Electromagnetic Braking Simulation by the CMU Hyperloop Team

Elon Musk’s Hyperloop concept, a futuristic train in a pneumatic tube that propels passengers across the country at near super-sonic speeds, could — if successful — revolutionize mass transportation. The Hyperloop, theoretically, can achieve fantastic speeds of up to 760 miles an hour because the train — or pod — magnetically levitates over an I-rail track inside the continuous metal tube, eliminating friction, while the vacuum in the tube itself minimizes air resistance and drag.

As a competitor in the Spacex Hyperloop pod competition, Carnegie Mellon University’s Hyperloop team is building a version of the Hyperloop pod using simulation with the theory that electromagnetic braking is the most effective way to slow the Hyperloop pod.

To validate this theory, we used ANSYS Maxwell to run simulations of the braking forces that can be generated by eddy currents induced on the I-rail track. I would like to share the simulation procedure we followed:

Simulation Setup

ANSYS Maxwell simulation set-up

ANSYS Maxwell simulation set-up

We imported the I-rail as a STEP file into Maxwell 3D. We created the magnet, band and region using the software’s 3-D Modeler options and the Simple Cube Generating option.

The band created for force analysis encapsulated the entire path of the magnet. Region was defined to run the transient simulation.

We assigned materials, colors, transparency and other properties to each solid in the geometry, which also helped in differentiating the parts visually. Materials assigned for this simulation were: Magnet – NdFe34; I-Rail – Aluminum 6061 T6; Band – Air; Region – Vacuum.

Meshing Setup

We used the default mesh settings for most of the geometry so we could focus on the area of interest, the I-Rail that takes the load. We improved the meshing on the I-Rail by generating a fine mesh on the face — where forces get generated — with the help of Skin-Depth mesh operation. This creates a skin of finer mesh on the required face and coarser mesh away from the face.

Mesh after skin-depth refinement hyperloop

Mesh after skin-depth refinement

Analysis Setup

This was a time-dependent study, so we activated the transient solver. We applied translatory motion to the band to translate the magnet along with the I-Rail, and added an initial time and estimated overall time in the solution setup. Using the Validation check ensured that all inputs were correctly taken by the solver before running the case.

Results

The results were post-processed for the magnet speed of 20 m/s. The magnetic induction/flux contours demonstrated graphically where magnetic flux was induced. We could see that flux is induced only in the region around the magnet, leading to the drag force which can be used for braking the Hyperloop pod. From the force against time plot, we observed that results converge to a value of 170 Newtons. Thus we can expect a drag force of 170 Newtons (which is a very high value) from one magnet at 20m/s which enables us to conclude that braking using magnets is a viable option.

 Drag Force vs Time plot

Drag Force vs Time plot

Magnetic Flux induced in I-rail hyperloop

Magnetic Flux induced in I-rail

Using ANSYS Maxwell to perform electromagnetic simulation has greatly enhanced our ability to test the validity of our hypotheses before building a protoype is helping us design a better Hyperloop pod that we hope will win the competition and contribute to a new era in public transportation.

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Siddhant Shivaram

About Siddhant Shivaram

Siddhant Shivaram is a Mechanical Engineering student pursuing his Master’s degree at Carnegie Mellon University (CMU). Apart from his course work and research at CMU, he is passionately working in the CMU Hyperloop team. He is studying the use of magnets for the levitation system, braking system and stability system of the Hyperloop pod.

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