceramic composite consists of portland cement, fine and coarse aggregate

Rubber tires

Carbon-polymer composite that enhances tensile strength, toughness, tear and abrasion resistance and thermal stability of rubber

Sandwich panels

consist of two strong outer sheets separated by a layer of less dense material or core which has lower stiffness and strength