Question

Advantages and disadvantages of polymers for aerospace applications

Answer 1

ADVANTAGES

Light Weight - Composites are light in weight, compared to most metals. Their lightness is important in aircraft, where less weight means better fuel efficiency (more miles to the gallon).

Strength Related to Weight - Strength-to-weight ratio is a material’s strength in relation to how much it weighs. Some materials are very strong and heavy, such as steel. Composite materials can be designed to be both strong and light. This property is why composites are used to build airplanes—which need a very high strength material at the lowest possible weight.

Corrosion Resistance - Composites resist damage from the weather and from harsh chemicals that can eat away at other materials. Outdoors, they stand up to severe weather and wide changes in temperature.

Design Flexibility - Composites can be molded into complicated shapes more easily than most other materials. This gives designers the freedom to create almost any shape or form.

Part Consolidation - A single piece made of composite materials can replace an entire assembly of metal parts. Reducing the number of parts in a machine or a structure saves time and cuts down on the maintenance needed over the life of the item.

Dimensional Stability - Composites retain their shape and size when they are hot or cool, wet or dry. They are used in aircraft wings, for example, so that the wing shape and size do not change as the plane gains or loses altitude.

Radar Transparent - Radar signals pass right through composites, a property that makes composites ideal materials for use anywhere radar equipment is operating, whether on the ground or in the air. Composites play a key role in stealth aircraft, such as the U.S. Air Force’s B-2 stealth bomber, which is nearly invisible to radar.

Durable - Structures made of composites have a long life and need little maintenance. We do not know how long composites last, because we have not come to the end of the life of many original composites. Many composites have been in service for half a century.

DISADVANTAGES

Delamination - Since composites are often constructed of different ply layers into a laminate structure, they can "delaminate" between layers where they are weaker.

High Cost - They are a relatively new material, and as such have a high cost.

Complex Fabrication - The fabrication process is usually labor intensive and complex, which further increases cost.

Damage inspection - Delamination and cracks in composites are mostly internal and hence require complicated inspection techniques for detection.

Composite to metal joining - Metals expand and contract more on variations in temperature as compared to composites. This may cause an imbalance at joinery and may lead to failure.

Barring for the few disadvantages, composite materials are an almost perfect material for aircraft and fulfill most of the structural requirements. With further research progress in composite material damage control, the existing problems could also be controlled.