What are the advantages and disadvantages of Composite Materials?
Advantage of composites
Composite materials posses a wide variety of features that makes it reliable when compared with metals.
Below are some of the most important features of composites, and the benefits they provide
Composites are incredibly lightweight, especially in comparison to materials like concrete, metal, and wood. Often a composite structure will weigh 1/4 that of a steel structure with the same strength. That means, a car made from composites can weigh 1/4 that of a car made from steel. This equates to serious fuel savings.
Composite materials are extremely strong, especially per unit of weight. An example of this are the high tenacity structural fibers used in composites such as Aramid and S-Glass, which are widely used in body armor. Due to high strength composites, soldiers are well protected from blast and ballistic threats.
Corrosion and Chemical Resistance
Composites are highly resistant to chemicals and will never rust or corrode. This is why the marine industry was one of the first to adopt the use of composites. Boats made with fiberglass can stay in the highly corrosive salt water without rusting.
Fiber reinforced composites have excellent elastic properties. When one bends metal, it will yield or dent. However, when composites are bent, they want to naturally snap back into place. This feature is ideal for springs, and is why composites are used in car leaf springs and in the limbs of archery bows.
Certain composites, such as composite made with fiberglass, are non-conductive. This is important because often a structure is needed that is strong, yet will not conduct electricity. An example of this is ladders. Aluminum ladders can be an electrocution hazard, while ladders made with fiberglass are not a risk if the ladder was to cross a power line.
dvantage of composites
Even though composites have distinct features over metals, they do have few limitations or drawbacks. So the drawbacks or limitations in use of composites include
High cost of fabrication of composites is a critical issue. For example, part made of graphite/epoxy composite may cost up to 10 to 15 times the material costs. A finished graphite/epoxy composite part may cost as much as $300 to $400 per pound ($650 to $900 per kilogram). Improvements in processing and manufacturing techniques will lower these costs in the future.
Complex Repair Procedure
Repair of composites is not a simple process compared to that for metals. Sometimes critical flaws and cracks in composite structures may go undetected.
Mechanical characterization of a composite structure is more complex than that of a metal structure. Unlike metals, composite materials are not isotropic, that is, their properties are not the same in all directions. Therefore, they require more material parameters. For example, a single layer of a graphite/epoxy composite requires nine
stiffness and strength constants for conducting mechanical analysis. In the case of a monolithic material such as steel, one requires only four
stiffness and strength constants. Such complexity makes structural analysis computationally and experimentally more complicated and intensive. In addition, evaluation and measurement techniques of some composite properties, such as compressive strengths, are still being debated.