3 ms·
I wrote my diploma thesis in an industry research group trying to figure out the optimal (non-cylindrical) shape of the cylinder bore. We attempted to model st
by InternetOfStuff 9y ago
I wrote my diploma thesis in an industry research group trying to figure out the optimal (non-cylindrical) shape of the cylinder bore.
We attempted to model static stresses from mounting the cylinder head, thermal stresses, and mechanical stresses from mass forces, combustion forces and the like.
Our goal was to achieve low combustion gas blow-by, low oil ingress into the combustion chamber, yet low friction between piston and cylinder wall.
We used simulations (about three months worth IIRC) and measurements to generate data points for a continuous ersatz model of the physical phenomena, then performed multi-criteria optimisation on that model. The resulting shape was interesting, but not exactly earth-shattering. Kinda randomly warped.
This work was tremendous fun, and I learned a lot.
If anyone is interested (and can read German), it resulted in this dissertation: https://books.google.de/books/about/Tribo_System_Kolbengruppe_Zylinderlaufba.html?id=p3H0XwAACAAJ&redir_esc=y https://books.google.de/books/about/Tribo_System_Kolbengrupp...
- csours 9y agoI see a picture of a book in that link, but no way to open it. Do you have a couple pictures of the piston handy?
- InternetOfStuff 9y agoHeh, your interest is quite flattering :-) Give me a few hours to dig up my old thesis. That was more than a decade ago! I'll reply to your post again with an image link once I've found it.
- InternetOfStuff 9y agoTurns out I lost all digital data of my thesis :-( I scanned a picture from the dead-tree version: https://imgur.com/vQLIQ1F https://imgur.com/vQLIQ1F Top image is the cylinder shape without optimisation, bottom is the optimised shape. Obviously, the contour distortion is massively exaggerated (ISTR a factor of 1000), otherwise it wouldn't have been visible; we're talking micron scale here.
- csours 9y agoSorry to hear you lost your digital version =( Thanks very much for the follow up!
- termain 9y agoYou're supposed to say "kriging" at least once in this post. :P