Page 237 - 04. Subyek Engineering Materials - Manufacturing, Engineering and Technology SI 6th Edition - Serope Kalpakjian, Stephen Schmid (2009)

Composite Materials:

Structure, General

Properties, ancl

Applications

9.I lntroduction 2l6 ° With their attractive properties-especially high strength-to-weight and stiffness-
9.2 The Structure of
Reinforced Plastics 2l7 to-vveight ratios-reinforced plastics and composites are among the most
9.3 Properties of Reinforced important engineered materials.
Plastics 222 ° Composites are Widely used as structural components, especially in the aero-
9.4 Applications of
Reinforced Plastics 225 space industry, Where weight savings are a major consideration.
9.5 Metal-matrix ' This chapter describes the major types of composite materials, the characteris-
Composites 227 tics of the commonly used reinforcing fibers, and their effect in improving
9.6 Ceramic-matrix
Composites 229 mechanical properties.
9.7 Other Composites 230 ' The role of the matrix is then described, and the three principal classes of
EXAMPLES: matrix materials (plastic, metal, and ceramic) are examined.
9.I Calculation of Stiffness of ° The chapter ends with a discussion of the selection and applications of a
a Composite and Load variety of reinforced plastics and composites.
Supported by Fibers 225
9.2 Composite Military
Helmets and Body
Armor 226 9.| Introduction
9.3 Aluminum-matrix
Composite Brake A composite material is a combination of tvvo or more chemically distinct and insol-
Calipers 228
9.4 Composites in the Aircraft uble phases with a recognizable interface, in such a manner that its properties and
lndustry 230 structural performance are superior to those of the constituents acting independently.
These combinations are known as metal-matrix and ceramic-matrix composites. As
shown in Table 7.1, fiber reinforcements significantly improve the strength, stiffness,
and creep resistance of plastics-particularly their strength-to-weight and stiffness-
to-Weight ratios. Composite materials have found increasingly Wider applications in
aircraft (Fig. 9.1), space vehicles, satellites, offshore structures, piping, electronics,
automobiles, boats, and sporting goods.
The oldest example of composites, dating back to 4000 B.C., is the addition of
straw to clay to make bricks for buildings. In this combination, the straws are the re-
inforcing fibers and the clay is the matrix. Another example of a composite material
is reinforced concrete, which was developed in the 18005. By itself, concrete is brit-
tle and has little or no useful tensile strength; reinforcing steel rods (rebar) impart
the necessary tensile strength to the composite.
Composites, in the most general sense, can be thought of as a wide variety of
materials, such as cermets (Section 82), tvvo-phase alloys (Section 4.2), natural
materials such as Wood and bone, and general reinforced or combined materials

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