German engineers recently unveiled a prototype of a high-speed train car made from a composite material — aluminum foam. This material is a kind of metal sandwich: two 2-millimeter aluminum plates are sandwiched between 25 millimeters of «foam» made of magnesium, silicon, copper and aluminum. They are connected not with glue, but with a metal bond, electrostatic attraction of negatively charged electrons and positively charged ions.
The resulting material is 20% lighter than traditional fiberglass, which is commonly used to build wagons on high-speed trains. And this means a lot for the construction of trains, as it gives an advantage in speed and efficiency while traveling. But the new aluminum foam does not add to the weakness of the very structure of the train. The outer shell remains so rigid that no ribs are required on the inside.
Aluminum foam has a high impact resistance, especially from small impacts that a train encounters along the way — stones, bottles, birds, etc. For example, in 2013, a traditional high-speed train traveling to Beijing was forced to stop due to a collision with birds, which caused cracks in the material. An aluminum foam train project engineer says their material is ready for this and will not suffer from such troubles..
The material is also comfortable for passengers, because it keeps warm inside. In addition, the inside of a structure made of this material is quite safe even in a collision. Scientists have conducted a series of crash tests and confirmed that the material efficiently absorbs energy and protects passengers from secondary impact. Even the aluminum foam on the backrests prevents the possibility of head grass in collisions by up to 80%..
Aluminum foam was invented in 1968, but the problem then was to create it on an industrial scale. The formation of the material was quite expensive. Today’s engineers have proven that material can be made on a budget. So, now the only question remains is to use this good material..
