Mushtaq 木塔

西

What is Composite Material? Any combination of two or more different

materials at the macroscopic level. OR

Two inherently different materials that when combined together produce a material with properties that exceed the constituent materials. ◦ Reinforcement phase (e.g., Fibers)◦ Binder phase (e.g., compliant matrix)

The use of natural composite materials has been a part of man's technology since the first ancient builder used straw to reinforce mud bricks.

Israelites' use of chopped straw in their brick

The Egyptian sarcophagi fashioned from glued and laminated wood veneer and also their use of cloth tape soaked in resin for mummy embalming

The Mongol warriors' high-performance, recurved archery bows of bullock tendon, horn, bamboo strips, silk and pine resin, which are 80% as strong as our modern fibreglass bows

Chinese bamboo rockets reinforced with rope wrappings

Japanese Samurai swords formed by the repeated folding of a steel bar back on itself

The early fabrication of steel and of iron gun barrels in Damascus

Roman artisans' use of ground marble in their lime plaster, frescoes and pozzolanic mortar.

Applications◦ Automotive ◦ Marine◦ Civil engineering◦ Space, aircraft and military◦ Sports

Classifications according to: Matrices

Polymer Thermoplastic Thermoset

Metal Ceramic Others

Classifications Fibers

Length short fiber reinforced continuous fiber reinforced

Composition Single fiber type Hybrid

Mechanical properties Conventional Flexible

◦ Advantages High strength to weight ratio High stiffness to weight ratio High fatigue resistance No catastrophic failure Low thermal expansion in fiber oriented

directions Resistance to chemicals and environmental

factors

◦ Disadvantages Good properties in one direction and poor

properties in other directions. High cost due to expensive material and

complicated fabrication processes. Some are brittle, such as carbon fiber reinforced

composites. Not enough data for safety criteria.

Mainly two components:◦ Fibers ◦ Matrices

Fibers Influences:

Specific gravity, Tensile and compressive strength and

modulus, Fatigue properties, Electrical and thermal properties, Cost.

Fibers◦ Fibers used in composites

Polymeric fibers such as PE (Spectra 900, 1000) PPTA: Poly(para-phenylene terephthalamide)

(Kevlar 29, 49, 149, 981, Twaron) Polyester (Vectran or Vectra) PBZT: Poly(p-phenylene benzobisthiozol)

◦ Fibers Inorganic fibers:

Glass fibers: S-glass and E-glass Carbon or graphite fibers: from PAN and Pitch Ceramic fibers: Boron, SiC, Al2O3 Metal fibers: steel, alloys of W, Ti, Ni, Mo etc.

(high melting temperature metal fibers)

Most frequently used fibers◦ Glass◦ Carbon/graphite◦ PPTA (Kevlar, etc.)◦ Polyethylene (Spectra)◦ Polyester (Vectra)

谢谢