Would you speed across the rails in a train car made of aluminum foam?
Sounds like a risky proposition, but it’s actually safe, strong, and mass-efficient. All of these things make this new aluminum-based composite one of the most exciting innovations the mass transit industry has seen in years. From Wired:
Americans have long been promised high-speed rail, but to date, we’re still far behind Europe and Asia when it comes to rolling stock. Now, we have one more train technology to envy our brethren across the pond: Trains made of aluminum foam, a material that’s stronger, lighter, and better in a crash than fiberglass or regular old metal.
Engineers in Chemitz, Germany unveiled a prototype high-speed train cab made with the stuff earlier this year. The composite material is built like a sandwich: Between two pieces of aluminum, each just two millimeters thick, is a 25-millimeter-thick layer of the “foam,” actually a low-density, sponge-like composite of magnesium, silicon, and copper, and aluminum. And like a good sandwich, there’s no glue. The layers are held together by metallic bonding, the electrostatic attraction of negatively charged electrons and positively charged ions.
The result is a material that’s 20 percent lighter than traditional fiberglass, which is commonly used on high-speed train cabs. That’s a big advantage when the goal is to move faster and more efficiently. Even better, it doesn’t come at the cost of a weaker train. “The outer shell is so stiff that you need no ribs inside,” says Dr. Thomas Hipke, head of lightweight construction at the Fraunhofer Institute for Machine Tools and Forming Technology, which helped to design the prototype train cab. Peel tests of aluminum foam—in which force is applied to pull apart the layers of the material—destroy the foam interior instead of breaking the bonds between the layers, demonstrating the strength of the bonding.
To the layperson, the idea of 200 MPH inside of an aluminum-based tube sounds frightening. However, the science behind it is solid: it’s safer and more efficient than traditional materials, meaning that it gets the job done while being less taxing on our energy resources. Just like the Ford F-150, it’s another breakthrough innovation thanks to aluminum.