4.2f Composites

Nature and Aims of Design

Nature of Design

Composites are an important material in an intensely competitive global market. New materials and technologies are being produced frequently for the design and rapid manufacture of high-quality composite products. Composites are replacing more traditional materials as they can be created with properties specifically designed for the intended application. Carbon fibre has played an important part in weight reduction for vehicles and aircraft. (2.2)

Aims

Aim 1: As designers develop new products, they should always be aware of the materials available. In an effort to increase productivity and lose weight, carbon fibre parts are often glued together. The use of an epoxy adhesive rather than traditional fastening methods allows manufacturers to create complex shapes quickly and easily. These materials and methods are being transferred to consumer products.

Guidance

As DP Design Technology student you should:

Concepts and principles:
Form: fibers/sheet/particles and matrix
Process: weaving, moulding, pultrusion and lamination
Composition and structure of composites: concrete, engineered wood, plywood, particleboard, fibreglass, Kevlar®, carbon-reinforced plastic, laminated veneer lumber (LVL)

Guidance:

Fibers/sheets/particles: textiles, glass, plastics and carbon
Matrix: thermoplastics, thermosetting plastics, ceramics, metals
Advantages and disadvantages of composite materials
Design contexts in which different types of composite materials are used

4.2a Metals & Alloys

4.2d Plastics

4.2b Timber

4.2e Textiles

4.2c Glass

4.2f Composites

Concepts and Principles

New materials and technologies are being produced frequently for the design and rapid manufacture of high-quality composite products. Composites are replacing more traditional materials as they can be created with properties specifically designed for the intended application. Carbon fibre has played an important part in weight reduction for vehicles and aircraft

Composite materials consist of two parts: a fiber, sheet, or particles, and a matrix (glue). The matrix holds all the fibers, sheets or particles together.

Common types of materials in composites include fibers, textiles, glass, plastic, wood, and carbon,

The matrix can be a type of thermoset or thermoplastic, concrete, or metal. Epoxy, a type of plastic, is also a common matrix (used in the manufacture of fiberglass and carbon fiber)

Manufacturing processes for composite materials include weaving, moulding, or lamination.

Form

Fiber

Fibers can be spun into threads, yarns, ropes, or strings. These can then be woven to create sheets or fabrics.

Fibers that are combined with a resin can overcome the limitations of the fiber by itself. For example, carbon fiber, when combined with a resin, becomes very strong and light.

Fibers can be added to concrete to increase the structural integrity of the material.

carbon fiber fabric

Carbon fiber elevator cables

Read about how KONE elevators uses this composite in its elevator installations.

Pultruded carbon fiber cables in an elevator shaft (KONE)

Sheet

Materials can be laminated or layered to create a composite material with unique properties. Laminated glass is one such example. See the 4.2c Glass section for more details.

Particle

Particles can be added to a composite mixture to provide unique properties.

In general, particles add little strength to a material, but can have a influence on properties such as hardness and durability.

Concrete is an example of composite made up of different particles.

Tungsten carbide particles can be mixed into a softer matrix to create hard materials for cutting.

particle board

concrete

Matrix

Matrix refers to the "glue" that binds particles and fibers together. It is typically a liquid that becomes hardened through a chemical reaction.

Glass fiber uses an epoxy resin to harden and give it form.

Carbon fiber sheets, similar in form to glass fiber sheets, are hardened with a resin.

For complex shapes, carbon fiber can be quite challenging to manufacture.

Process

Weaving

Weaving is used to produce carbon fiber and glass fiber sheets.

Depending on the application, these sheets may then be used in moulding process (see below).

In bicycle manufacturing, carbon fiber has become the leading material for its high strength and low weight.

Design Context:

Carbon Fiber applications
Kevlar®
carbon-reinforced plastic

Moulding

Composites can be formed into moulds. For woven materials, the sheet would be applied in a form and then resin added.

Design Context

fiber glass

Pultrusion

Pultrusion is the opposite of extrusion: the composite material containing fibers is pulled through a former.

Design Context

Carbon Fiber Cables (See above)

Lamination

Lamination involved the laying down of sheets, with a matrix between them. Plywood is a common example of this, where thin sheets are laid at right-angles to each other and bonded together with glue.

Design Context

plywood
formica
engineered wood
laminated veneer lumber (LVL)

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