Understanding the uses, strengths and
limitations of structural metals is essential for proper construction and
maintenance of equipments, particularly air components. For maintenance and
repair of aircraft components, a nominal difference from required design or
using lower quality materials may cause loss of lives and equipments. Using
unsuitable materials can affect the craftsmanship. Choosing right material for
a required repair job needs the knowledge of physical properties of the
different metals.
Crucial properties of aircraft materials
a.
Hardness- It describes an
ability of a material to prevent abrasion, penetration, cutting and physical distortion.
Hardness can be increased by cold processing the material, for steel, heat
processing is required. Structural components are usually made from materials
in the soft form and are heat treated to harden to retain a finished shape.
Hardness and strength are closely related to each other.
b.
Strength- The essential
characteristics of a material is strength. Strength is the potential of a
material to prevent deformation. It is also a potential of a material to
prevent stress without cracking. The load or stress type affects the strength
it attains.
c.
Density- It describes the
weight of a material per unit of volume. In aerospace, the specific weight of a
material per unit volume is recommended as this property is used in measuring
the weight of a component before its production. Density is a crucial property
while choosing a material for use in the design of a component to maintain the
required weight and aircraft balance.
d.
Malleability- A metal that can
be hammered, rolled or pressed in different shapes without cracking, breaking
and leaving any other rigorous effect is called malleable. Malleability is an
essential property of a sheet metal that is formed in curved shapes like
cowlings, fairings etc. Copper is a common malleable metal.
e.
Ductility- It is a characteristic
of a metal that allows it to be fully drawn, bent or twisted in different
shapes without cracking. It is an important property of a metal that is used in
producing wire and tubes. Ductile metals are widely used in the production of
aircrafts for their easy forming and resistance to damage under shock loads.
Therefore aluminum alloys are used for cowl rings, fuselage and wing skin and
developed or extruded components like ribs, spars and bulkheads. Chome based
steel is easily produced in required shapes. Ductility and malleability are
similar properties of a metal.
f.
Conductivity- It is a property
that allows a metal to conduct heat or electricity. The heat conductivity of a
metal is essential in welding because it allows the magnitude of heat that will
be needed for complete fusion. Metal conductivity to a specific limit shows the
jig type to be used to limit expansion and contraction. In aircraft, electrical
conductivity is considered in addition of bonding to prevent radio
interference.
g.
Thermal expansion- It descries
contraction and expansion occurred in metals due to heating and cooling. Heat
given to a metal results into its expansion. Cooling and heating create a
negative effect on the design of welding.
Aircraft materials
Commonly used metals in the production of
aircraft components are Titanium, aluminum, alloy Inconel bar, ferrous
metals etc.
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