What are the advantages and disadvantages of composite materials?
Understanding the advantages and disadvantages of composite materials is key - this article explains all there is to know as to why engineers may wish to consider using composite materials in their applications and processes.
But first, let's discuss exactly what composite materials are. They’re a blend of two or more base materials. One material is the matrix, or binder. It surrounds and binds together fibres or fragments of the other material, which is called the reinforcement.
By mixing these materials, manufacturers can get the best properties of each. One material might give you enhanced strength and durability, while the other offers moisture or corrosion resistance. Put them together and you can get the best of both worlds. Think thermoplastics, fibreglass, or cement, and you’ve got some examples.
The global composites market was USD $288 billion in 2014, and has been growing at around 15% to 20% a year. Here’s why:
Flexibility in design
Designers love composites for good reason. They can mould these materials into complex shapes far easier than most other materials. There’s no need for high-pressure tools, as composites form when the resin solidifies. This means composite parts can take on any shape the designer can dream of, and manufacture the product at any volume, high or low, using automated processes. Thermoset composites tend to be a popular material in these applications due to cost.
Lightweight
Compared to metals and woods, composites are lightweight, and important factor in the automotive and aerospace industries. Less weight equals better fuel efficiency. NASA and Boeing engineers are testing a composite cryogenic tank, used to carry fuel on deep space missions. The goal is to reduce the weight of rocket tanks by 30%, which could cut launch costs by 25%.
Strength
Composites have very high strength-to-weight ratios. The strength-to-weight ratio of any material is simply a comparison of its strength compared to its weight. Divide the strength by its density, and you have its specific strength.
By combining specific resins and reinforcements, you can create a composite material to meet specific strength demands of any application. For example, metals are equally strong in all directions. By changing the ratio of the resin or reinforcement, the composite can be engineered to offer strength in a specific direction.
Composites are especially useful in infrastructure applications, such as bridge decks.
Corrosion resistance
Throw harsh weather or chemicals at certain composites and they won’t corrode or rust. Composites can be tailored to stand up to acids, alkalis, fuels, hydraulic and brake fluids, paint strippers, lubricants, so many more chemicals. Many resin systems offer corrosion and temperature resistance, but you have fewer choices for reinforcement materials. The choice you make is vital in producing a composite material for chemical environments.
Because composites provide corrosion resistance, they’re often used in chemical manufacturing plants, for example, as glass-fibre reinforced polymer ductwork. You’ll also find composites in air-pollution control, mineral processing, mining, oil and gas, solid waste landfill and water treatment industries. Aerospace rely on composites not just because they’re lightweight, but because aircraft operates in very corrosive environments.
Durability
Metals are susceptible to fatigue. The Aloha Airlines disaster in the 1980s was the result of this. Quite simply, composites have a long life. Those composites we mentioned that are found in ductwork in chemical manufacturing plants? In some cases, they’re still doing their job after 25 years.
No one can say with any certainty what the lifespan of composites are. The reason: the first composites put to work more than 50 years ago are still going strong. For instance, the American classic, the Chevy Corvette, was built with fibre-reinforced plastic back in 1953. Then, 300 cars were produced. Two-thirds of them are still around today.
Construction is another industry that makes great use of composites. Entire homes can be framed using composites instead of traditional wood framing. By reducing the risk of rot or termite damage, they’re extending the structure’s life expectancy. Composites are especially popular with U.S. builders, where fibre-reinforced cement shingles give their customers a maintenance-free roof that lasts decades. Fibre-cement siding mimics the look of wood without the hassle of maintenance. These are just a few areas of a home that can take advantage of what composites have to offer.
Reduced maintenance
Perhaps this belongs under ‘Corrosion resistant’ and ‘Durability’, but it deserves its own distinction. The aerospace industry is a big fan of composites because they require less maintenance. Example: the composite tail of the Boeing 777 is 25% larger than their 767 aluminium tail. Yet the 777 needs 35% fewer scheduled maintenance hours, Boeing says.
Their 787 Dreamliner is the first plane with an airframe constructed mostly of composite materials. While the FAA grounded all 787s for a month back in 2013, this was due to problems with their lithium-ion batteries.
Good insulators
While we’re talking about the Aerospace industry, it’s worth noting another attraction to composites. They’re poor conductors of heat and electricity, which means they’re good insulators for parts that need insulating. But keep in mind, if you need thermally conducive parts, a material can be developed.
The cost of using composite materials explained:
There are low-cost composites, such as thermosets, but polymer composites are manufactured by a time-consuming process that slows down production rates. This makes whatever you’re manufacturing less cost-effective for high-production volumes. Another factor impacting costs: staff training is required for working with these advanced formulas and there are higher environmental and health issues at stake.
The long-term gains will have to be considered against the upfront costs. For instance, the aerospace industry uses fibre reinforced polymer composites (FRPs), but the fuel savings they get back in lighter aircraft make the investment well worth it. If your return on your investment doesn’t offset the cost, then it might be worth looking at a thermoset composite, depending on your application. Or, choose a more cost-efficient material that’s better suited for your application.
The disadvantages of composite materials
So, we have explained the advantages, but what about the disadvantages? Composite materials don’t break easily. While that sounds like an advantage – and it is – there’s a downside. How can you tell if the interior structure has been damaged? Repairs can be much more complex, which translates into higher costs.
Another problem: the resin used in composites weakens at temperatures of 150ᵒ, so aircraft, for example, have to take extra care to avoid fires. If temperatures reach above 300ᵒ, then we’re talking about structural failure. You should also know that fires involving composites release toxic fumes and micro-particles, creating health hazards.
Composite materials - the conclusion:
Like everything, you have to weigh the advantages against the disadvantages. If composite materials give you the properties you’re looking for, and are worth the trade-offs in terms of disadvantages, don’t hesitate to explore the possibilities.
Download free CADs and try before you buy
Free CADs are available for most solutions, which you can download for free. You can also request free samples to ensure the solutions you’ve chosen are exactly what you need. If you’re not quite sure which product will work best for your application, our experts are always happy to advise you.
Request your free samples or download free CADs now.
Questions?
Email us at sales@essentracomponents.co.uk or speak to one of our experts for further information on the ideal solution for your application 0345 528 0474.