Transcript Composite materials – Introduction

Composite Materials
Manufacturing
정분방
Introduction

Definition: a material composed of 2 or more
constituents



Reinforcement (e.g., Fibers)
matrix (e.g.,epoxy)
Advantages




High strength and stiffness
Low weight ratio
Material can be designed in addition to the structure
Can manufacture structures and eliminate joints
Applications




Aerospace industry
Sporting goods
Automotive
Construction
Costs of composite manufacture

Material costs -- higher for composites



Constituent materials (e.g., fibers and resin)
Processing costs -- embedding fibers in matrix
Design costs -- lower for composites

Can reduce the number of parts in a complex assembly by
designing the material in combination with the structure
Material Forms and manufacturing

Objectives of material production




assemble fibers
impregnate resin
shape product
cure resin
Sheet Molding Compound (SMC)

Chopped glass fiber added to polyester resin
mixture
Manufacturing - Filament Winding

Highly automated



low manufacturing costs if
high throughput
e.g., Glass fiber pipe,
sailboard masts
the only manufacturing
technique suitable for
making certain specialized
structures, such as
pressure vessels.
Prepregs

Prepreg and prepreg layup

“prepreg” - partially cured mixture of fiber and
resin

Unidirectional prepreg tape with paper backing



wound on spools
Cut and stacked
Curing conditions

Typical temperature and pressure in autoclave is 120200C, 100 psi
Manufacturing - Layups
compression
molding
vacuum bagging
Autoclave
Limitations
labor intensive, high
labor cost
Advantages
good for building prototype
parts and small quantity runs
Resin transfer molding (RTM)

Dry-fiber preform placed in a closed mold, resin
injected into mold, then cured

High cost, tooling design is complex
Manufacturing - Pultrusion


Fiber and matrix are pulled through a die, like extrusion
of metals -- assembles fibers, impregnates the resin,
shapes the product, and cures the resin in one step.
Example:Fishing rods
Advantages:
simple low-cost, continuous, and automatic process.
Limitations:
the axial direction, fiber angles 0°, not suit for tapered
and complex shapes
Pultrusion

Thank
you