Three reasons to wave goodbye to steel

Jon Lawson

Composite materials are not a new concept, but advancements in technology mean that these materials are beginning to surpass traditional building resources in popularity. Nick Cowley explains the advantages of choosing a composite over steel

According to discoveries by archaeologists, the earliest examples of composite materials were documented through ancient tomb paintings, illustrating the combination of straw and mud to build homes and other structures. Composite materials are certainly not a new concept, but technology advancements mean that the benefits these materials afford is seeing them surpass traditional building resources.

Lightweight and low cost

As a general rule of thumb, composite materials are significantly lighter than traditional alternatives. Glass reinforced plastic (GRP) composites, for example, are 80 percent lighter than steel and 30% lighter than standard aluminium. For the transportation, infrastructure and aerospace industries, this weight reduction can dramatically lower the cost of transportation and installation. The potential to ease the installation process may be music to the ears for many end users, but the benefits of lightweight composites go beyond this basic advantage.

Opting for a lighter alternative can generate long-term operational savings. For example, NASA and Boeing recently collaborated to develop the world’s lightest and largest composite cryogenic tank. The tank was created using lightweight composite materials and was designed to hold fuel on deep space missions - a positive step towards a NASA objective to reduce rocket launch costs by 2%.

The lightweight properties of composite materials can also assist in adhering to industry regulations and mean reduced health and safety hazards. Something that is 80% lighter than steel is much less likely to cause serious injury during installation if it were dropped while being moved.

Strong yet flexible

Humans have been combining materials to create stronger and denser compounds for years, so it comes as no surprise that composites have become the material of choice for modern aircrafts, civil structures and automobiles. However, compared to the ancient approach of combining mud and straw, today’s composites are increasingly complex and, in turn, much more flexible.

By combining specific resins and reinforcements, end users are able to meet the specific strength requirements of any application. For design engineers, this provides the flexibility to tailor the properties of the final product depending on what the product will be used for and the stress it is likely to be exposed to.

The specific strength of a material, also known as its strength-to-weight ratio, is a vital consideration during product design. Steel is indisputably strong, but in comparison to its heavy mass, the strength-to-weight ratio is relatively poor. As an alternative, engineers and designers are beginning to discard traditional heavy-duty metals and are choosing strong - but lightweight - alternatives instead, like GRP.

Composite materials also come out on top when measuring tensile strength. Tensile strength describes the amount of stress, damage or friction a material can withstand before it breaks, cracks or bends out of shape. Ultimately, the strength of composites can vary depending on its design factors, however, the tensile strength of a composite material can range up to 2,410 mega-pascals (MPa) compared to a disappointing 690 MPa for steel.

Durable with low maintenance

The popularity of steel came about due to its long-term durability. Admittedly, the long-term sturdiness of modern composites is slightly harder to estimate, as many modern composite structures in use are yet to reach the end of their lifespan.

For example, the first all-composite bridge in the United States was installed more than 20 years ago and has been in constant service ever since. Despite dealing with repeatedly applied loads, the bridge shows no sign of damage. Judging by this example and the low levels of wear on many other composite structures, it would appear that composite materials rival their metal predecessors for durability.

It is not only brute force that composite materials are able to withstand. Composites are also robust when dealing with adverse weather conditions. Unlike metal, composites will not warp, shrink or rust. They also hold up well against environmental factors like UV damage, temperature changes and chemical exposure. Composites are unlikely to suffer from unexpected damage and as a result, require virtually no upkeep, keeping maintenance costs to a minimum.

The technological advancements of composite materials have come a long way since the straw and mud used by the ancient Egyptians. However, the advantages of this manufacturing concept have remained the same; taking the individual benefits of a number of different materials to create a superior product.

Nick Cowley is country manager of composite technology specialist, MCL Group.

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