Advantages and Disadvantages of Composites

Composite parts have both advantages and disadvantages when compared to the metal parts they are being used to replace.

Advantages of Composites

1. A higher performance for a given weight leads to fuel savings. Excellent strength-toweight and stiffness-to-weight ratios can be achieved by composite materials. This is usually expressed as strength divided by density and stiffness (modulus) divided by density. These are so-called "specific" strength and "specific" modulus characteristics.

2. Laminate patterns and ply buildup in a part can be tailored to give the required mechanical properties in various directions

3. It is easier to achieve smooth aerodynamic profiles for drag reduction. Complex double-curvature parts with a smooth surface finish can be made in one manufacturing operation.

4. Part count is reduced.

5. Production cost is reduced. Composites may be made by a wide range of processes.

6. Composites offer excellent resistance to corrosion, chemical attack, and outdoor weath- ering;however,some chemicals are damaging to composites(e.g.,paintstripper),and new types of paint and stripper are being developed to deal with this. Some thermoplastics are not very resistat to some solvents. Check the data sheets for each type

Disadvantages of Composites

1. Composites are more brittle than wrought metals and thus are more easily damaged. Cast metals also tend to be brittle.

2. Repair introduces new problems, for the following reasons: Materials require refrigerated transport and storage and have limited shelf lives. . Hot curing is necessary in many cases, requiring special equipment. Curing either hot or cold takes time. The job is not finished when the last rivet has been installed.

3. If rivets have been used and must be removed, this presents problems of removal without causing further damage.

4. Repair at the original cure temperature requires tooling and pressure.

5. Composites must be thoroughly cleaned of all contamination before repair.

6. Composites must be dried before repair because all resin matrices and some fibers absorbmoisture.

Reference: http://www.ae.metu.edu.tr/~ae469/Advantages%20and%20Disadvantages%20of%20Composite%20Materials_Resin%20Systems.pdf