1 02, 2018

Lightweight construction – a rethink, as seen in the example of modern shipbuilding

2018-11-07T13:56:02+00:00

Lightweight construction – a rethink, as seen in the example of modern shipbuilding.

 

The construction of the Eiffel Tower definitely established steel as the number one construction material. The era of wood, the oldest construction material of all, was over. From then on, buildings, machines and ships were made almost exclusively of steel. It would be almost 100 years until the industrialisation of plastics brought with it the use of fibre-reinforced materials. [1][2]

This came about because of the special properties of these materials. They are manufactured from so-called reinforcement fibres and a matrix that surrounds the fibres.

 

The four paradoxes of materials:

Depending on their structure, composite materials can take on particular properties. To understand why, we must consider the four paradoxes of materials.

1. The paradox of the solid material
The true solidity of a solid substance is considerably lower than that which is theoretically calculated (F. Zwicky).

2. The paradox of the fibre form
A material in fibre form is many times more solid than the same material in another form – and the thinner the fibre, the higher the solidity (A. A. Griffith).

3. The paradox of clamping length
The shorter the clamping length, the greater the measured solidity of a sample or fibre.

4. The paradox of composite materials
A composite material as a whole can accommodate stresses that would break the weaker components; meanwhile, a greater portion of the theoretical solidity of the stronger components in the composite can be carried over than would be possible if these elements were subjected to the same stresses on their own (G. Slayter).

THE AIM IS TO OBTAIN IMPROVED PROPERTIES BY COMBINING A DIVERSE REANGE OF MATERIALS INTO A COMPOSITE.

 

The aim is to obtain improved properties by combining a diverse reange of materials into a composite.

One major advantage is weight reduction.

One of the decisive benefits generated here is reduced weight combined with unimpaired solidity or rigidity [2]. Today, weight reduction is more vital than ever – that much is evident if we consider our environment and energy resources. Even before the Club of Rome published its first report, “The Limits to Growth” (1972), it was clear that changes would be necessary in the population’s energy consumption [3].

The environmental goals of the European Union plan for an 80% reduction in greenhouse gases and other emissions by 2050 (compared to 1990) [4]. However, one of the most prolific emitters of such gases continues to grow significantly year by year: the transport sector. Both people and goods are now being transported over greater distances than ever before. This accounts for around a third of the total energy expenditure in Europe [5].

Lower weight means lower emissions

Newton’s equation [6] “force = mass × acceleration” demonstrates that if we reduce mass while retaining the same acceleration, we will need less force. Or to put it another way: if we reduce a car’s weight while keeping the speed constant, it will require less fuel.

Cars, HGVs, buses and ships are under close scrutiny, and they have been since before the emissions scandal and people started using electric vehicles. If we consider how much weight has to be transported in addition to its passengers on average, it is clear where the potential lies. For combusion engines, each kilogram of weight means higher fuel consumption.

WHEN WE TRAVEL BY CAR, WE ARE MOVING APPROXIMATELY TEN TIMES OUR OWN BODY WEIGHT IN ADDITION. IF WE TAKE A CRUISE ON THE QUEEN MARY 2, AROUND 350 TIMES OUR OWN WEIGHT TRAVELS WITH US!

When we travel by car, we are moving approximately ten times our own body weight in addition. If we take a cruise on the Queen Mary 2, around 350 times our own weight travels with us!

The renaissance of composite materials.

Our modern transport systems are already lightweight affairs compared to older versions. But there is one thing both have in common: steel and other metals are the main construction materials. The opportunities for further weight reduction through sophisticated construction or the use of special steel have virtually been exhausted.

This is where the renaissance of composite materials begins. Glass-fibre-reinforced or carbon-fibre-reinforced polymers can be enormously versatile, and so too can their properties – unlike standard metallic materials such as steel.

“Lightweight yet highly solid” or “the possibility of load-appropriate construction” are a couple of key phrases that demonstrate the potential of such materials in comparison to steel. The list of positive properties is long, but well worth setting out:

– less weight while meeting the same requirements
– high design potential thanks to free-form surfaces
– no corrosion
– shock absorption
– integrated functionality [2]

However, in many instances, the benefits of composite materials are not yet being exploited at all. The shipbuilding sector is an example that highlights one of the major problems.

IN MANY INSTANCES, THE BENEFITS OF COMPOSITE MATERIALS ARE NOT YET BEING EXPLOITED AT ALL.

In many instances, the benefits of composite materials are not yet being exploited at all.

Why are composite materials not yet used extensively within the shipbuilding sector?

Every shipbuilding engineer is aware of composite materials – these “new” materials with their outstanding properties – but also of the challenges associated with them. These should not be underestimated, particularly in the shipbuilding sector – an industry characterised by large-scale projects whose construction and building times overlap, strict regulations from a UN institution and last but not least customers who expect a sophisticated ship that is ready for use on the day of delivery [7][8].

The use of composite materials is already well established in many sectors. There is no longer a need to develop the material or the processes. Rather, it is now a matter of transfer and adaptation [10].

The most common argument against composite materials is that they are more expensive than steel. But is this really the case? The argument is undercut by the benefits of lightweight contruction, by the lower maintenance expenditure required once the unit is operational and indeed by the ever-growing demands for efficiency and environmental balance. Equally, the opportunities are enormous. The ships currently being built in Germany and other parts of Europe demonstrate that customers are becoming increasingly concerned with individuality and design.

Naturally, composite materials are not the ultimate solution for every challenge, component or even ship. But where they do offer advantages, they should be used, thereby providing the customer with a convincing overall product.

IF WE LOOK AT THE SHIPS CURRENTLY BEING BUILT IN GERMANY AND OTHER PARTS OF EUROPE, WE CAN SEE THAT CUSTOMER DEMANDS ARE INCEASING IN RESPECT OF INDIVIDUALITY AND DESIGN.

If we look at the ships currently being built in Germany and other parts of Europe, we can see that customer demands are inceasing in respect of individuality and design.

Main cause of reticence – the prospective application. 

When using composite materials, there are a lot of deicions to make: how should I introduce the loads, what is the structure, which fibres should I use? However, it does not have to be as complex as it seems.

The steel sector too offers a large range of potential steel types for use in construction, but the industry has confined itself to a few types. The situation is similar when it comes to fibre composite materials. Frequently, optimisation down to the last detail is neither necessary nor sensible. What is far more important is to be aware of the advantages. There are in the meantime plenty of companies who have specialised in the construction and building of fibre composite products. These companies help engineers find the best solution.

Our contribution

HYCONNECT actively promotes the demonstration of possibilities and the development of solutions in respect of the use of composite materials. 

Our team menbers belong to lightweight construction networks [11], support the Work Group for the Restructuring of Construction Regulations in Shipbuilding [12] and advise shipyards on the use of composite materials.

ONLY BY EMBRACING A NEW ERA OF TECHNOLOGY AND MATERIALS CAN WE MAKE OUR TRANSPORT SYSTEMS FIT FOR TODAY’S EVOLVED DEMANDS.

 

Only by embracing a new era of technology and materials can we make our transport systems fit for today’s evolved demands.

Summary.

Rising expectations on the part of customers and the objectives of contemporary environmental policy mean a rethink is necessary. More and more, lightweight construction materials such as composite materials are taking centre stage. Wherever you turn, efforts are underway to boost the use of composite materials – even in conservative sectors like shipbuilding. Specialist companies are offering solutions for the challenges mentioned.
It is vital to embrace a new era of technology and materials if we are to make our transport systems fit for today’s evolved demands. Manufacturers aiming to hold their own in the market must learn to think more sustainably. From cars to ships to aircraft, lightweight construction is now one of the key factors. 

Bibliography and list of sources

[1] https://de.wikipedia.org/wiki/Stahl
[2] Faserverbundwerkstoffe Einführung – Suter-Kunststoffe AG
[3] https://www.nachhaltigkeit.info/artikel/entstehung_des_berichtes_541.htm
[4] https://ec.europa.eu/clima/policies/strategies/2050_de
[5] https://ec.europa.eu/eurostat/statistics-explained/index.php?title=Consumption_of_energy/de
[6] Principia Mathematica – Sir Isaac Newton – https://de.wikipedia.org/wiki/Newtonsche_Gesetze
[7] https://ec.europa.eu/growth/sectors/maritime/shipbuilding_en and https://www.maritime-executive.com/article/europes-shipbuilding-industry-under-threat#gs.saIwjAU
[8] https://www.wd-deo.gc.ca/eng/13785.asp and http://www.imo.org/en/About/conventions/listofconventions/pages/international-convention-for-the-safety-of-life-at-sea-(solas),-1974.aspx
[9] Aluminium im Schiffbau – Aluminium Zentrale Düsseldorf
[10] https://www.plastverarbeiter.de/71620/noch-viel-ungenutzes-potenzial-bei-faserverbundwerkstoffen/
[11] Maritimes Leichtbaunetzwerk E-Lass – www.e-lass.eu
[12] http://www.imo.org/fr/MediaCentre/MeetingSummaries/SDC/Pages/SDC-2.aspx

Lightweight construction – a rethink, as seen in the example of modern shipbuilding2018-11-07T13:56:02+00:00

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