Thermoplastic composites support hyper-speed travel
In the not-so-distant future, people looking for the fastest way to get from point A to B might skip the airport check-in counter all together – and hop on a high-speed train. High-speed travel still faces many challenges. But with some help from advanced materials, rail cars could soon learn how to fly.
The Hyperloop is a network of sealed tubes with rolling (or in this case “hovering”) stock in the form of “pods” or capsules. The tubes are depressurized to eliminate drag forces so the pods might reach speeds of around 750 mph (1,207 km/h) with very little power. In other words, the Hyperloop turns the table on planes and makes trains the superior alternative for high-speed travel.
The Hyperloop could bring several advantages. In the face of rising fuel prices, it presents an affordable alternative to car or plane travel. Because it requires significantly less power, the Hyperloop would also be an environmentally sustainable form of travel. One capsule model even features solar paneling on its roof.
With a glance at the global players, China has surpassed Japan to become the world’s largest HSR network, totaling over 29,000 km (18,000 mi). Nearly half of those tracks consist of “bullet train” routes operating in excess of 250km/h. The country has also adopted a forerunner role in the development of hyperloop tech. The China Aerospace Science and Industrial Corporation (CASIC) has announced plans to build its supersonic T Flight system of “flying trains” which would take the Hyperloop one step further and, in theory, reach top speeds of over 2,300 mph (3,701 km/h) – or almost four times the speed of a passenger jet. Whether they go by the name of super-maglev, vactrains or flying trains, one thing is for certain: train travel is poised to give airline carriers a run for their money.
Hyperloop Technologies, one of the companies that decided to rise to the challenge of making hyperloop technologies a reality, completed the world’s first test track in the Nevada desert in 2017. Two other companies have since followed suit with their own test tracks. Prototype pods have been built and equipped with entertainment screens and leather seating. Meanwhile, a number of challenges still need to be addressed, many of which require their own technological advancements – like cutting-edge magnetic levitation (maglev) technology, or exhaust air solutions for the pneumatic tubes. Potential routes for the long-distance stretches of over- or underground steel tubes also need to be chosen carefully to avoid sudden twists or turns.
Apart from these engineering challenges, the search is on for high-performance materials that would allow Hyperloop capsules to jet through the tubes at hyper speeds.
The Hyperloop combines the idea of high-speed plane travel with train-like optics and a revolutionary propulsion technology. So it’s fitting that this hybrid technology which is more than the sum of its parts also rely on hybrid materials. Here, composites present an affordable, scalable and sustainable solution for the future of rolling stock.
For those who might need a refresher, composites are materials which consist of two or more materials with widely varying properties, for example a malleable plastic and a hard metal. Their combination results in a unique, and often superior, product with wholly new properties such as superior strength and chemical resistance. Composites have been around since humans made the first straw bricks; nevertheless, new materials and advanced processes such as pultrusion have enabled exciting new combinations.
Which brings us back to the Hyperloop. For the interiors of the passenger pods, a new generation of materials are being sought out to help make the rolling stock lighter, stronger, more energy-efficient, and sustainable. Both materials and technologies with the potential to reduce the volume, weight and energy consumption of the capsules are in demand on a mass production scale. At present, materials such as aluminum and sheet molding compounds (SMC) are applied for several applications in the rail sector. However, these materials have their limits in terms of reducing weight and thickness. For example, while SMC can offer a higher lightweight potential than aluminum for some train interior applications, it is limited to a certain degree regarding cycle times and costs for very high production volumes as well as the emission of volatile organic compounds (VOCs).
To overcome these limits, some industry players and manufacturers are eyeing new solutions like continuous fiber-reinforced thermoplastic composites. These solutions have demonstrated extraordinary potential in pushing past the performance boundaries of traditional metal and plastic materials while offering appealing aesthetics and design flexibility, and especially scalable production processes.
For large volume requirements, our customers need a product that enables efficient processing and short cycle times. Maezio™ does this and also offers significant benefits over magnesium alloys, thermoset plastics and injection molded plastics.
One such composite is Maezio™, a class of continuous fiber-reinforced thermoplastic (CFRTP) composites developed by Covestro engineers. It is composed of carbon fibers and a thermoplastic resin base such as polycarbonate.
Compared to aluminum (7020), Maezio™ composites can be up to 40 percent lighter, 2.5 stiffer and 6 times stronger than its bauxite-based counterpart due to their tunable anisotropic mechanical properties. Depending on the application, they can also be up to 20 percent lighter than SMC.
When it comes to aesthetics, Maezio™ looks and feels like metal but provides the design flexibility of thermoplastics, plus a premium surface quality marked by the organic beauty of carbon fiber. Furthermore, it can be combined with thermoplastic injection molding to achieve complex shapes and functional integration.
In terms of safety and stability, Maezio™ thermoplastic composites have shown promising potential. In preliminary FST (Fire, Smoke, Toxicity) tests, they demonstrated strong fire-resistant properties with very low toxicity and smoking density using modified polycarbonate grades as their matrix material. These positive initial results are currently being verified in rigorous tests with different material combinations. What’s more, they are free of harmful VOCs and to a certain degree recyclable. At the end of their life, they can be reground and used in an injection molding process for chopped fiber composite materials.
For next-generation applications like the “flying” pods of the Hyperloop, Maezio™ holds the potential to create lightweight, slim-line interior concepts with stellar surface properties and all the strength of traditional metals and plastics. High-performance thermoplastic composites could be used to manufacture seatbacks, luggage racks, wall cladding, tables and flooring, for example. The material is tunable to specific needs and manufactured using a patented one-step forming process with short cycle times, making it scalable for mass production.
The advanced composite has already captured the attention of automotive, luggage and electronics manufacturers interested in producing designs that are lighter than ever before. A prototype laptop cover molded from Maezio™ also took home an Innovation Award at the 2017 European Plastics Innovation Awards.
Covestro experts look forward to supporting various industry partners interested in employing Maezio™ – and supplying their long-standing expertise to solve whatever specific requirements they have and any production issues that come up along the way, for a brighter, more sustainable future.
Every new material development is a source of innovation for us as designers – especially if we can get rid of weight and thickness. Then we have a lot of chances to create new form factors.
- Significant weight reduction combined with mechanical strength
- Enables thinner designs
- High productivity with short cycle times
- Low emissions
- Excellent surface quality and options for coating, embossing and laser-etched surfaces
- Premium aesthetics of carbon