Brake Rotor Transient Thermal Analysis - ANSYS

[Jackie L]

I've found help with my troubles through a professor on campus. Thanks for your responses.

[Ahmad Rezq]

Jackie,
There are many tutorials you can find on youtube on transient thermal analysis using ansys.
but remember it starts from your of understanding the concept of heat transfer on brake disc not from a simulation softwares so do some calculations with your hand or with your matlab to make sure that you got the whole picture of what you gonna add to the simulator.
Regards

[Jay Lawrence]

Hi Jackie,

I haven't done this analysis in ANSYS myself, but the guy who did do it had some troubles (can't remember exactly, but it wasn't completely straight forward). What sort of fishy solutions is it giving you and how do you know they are fishy? From doing the hand calcs I think the biggest factor was determining what heat transfer coefficient to use! There doesn't appear to be a whole lot of consensus on this.

If you have a test bed already, a good option is to buy some thermal paint and put some on your rotor before doing a brake-intensive run. This will give you an idea of peak temperatures at least.

[Claude Rouelle]

Before you use any simulations make your own, simple Excel spreadsheet with equations which do make sense

I see too many students using simulation software the same way you create a cocktail: introduce the inputs, shake it, taste the outputs. But how the calculations are made, and are they relevant and logical, do they pass simple "sanity checks" ...only a few students do that. They surrender their intelligence (intelligence = ability to find a solution to a problem they never met before) to a simulation software they barely know.

Make it simple by writing your equations on a piece of paper then use simple calculations in Excel before you rush to any complicated software that you did not create

[Jackie L]

Before you use any simulations make your own, simple Excel spreadsheet with equations which do make sense

I see too many students using simulation software the same way you create a cocktail: introduce the inputs, shake it, taste the outputs. But how the calculations are made, and are they relevant and logical, do they pass simple "sanity checks" ...only a few students do that. They surrender their intelligence (intelligence = ability to find a solution to a problem they never met before) to a simulation software they barely know.

Make it simple by writing your equations on a piece of paper then use simple calculations in Excel before you rush to any complicated software that you did not create

Claude,
Thanks for your response, I hope you're doing well. I have already performed many calculations by hand. I would like to use ANSYS to illustrate and validate my findings. I have been using Solidworks for this, but I know that it falls short when it comes into thermal analysis of 4130. Additionally, it limits users to single stopping events. I'm not particularly familiar with the ANSYS platform, but I'd like to see if the results I obtain through ANSYS can confirm or refine my work in Solidworks.




Jackie,
There are many tutorials you can find on youtube on transient thermal analysis using ansys.
but remember it starts from your of understanding the concept of heat transfer on brake disc not from a simulation softwares so do some calculations with your hand or with your matlab to make sure that you got the whole picture of what you gonna add to the simulator.
Regards

Ahmad,
I have been referencing those videos, but the results I've found don't seem quite right and definitely don't match my calculations.




Hi Jackie,

I haven't done this analysis in ANSYS myself, but the guy who did do it had some troubles (can't remember exactly, but it wasn't completely straight forward). What sort of fishy solutions is it giving you and how do you know they are fishy? From doing the hand calcs I think the biggest factor was determining what heat transfer coefficient to use! There doesn't appear to be a whole lot of consensus on this.

If you have a test bed already, a good option is to buy some thermal paint and put some on your rotor before doing a brake-intensive run. This will give you an idea of peak temperatures at least.

Jay,
I'm getting max temps over over 1000F in a single 2G, 1.6-second stop. Definitely fishy, and definitely not right for our vehicle. I plan on reaching out to professors on campus who may have more experience with the platform to offer suggestions. My guess is that I'm just defining the wrong parameters.




Thanks for your help, everyone!

[Mumpitz]

How far out is the energy balance in the sim? Kenetic energy lost vs. thermal energy gained.
I found a pretty glaring error in a widely used 1-D simulation software that was reporting kW instead of W (or maybe it was the other way around), "trust but verify" -someone smart.
I have made it a habit to double check my sim results with the most zoomed out big picture reality checks I can.
It may look like a duck and quack like a duck but if it's the size of a school bus (or the USF bus if you will) and eats goats, run, that's not a duck!
http://www.designboom.com/wp-content/uploads/2013/01/hofman_duck_01.jpg

[Jay Lawrence]

Jackie,

1000F (~540°C for everyone who isn't American) is not as crazy as you might think. Looks like you're stopping from about 110km/h which is not slow, and remember that the temperature you are getting will probably be the maximum surface temperature only. I'm assuming that you're doing this analysis so that you can work out some tolerances for a floating rotor setup? If that's the case have a good look at how bikes manage this (similar vehicle masses but typically higher speeds). Also, just to be sure, you are dividing the braking forces up appropriately aren't you? Might be helpful if you post some more information (hand/excel calcs vs. Ansys inputs/results)