In the loop

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The hyperloop is more than just a pipe dream. Here, Benjamin Stafford, materials science specialist at Matmatch, ponders the design considerations for engineers developing the next generation of transportation systems

Human kind has come a long way since the days of travelling on foot. The 20th century, in particular, saw a significant number of developments and improvements to land and air transportation.

Today, automotive and aviation manufacturers are under increasing pressure to reduce harmful emissions and meet global targets to tackle climate change. In addition to creating faster and more efficient transportation modes, like those we’re seeing with the advances in the electrification of both cars and planes, governments have another issue to address.

Our roads, airports and ports are congested. Countries like Mexico, Thailand and Indonesia currently rank as having cities with the highest traffic-related congestion but there are few ideas on how to reduce it. Well, that was the case before Elon Musk’s 2012 revelation of the hyperloop.

Hyperloop is an ultra-high-speed transportation ecosystem, made up of a system of tubes that pods can travel through free of air resistance and friction. It works by replicating high altitudes in a low-pressure environment inside the tube system by removing most of the air with vacuum pumps, which drastically reduces the drag forces.

Due to the ultra-low aerodynamic drag, the pods can glide at airline speeds for long distances, providing rapid transit across densely populated regions. In the US for example, a hyperloop could enable travel from New York to Washington DC in less than 30 minutes. Its estimated that the hyperloop’s pods will be able to travel at around 600 miles per hour, carrying up to 16 passengers.

Member of the Delft University of Technology’s Hyperloop team, Mark Geuze, described the hyperloop as “being able to connect cities, making it more efficient than a plane, but as convenient as a train.” While projects like Virgin Hyperloop One Systems and Hyperloop Transportation Technologies (HTT) are working to make Musk’s concept a reality, there are still some elements of design that need refining.

For the hyperloop to be two to three times faster than existing high-speed rail and magnetic levitation trains, and ten to fifteen times faster than traditional rail, design and mechanical engineers are looking to materials used in the aerospace industry for inspiration. This is because the hyperloop needs to be constructed with robust materials that are light and able to withstand extreme conditions, particularly at low-pressures, like those used in aircrafts.

While most modern aircrafts are currently made from aluminium, composite materials such as carbon fibre are becoming increasingly popular.

Composite materials include some of the most advanced engineering materials today and Matmatch has over 100 composites listed on its site. The addition of high strength fibres a polymer matrix can greatly improve mechanical properties, such as the tensile strength and temperature resistance.

Boeing, for example, has made greater use of composite materials in the airframe and primary structure of one of its latest developments, the Boeing 787, claiming that the plane offers weight savings on average of 20% compared to its aluminium designs.

In the development of its hyperloop pods, HTT has developed a new type of carbon fibre composite that is eight times stronger than aluminium and ten times stronger than steel alternatives. The material, named Vibranium (inspired by Marvel’s fictional metal), has been designed to be a skin-type material to protect the hyperloop pods.

The pods are constructed with two layers of Vibranium, one for the exterior and one for the interior of the pod, with an array of 72 sensors sandwiched between the two layers. These sensors can monitor the pod’s stability, temperature and integrity in real time to maximise passenger safety. In all there are 82 panels secured by 75,000 rivets. Assembly takes 5,000 hours.

As if selecting the materials for the hyperloop’s pods wasn’t complex enough, designers will also have to consider the tubes when this new mode of transportation becomes a reality.

While the hyperloop certainly offers a faster, safer and more efficient mode of transport, it will be a few years before we will be able to use these underground systems as part of our daily commute. In the meantime, we can expect modern aircraft to become even more advanced, thanks to better materials selection.

In theory the capsules could travel almost as fast as the speed of sound

In theory the capsules could travel almost as fast as the speed of sound