AMAT`CONREP PPT 1 (Midterm)

Aircraft Materials, Construction and Repair (Aircraft Metals)

Aircraft Structure

must be strong, lightweight, streamlined, and durable.

Wooden Monocoque Design

does provide a streamlined from with high strength, but with compromise due to the limited useful life of wood, as well as the high cost involved with fabric-catting a laminated wood structure.

Riveted or Bonded sheet

Today, the high volume of aircraft production has caused _________ or _________ designs to become the most common method of construction.

Aluminum Alloys

most widely used metal used for aircraft structures which account for as much as 90 % of the metals used for civil aircraft.

Heat-treated aluminum alloys

have the advantage of being lightweight with the ability to carry high structural loads, while being comparably inexpensive with regard to other similar strength metals.

titanium, stainless steel, and assorted exotic metals

These assets make aluminum alloy an excellent choice to use for the construction of most modern civil aircraft. The remaining 10% of metals used include _________, _________ and _________ that are predominantly used on military or large transport category aircraft.

Monocoque and Semi-Monocoque

What are the two basic types of sheet metal structures used for aircraft

Monocoque Construction

It is a structural system where loads are supported through an object’s external skin. It can support a large load if a force is applied evenly across the containers. Its downside is that with a small dent or crease in a side wall can destroy its ability to support load.

Semi-monocoque Construction

It refers to a stressed shell structure that is similar to a true monocoque, but which derives at least some of its strength from conventional reinforcement.

Semi-Monocoque airframe

It utilizes stringers and longerons to add rigidity and strength to the structure.

Hardness

Refers to the ability of a material to resist abrasion, penetration, cutting action, or permanent distortion. It may be increased by cold working the metal and, in the case of steel and certain aluminum alloys, by heat treatment.

Strength

It is the ability of the material to resist deformation and resist stress without breaking.

Density

It is the weight of a unit volume of a material. In aircraft work, the specified weight of a material per cubic inch is preferred since this figure can be used in determining the weight of a part before actual manufacture.

Malleability

A metal which can be hammered rolled, or pressed into various shapes without cracking, breaking, or leaving some other detrimental effect.

Ductility

It is the property of a metal which permits it to be permanently drawn, bent, or twisted into various shapes without breaking. This property is essential for metals used in making wire and tubing.

Elasticity

It is that property that enables a metal to return to its original size and shape when the force which causes the change of shape is removed. This property is extremely valuable because it would be highly undesirable to have part permanently distorted after an applied load was removed.

Toughness

A material which possesses toughness will withstand tearing or shearing and may be stretched or otherwise deformed without breaking. This is known to be desirable in aircraft metals.

Brittleness

Is the property of a metal which allows little bending or deformation without shattering. It is apt to break or crack without change of shape.

Fusibility

It is the ability of a metal to become liquid by the application of heat.

Conductivity

Is the property which enables a metal to carry heat or electricity.

Thermal Expansion

Refers to the contraction and expansion that are reactions produced in metals as the result of heating or cooling

Ferrous Metal

any alloy containing iron as its chief constituent.

Non-ferrous Metal

much of the metal used on today’s aircraft contains no iron. The term that describes metals which have elements other than iron as their base is _________.

Iron

It is a chemical element which fairly soft, malleable, and ductile in its pure form. It combines readily with oxygen to form iron oxide, which is more commonly known as rust.

rust

It is when iron is combine with oxygen to form Iron Oxide

Iron Oxide

also known as rust

Steel

pig iron is remelted in a special furnace. Pure oxygen is then forced through the molten metal where it combines with carbon and burns. A controlled amount of carbon is then put back into the molten metal along with other elements to produce the desired characteristics.

Pig Iron

What is reheated on a special furnace when making steel.

Carbon

The greater its content. the more receptive steel is to heat treatment and, therefore, the higher its tensile strength and hardness. However, higher carbon content decreases the malleability and weldability of steel.

Sulfur

causes steel to be brittle when rolled or forged and, therefore, it must be removed in the refining process. If this element cannot be removed its effects can be countered by adding manganese.

Phosphorus

raises the yield strength of steel and improves low carbon steel’s resistance to atmospheric corrosion.

Nickel

adds strength and hardness to steel and increases its yield strength. It also slows the rate of hardening when steel is heat-treated, which increases the depth of hardening and produces a finer grain structure.

Chromium

It is alloyed with steel to increase strength and hardness as well as improve its wear and corrosion resistance.

Society of Automotive Engineers (SAE)

An organization that has established standards for materials and processes that are widely use din aviation industry.

Aerospace Recommended Practices

are recommendations for engineering practice, and Aerospace Information Reports contain general accepted engineering data and information.

Carbon Steels

SEA Classification of Steel : 1XXX

Nickel Steels

SEA Classification of Steel : 2XXX

Nickel-Chromium Steels

SEA Classification of Steel : 3XXX

Molybdenum Steels

SEA Classification of Steel : 4XXX

Chromium Steels

SEA Classification of Steel : 5XXX

Chromium-vanadium Steels

SEA Classification of Steel : 6XXX

Tungsten Steels

SEA Classification of Steel : 7XXX

Nickel-Chromium-Vanadium Steels

SEA Classification of Steel : 8XXX

Silicon-Manganese Steels

SEA Classification of Steel : 9XXX

Aluminum

It is vital to the aviation industry because of its high strength to weight ratio and its comparative ease of fabrication.

Pure Aluminum

is light weight and corrosion resistant, but it lacks strength for use as a structural material.

Four Digit Index System

Aluminum and aluminum alloys are designated by a _______________ which is broken into three distinct groups: 1XXX group, 2XXX through 8XXX group. and 9XXX group (which is currently unused)

Aluminum

Wrought Alloy Designation System: 1XXX

Copper

Wrought Alloy Designation System: 2XXX

Manganese

Wrought Alloy Designation System: 3XXX

Silicon

Wrought Alloy Designation System: 4XXX

Magnesium

Wrought Alloy Designation System: 5XXX

Magnesium and Silicon

Wrought Alloy Designation System: 6XXX

Zinc

Wrought Alloy Designation System: 7XXX

Other Elements

Wrought Alloy Designation System: 8XXX

1100

99\.00 percent pure aluminum with one control over individual impurities.

1130

99\.30 percent pure aluminum with one control over individual impurities.

1275

99\.75 percent pure aluminum with two control over individual impurities.

Wrought Aluminum

has exceptional mechanical properties and can be formed into various standard and nonstandard shapes.

\-is when the metal is worked in the solid form with the help of specific tools.

Cast Aluminum

contains larger percentages of alloying elements when compared to wrought aluminum. It also has a generally lower tensile strength than rough aluminum due to the difficulty in eliminating casting defects. It is the resulting product created after molten aluminum is poured into a mold.

Titanium and titanium Alloy

has high structural strength which it retains to high temperature. It is used in turbine engines, and for aircraft skins in areas where the temperature is high.

A-B-C classification of titanium alloys

were established to provide a convenient and simple mean of describing all titanium alloys.

A(alpha), B(Beta), and C(combined alpha and beta)

Titanium and Titanium alloys possess three basic types of crystals.

A (Alpha)

all around performance; good weldability; tough and strong both cold and hot, and resistant to oxidation.

B (Beta)

bendability; excellent bend ductility; strong both cold and hot, but vulnerable to contamination.

C (combined alpha and beta for compromise performances)

Strong when cold and warm, but weak when hot; good bendability; moderate contamination resistance; excellent forgeability.