I have recently begun a project to optimize a flywheel design based on the ratio of mass to moment of inertia. I started with a few set dimensions and some vague limits for each variable I was going to test.
This is the sketch I revolved to create my flywheel, I chose this shape based on intuition and some not very scientific guesses. The pink dimensions are the variables I was modifying.
This is one (of many) configurations that I made in 3D, just so the shape makes sense.
I used a design table to create multiple configurations that modified each variable independently. I used an outer thickness of .25in-1in in .25in increments and I found that this dimension can be optimized, and the the best value is close to .5in. I used the same increments for the center thickness and found (unsurprisingly) that the thinner, or more importantly lighter, that section was the higher the ratio of mass:MOI. And here enters FEA, an aspect of CAD that I have some basic experience with, but I felt a little in over my head taking on this project. After all this is a 3-5lbs chunk of aluminum spinning at up to 6000rpm, breaking is not an option. So based on all of this my current goal is to reduce the mass of the center disc section as much as possible before the wheel can no longer spin to 6000RPM safely. I have run lots of simulations with different configurations of center thickness and random fillet size/location, Ill include some pictures of these simulations below. Like the title says I am looking for a factor of safety to use after my simulation to ensure that the wheel will not fail, has anybody else done simulations of you flywheel? What factor of safety did you use? Am I doing all of this completely wrong? I’m also open to any suggestions for changing the overall design to improve the mass to MOI ratio. I have considered pocketing the center disc and using “spokes” like the AndyMark performance wheel but that increases the complexity of machining considerably so I would like to avoid that.
This is the standard no fillet version, this is using a .5in outer thickness and a .5in inner disc thickness
This version has a fillet with radius .75in between the outer section and the inner disc, this is using a .5in outer thickness and a .5in inner disc thickness
This is a standard, no fillet, version that uses a .5in outer thickness and a .25in inner disc thickness
I can provide any additional information or simulations if it is necessary, including CAD files.